Non-indigenous species from hull fouling in Danish marine ...lfst.dk/fileadmin/user_upload/NaturErhverv/Filer/Udbud/Monitering_af... · the context of the Marine Strategy Framework

Non-indigenous species from hull fouling in Danish marine waters

January 2016

2 Non-indigenous species from hull fouling in Danish marine waters

Title:

Non-indigenous species from hull fouling in

Danish marine waters

Project group:

LITEHAUZ ApS

Pernille Bohn,

Simone L. Hansen,

Jens K. Møller

Frank Stuer-Lauridsen

Published by:

The Danish Nature Agency

Haraldsgade 53

DK-2100 Copenhagen Ø

Denmark

www.nst.dk

Year:

2016

Editing

Ucb/Lomu

ISBN no. 978-87-7175-558-9

Disclaimer:

The Danish Nature Agency publishes reports and papers about research and development projects within the

environmental sector, financed by the Agency. The contents of this publication do not necessarily represent the official

views of the Danish Nature Agency. By publishing this report, the Danish Nature Agency expresses that the content

represents an important contribution to the related discourse on Danish environmental policy.

Sources must be acknowledged.

Non-indigenous species from hull fouling in Danish marine waters 3

Contents

Preface ............................................................................................................................... 5

Summary............................................................................................................................ 6

Sammenfatning .................................................................................................................. 9

Abbreviations .................................................................................................................... 12

1. Introduction .............................................................................................................. 13

2. Hull fouling ................................................................................................................ 15

2.1 Biofouling on ships................................................................................................ 15

2.2 Non-indigenous species via hull to Danish marine waters ......................................18

2.3 Hot spots for hull borne non-indigenous species ................................................... 19

2.3.1 Dry-docks ..................................................................................................................................... 20

2.3.2 In-water hull cleaning ................................................................................................................. 20

2.3.3 Ports and marinas........................................................................................................................ 20

2.3.4 Ports of refuge and STS areas ..................................................................................................... 20

2.3.5 Stepping stone substrata ............................................................................................................. 23

2.4 Diversity of hull fouling ........................................................................................ 23

2.5 Biofouling transfer - characterization of three ship categories .............................. 24

2.5.1 Merchant fleet including passenger vessels ............................................................................... 24

2.5.2 Fishing vessels ............................................................................................................................. 26

2.5.3 Recreational crafts ....................................................................................................................... 26

3. In-water cleaning ...................................................................................................... 29

3.1 To clean or not to clean......................................................................................... 29

3.2 Hull cleaning in Denmark ..................................................................................... 29

3.2.1 Actors ........................................................................................................................................... 29


3.2.2 Licenses for in-water hull cleaning ............................................................................................. 30

3.2.3 Practical experiences ................................................................................................................... 30

3.3 Cost of hull cleaning .............................................................................................. 31

3.4 Neighbouring countries ......................................................................................... 31

4. Monitoring ................................................................................................................ 34

4.1 Monitoring of NIS from ship hulls ........................................................................ 34

4.1.1 Danish monitoring programmes of marine waters .................................................................... 34

4.1.2 Ad hoc monitoring ....................................................................................................................... 35

4.1.3 Regional monitoring programmes .............................................................................................. 35

4.2 Biofouling risk assessment tools ........................................................................... 35

4.3 How to monitor for MSFD D-2? ............................................................................ 36

5. Antifouling technologies ........................................................................................... 39

5.1 Best available technology ..................................................................................... 39

5.2 Pre-fouling technologies: Vessel antifouling systems ............................................ 40

5.2.1 Conventional antifouling systems containing biocides .............................................................. 40

5.2.2 Other antifouling coatings........................................................................................................... 41

5.3 Post-fouling mitigation: Technologies for in-water biofouling removal .................. 41

5.3.1 Other technologies ....................................................................................................................... 44

5.4 Improvement: Capture and removal of solid waste ............................................... 45

5.5 Examples of commercially available in-water cleaning solutions .......................... 46

6. Conclusions and recommendations ........................................................................... 47

6.1 Conclusions .......................................................................................................... 47

6.2 Recommendations ............................................................................................... 48

References ....................................................................................................................... 49

Appendices ....................................................................................................................... 54


Preface

This report was funded by the Danish Nature Agency, Ministry of Environment and Food, and the work

was carried out from September to December 2015. The report was compiled by Pernille Bohn (project

manager), Simone L. Hansen, Jens K. Møller, and Frank Stuer-Lauridsen from LITEHAUZ Aps.

The objectives have been to assess the possible contribution from ship’s hulls and anti-biofouling activities

to the impacts of non-indigenous species (NIS) in Danish waters and describe methods to address this. In

the context of the Marine Strategy Framework Directive (MSFD) this is an input to monitoring programme

targeting (MSFD Descriptor 2; or simply D2) on the way to fulfilment of the overarching MSFD target of

‘good environmental status’. The report provide the following:

1. An overview of the extent of the potential problem, made by the following measures:

a. Investigate if NIS imported via biofouling on ship hulls (commercial, fishing and recreational

vessels) can be expected to be a problem and where they are located.

b. Investigate if the imported NIS can be measured and if knowledge exists that will be useful in

the future monitoring and management of NIS.

2. Identification of technologies and methods that can reduce the impact of ship biofouling.

a. Name relevant technologies and methods used for in-water hull cleaning.

Information on the issue of hull fouling as a source of invasive species has been collected from a number of

different sources. Interviews with stakeholders have been conducted via phone or e-mail. The interviewees

from Denmark were employees from municipal authorities, staff from hull cleaning companies, marina

and shipyard representatives, shipowners, and representatives of various NGOs and industry

organisations.

Information about the situation in neighbouring countries has generally been obtained via e-mail

correspondence with representatives from the respective government agencies, providing information on

the procedures and guidelines that are followed.


Summary

Biofouling starts as soon as an unprotected surface is immersed in water. Ship hulls are therefore covered

with protective antifouling coatings, but this only serves to delay the process and eventually ships

inadvertently transfer living organisms around the globe on their hulls. Although the ship’s hull is a large

area with amble space for organisms, it is also subject to the full abrasive force of water. Severe biofouling

is often found in less exposed niche areas of the vessel such as the rudder area, thruster tunnels and sea

chests. By this pathway, and through ballast water and aquaculture, non-indigenous species (NIS) are

introduced and sometimes become invasive in the marine environment. The estimated number of hull

associated NIS varies between expert sources from 7 to 19 species, and a tentative list of 12 species (mainly

macroalgae and barnacles) introduced with ships’ hulls is compiled from the existing lists. Based on data

from one of these sources, hull borne species comprise 20% of the NIS imported to Danish marine waters.

Potential hot spot areas for hull fouling NIS.

Hot spots for hull fouling NIS include locations where vessels may spend longer time periods such as

industrial ports and marinas. The activities of the merchant fleet adds potential hot spots: Danish port of

refuge areas are used for shorter lay-up periods awaiting new cargo, and ship-to-ship (STS) areas are used

for cargo transfer operations at sea between two or more ships. Areas with frequent bunkering operations

are possible hot spots too, as well as the four ports, in which ship recycling takes place, because obsolete

vessels may be moored for some time while being dismantled.

Port of Refuge areas STS transfer areas Frequent bunkering

operations

Ports with recycling

facilities

In particular Ålbæk

Bight, Kalundborg Fjord

and Tragten near

Fredericia

West of Kalundborg and

east of Frederikshavn

In Ålbæk Bight, Tannis

Bight, Kalundborg Fjord

and on the Anchorage of

Copenhagen

Esbjerg, Frederikshavn,

Odense (Lindø) and

Grenaa

The existing biological monitoring activities in Danish waters do not include NIS and they are only

recorded on a non-continuous basis. Thus, there is currently no coherent data available specifically on NIS

from hull fouling. However, data from other countries suggest that while commercial vessels may be a key

vector for primary transfer of NIS into an area, the fleet of slow-sailing recreational crafts may aid

secondary transfer suggesting that marinas should be included when monitoring for NIS related to hull

fouling.

The cleaning of ships' biofouling is potentially an overlooked source of NIS, although it is a recurring event

in shipping, because it reduces the drag and therefore the fuel cost. Cleaning performed in dry docks or on

slipways where the waste is collected and properly disposed of, is not considered a source of NIS, although

this does not preclude historical introductions via this route. Increasingly popular methods for

intermediate cleaning of the hull are in-water technologies. In Denmark, this is carried out by specialist

companies in port areas, where the municipal authorities issue licences for the activity. The licence may be

conditioned by monitoring. However, it appears that in recent years in-water cleaning in Danish waters is

also performed on anchorage further from shore, which currently is unreported to the authorities. There

are no specific guidelines issued regarding in-water hull cleaning in Denmark and neighbouring countries

(Finland, Germany, Netherlands, Norway, Poland, Scotland, Sweden), and most authorities refer users to


the more general IMO hull fouling guidance document. Some authorities express concerns regarding the

hull fouling issue in general and in-water hull cleaning in particular, and a few initial assessments are now

available (Netherlands, Denmark).

Best available technologies regarding in-water hull cleaning

The technologies used for in-water cleaning in Denmark are mainly diver-operated vehicles employing

rotary brushes systems, but remotely operated vehicles or high-pressure water jets are also utilized.

Operators occasionally collect debris when in-water cleaning is performed in ports but this is not the case if

the cleaning takes place at anchorage or further from shore. There is no onsite treatment of discharged

process water, but the licenced activities are often conditioned by sampling and analysis of ambient water

taken during cleaning.

The table below shows recommended (Yes) and discouraged (No) combinations of the most common hull

antifouling systems and in-water hull cleaning technologies. Not every in-water technology is suitable for

every surface and a best available technology (BAT) for one ship’s coating may be detrimental to another.

The service supplier will attempt to match coating in each case as there are market drivers for causing no

or insignificant damage to the coating while removing as much biofouling as possible. The BAT from an

environmental point of view are the ones which applies a capture and/or treatment technology of the

biofouling waste and process water. Technologies applied for water treatment after hull cleaning are

filtering, flocculation and disinfection by UV irradiation or heat treatment. Such new technologies are

entering or are already on the market although they may still be in the early stages.

In-water hull

cleaning technology

Antifouling coating

Biocidal systems Silicones Mechanically resistant

Self-polishing copolymers,

rosin-based, metalacrylates,

nanoacrylates, etc.

Fouling release, fouling defence Epoxy, ceramic or polyester

resins

Multiple brushes Yes No Yes

Contactless Counter-rotating brushes to

create suction Yes Yes No

Water jets High-pressure systems

Yes Yes No

Shrouding* Encapsulation

Yes Yes Yes

Hand tools Hand-picking, single-brush,

scrapers etc. Yes Yes Yes

Heat treatment No No Yes

Ultrasonic treatment No information No information No information

*Not developed for merchant vessels.

Recommendations

The following four recommendations are given. They are not ranked or hierarchically presented.

Recommendation 1:

Identify areas relevant for the Marine Framework Strategy Directive through a desktop risk assessment

exercise: Use the extensive traffic data from shipping to depict detailed images and key indicators relevant

for hull fouling such as residence time. For example, the number of days that the wetted surfaces of ships

are exposed in Danish EEZ can relatively easily be calculated (m2 * d) and mapped showing areas where

ships stay longer and thus presents an increased risk of introducing NIS. Further elaboration may include

biological parameters of target species, seasonal biological changes (i.e. spawning periods), port of origin,

time since docking and other key risk characteristics.


Recommendation 2:

Monitor NIS in a selection of hot spots such as industrial harbours, marinas, STS areas, port of refuge,

bunkering locations and ports with recycling facilities. The surveillance could be in combination with

samples that is already required in connection with dredging and hull cleanings, i.e. samples used for

determination of metal or biocide concentrations. A useful and cost effective solution to this monitoring

could be to utilize the eDNA technique.

Recommendation 3:

Clarify the responsibilities for managing in-water cleaning outside of port areas and develop a uniform

monitoring guidelines for this and for port in-water cleaning that the municipalities can use. This may

include an updated BAT.

Recommendation 4:

Initiate communications: Communicate BAT relevant for in-water hull cleaning, i.e. the importance of

including capture and treatment of waste and process water, to shipowners, local municipalities, and

service suppliers. Increase awareness of the hull fouling issue in relation to NIS on recreational crafts

among owners, local marinas, and local municipalities.


Sammenfatning

Begroning starter så snart en ubeskyttet overflade kommer i kontakt med vand. Skibsskrog beskyttes med

dækkende bundsmøring, men det er kun et spørgsmål om tid, før skibet uundgåeligt transporterer levende

organismer rundt på kloden. Et skibskrog er et stort område med rigelig plads til organismer, men det

udsættes også for store påvirkninger fra vandet under sejlads. Derfor findes den kraftigste begroning ofte i

mindre udsatte nicheområder på skibet, såsom ror-området, bovpropeltunneller og søkister. På denne

måde, sammen med ballastvand og akvakultur, introduceres ikke-hjemmehørende arter (NIS) og bliver

nogle gange invasive i det marine miljø. Det opgjorte antal NIS arter introduceret med skibsskrog til dansk

farvand varierer fra 7 til 19 i følge forskellige kilder og en foreløbig liste på 12 arter (mest makroalger og

rurer) er samlet fra eksisterende lister. Ifølge data fra en af disse kilder udgør arter transporteret med

skibsskrog 20% af de NIS, som er blevet importeret til dansk farvand.

Mulige fokusområder for NIS på skibsskrog

De områder som er mest belastet af NIS fra skibsskrog, inkluderer steder hvor fartøjer opholder sig i

længere tid såsom industrihavne og lystbådshavne. Handelsflådens aktiviteter øger antallet af potentielt

belastede områder: De danske nødhavne bruges til kortere ophold indtil ny last er tilgængelig, og områder

til brug for skib til skib (STS) operationer bruges til overførsler af last mellem to eller flere skibe. I tillæg

kommer områder som hyppigt bruges til bunkeroperationer, samt de fire havne hvor der udføres

skibsophugning fordi de udfasede skibe kan ligge fortøjet i en rum tid, mens de demonteres.

Nødhavne STS operationer Hyppige

bunkeroperationer

Havne med ophug-

ningsfaciliteter

Specielt Ålbæk bugt,

Kalundborg fjord og

Tragten nær Fredericia

Vest for Kalundborg og

øst for Frederikshavn

I Ålbæk bugt, Tannis

bugt, Kalundborg fjord

og Øresund

Esbjerg, Frederikshavn,

Odense (Lindø) og

Grenaa

De eksisterende, biologiske overvågningsprogrammer i dansk farvand omfatter ikke NIS, og NIS

registreres kun på ikke-kontinuerlig vis. Der er derfor på nuværende tidspunkt ingen sammenhængende

data tilgængelig for NIS specielt fra begroning. Der er dog data fra andre lande, der tyder på at selvom

handelsskibe kan være en hovedvektor for primær overføring af NIS til et område, så er flåden af langsomt

sejlende lystfartøjer vigtige for den sekundære spredning. Lystbådehavne bør derfor ikke ignoreres når NIS

fra skibsskrog skal overvåges.

Afrensning af et skibs skrog udgør en formodet kilde til NIS og er en gentaget begivenhed inden for

shipping fordi rensning reducerer modstanden og dermed brændselsudgiften. Afrensning der foretages i

tørdok eller på bedding hvor det afrensede materiale samles og håndteres forsvarligt, anses ikke for at være

en kilde til NIS, selvom dette ikke udelukker historiske introduktioner ad denne rute. Metoder til

rensninger af skrog i vand uden at gå i dok, benyttes imellem tørdokrensninger. I Danmark udføres disse

afrensninger af specialiserede firmaer i havneområder, hvor de kommunale myndigheder udsteder

tilladelser til aktiviteten. Tilladelsen kan være forudsat af at der monitoreres. Der ser dog ud til at der i de

seneste år også er foretaget afrensninger i danske farvande under opankring længere fra kysten, som lige

nu ikke meldes til myndighederne. Der er ikke udgivet nationale retningslinjer specifikt for afrensning i

vand i hverken Danmark eller Danmarks nabolande (Finland, Holland, Norge, Polen, Skotland, Sverige og

Tyskland) og de fleste myndigheder henviser til IMOs retningslinjer for generel skrogrensning. Nogle


myndigheder udtrykker bekymring over skrogbegroning generelt og i særdeleshed over afrensning i vand,

og nogle få indledende undersøgelser er nu tilgængelige (Holland, Danmark).

Bedste, tilgængelige teknologier til skrogrensning i vand

Teknologier brugt til afrensning i vand er i Danmark hovedsageligt dykkerkontrollerede fartøjer som

benytter roterende børstesystemer, men fjernstyrede fartøjer eller højtryksspuling tilbydes også.

Operatørerne opsamler indimellem det afrensede materiale når afrensningen foregår i havnevand, men

dette er ikke tilfældet hvis afrensningen foregår på red eller længere fra land. Der er ikke behandling af

udledt procesvand på stedet, men det er ofte betinget i de udstedte tilladelser at der skal indsamles

miljøprøver til kemisk analyse.

Tabellen under viser anbefalede (Ja) og frarådede (Nej) kombinationer af typiske metoder antibegronings-

systemer og teknologier til afrensning i vand. Ikke enhver teknologi til afrensning i vand kan kombineres

med enhver overflade, og en bedste, tilgængelig teknologi (BAT) til et skibs overflade kan beskadige et

andet skibs overflade. Leverandøren vil forsøge at matche bundsmøringen i hvert tilfælde, fordi der er

markedsfordele i at beskadige bundsmøringen ubetydeligt eller slet ikke, samtidig med at begroningen

afrenses så fuldstændigt som muligt. BAT er fra et miljøsynspunkt de teknologier, som benytter opsamling

og/eller behandling af den afrensede begroning og af spildevandet. Teknologier der benyttes til behandling

af vand efter skrogrensning, er filtrering, flokkulering og desinfektion med UV-lys eller varmebehandling.

Sådanne nye teknologier er på vej eller er allerede på markedet i tidlig version.

Teknologi til

skrogrensning i vand

Antibegroningsystem

Biocidholdige Silikoner Mekanisk resistente

Selvpolerende copolymerer,

kolofoniumbaserede, metal-

akrylater, nanoakrylater, osv.

Fouling release, fouling defence Epoxy, keramisk eller polyester

resiner

Multibørstesystemer Ja Nej Ja

Kontaktfrit Modsatkørende børster der

genererer sug Ja Ja Nej

Spuling Højtryksystemer

Ja Ja Nej

Tildækning* Indkapsling

Ja Ja Ja

Hånddrevent Håndafpilning, enkeltbørster,

skrabere, osv. Ja Ja Ja

Varmebehandling Nej Nej Ja

Ultrasonisk behandling Ingen information Ingen information Ingen information

* Ikke udviklet til handelsflådens større skibe

Anbefalinger

De ovenstående resultater leder til de følgende fire konklusioner, som ikke er rangeret eller hierarkisk

præsenteret.

Anbefaling 1:

Identificér arealer relevante for havstrategidirektivet ved gennemføring af en teoretisk risikovurdering:

Benyt skibsfartens omfattende databaser med trafikinformation og skibsdata til at vise detaljerede kort

over hovedindikatorer for skibsbegroning såsom opholdstid i dansk farvand. For eksempel kan den

samlede eksponering af skibes våde overflade (m2 * d) relativt let beregnes og vises som

eksponeringsintensitet på et kort, der således viser den forhøjede risiko for at introducere NIS. Denne

simple risikoindikator kan udbygges med f.eks. biologiske parametre for valgte NIS, biologiske

sæsonvariationer (dvs. gydeperioder), udskibningshavn, tid siden sidste dokning og andre risikoelementer.


Anbefaling 2:

Overvåg NIS i et udvalg af fokusområder såsom industrihavne, lystbådshavne, STS-områder, nødhavne,

bunkringsområder og havne med ophugningsfaciliteter. Overvågningen kan ske i forbindelse med allerede

krævede prøver i forbindelse med klapning of afrensning, dvs. prøver til bestemmelse af metal- eller

biocidkoncentrationer. En anvendelig og kosteffektiv udførelse af overvågningen kunne være ved brug af

eDNA-teknik.

Anbefaling 3:

Afklar forvaltningsansvaret for afrensning i vand uden for havneområder, og udvikl en ensartet

forvaltningsvejledning til brug i både dette tilfælde og til afrensning foretaget inden for havneområder,

som kommunerne kan benytte. Denne vejledning kan indeholde en opdateret BAT.

Anbefaling 4:

Kommunikationsinitiativer: Oplys skibsejere, kommuner og serviceudbydere om BAT til afrensning i vand,

dvs. vigtigheden af inkludere opsamling og behandling af faste og flydende restmaterialer. Øg

lystbådsejere, lokale lystbådshavne, og lokale myndigheders kendskab til problematikken omkring NIS fra

lystfartøjer.


Abbreviations

AIS Automatic Identification System

BAT Best Available Technology

DCF Data Collection Framework

DTU Technical University of Denmark

EU European Union

GPS Global Positioning System

MEPC Marine Environment Protection Committee

MSFD Marine Strategy Framework Directive

NIS Non-Indigenous Species

NOBANIS The European Network on Invasive Alien Species

ROV Remotely Operated Vehicle

STS Ship to Ship

SPC Self-Polishing Copolymer

TBT Tributyltin

UN United Nations

USD United States Dollar

UV Ultra Violet


1. Introduction

Non-indigenous aquatic species have been described in the following way in a previous report from the

Danish Nature Agency: Non-indigenous species (NIS; synonyms: alien, exotic, non-native, allochthonous)

are species, subspecies or lower taxa introduced outside of their natural range (past or present) and

outside of their natural dispersal potential. This includes any part, gamete or propagule of such species

that might survive and subsequently reproduce. Their presence in the given region is due to intentional

or unintentional introduction resulting from human activities. Natural shifts in distribution ranges (e.g.

due to climate change or dispersal by ocean currents) do not qualify a species as a NIS. However,

secondary introductions of NIS from the area(s) of their first arrival could occur without human

involvement due to spread by natural means (Andersen et al. 2014).

Non-indigenous species (NIS) can enter an area by a variety of pathways such as angling, agriculture,

escapes, forestry, or sectors within transportation, and each pathway may have a number of vectors that

are involved in the species transmission. The current document focuses on ship hulls as a vector for NIS

introduction via the shipping pathway.

The Danish Nature Agency is occasionally requested to provide information on the regulations concerning

ship hull cleanings in harbour or anchorage. There is currently little legislation in the field, and the extent

of the cleaning is unknown as well as the ecologic consequences. The advantages of a clean hull comprise a

minimum of both fuel expenses and reduced risk of NIS transfer, and therefore both society and private

sector are interested in keeping ship hulls biofouling free. It is recommended to remove biofouling from all

underwater surfaces when a ship is in dry-dock (MEPC, 2011) where it is easier to both clean the hull and

niche (e.g. higher visibility) and to retain all waste material in order to avoid live biological material being

released to the aquatic environment.

To help shipowners reduce biofouling, the International Maritime Organisation (IMO) has published

international guidelines in resolution MEPC.207(62) with the title "2011 Guidelines for the Control and

Management of Ships' Biofouling to Minimize the Transfer of Invasive Aquatic Species". The voluntary

guidelines are global and apply to all ships. The most important chapters in the guidelines are:

Logbook and plan for biofouling management (including ship data, antifouling system data,

operation profile, niche area overview, safety procedures, and training)

Antifouling system: Installation and maintenance

Inspection and hull cleaning

Design and construction

Training and education

Recreational crafts shorter than 24 m in length, may instead find relevant guidance in IMO's 2012

document "Guidance for Minimizing the Transfer of Invasive Aquatic Species as Biofouling (Hull fouling)

for Recreational Craft" (MEPC, 2012).

In the EU, the Marine Strategy Framework Directive (MSFD), or in full “Directive 2008/56/EC of the

European Parliament and of the Council of 17 June 2008 establishing a framework for community action

in the field of marine environmental policy (Marine Strategy Framework Directive)” governs the marine

environment, including the management of invasive species. The directive focuses on implementing an


ecosystem-based approach to the management of human activities and the collective pressures affecting

the marine environment. The MSFD itself does not provide a definition of the ecosystems approach in

contrast to other organisations such as the UN (in Convention on Biological Diversity), HELCOM, and

OSPAR. In principle, the MSFD covers all European marine waters including coastal waters, although the

latter only in regard to issues not dealt with by the Water Framework Directive. The overarching aim is to

obtain or maintain “good environmental status” in European marine waters by 2020 (Andersen et al,

2014).

In order to reach this goal a timeline with a set of milestones is defined by the MSFD. In 2012 an initial

assessment of the current environmental status of Danish marine waters and the environmental impact of

human activities thereon was completed. National definitions of good environmental status were specified

and environmental targets and associated indicators were established by the Danish Nature Agency (The

Danish Nature Agency, 2013). The Danish description of good environmental status for NIS reads as

follows:

The presence of invasive non-indigenous species may not result in unacceptable direct or

indirect effects on marine fauna and flora.

The developed Danish environmental targets for the occurring NIS and their environmental effects are:

(1) Efforts are being made to reduce the shipborne transport of non-indigenous species

(criterion D2.1.1), and

(2) Efforts are being made to reduce the transport of non-indigenous species via fishery and

aqua-culture activities (criterion D2.1.1).

Indicator(s) for the environmental targets:

(1) Screening of abundance, occurrence in risk areas for selected invasive species,

(2) Monitoring / screening of the ratio between invasive species and native species in selected

species groups, and

(3) Impact of invasive species, where feasible (ad hoc basis).

In order to assess the impact of the work done to achieve the environmental targets mentioned above,

Denmark must investigate which pathways and vectors are substantial in the transport of NIS (Danish

Nature Agency, 2015a). An outline of the planned and possible MSFD monitoring activities has been

compiled by the Danish Nature Agency (Danish Nature Agency, 2014) and is still under development.

Specifically with respect to the monitoring of NIS in relation to MSFD the reader is referred to the recent

report on this matter (Andersen et al, 2014). In parallel, monitoring activities are also required by EU

regulation No 1143/2014 of the European Parliament and of the Council of 22 October 2014 on the

prevention and management of the introduction and spread of invasive alien species (Danish Nature

Agency, 2015a).

Besides ship hull being able to carry NIS into Danish marine waters, another important vector is ballast

water. However, the International Convention for the Control and Management of Ships’ Ballast Water and

Sediments (the Ballast Water Management Convention) from 2004 is expected to enter into force within a

couple of years, so that the risk from ballast water will be managed in Denmark under this convention.

Generally, there is little information available on the introduction pathways for NIS and especially the

possible sources of ship borne biofouling in Danish marine waters are largely unknown (Danish Nature

Agency, 2015a). This project aims at collecting existing information on external ship hull biofouling as a

vector for introduction of NIS, and to inform of technologies that may minimise the impact of the

biofouling.


2. Hull fouling

2.1 Biofouling on ships

Hull fouling starts as soon as an unprotected surface is immersed in water, first with a layer of bacteria

(slime layer) followed by progressively larger organisms; the process is illustrated in Figure 1. Treating the

surface with antifouling coatings serves to delay the process and there is presently no practical way of

completely preventing fouling and the consequential transfer of non-indigenous bacteria, viruses, and

microalgae via vessel hull fouling (Georgiades & Kluza, 2014). The biofouling layer also creates a friction

proportional to the thickness of the fouling, i.e. a noticeable drag is created when larger organisms begin to

settle on the hull.

Figure 1: When microfouling settle onto a hard surface (1), they proliferate and produce slime (2), which creates a biofilm that

larger organisms can live of and adhere to (4+5). Smaller or larger organisms will detach (3) and may survive in a new location

(Cook, 2012).

Biofouling has a higher chance of growing to a thick layer in “niche areas”, which are areas on a ship that

may be more susceptible to biofouling due to different hydrodynamic forces, susceptibility to coating

system wear or damage, or being inadequately, or not, painted (MEPC, 2011). The MEPC has pointed to

several niche areas on the hull were biofouling may build up, including rudder stock and hinge, overboard

discharge outlets and sea inlets, and the points visualised in Figure 2. These niche areas are often hard to


clean due to their special structures, enhancing the risk of being heavily fouled. Mitigation of the problem

is attempted with antifouling systems, which will be discussed in section 5.2. Finding high numbers of

biofouling in niche areas on commercial vessels, a Canadian study of 82 sea chests in 39 vessels observed

that 80% of the vessels contained fouling, and 46% harboured at least one NIS (Frey et al, 2014).

Biofouling of internal seawater systems is managed with marine growth prevention systems, which

includes the use of electrolysis, injection systems, and anodes (MEPC, 2011); however, these technologies

are out of scope of this study.

Figure 2: Examples of places where biofouling can be found on a petroleum industry vessel (Seamaster Fishingsupplies, 2013).

Aquatic organisms on a ship have the short term effect of creating drag, which results in more power

needed in order to move the ship, i.e. increased fuel consumption. On the longer term, aquatic organisms

transferred to a new location may become invasive in that area and cause harmful effects to plant, animal

and human life, and cultural and economic activities (MEPC, 2012).

Transfer of species happens as a ship is infected while operating in the species donor region. An organism

settles on the ship and is transported to a new region. If the organisms at this point produce surviving

offspring, the new region becomes recipient of the species. The NIS may now reproduce in such a degree


that it becomes established locally or even spreads. When it is observed that a NIS cause harmful effect, it

is called an invasive species. Many factors affects each step of the transfer, and it is thus very challenging to

predict which species will arrive, survive, persist and proliferate (Department of Agriculture and Water

Resources, 2015). All organisms with a sessile life stage may be hull borne, but only the ones surviving the

various conditions may settle as NIS in a recipient region (Figure 3).

Of the many influencing factors contributing to organism survival, a study on sea-chests in commercial

vessels observed that the period of in-service (i.e., duration since last sea-chest cleaning) and vessel origin

(i.e., international versus domestic) partly determined the nature and extent of sea-chest fouling. There

was found a significant difference (p=0.01) between domestic and international vessels when looking at the

part of NIS, which was still non-established. On the other side, vessel size and average number of days

spent in the last five ports of call were unable to explain the taxonomic richness or abundance of the

organisms (Frey et al., 2014). A final complication in the assessment of biofouling is that the vast of

majority of species that are sessile and prefer to attach themselves to hard substrates have vigorous

spawning and life stage(s) tied to the water column and while shipping may be their primary mode of

transportation when becoming invasive these species may very well travel in the ballast water rather than

on the hull.

Figure 3: Contributing factors to the successful transfer of NIS from donor to recipient region (Department of Agriculture and

Water Resources, 2015).


2.2 Non-indigenous species via hull to Danish marine waters

In 2012, at least 43 NIS had been observed in Danish marine waters (Stæhr & Thomsen, 2012) and the

species are listed in Appendix 1, also suggesting the relevant vector. The list is based on data from the

European Network on Invasive Alien Species (NOBANIS).

Species from other bioregions introduced via hull have been traveling through marine or brackish waters

before entering Danish territory, and this is expected to kill most freshwater organisms. Thus, hull fouling

may be more of a hazard towards marine ecosystems compared to freshwater systems due the higher

frequency of surviving marine organisms. Most of the NIS observed in Denmark has indeed been found in

areas of high salinity such as the Limfjord, whereas the Baltic Sea with a lower salinity habitats fewer NIS

(Stæhr & Thomsen, 2012).

As mentioned earlier, it often cannot be determined whether an introduced marine species came by hull or

by ballast water. In addition, the NIS attributed to shipping may also have come to Denmark via secondary

dispersal from the original location of introduction (Jensen & Knudsen, 2005). In the absence of Danish

monitoring data specifically related to ship hulls an attempt to establish the share of NIS transferred by

hull fouling and other vectors is seen in Figure 4 based the species and vectors listed in Stæhr and

Thomsen 2012), and for species where more than one vector is mentioned an equal proportion assigned

pragmatically. In this case the contribution from ship hull biofouling is estimated to have be approximately

20% of the 43 species introduced to Danish marine waters, i.e. 8-9 species, bearing in mind that the many

species are still assigned to an unknown vector and that both oysters and driftwood are vectors that may

harbour sessile species.

Figure 4: Proportion of introduced species to Danish marine waters via different vectors. Diagram is based on information in

Appendix 1, making one species count for 1, divided into the categories in question. The one species with "epiphyte?" as vector

was assigned 50% to ship hull and 50% to driftwood.

The recent review from Madsen et al. (2014) is also based on NOBANIS data in conjunction with other

sources, and the authors sum up that 19 species have a hull based pathway of introduction, but here both

marine and freshwater species are included. According to the NOBANIS website, 62 NIS are found in

Danish waters (marine + estuarine/brackish), and ten species are assessed to have entered Danish marine

Aquaculture 6% Artificial channels

1%

Ballast water 21%

Driftwood 4%

Imported? 2%

Japanese Eels 7%

Natural spreading 5%

Oysters 20%

Ship hulls 20%

Unknown 14%


waters via ship hulls (NOBANIS, 2015). A poster presentation by Stæhr (2011) records seven hull borne

NIS.

Two other available NIS lists are available: Jensen (2013) selected target species for Danish ports placing

ten species on “established species list” and eight species on the “alert list” of not yet established species;

and the black list of invasive species list published by the Danish Nature Agency (2015). None of these

include hull fouling species on their top priorities, although the “alert” list of Jensen (2013) does include

species associated with hull fouling. This could be due to many factors, including the scoping of the tasks or

that hull fouling species are not among the species of severest impact.

Some of the mentioned sources reveal the names of the species of interest and some do not. Lists of

possible most important species for the marine environment are also available from a number of sources,

and a compiled list is seen in Table 1. The species on the list have been included if they were benthic

organisms living in marine or brackish waters, or species associated with these organisms, or they had ship

hulls as suggested vector by at least one of the references.

Table 1: Compiled list of aquatic NIS imported to Danish marine waters via hull fouling. An "x" signifies inclusion of the species

in the list and a "-" signifies that the species is not mentioned. Stæhr and Thomsen (2012) characterised NIS in Danish marine

waters and Madsen et al. (2014) compiled background data and reassessed a number of species for a report on the pathways on

NIS introduction. The original lists were reduced by only including species described as benthic (sessile) organisms living in

marine or brackish waters, or species associated with these organisms.

# Species Taxa Stæhr & Thomsen

(2012)

Madsen et al.

(2014)

1 Aglaothamnion halliae Macroalgae x -

2 Balanus improvisus Barnacles x x

3 Bonnemaisonia hamifera Algae x x

4 Caprella mutica Crustaceans - x

5 Codium fragile Macroalgae x -

6 Cordylophora caspia Hydroids x x

7 Dasya baillouviana Macroalgae x x

8 Elminius modestus Barnacles x -

9 Ficopomatus enigmaticus Annelids x x

10 Fucus evanescens Macroalgae x x

11 Heterosiphonia japonica Macroalgae x x

12 Molgula manhattensis Cnidaria - x

A few of the NIS often associated with fouling of vessels are not included, e.g. Teredo navalis and other

wood borers, since it according to Jensen (2013) is “... unlikely to be spread in Danish waters by present-

day shipping activities."

2.3 Hot spots for hull borne non-indigenous species

Compared to ballast water driven transfers of NIS, which takes place mainly in ports where ballast water is

discharged, the loss of hull borne organisms to the environment may potentially occur anywhere a vessel is

located. Assuming that the loss of organisms from the hull are stochastic events, the voyage itself is not a

high risk occasion, whereas stopping for maintenance, calling ports, lay-up time, and other events

prolonging the stay in a given location should lead to accumulation of the risk of loss of NIS (more on this

in section 4.2). Environmental conditions during a voyage such as abrasive ice cover or rapidly changing

salinity gradients in estuaries or locks may also lead to sudden loss of fouling, but ice cover in Denmark is

not restricted to certain areas and there are no navigational estuaries and freshwater canals in Denmark

that are not already in ports. This section addresses some of the potential hot spots for loss of NIS.


2.3.1 Dry-docks

Shipyards conduct hull cleaning and reapplication of antifouling paint in accordance with BEK nr. 1188 af

12/12/2011. Shipyards with dry-docks for maintenance work, including hull cleaning, exist throughout the

country and service ships as large as their dry-dock can accommodate. The land based hull cleaning occur

in facilities under municipal licenses and is followed by waste removal to local waste facilities (Heisel,

2015). The biosecurity risk is expected to be low from these facilities. This is in accordance with what has

previously been reported (Hopkins & Forrest, 2008).

2.3.2 In-water hull cleaning

In-water cleaning of hulls might represent a higher risk of introducing NIS relative to land based cleaning

in dry-docks with land based waste disposal because physical disturbance of the fouling communities may

trigger the release of propagules or viable gametes (Hopkins & Forrest, 2008). Both merchant ports and

marinas may be subject to this. In-water cleaning by professionals is offered in larger commercial ports

only and by off-site companies. A ship's propellers are important to keep biofouling free in order to assure

proper function and minimise cavitation and these may thus be cleaned more often than only when in dry

dock, i.e. be typical cases for in-water cleaning (please see section 3 for a detailed assessment of in-water

cleaning). In support, DS NORDEN conducted approximately 150 propeller polishings in 2015 compared

to 90 hull cleanings (Sinding, 2015).

2.3.3 Ports and marinas

The more time a vessel spends in an aquatic area, the more likely it is for an aquatic organism to reach a

reproductive life-stage. Vessels not in operation often stay in port or close to ports, and NIS thus has longer

time to reproduce in this environment. NIS may additionally exploit the relatively calm and nutrient rich

water and port and marinas thus contain the higher numbers of introduced species (Gittenberger et al,

2011). Also, port and marinas include piers and jetties and are surrounded by breakwaters offering prime

substrates for the typical hull-fouling organism. A special case is the four ports in Denmark where ship

recycling takes place and obsolete vessels await final dismantling (Esbjerg, Frederikshavn, Odense (Lindø)

and Grenaa).

2.3.4 Ports of refuge and STS areas

In addition to regular ports or marinas being possible hotspots for NIS, areas designated as Port of Refuge

or used for ship to ship (STS) operations might be hotspots too due to the longer residence time of vessels.

A ship in need of assistance may find a port of refuge in order to minimize or eliminate the risk of pollution

of the environment as well as for occupational safety. The areas are appointed ports of refuge in Danish

waters can be found in BEK nr 33 af 07/01/2011 and the locations are seen in Figure 5. These locations are

also used for shorter lay-up periods awaiting new cargo.

An STS operation occurs when cargo is transferred between two ships (or more) and vessels are in

principle free to carry this out anywhere not specifically prohibited in Danish waters. However, the STS

location is typically designated based on currents and weather conditions in agreement between the ship’s

operator, the ship pilot and the Naval Defence Command Denmark. A suitable area is agreed and

communicated to the other ship(s) in the operation. Often used locations include the waters near

Frederikshavn/Skagen (Ålbæk) and west of Kalundborg (Figure 6). In 2014, there were 58 STS operations

taking place in Danish waters with an average duration of 3.2 days. Bunkering is a common operation that

may also take place in an STS area. Bunkering operations were recorded 3069 times in Danish waters in

2014 and lasted on average 6 hours (Based on data from Arrias, 2015).


Following the live map on marinetraffic.com during October 2015 revealed that moored or anchored

tankers and cargo vessels are often found in Ålbæk Bight, Kalundborg Fjord and in Tragten by Fredericia.

It is possible that ships use the ports of refuge as anchoring points between assignments, but there are no

recordings of such lay over events.

Figure 5: Map of Danish Ports of Refuge (light and dark red dots) and 2014 STS locations (blue dots). Light red dots are for ships

with a low pollution potential and dark red dots are for ships with a high pollution potential. Bunkering operations also take

place, however, coordinates for these operations are unknown. Figure based on data from Arrias (2015) and Olsen (2008).

Sweden

Germany

Denmark

Ålbæk Hirtshals

Frede-

rikshavn Hanstholm

Thyborøn

Grenaa

Esbjerg

Nyborg

Langeland Bøtø

Rønne

Vang Tejn

Køge

Agersø

Kalundborg Copenhagen

Romsø Tragten

Pakhusbugten


Figure 6: Number of ship to ship and bunkering operations recorded in Danish waters in 2014, based on data from Arrias

(2015). The STS operations in "Kalundborg Fjord" and "Other areas" all have coordinates from the area west of Kalundborg

Fjord (the lower of the two blue clusters seen in the previous figure).

Table 2: Examples of hard substrata that can be used as stepping stones for maritime species besides growing on vessel hulls.

Natural Man-made

Offshore Stone reefs

Coral reefs

Buoys

Wind farm foundations

Oil rig structures

Cables

Pipes

Floating docks

Ship wrecks and sunken freight

Coastal Bedrock

Driftwood

Stone reefs

Loose boulders

Limestone formations

Buoys

Wharves

Anchorages

Channel

Tug base / Pilot base

Bunker and barges

Marinas

Boat ramps

Navy areas

Boat yards

Slipways

Dry-docks

Floating docks

Aquaculture leases

Dikes

Ship wrecks

Bridges

1

22

35

2886

57

39

37

20

10

6

5

4

2

2

0,5 5 50 500 5000

Ålbæk Bight

Kalundborg Fjord

Other areas

Unknown

Frederikshavn…

Copenhagen…

Tannis Bight

Århus Bight

Off Grenaa

Off Gilleleje

Aabenraa Fjord

Off Fredericia

Operations in 2014

Ship to ship

Bunkering


2.3.5 Stepping stone substrata

Biofouling on hard substrata is extensive, and NIS can grow on breakwaters, pier and floating docks inside

harbours even though the surrounding water has a soft bottom substrate without the same organisms. In

the Dutch part of Wadden Sea, fewer NIS were observed on hard substrata outside the sheltered

environment of harbours, i.e. dikes and shellfish areas (Gittenberger et al, 2011). The environment offshore

may thus harbour fewer introduced species than a near-shore environment. However, as all sorts of hard

substrata may be used as a stepping stone, offshore structures act as stepping-stones over areas that

previously was a barrier for species spreading (Adams et al, 2014) and may thus be key to secondary

transfer of NIS. Examples of such areas are listed in Table 2. It has been customary in the offshore

exploration industry to remove drilling rigs or drill ships from operation at least every five years to undergo

maintenance work in a shipyard, which might take many months. However, a shift towards keeping the

rigs or ships in operation during maintenance work is planned (Brandt-Jensen, 2015), which may require

new standards for in-water surface cleaning. A guideline for managing NIS in the oil and gas industry is

avilable in OGP/IPIECA (2010).

2.4 Diversity of hull fouling

The biofouling process of a ship’s hull, will be driven by a large number of variables including the

antifouling history (time passed since treatment), the typical speed of operation, lay-up and mooring time,

the temperature of the travelled water, and the availability of biofouling propagules. In a limited study of

the fouling removed from the sea chest of the German research vessel METEOR, acorn and stalked

barnacles were prominent along with species of crustaceans and blue-green algae. It was concluded that all

the barnacles must have settled in warmer waters (Reuland, 2015).

A New Zealand study observed the biological phyla of fouling as seen in Figure 7. The study not only

illustrates that practically all vessels may harbour biofouling, but also that vessels belonging to the

comparatively frequently operated commercial and passenger categories are home to fewer bryozoans and

tubeworms, whereas barnacles and to some extent macroalgae are ubiquitously found in fouling

(Georgiades & Kluza, 2014).

A Scottish study observed no distinct species differences within the commercial vessel types standby,

supply, tugs, and ferries (McCollin & Brown, 2014).

A Danish in-water hull cleaning company reported that it is normally barnacles and tubeworms as well as

slime that is cleaned off ship hulls, whereas macroalgae are generally not observed (Petersen, 2015a).

Figure 7 Per cent observed biofouling on vessels in a New Zealand study. n = number of vessels in survey. Fouling assemblages

on passenger vessels and merchant vessels were found to be similar. The figure is based on data from Georgiades & Kluza

(2014).

0

25

50

75

100

Commercial(n=270)

Passenger(n=49)

Fishing(n=3)

Recreational(n=182)

All vessels(n=504)

Sh

ip h

ull

s w

ith

b

iofo

uli

ng

[%

]

Macroalgae

Bryozoans

Barnacles

Tubeworms


2.5 Biofouling transfer - characterization of three ship categories

In this section, the key differences between of three major types of ships will be covered, including the

guidelines and methods employed in hull cleaning. It must be noted that there are huge variations within

each ship type, which cannot all be described.

The potential for introducing NIS with ships’ hulls is among other things a product of shipping intensity

and residence time, i.e. the risk of NIS to settle in Danish marine ecosystems may be proportional to the

frequency of infected vessels entering and the length of an infected vessel's stay. It is thus relevant to know

the fleet size as well as a vessel type's operational pattern.

In order to save money on fuel costs by reducing drag and (inadvertently) mitigate the biofouling risk,

vessel owners normally clean their ship of external biofouling on a regular basis. However, the methods for

the cleaning may spread NIS too, especially when cleaning in water with direct release of the fouling. The

alternative where a vessel is cleaned during dry-docking in a shipyard generates a very low biosecurity risk

because the debris is sent to local deposit and residue water from cleaning is collected (Heisel, 2015).

The topics mentioned above have been investigated and are presented for the three ship types Merchant

fleet, Fishing vessels, and Recreational crafts, in Table 3 and in the following subchapters.

Table 3: Characteristics of three vessel types and their hull cleaning methods.

Ship Types Merchant ships includ-

ing passenger vessels (1) Fishing vessels (2) Recreational crafts (3)

Transport

pattern

Between several ports, often

international waters. Weeks

at sea may be followed by

days at anchorage or

harbour.

Mostly to and from the

same port. Yearly 150-200

days at sea; few with 330-

340 days. Mainly national

waters.

Mostly to and from the

same port with few longer

trips. Mainly national

waters. Relatively few days

at sea.

Biofouling

risk

Large area to foul; high

interest in being clean to

save fuel when operated.

Medium area to foul;

interest in being clean to

save fuel.

Small area to foul; many

harbour days and low

operational speed.

Required

Facilities

Dry-docks or floating

docks; nothing for in-water

cleaning.

Dry-dock, slipway or

floating docks.

Slipway, crane.

Cleaning

operator

Professionals in dry-dock;

divers or ROV in water.

Professionals. Private.

Methods

employed

Sand blasting, water jets,

brushes. Inconsistent waste

handling in-water; land

based as fishing vessels.

Residue waste is collected

and disposed according to

local waste regulations.

Manual cleaning by scrapers

and water jets. Very

inconsistent waste handling.

Frequency 0,5-5 year intervals. 1-year intervals. 1-year intervals.

(1) Interviews with municipality representatives: Andersen from Copenhagen; Hiorth from Kalundborg, and Bennetzen

from Fredericia (2) Interviews with Finn Jørgensen from Værftet A/S and Henrik Lund from Danish Fishermen's Association (3) Interviews with the marinas Egå, Lynetten, Aalborg, and Marina Minde

2.5.1 Merchant fleet including passenger vessels

There is a wide diversity of commercial ships, such as tankers, container ships and ferries. Fifteen

thousand port calls was registered in Denmark in 2014 (Statistics Denmark, 2015a) and this results in

many hours spent still in port for a ship; tankers and bulk carriers from a Danish shipping company spend

26-58 % of their time in port (Sinding, 2015). However, many more ships spend little time in Danish


waters because they are only in transit: According to De Danske Lodser, 60 thousand ships are estimated

to traverse Danish waters each year (Board of Foreningen Danske Lodser, 2013). Figure 8 shows where one

type of these merchant vessels (cargo carriers) sailed in 2014. Commercial vessels normally operate at

speed of 10-20 knots and have an average wetted area of 2800 m2 (City of Copenhagen, 2015a).

Figure 8: Traffic density of cargo carriers in 2014 (MarineTraffic, 2015); lighter green is higher traffic density. As an example of

the commercial ships sailing through Danish waters, it is observed that cargo carriers operate in all Danish seas and that many

vessels are sail the corridors along Sweden's west coast or south of Denmark via the Kiel Canal.

Merchant vessels have an overall cleaning frequency in dry-dock of up to five years (Nobles, 2015; Sinding,

2015) and this corresponds with a Swedish estimate of ships being cleaned in dry-dock every 3-5 years

(Granhag, 2015). The costs involved in dry-docking large vessels motivate owners of merchant and

passenger vessels to schedule hull cleaning and reapplication of antifouling systems in conjunction with

maintenance work, urgent repairs or major certification surveys of the vessel.

The classification societies' requirements for vessels which are ≥500 GT and operate internationally are

based on the International Convention for the Safety of Life at Sea, 1974, (SOLAS). Non-passenger vessels

that are subject to SOLAS are required to undertake a certification renewal survey at least every five years

by an out-of-water inspection of the vessel's hull and a minimum of two surveys of the vessel's hull during

any five year period. Passenger vessels subject to SOLAS normally enter dry-dock every 2-3 years to satisfy

certification requirements (Inglis et al, 2013). Ferries enter dry-dock once a year (Heisel, 2015; McCollin &

Brown, 2014).

An increasing number of ship owners/operators allow performance monitoring to dictate hull cleaning.

The tankers and bulk carriers operated by DS NORDEN are performance monitored and cleaned when

needed (Sinding, 2015), i.e. when the fuel consumption per nautical mile reaches a threshold. This is in line

with a recently published Scottish study that investigated biofouling on 35 commercial vessels. They

generally observed that the antifouling coating was in good condition, probably because commercial

vessels have relatively large fuel savings on keeping a smooth hull. Biofouling was therefore observed and

sampled where paint was damaged or in niche areas (McCollin & Brown, 2014). Propellers are subject to

intense wear, and most antifouling systems are not resistant enough for long-time propeller protection.

Propellers thus require extra maintenance; NORDEN operates with intervals of maximum 6 months

(Sinding, 2015).

The company Mermaid Marine Service expected an average wetted area of 2800 m2 for ships undergoing

hull cleaning in Port of Copenhagen (City of Copenhagen, 2015a). Commercial ships on a tight schedule


may combine in-water cleaning of biofouling with loading/unloading activities at a pier: A 200 m long

container ship takes 6-8 hours to rinse (Kruger, 2015). In-water propeller polishings are always conducted

by diver, while hull cleanings are conducted mainly by remote operated vehicle (ROV) and sometimes by

diver. The cleanings are performed where the ship is, i.e. in globally distributed shipyards (Sinding, 2015).

2.5.2 Fishing vessels

The Danish fleet of 2014 comprised 2455 fishing vessels with a total gross tonnage of 69,138. Three

quarters of the fleet are of a length less than 10 meters, and only 32 vessels are ≥40 meters in length

(Statistics Denmark, 2015b). The traffic density of fishing vessel operations around Denmark recorded in

2014 can be seen in Figure 9. Most operations were west and north of Jutland, and west and south of

Sweden.

Figure 9: Traffic density of fishing vessels in 2014 (MarineTraffic, 2015); lighter orange is higher traffic density.

According to biologist Henrik Lund from The Danish Fishermen’s Association, the fishing fleet typically

spend workdays at sea (averaging 150-200 days), even though some trawlers are at sea 330-340 days per

year. Most fishing boats go to and from the homeport only and some may operate in one region during

summer and another region during winter. Approximately 5% of the latter boats go to other countries on a

seasonal basis. Thus, commercial fishing is expected to operate mainly to/from one port and only to a

limited degree spread fouling between ports.

Vessels in Denmark are cleaned yearly (Lund (2015); North Sea Yard (2015). Owners have the commercial

interest in maintaining a smooth hull in order to keep the fuel consumption low, like the commercial

vessels engaged in trade. It is normal that the cleaning of a fishing vessel is organised after a call for

tenders, where 3-4 yards submit a tender and the vessel subsequently is cleaned in dry-dock (Heisel, 2015).

Only a decade ago, the biofouling waste after cleaning was thrown back into the sea, however, nowadays

the waste is collected and according to guidelines by all facilities being slipway or dry docks (Lund, 2015).

2.5.3 Recreational crafts

The Danish recreational fleet has been estimated to consist of at least 57 thousand crafts and there are

300-400 Danish ports (Rasmussen & Bjergstrøm, 2014). Recreational crafts move close to the home port

and seldom visit foreign waters. However, longer trips are often made in summertime when the water is

warmest and fouling thus grows the quickest. Over the 2013-2015 seasons, there were on average as many


foreign as Danish guests spending a night in Danish marinas, resulting in approximately a million

registered overnight stays (Statistics Denmark, 2015c). Compared to the commercial fleet, these crafts are

much smaller with an average of 30-32 feet (approximately 9.5 m), however, they are sailing slower (3.5-5

knot depending on boat type) which enhances the chance of biofouling settlement. Average wetted area on

a 30 foot craft is 16 m2 (Højenvang, 2002).

Recreational crafts spend a varying amount of time at sea, depending on the time and interest of the

owner. Danish crafts typically spend most time of a summer season in water and are put on land for the

winter season due to the risk of ice. This pattern may change due to climate changes.

Recorded operational patterns are seen in Figure 10 and Figure 11. The map on Figure 10 is based on AIS

data from international sources: The AIS version of class A is mandatory on vessels larger than 300 gross

tonnage, but smaller vessels can have the AIS of class B, which is technically simpler and also cheaper. The

map on Figure 11 is based on a voluntary smartphone app and reports via whatever positioning technology

the smartphone is utilizing (often GPS). The app recording the information is free of charge and marketed

towards Danish, private craft owners, who can use it as often or rarely as they like. An implication is also

that the users may turn off the app when exiting Danish waters in order to minimize roaming costs.

Focusing on Denmark, recreational crafts travelling from Western Europe via the Kiel Canal are exposed to

fluctuating salinity changes and these are likely to inhibit species transfer to a high degree (Gittenberger et

al, 2011).

Hull cleaning of recreational crafts is also a matter of personal prioritizing, as reduced voyage speed does

not have the same economic consequences for recreational crafts as it does for commercial vessels (Inglis

et al., 2012). A recent survey among Norwegian leisure boat owners found that 60% of the owners do all

the maintenance work, 30% do some of the work, and 10% of the boat owners use a marina or shipyard to

conduct professional maintenance work (Sundt et al, 2014). In Denmark, nearly all (80-100%) of the craft

owners are estimated to clean their craft once a year. The rest were either estimated to clean more

frequently or to leave their craft in the water resulting in 3-4 days of cleaning every 3rd year.

In-water cleaning is used for removing patches of macrofouling; regular hull cleaning is conducted on land

(Jensen, 2015; Møller, 2015). In Australia, 53% of recreational boat owners were found to manually clean

their boats, either in or out of water, between applications of antifouling paint (Morrisey et al., 2013).

It is customary that the boat owner cleans the boat of biofouling with water jet or mechanical scrapers on

land before the winter lay-up and re-cover the craft with an antifouling paint before the new season

(Jensen, 2015). The scrape-off is often not cared for and may be washed directly into the harbour basin

(Egå Marina, 2015; Jensen, 2015) and few boat owners has access to solid substance removal technologies

like down-hill grates with piping leading to sedimentation chambers. Craft owners hiring professionals to

do their maintenance work are more likely to also have the debris collected and disposed of on land

(Møller, 2015).

The large number of vessels is important because a recent study concluded that frequent small

introductions of oyster larvae were more likely to succeed in settling than infrequent large introductions

(Hedge et al, 2012). The same may be the case for other species. A study conducted in the Dutch part of

Wadden Sea found that the highest density of NIS were found in marinas, leading to the hypothesis that

recreational crafts are a very important vector in this area (Gittenberger et al, 2011). The study refers to

other studies finding elevated numbers of invasive species in marinas also along the US coast and in

Ireland. Investigations of Scottish marinas in the mid-2000s found that 59% of the yachts surveyed had

macrofouling and also suggested that recreational crafts is an important vector for the spread of NIS

(McCollin & Brown, 2014).


Figure 10: Traffic density of recreational crafts in 2014 (MarineTraffic, 2015); lighter purple is higher traffic density. The

recreational crafts included are presumably larger than those depicted in Figure 11 due to differences in tracking technology.

Figure 11: Recreational craft traffic density from 1 May to 15 August 2015. Red colouring marks a higher and light green

colouring marks a lower number of visitors in an area. The map is based on a smartphone app marketed as an electronic logbook

to Danish recreational craft owners and currently having approximately 3000 active users (Hansen, 2015a).


3. In-water cleaning

3.1 To clean or not to clean

When a vessel has its hull or niche areas cleaned, the risk of NIS transfer is the lowest when the vessel is

cleaned on land or in a dry-dock where the waste is collected and disposed of via on-land facilities. Vessels

that are not docked as often as hull cleaning is needed can choose in-water hull cleaning to obtain a clean

hull. The merchant fleet may use a growing number of commercial suppliers of in-water hull cleaning.

Danish recreational craft owners are more likely to only occasionally clean their vessel patchwise in-water

and one a year on land, and the same may be the case for Danish fishing vessels because both vessel types

are typically much too small to be targets of in-water cleaning companies' preferred market of ships >99 m.

There is potential for the release of propagules during in-water hull cleaning: Indirect gamete or larval

release due to physical disturbance or direct release of viable fragments, gametes, or larvae as a result of

physical damage. The extent of these effects dependents on the type of fouling organisms, their

reproductive status, and environmental conditions. The impact will thus be very variable and difficult to

predict for each cleaning (Morrisey et al., 2013).

If the alternative to in-water cleaning is that no actions are taken, there is still a risk of propagule release.

According to Morrisey et al. (2013) there have been no studies on the release rate of propagules directly

from ship hulls, but studies have been conducted on similar environments such as wharf pilings and

aquaculture structures. Examples of the identified release rates include the average fecundity of Hydroides

elegans (a polychaete worm), which ranges from 1,100-9,050 oocytes released per female after sexual

maturity is reached after 16-21 days. The average fecundity of Crassostrea gigas (Stillehavsøsters) ranges

from 12.2-146 million eggs released per female after sexual maturity is reached after 1 year and this species

is also invasive in Denmark. There is thus considerable potential for release of propagules from a fouled

vessel both during port stay and while operating in Danish waters.

3.2 Hull cleaning in Denmark

3.2.1 Actors

Several actors are involved in hull cleaning. For a start, there are several shipyards providing this service in

Denmark. Vessels have their surfaces cleaned in dry-dock before other maintenance work is conducted.

Commercial shipowners have their vessels cleaned in order to decrease their fuel consumption. If the

cleaning cannot be conducted during a scheduled dry-docking, in-water hull cleaning is an option. Also

between dry-docking sessions, in-water cleaning is a way to clean the hull of biofouling. Private companies

specializing in in-water cleaning offer their services to relatively large ships (>99 m). Two companies, GAC

and Mermaid Marine Services have obtained permission to conduct in-water cleaning in Danish harbours

and anchorages, but more companies are available, e.g. Ship-Maintenance Underwater, which is involved

in hull cleanings, but do not operate in harbours.

In marinas, leisure boat owners may remove hull fouling patchwise in water; however, most of the hull

cleaning is conducted on land. There is generally no cleaning of submersed structures in marinas, and no

monitoring of the fouling, even though some cleaning the top of floating bridges is conducted and

barnacles may be scraped off semi-submerged structures if they attract annoyances like sea gulls (Møller,


2015). Lastly, antifouling paint companies are interested in assisting the shipyards in reapplying the

antifouling systems correctly and normally have pamphlets for recreational boat owners with guidance on

boat maintenance with a focus on materials and human safety.

3.2.2 Licenses for in-water hull cleaning

In Denmark local municipalities managed the service providers' license apllications for in-water cleaning.

The municipalities grant licenses to in-port cleaning in designated areas, approve programs for in-water

hull cleaning in the large harbours, and the companies conducting the cleaning must obtain a permission

to operate in each harbour. Before cleaning can commence in Danish ports, a plan for waste collection,

filtering and disposal must be in place (Andersen, 2015). In 2015, only the City of Copenhagen recorded a

single cleaning of a ship even though the municipalities of Kalundborg, Fredericia, and Aalborg have also

granted hull-cleaning licenses (Hiorth, 2015). Elsinore and Halsnæs municipalities have also previously

granted such licenses. The demand for hull cleaning activities is presently low presumably because of the

low fuel prices (Borg, 2015).

The local licenses are granted according to an overall assessment on environmental impact and are valid

for 1 year to ensure that Best Available Technologies are employed. City of Copenhagen (2015a+b) has the

following representative considerations:

Permission from the harbour is received before activities are begun.

The method must be described in the application.

The hull cleaning must be conducted in the approved area.

Only soft brushes presented to the Environmental Protection Department are to be used.

Environmentally dangerous waste is to be disposed in accordance with local rules.

Self-assessments must be made, including sampling, analysis and reporting.

o Collection of samples before and after the filter, and 10 meters from the where the filtrate is

discharged.

o An approved laboratory is to analyse for arsenic, lead, cadmium, copper, zinc, and suspended

matter.

o A report must be made and sent to Environmental Protection Department

These precautions are justified with the global sailing patterns of commercial ships, along with their

relatively large size. According to an environmental evaluation made by City of Copenhagen, these methods

will release some antifouling paint particles, but due to the large water replacement in the harbour, the

operations will not affect animals or plants (Andersen, 2015).

3.2.3 Practical experiences

The contacted in-water cleaning companies (Mermaid Marine Service, GAC / Frog Marine Service, Ship-

Maintenance Underwater) clean larger ships (>99 m) by diver or remotely operated vehicle (ROV). They

follow the handling directions given by the local municipality when cleaning in the harbour. When cleaning

outside a harbour, i.e. in an anchorage, the activities are generally not reported to anyone, as there seem to

be no regulation or enforcement covering this exact field. One company servicing ships in Danish waters

reported to have conducted in-water cleaning of approximately 20 ships in 2015, and another had

conducted seven jobs of in-water cleaning of ships. This mostly happened at anchorage outside

Copenhagen, Kalundborg, and Frederikshavn, i.e. some of the areas seen in Figure 5 on page 21.

When the in-water cleaning company employs a mechanism for capturing the biofouling debris it is

removed from the water, but when a technology is used that does not include capturing or a diver removes

biofouling manually, biofouling debris is normally released to the sea floor and the excess water from water

jetting to the surrounding water body. One of the interviewed companies, which does not use capture


technology released material or excess water, try minimizing the pollution with potentially toxic coating by

only servicing ships with a certified biocide-free antifouling system. The company also conduct self-

monitoring activities although it is not required in the out-of-port areas where they operate.

Discharges to the recipient vary both with the applied method and with the contents in the coating of the

ship. According to a Swedish company, which also operates in Denmark, their hull cleanings in Port of

Gothenburg are not yet satisfactory for all demands. However, the municipality is allowing the operations

in order to make room for monitoring of their continuous improvements (Söderberg, 2015). In-port trials

in Frederikshavn are expected to be above the required maximum for dissolved zinc in a marine recipient

(Müller, 2015). In port of Copenhagen, the ship cleaned in 2015 by Mermaid Marine Service exceeded the

lead limit, but the exceedance was perceived to be very little and the performance thus very good

(Andersen, 2015).

3.3 Cost of hull cleaning

For a given vessel type and size, the cost of dry-docking could be up to five times the cost of in-water hull

cleaning (Hagan et al. 2014) and this creates potential for a market for in-water cleaning between required

dry-docking sessions in addition to the possibility of the ship to keep its normal operation schedule and

operational pattern. The cost ratio estimate was made by an Australian developer of an in-water cleaning

vehicle, but does not favour in-water cleaning costs based on the cleaning costs for commercial presented

below.

Traditional dry-docking costs hundreds of thousands of dollars, and the cost of reapplying a new layer of

antifouling amounts to half the total cost. The cleanings are performed in globally distributed shipyards

(Sinding, 2015).

Commercial ships on a tight schedule may combine in-water cleaning of biofouling with loading/unloading

activities at a pier: A 200 m long container ship takes 6-8 hours to rinse according to Kruger (2015). Hagan

et al (2014), however, reported that typical in-water cleaning of a 180-200 m container vessel conducted by

companies in the U.S. East Coast would take approximately two days for an entire hull; larger vessels could

take up to four days to clean. The reported price is in the range of 20-50 thousand USD for the 200 m

container vessel and proportionately higher for larger ships. A comparison is made to a 2012 report finding

a similar price in the high part of the range for a large commercial vessel. Sinding (2015) reported costs to

be in the lower part of the range.

The price of propeller polishing varies a lot globally, but may on average cost 3,000 USD. Divers always

conduct these polishings according to Sinding (2015).

3.4 Neighbouring countries

Table 4 provides an overview of how and where hull cleaning is performed in Denmark and neighbouring

countries. Deduced from the given information, the picture is commonly that ships are always cleaned in

dry-docks with in-water cleaning as an additional tool. This is in line with the IMO biofouling guidelines

from 2011 (MEPC, 2011), which are also what the governments promote, as there are no other national

guidelines.

HELCOM does not have available information on the Baltic Sea in general, and refers to the individual

countries (Backer, 2015). No information was obtained on procedures for the OSPAR region in general. It

is worth to note that OSPAR has formed a correspondence group on biodiversity monitoring and

assessment, with the first assessments to be delivered in 2017 (OSPAR, 2015).

Table 4: General management of ship hull cleaning in Northern Europe based on response from national authorities. "-" marks that no information was obtained.

Hull cleaning

locations

Required

facilities

Methods employed Frequency Guidelines

Denmark Mainly shipyards. In-

water cleaning in ports

and anchorage.

Dry-docks,

robot/divers in-

water.

Sandblasting and water jet streams

in ship yards. Under-water ROVs

apply brushes or jet streams.

Parallel with repairs or servicing,

i.e. variations between 0.5-5 year

intervals.

The authorities promote the IMO guidelines.

Harbour permissions given locally.

Finland (a) - Divers for in-

water cleaning.

One Finnish company offers in-

water cleaning by divers using

brushes and residue collection.

When needed. No national guidelines.

Germany (b) Large Dockyards Dry-docks. Sand blasting - International guidelines.

Netherlands(c) Dockyards. However,

an initiative involving

in-water ROVs in one

port is mentioned.

Dry-docks with

high-pressure

jet streams.

Removed fouling material is

sampled for toxic levels of

inorganics, then discarded as waste

and thus not returned into the

water. Fouling comprising layers of

molluscs can be impossible to

detach with high-pressure jet

streams. Instead, spades or chisels

are used. Professional application

of new antifouling systems can only

be done with certified paints.

No information available.

A survey among officers in 5

Dutch ports found that all

stakeholders were aware that hull

fouling can be a vector for the

spread of alien species, and that

only a few stakeholders were

familiar with legislation or

regulation preventing the spread

of alien species.

The government promotes the IMO guidelines.

Norway (d) Shipyards. Dry-dock. - Parallel with repairs or servicing. The authorities promote the IMO guidelines.

Harbour permissions given locally.

Poland (e) Repair shipyards Dry-docks. The mechanical methods like

sandblasting, washing under high

pressure by means of hydro

monitors are used in the shipyards.

Parallel with repairs or servicing. No national guidelines.


Hull cleaning

locations

Required

facilities

Methods employed Frequency Guidelines

Scotland (f) Dry-docks in e.g.

Aberdeen, Edinburgh

and Garval Clyde.

Dry-docks. Power wash with dock hoses to

remove fouling and the current

paint, then re-coating with new

antifoulant.

In some cases a couple of layers can

be applied, with a primer being

used as a base.

Generally every 1-3 year.

Ferries typically have yearly

turnarounds.

Oil and gas vessels every 2-3 year.

Pollution Prevention and Control Regulations.

MEPC’s biofouling guidelines are recommended.

Sweden (g) Dry-doks, in port at

designated quays or in

designated areas. Hull

cleaning is performed

(at least) in Helsing-

borg, Göteborg, and

Stockholm

Dry-docks,

robots/divers

in-water.

In general, divers use brushes and

hull cleaning robots use water jet

technique.

One company uses cleaning robots,

and another company uses brushes

and residue collection.

When ships are to be repainted

every 3-5 years they dry-dock

but in-water hull cleaning takes

place in between those intervals.

Dependent on the grade of

fouling, some ship-operators

performs hull cleaning every 6th

month.

No national guidelines.

Ships do not have to report the cleaning or to have a

permit before they start. The cleaning is however an

environmentally hazardous activity and needs to ful-

fil BAT according to general environmental legisla-

tion. Local environmental authorities are responsible

for local legislation and e.g. under-water activities in

ports need a permit. The port authority gives the

permit for the activity after consultation with the City

Environment Administration, which gives a formal

order of precautionary measures that the hull

cleaning company must fulfil.

(a) Dr. Anita Mäkinen from Finnish Transport Safety Agency. Personal communication. October 2015 (b) Mariusz Zabrocki, Germany. Personal communication. September 2015 (c) van der Have et al, 2015 (d) Geir Hansen from Norwegian Maritime Authority. Personal communication. December 2015 (e) Ewa Makowska, from Ministry of Infrastructure and Development. Personal communication. October 2015

(f) Lyndsay Brown from Marine Scotland. Personal communication. September 2015 (g) Lena Granhag from Chalmers University of Technology, Sweden. Personal communication. November 2015

4. Monitoring

4.1 Monitoring of NIS from ship hulls

In Denmark there is no monitoring specifically for NIS from ship hulls as mentioned in the Introduction.

The hull cleaning activities in shipyards are part of the facilities' general environmental long-term

operating permits (>5 years), and the in-water cleaning operations are licenced by the local municipality

annually for a specific location. In practise, the in-water hull cleaning activity in a port is coordinated

between the supplier and the harbourmaster as part of the logistics of the operation, and as long as a

cleaning company holds a valid licence to clean, the individual activity need not be reported elsewhere. The

local municipalities in Denmark may require in-water cleaning companies to self-monitor their activities

by taking samples around the cleaning site for chemical analysis and reporting to the municipality. The

frequency of the required tests varies with number of ships cleaned (City of Copenhagen, 2015a and b).

Internationally, Australia, New Zealand, and California are the only countries/state, which has guidelines

on regular monitoring of vessel biofouling. However, the National Monitoring Strategy in Australia has

been criticised of significant costs, and unclear and unsuitable objectives, which have hampered its

acceptance and implementation. Recently, a new strategy for obtaining surveillance information was

recommended including a wider range of resources in a marine pest network, monitoring of preventive

measures, and that Australia adopts an international approach to biofouling management because

regulatory consistency will help the shipping industry (Department of Agriculture and Water Resources,

2015).

The existing monitoring activities on marine species in Danish water are briefly assessed for their

usefulness for monitoring NIS via Danish or regional species monitoring programmes, as described in

section 4.1.1 and section 4.1.2, respectively. For a more detailed account a proposal for a national strategy

on monitoring of NIS in Danish marine waters was recently developed and the reader is kindly referred

thereto (Andersen et al, 2014).

4.1.1 Danish monitoring programmes of marine waters

The NOVANA programme is the umbrella, under which Danish national monitoring of marine waters takes

place. NOVANA contains a marine sub-programme with focus on nutrient enrichment and eutrophication,

hazardous substances, and marine nature types in Natura 2000 areas. Monitoring concerned with nutrient

enrichment and eutrophication includes investigations of chlorophyll-a; species composition of phyto-

plankton, zooplankton, and benthic invertebrates; and coverage and species composition of angiosperms

and macroalgae. Monitoring concerned with marine nature types focuses on species coverage and

composition of macro-algae on cold coral reefs and stone reefs. Seabirds and marine mammals are also

included in the biodiversity sub-programme, which otherwise focuses primarily on terrestrial ecosystems

(Andersen et al, 2014).

The National Institute of Aquatic Resources is an institute at the Technical University of Denmark (DTU

Aqua) is responsible for a wide range of monitoring activities in Danish marine waters, such as

commercially important fish and shellfish species, but will report on observed NIS when exploitable

resources may be threatened. Most of the open marine water in Denmark is monitored through several

standardized surveys; the number of sampling days and stations are similar over the years in order to

compare the results over time.


4.1.2 Ad hoc monitoring

The local municipalities require a report of the chemical analysis of samples taken after in-water hull

cleaning (City of Copenhagen, 2015a and b; Bennetzen, 2015). Thus, samples are already required from

hull cleaning sites in commercial ports and it is thus a possibility to extend the analytical requirements.

Data on sediment concentrations of a range of antifouling relevant contaminant are available from ports,

marinas and waterways, when these are dredged, but this activity occurs only infrequent and with intervals

of several years.

4.1.3 Regional monitoring programmes

The online information system AquaNIS contains already acquired information on species introduction

histories, recipient regions, taxonomy, biological traits, impacts, and other relevant documented data also

for Danish marine waters (AquaNIS, Editorial Board, 2015).

HELCOM established a baseline for the good environmental status in the Baltic Area as of 2012 (HELCOM,

2012). This only includes the eastern part of Denmark. In 2018, a review will be conducted in the region in

line with the Marine Strategy Framework Directive and regarding NIS, the trend in arrival of new species

will be presented by comparing the number of new arrivals against the baseline number of NIS. The report

points to shipping being the main vector (biofouling included), but that it is difficult to distinguish this

from other vectors of NIS. The western marine waters are a part of the OSPAR area. An intersessional

correspondence group on coordinated biodiversity assessment and monitoring (ICG-COBAM) has been

assembled with first reports available in 2017 (OSPAR, 2015).

Summing up for both Danish and regional monitoring, the currently available data on Denmark are from a

variety of unevenly scoped resources, with information comprising local observations, regional databases

and various public monitoring programs, which will not necessarily provide information relevant for

assessment of environmental status or a proxy thereof, with respect to NIS from biofouling.

4.2 Biofouling risk assessment tools

Australia and New Zealand are among the strongest drivers on the management of ship borne NIS, and

Australian public and private entities are also responsible for the two following management systems,

whereas New Zealand researchers have put forward a prediction of organism escaping from ship’s hull,

which may be used as a proxy in risk assessment.

The Government of Western Australia, Department of Fisheries, has developed a biofouling risk

assessment tool intended for use by managers of commercial, non-trading, petroleum and commercial

fishing vessels, that intend to the state of Western Australia (Department of Fisheries, 2015). An online

questionnaire categorizes vessels of low/acceptable, uncertain, or high risk of importing NIS to the area.

The tool provides a risk assessment report detailing a range of recommended management actions to

reduce the biosecurity risk of the vessel, which can be chosen according to vessel and situation. The

'scenario' feature tests which vessels that presents the lowest risk for a particular mobilisation, the future

risk status of a vessel, or the projected risk status after maintenance.

A private company (Woodside Energy Ltd) located in Western Australia has developed an Invasive Species

Management Plan, which conducts a biosecurity risk assessment leading to acceptance or rejection of a

vessel, rig or immersible equipment (Box, 2014). The flow chart of the vessel assessment can be found in

Appendix 3 and is developed for vessels in three categories, namely commercial, petroleum production and

exploration industry, and non-trading vessels. The company employs a stepwise risk assessment, starting

off with a series of questions concerning where the vessel plans to operate, prior out-of-water period, type


of antifouling system, etc. The answers are assigned a score, and after a series of additions and

multiplications, the total vessel risk score determines the risk of infection with invasive marine species

with the subsequent consequences:

Low risk - Vessel details require checks/confirmation only

Uncertain risk - Precautionary principal applied: Confirmatory independent inspection and/or

management measures required

High risk - premobilisation inspection actions required

Depending on the results of an inspection, a vessel in the categories uncertain risk or high risk may be

assigned the low risk category or may be denied entrance to the invasive species management area (12

nautical miles from the Australian shores).

A model to estimate the probability of organisms spawning or escaping from a vessel is described in Inglis

et al. (2012). According to this New Zealand model, the total probability that spawning will occur (S) can be

modelled as the complement of the probabilities that spawning will not occur on any day during the visit:

S(N) = 1-(1-p)N

where p is the probability of spawning on any single day, and N is the number of days of the vessel's stay.

As seen in Figure 12, the largest risk difference between a vessel staying 1 day and 14 days is seen when p is

large (e.g. p=0.1). Thus, when the risk of spawning is low (i.e. clean hull), the risk of a ship staying in local

waters does not change much over time and when risk is high (i.e. fouling on hull) there will sooner be a

relatively high biosecurity risk from the ship. As p declines, so does the relative difference between

scenarios. The model was applied to both entire stays in New Zealand waters and to stays in a port.

Figure 12: The probability of spawning as a function of a vessel's duration of stay. The broken lines are examples of readings

(Inglis et al., 2012).

4.3 How to monitor for MSFD D-2?

A comprehensive summary of the D-2 standard in Denmark was presented in Andersen et al. (2014). Much

work has already gone into developing lists of target species to monitor such as the list presented in

Appendix 1.

Specifically for hull fouling organisms at offshore sites (oil terminals, platforms and windmill foundations),

ports of refuge and STS areas are potential habitats for NIS, and offshore installations also exist in the


vicinity of environmentally important areas as seen in Figure 13. Consideration may therefore be given to

the value of including such sites into a surveillance programme due to their potential stepping stone effect

by providing the hard substrates specifically preferred by hull fouling organisms.

Figure 13: Current wind power sites and protected areas in Danish waters. Offshore structures like wind farms may act as

stepping-stones for NIS. The map is based on data from the Danish Energy Agency (2015) and Danish Natural Environment

Portal (2015). Note that the habitat areas of the European Community (EC) overlays the Ramsar areas.

As suggested in the report by the Andersen et al. (2014), analysis of environmental DNA (eDNA) holds a

high potential to establish a comprehensive and cost effective routine monitoring programme of NIS and

other species. The method builds on the underlying fundamental principle that all living organisms have

species specific DNA, which will be shed in various forms into the environment and which can be collected

from the environment and identified. DNA enters the aquatic ecosystem through a variety of mechanisms,

including sloughing of external epidermal cells and natural secretions, sloughing of internal epidermal cells

into faeces, and tissue residues following reproduction, moulting, injury or predation. The detection of this

environmental DNA is based on whole DNA extraction found in a water sample and polymerase chain

reaction (PCR) assays using species-specific DNA sequences. In the aquatic environment, eDNA has been

shown to have persistency restricted to some weeks. Therefore, positive detection of a target species via

eDNA indicate a relative recent occupation or presence in the sampled area, when sampling lakes or ponds,

and up to nine km down-stream from sampling position in running water.

It may be feasible to combine monitoring of NIS in harbours, marinas and hot spots such as STS areas,

port of refuge and bunkering locations with the NIS hot spots suggested in Andersen et al (2014). Their 10

listed sites already includes four ports are also relevant for hull fouling: Esbjerg, Kalundborg,

Frederikshavn, and Grenaa. The offshore STS sites south or Samsø and east of Frederikshavn, and the Port

of Refuge are in Kalundborg fjord could be included in eDNA monitoring of target species. Secondary

transfers may be picked up in marinas if monitored for NIS related to hull fouling. Also, stepping stones for


NIS may be the permanently immersed structures such as windmill foundations and other open water

installations on soft bottoms.

Should biological monitoring be unfeasible for hull fouling NIS there may be a number of assessment

proxies that on a desk top basis can be used to establish a current status or baseline and the effect of any

mitigating measures. In parallel with the estimates brought forward for potential ballast water borne NIS

in Andersen et al (2014), it is possible to use the extensive traffic data from shipping to depict detailed

images and key indicators relevant for hull fouling. E.g. the number of days wetted surfaces of ships are

exposed in Danish EEZ relatively easily be calculated (m2 * d) and mapped showing areas where ships stay

longer thus increasing risks. This can be elaborated further including biological parameters of target

species, seasonal biological changes (i.e. spawning periods), port of origin, time since docking and other

risk characteristics.


5. Antifouling technologies

5.1 Best available technology

Antifouling coatings are applied in order to avoid biofouling typically through a chemical or physical action

(see more in section 5.2). However, as these systems do not prevent biofouling indefinitely, biofouling

management technologies also exist. These technologies either treat/kill biofouling and leave it on the ship

or they remove biofouling from the ship hull. Because the surface characteristics and the abrasiveness of

the cleaning technology are interlinked, the present chapter investigates coatings and technologies for in-

water hull cleaning.

There are no publicly acknowledged BATs for in-water hull cleaning, even though California has designated

"interim best management practice" to an in-water scrubber unit with rotating brushes and capture of

biological debris (Hagan et al, 2014). In a recent review by the Ministry of Primary Industries in New

Zealand (Morrisey and Woods, 2015) of in-water hull cleaning no single technology is pointed out as being

superior. In-water technologies are not suitable for all surfaces (Table 5), so what is a BAT for one ship and

its coating may not be as good for another one. The BAT from the environment point of view are the ones

which damage the coating as little as possible, removes as much hull fouling as possible, and also have

capture and cleaning of the produced waste including both residues of ship coating and biofouling.

Table 5: Combinations of hull antifouling systems and in-water hull cleaning technologies, with specified technology and coating

type. SPC: Self-polishing copolymers. "Yes" means that the combination is recommended, "No" means the combination is

discouraged. The table is based on expert information from the coating companies Hempel (Olsen, 2015) and Jotun (Ottosen,

2015) and the underwater cleaning companies DG-Diving Group (Rouhola, 2015) and Gage Roads Franmarine (Taylor, 2015).

In-water hull

cleaning technology

Antifouling coating

Biocidal systems Silicones Mechanically resistant

SPC, rosin-based, metal-

acrylates, nanoacrylates, etc. Fouling release, fouling defence

Epoxy, ceramic or polyester

resins

Multiple brushes Yes No Yes

Contactless system Specialised brush system

Yes Yes No

Water jets High-pressure systems

Yes Yes No

Shrouding Encapsulation

Yes Yes Yes

Hand tools Hand-picking, single-brush,

scrapers etc. Yes Yes Yes

Heat treatment No No Yes

Ultrasonic treatment No information No information No information

Technologies for cleaning the hull and for cleaning the wastewater generated from this activity is explained

in section 5.3 and section 5.4, respectively. A New Zealand report from 2012 focuses on mechanical

removal with the ability to capture debris. Other options for capturing vessel biofouling debris are largely

dismissed because of the amount of time required, difficulty of containing debris, need to apply and

discharge biocides, or other factors (Inglis et al, 2012). In Table 5 the combinations of cleaning

technologies and the coating are assessed with respect to compatibility. The effectiveness with respect to


risk reduction capability and effectiveness regarding NIS removal is not assessed, since no data are

available but recently “procedures for evaluating in-water systems to remove or treat vessel biofouling”

have been presented to close this gap (Morrisey et al 2015).

5.2 Pre-fouling technologies: Vessel antifouling systems

Several types of antifouling systems exist in order to minimise the rate of biofouling settlement and growth

and thus the need for cleaning in either dry-dock or water.

Conventional systems are coatings with or without biocides that can be applied to the vessel hull, but other

systems include the mechanically resistant surfaces, which are made to withstand frequent mechanical

cleaning (Inglis et al, 2013).

5.2.1 Conventional antifouling systems containing biocides

Originally, self-polishing copolymer (SPC) coatings contained tributyltin (TBT), which was effective

against biofouling, but the toxicity was not limited to organisms adhering to the ship and TBT is now

banned in many countries world-wide, including those in the EU. As a response to the TBT ban, SPC

coatings containing copper, zinc, and silyl acrylate have been developed (Morrisey et al, 2013). There are

two types of SPC coatings: fast and slow types which differentiates by softer and harder coating properties.

Fast SPC coatings are applied to slow or rarely used vessels, whereas slow SPC coatings are applied to fast

or busy vessels, since it is the wear and tear of the water that releases the biocide. The lifespan for this type

of coating is 5 years or more (Floerl et al, 2015).

Soluble matrix coatings (or ablative coatings) are coatings where the biocide is dispersed through a

sparsely soluble paint matrix. Hydration causes the surface to slowly dissolve, which enable release of the

freely associated biocide. The matrix is often resin, extracted from pine trees. To control the dissolution of

the soluble biocide, plasticizer or other components are often added (Morrisey et al, 2013). Soluble matrix

coatings are not recommended for vessels that are idle for a longer period, because the coating needs water

movement for the biocide to disperse. The soluble matrix coating has a lifespan of up to 36 months (Floerl

et al, 2015).

Insoluble matrix coatings, also known as hard coatings, contact leaching or diffuse coatings, contain a

binder that is largely insoluble so that biocide release is determined by the biocide content being high

enough to ensure that all biocide molecules are in contact through the dry film. This enables diffusion of

the biocide from within the coating to the surface of the antifouling system though micro-channels created

when the more surficial biocide dissolves. Insoluble matrix coatings are usually made from vinyl or

chlorinated rubber resins, making it harder and thus more resistant than a soluble matrix. The lifetime is

approximately proportional to the logarithm of thickness of the coating layer with a maximum of 1-1.5

years, which has largely restricted their use to the recreational market (Morrisey et al, 2013; Floerl et al,

2015).

Metal-containing coatings often contain particles of copper or a copper-nickel mixed into a polymer

matrix such as epoxy. Commercially available products have extremely hard and impervious resin matrices

with the antifouling effect dependent on exposed metal particles. Toxic material is released and loosely

attached or slightly soluble oxide layer is exfoliated to produce the antifouling effect. These systems are

mostly used in fixed installations where long-term minimisation is need and renewal of antifouling paint

systems is not possible (Morrisey et al, 2013).

Biocide from antifouling coatings will over time be released to the water column, and copper is the most

common biocide. Sweden has banned copper containing antifouling paint for pleasure vessels on the east

coast and restricted the use on the west coast. Also Denmark has restricted the use of copper containing


antifouling paint on leisure boats, depending on the cuprous oxide (Cu2O) leaching rates and on the size of

the vessel. Dissolved Cu2O may reach a concentration that is harmful to marine life and may change the

phytoplankton species that are able to live in a harbour. Laboratory tests have shown that copper

concentrations corresponding to that of German coastal waters causes a significant decrease in

photosynthetic efficiency of microalgae (van Rompay, 2011). In response to these environmental impacts,

biocide-free coatings have been developed.

5.2.2 Other antifouling coatings

Fouling release coatings function without biocides as they have an exceptionally slippery surface that

reduces the strength of the biofouling adhesion and result in macrofouling detaching from the vessel when

the vessel operates at sufficient speed. Common fouling release coatings are based on silicone, as these

have proved more effective than fluorinated polymers. However, these silicone coatings are prone to

damage by conventional in-water cleaning methods (Inglis et al, 2012). Fouling release coatings have a

lifespan of 5 years or more (Floerl et al, 2015). A fouling defence coating has been developed based on

fouling release coatings, and combines the properties of silicone-hydrogel with a biocide (Hempel, 2015).

Mechanically resistant coatings are based on epoxy, ceramic or polyester resins and are hard, smooth and

abrasion resistant (Morrisey et al, 2013). The so-called surface treated composite (STC) coating is an

example of this type of antifouling coating. It that can withstand vigorous cleaning and is thus designed to

be cleaned mechanically on a regular basis (Inglis et al, 2012). A study performed on the STC coating

"Ecospeed" observed traces of solvents and softeners associated with the hardener applied due to cleaning

of the surface, however, the levels were not to have adverse effect on marine life (Inglis et al, 2012).

5.3 Post-fouling mitigation: Technologies for in-water biofouling removal

Elimination of the hull borne species is technically not yet possible even though reduction can be achieved

through the use of pre-fouling technologies (van der Have et al, 2015). Cleaning of the vessels' hull is thus

necessary, e.g. by the in-water technologies. Methods used for biofouling removal in-water vary in size

from manual scrape-off to remotely controlled robots, due to their availability and ability to treat large hull

areas fast versus their ability to treat niche areas. Target areas and restrictions of a technology can be

found in


Table 6 for several types of vessels and in Appendix 2: Summary of methods for removing biofouling from

merchant vessels.

The majority of hull cleaning machines make use of rotating brushes and this technology has been used for

several decades (Bohlander, 2009). The technology is divided into three levels; hand-held devices, diver-

operated brush carts as seen in Figure 14, and ROV or robotic hull cleaners controlled from above water

(Floerl et al, 2015). There are several kinds of brushes available, including soft plastic bristle brushes,

stiffer polymer bristle brushes, composite brushes with both plastic and metal bristles, and all metal bristle

brushes for propeller cleaning and polishing. The brush fit for a certain scenario (combination of fouling

severity, hull construction and coating type) is the brush, which remove fouling effectively without

removing the antifouling coating. Curvature of the hull is a limiting factor especially for multi brush

devices, but systems using one or two brushes for cleaning niche areas have been developed (Grant et al,

2009). A limiting factor is that divers might miss patches of fouling on the hull even when the water clarity

is reasonable good (approximately 1-2 meters). Most of the systems do not have an inherent capability of

capturing and treating the waste from the hull and will have to develop this technology additionally.


Table 6: Overview of treatment technologies that are available for vessel biofouling in New Zealand. The respective vessel

suitability and target application for the technology are specified (Floerl et al, 2015). A similar table can be found in the even

more recent (Morrisey and Woods, 2015).

Treatment method Land

based

In-

water Vessel suitability Target application

Manual removal

Hand-picking • • Recreational and light

commercial vessels Isolated patches of fouling

Hand—removal with brushes,

scrapers and pads • •

Recreational and light

commercial vessels Isolated patches of fouling

Desiccation •

Smaller vessels not restricted

by time in port

All hull surfaces, sea chests

and external structures

Mechanical removal

Rotary brush / pad (hand-held

devices) •

Small commercial vessels

and/or small patches of fouling Continuous sections of hull

Rotary brush / pad (diver-

operated brush carts) • Merchant shipping vessels Continuous sections of hull

Rotary brush / pad (robots and

ROVs) • Merchant shipping vessels Continuous sections of hull

Rotary brush / pad (contactless)

• Merchant shipping vessels Continuous sections of hull

High-pressure water jet (hand

tools) • •

Recreational and light

commercial vessels

Hull sections, sea chests if

gratings removed, isolated

patches of fouling

High-pressure water jet (carts

and ROVs) • Merchant shipping vessels Continuous sections of hull

Cavitational jet (self—propelled,

diver-operated carts and hand-

held pistols)

• Merchant shipping vessels Continuous sections of hull

Vacuum systems *

• Light commercial vessels Isolated patches of fouling

Surface treatment

Hot water / heat / steam

• Merchant shipping vessels

Shrouding technologies

Wrapping

• No length restrictions All hull surfaces including

niche areas

Floating docks

• At present restricted to vessels

< 30 m length

All hull surfaces including

niche areas

Shrouding with toxicant

• All vessels that can be wrapped All hull surfaces including

niche areas

Shrouding with manual or

mechanical cleaning •

Safety considerations will likely

restrict to < 20 m length

All hull surfaces including

niche areas

* Vacuum systems are generally used in conjunction with other removal systems/devices (e.g. hand—picking,

mechanical removal)

Figure 14: To the left a diver cleans a ship hull with a cart (Bohlander, 2009) and to the right another cart is seen from the

bottom. Blades can be attached to the rotating discs and used for silicon and copper oxide coatings (censored by the

manufacturer: Gage Roads Diving Franmarine, 2015).


The contactless mechanical system was developed due to concern of damaging the antifouling coat on the

hull and releasing biocidal waste to the surrounding water with the regular rotating brushes. The systems

consist of counter-rotating brushes, which create suction and hold the cart to the hull, in such way that the

brushes are only just in contact with the hull surface to avoid damage to the coating. As the rotating brush

technology, the contactless system has trouble cleaning curvature on the hull, but two manufacturers apply

it on large ships (Floerl et al, 2015).

The water-jet technology can be divided into three levels like the brush-based system; hand-held devices,

diver-operated carts, and ROVs + robotic carts. Two Norwegian underwater cleaning vehicles are in

production; ECOsubsea and CleanROV are designed to treat biofouling at an early stage of development,

such as slime, algae and soft-bodied organisms, and to retain the organic and inorganic waste. As other

large technologies, the underwater vehicles with water-jets are challenged by curved or structurally

complex surfaces (Floerl et al, 2015). Hand-held water jets function well for niche areas and can be used

for all vessel types as well as for offshore and submersible structures. The high pressure of e.g. 250 bar kills

many organisms during the cleaning, but may spread species that are able to regrow from organism

fractions, as there is generally no method to retain the generated biological and contaminant waste (Inglis

et al, 2012).

The advantage of using robots is that a diver is redundant when the vehicle is operated from above water.

This eliminates the need for a specially trained diver, his surface assistant and the diver's equipment, and it

eliminates the risk for a diver of working in a port, which may have periods of intense traffic. Treatment

times when using water-jet is almost the same as the brush-based cleaning: 800-1000 m2 can be treated

per hour. Even though technologies without a diver may be preferable for cleaning of large hull areas, a

diver with hand tools can clean niche areas that cannot be cleaned with the current large robots. The diver

methods vary from brushes and scrapers to handpicking. However, the latter method can result in

releasing antifouling particles to the water and a risk that the organisms removed from the hull will still be

viable (Floerl et al, 2015).

5.3.1 Other technologies

This section provides information on technologies that have not been found on the Danish market, to

provide an indication of the many emerging technologies.

In heat treatment, the water surrounding fouling is heated to approximately 60 °C, which kills biofouling

on steel-hulled vessels. Two prototype systems have done this effectively when treating biofilm and algal

biofouling. Heat treatment is not intended for heavy biofouling and often does not remove the dead

fouling, which is left for the water to slough it off the hull when the vessel is moving (Floerl et al, 2015).

This treatment has been built into a box, which can heat the water around protruding niche areas

(Morrisey and Woods, 2015).

Ultrasound is sound pressure waves with a frequency above 20 kHz (upper limit of human hearing). The

pressure waves from ultrasonic treatment will inhibit or even kill the biofouling by ultrasonic wave-

induced forces, ultrasonic cavitation, or generating heat. The latter has still not been assessed for their

ability to remove biofouling and is still in development (Floerl et al, 2015). Ultrasound may be combined

with water-jets, incorporating microscopic bubbles into the water. This allegedly allows relatively low

water jet pressure to be used because the bubbles collapse (implode) on contact with the treated surface,

creating very high, localised pressures (Morrisey and Woods, 2015).

Shrouding technologies use impermeable materials such as polythene sheeting or tarpaulins to enclose the

vessel. "Shrouding" is done by a waterproof material in one piece and "wrapping” by a strip that is

wrapped round and round the vessel. When the vessel is encapsulated, the fouling organisms are deprived

of light and food. As the organisms continue their respiration, the dissolved oxygen in the encapsulated


water is depleted. The anoxic environment is over time lethal to the enclosed organisms and is an effective

treatment for vessels that are heavily fouled, but takes weeks rather than days to complete. If rapider

mortality is desired, chemicals can be added to the enclosure, such as sodium hypochlorite, sodium

sulphide, acetic acid, and sugar, of which the latter can stimulate bacterial decomposition. If water

containing these chemicals is discharged directly from the enclosed system it can have unwanted effects on

surrounding environment. Freshwater can also be added to wrapping around a boat normally sailing in

saline waters (Inglis et al, 2013).

Another shrouding technology is the floating dock, which can bee seen in Figure 15. This method can be

used by smaller vessels (4.5 to 30 meter) and keeps the vessel dry with a water pump built into the dock

floor. During dry docking mode, electronic sensors activate the pump if it rains or the waves are high, and

the pump switches off when there is no more water in the floating dock (FAB Dock, 2015).

Figure 15: Shrouding technology – a floating dock in use (FAB Dock, 2015).

5.4 Improvement: Capture and removal of solid waste

Hagen et al. (2014) noted that underwater hull cleaning service providers are reluctant to invest in

development of in-water cleaning technologies that also capture waste in absence of regulatory drivers that

require shipping companies to use them. Ship hull and niche cleaning technologies either treat/kill

biofouling and leave it on the ship or they remove biofouling from the ship hull. The technologies that

remove biofouling aim at removing as little as possible of the antifouling system. This protects the

surrounding environment from excessive contamination in form of biocidal products, but in order to

protect the environment from NIS on-site capture of detached live organisms is needed too. Examples are

given below.

Professionally used technologies such as ROVs and diver operated carts have the possibility of building in a

method to remove the generated waste, such as a suction hose connected to a pump connected to a

separation unit. This is relatively straightforward in conjunction with technologies such as vacuum systems

that already apply suction. Dispersing technologies such as high-pressure water jets, which forces the

biofouling off the surface are more challenged since containment of the detached biofouling waste is

difficult. These systems may instead apply a much bigger enclosure that can contain ship, instruments and

operator(s) during the session of managing biofouling with the treatment or removal technology of choice

(Morrisey and Woods 2015)

Water may be treated where the cleaning takes place either above water, e.g. filtration on a nearby vessel,

or in-water such as a filter built into the ROV. When filtrating the wastewater on a nearby vessel, there is a

tube connected to the cleaning method that through hydraulic suction leads the wastewater to the vessel,

where the filter is mounted. The effect of filtration depends on the filter pore size because smaller


organisms can pass the filter and some larger organisms may regrow from debris or micro-size life stages

(Morrisey and Woods 2015). Some companies use several filtration steps, each with different filter pores,

in order to filter out as much of the solid substances as possible. After the process water is treated, it is

discharged to the sea as waste water, which in practice means that it may to have to be cleaned to a better

quality than before it was taken up for the in-water cleaning (Petersen, 2015a).

In addition to the filter technology on a nearby vessel, pre-filter flocculation can be added to remove more

of the soluble and fine particles and ultraviolet (UV) irradiation can be added as a final treatment before

discharge of the water into the sea in order to treat organisms smaller than the filter pore size. Heating or

biocides such as chlorine may also be used for treating the water.

Another way to spare the surrounding environment of most of the hull cleaning waste is to collect the

process water and let a land-based wastewater plant handle the treatment (Petersen, 2015b). Likewise,

the solid waste from the filtration steps etc. described above may be disposed of via land-based waste

management (City of Copenhagen, 2015a; Hansen, 2015b).

5.5 Examples of commercially available in-water cleaning solutions

The company Mermaid Marine Service ApS offers in-water hull cleaning from a nearby vessel. A diver

controls a cleaning head mounted on the end of a hose from the vessel. The head consists of three rotation

brushes made of soft polypropylene, and sucks the released fouling through a filter placed up on the ship.

To minimise the release of particles to mix with the surrounding water, “curtains” are attached to the

cleaning head and a colouring is used to monitor the suction efficacy. The filter pore size can be from 10

microns and up. After cleansing and separating the solid particles from the water, the water is returned to

the harbour (City of Copenhagen, 2015a).

The company GAC EnvironHull Ltd has presented a remotely operated vehicle (ROV) to operate a cleaning

head that cleans ship hulls with adjustable water pressure jets. The cleaning unit sucks water into the ROV,

where it is filtered down to 25 microns before discharge into the harbour (City of Copenhagen, 2015b).

Gage Roads Diving Franmarine in Australia has developed a portable multi-filter system called

"Envirocart". The system is a diver-operated cart, which have hydraulically powered rotating discs that can

either be fitted with blades or brushes. A vacuum pump and a shroud system are also incorporated to

contain the particles within the suction area. The water and particles are lead to a two-stage treatment

system located on a supporting vessel. The filters remove particles >5 μm before the filtrate is irradiated

with UV light and discharged back into the ocean (Inglis et al, 2013). The company also has a series of

solutions for niche area cleaning with waste collection. The company is planning on offering their services

in Danish waters during 2016 (Taylor, 2015).

The Norwegian company ECOsubsea using water pressure jets on a ROV also plans on offering their

services in Danish waters during 2016 (Andersen, 2015).


6. Conclusions and recommendations

6.1 Conclusions

Non-indigenous species (NIS) most likely carried with ship hulls are found in the Danish environment

based on the information from studies and limited surveys of the marine environment. The actual number

of species varies according to the source (from 7 to 19) and a tentative list of 12 species is provided. There

is currently no monitoring of the targets for NIS, or for hull fouling NIS, in relation to the MSFD D-2. A

proposal for general NIS monitoring is available in Andersen et al (2014), but it is not directed towards

risks associated with biofouling.

The commercial fleet is likely to be an important vector for primary dispersal of NIS from biofouling,

whereas recreational crafts are an important vector for secondary dispersal. Commercial fishing vessels

may be a less important vector. The potential risk areas for hull fouling NIS include locations where the

merchant fleet’s vessels may spend longer time periods. This would be the Danish Port of Refuge areas, in

particular Ålbæk Bight, Kalundborg Fjord and in Tragten by Fredericia, which are used for shorter lay-up

periods awaiting new cargo and the areas for ship-to-ship transfer south of Samsø and east of

Frederikshavn. In addition, frequent bunkering operations areas takes place in Ålbæk Bight, Tannis Bight,

Kalundborg Fjord and in the Sound off Copenhagen. Ship recycling takes place in four ports where the

obsolete vessels may be found moored for some time while being dismantled (Esbjerg, Frederikshavn,

Odense (Lindø) and Grenaa).

Secondary transfers may be picked up in marinas if monitored for NIS related to hull fouling. Also,

stepping stones for NIS may be permanently immersed structures such as windmill foundations and other

open water installations on soft bottoms. Shore based structures includes floating docks and wharves, and

offshore structures includes buoys and rig structures.

The risk of NIS transfer is the lowest when a hull is cleaned in dry docks or on slipways where the waste is

collected and properly disposed of via land-based facilities. Vessels with larger docking intervals

increasingly choose intermediate cleaning of the hull with in-water technologies. The technologies used for

in-water cleaning in Denmark are mainly diver-operated vehicles employing rotary brushes systems, but

remotely operated vehicles or high-pressure water jets are also offered. Operators occasionally collect

debris when in-water cleaning is performed in ports but this is not the case if the cleaning takes place at

anchorage or further from shore.

The in-water hull cleaning activities in ports are managed by local municipalities, which grant a cleaning

company license to clean for one year at a time in order to ensure that best available technology (BAT) is

used. The cleanings performed at anchorages and further from shore are subject to no surveillance. The

cleaning frequency in Danish ports was low in 2015: Only one ship was reportedly cleaned in one harbour.

In comparison, at least 25 hull cleanings were conducted outside the defined port areas in 2015.

The BAT would include capturing and treating the generated solid waste and wastewater, so that all

biological material is removed or non-viable when released back into the sea. Systems that use rotating


brushes or water jets in a vehicle with a suction mechanism to contain the waste for treatment are likely to

achieve this goal. Technologies applied for water treatment after hull cleaning are filtering, flocculation and

disinfection by UV irradiation or heat treatment. Such new technologies are entering or already on the

market although they may still be in the early stages. The BAT within in-water hull cleaning for the

merchant fleet is in the possession of companies, providing services on a commercial basis to shipowners,

and under the environmental authorities’ supervision. This market has few players in Denmark and can be

influenced regarding BAT with relative ease, with a possible minor challenge regarding off site in-water

cleaning activities. In contrast, recreational crafts are normally maintained by the owner in the marinas

(57,000 boats and 300-400 marinas), and there appear to be room for improvement as to the BAT and on

how or where the hull cleaning activities on boats should be conducted. It was reported that biofouling

waste in some marinas was discarded back into the water.

In Denmark and neighbouring countries (Finland, Germany, Netherlands, Norway, Poland, Scotland,

Sweden) no specific guidelines are issued regarding in-water hull cleaning, and most authorities refer users

to the IMO Hull fouling guidance document.

The currently available data on Denmark from national and regional monitoring are from a variety of

unevenly scoped resources, with information comprising local observations, regional databases and

various public monitoring programs, which will not necessarily provide information relevant for

assessment of environmental status or a proxy thereof, with respect to NIS from biofouling.

6.2 Recommendations

These recommendations are not ranked or hierarchically presented.

Recommendation 1:

Desktop identification of D-2 relevant risk areas through a risk assessment exercise: Use the extensive

traffic data from shipping to depict detailed images and key indicators relevant for hull fouling such as

residence time. E.g. the number of days that the wetted surfaces of ships are exposed in Danish EEZ can

relatively easily be calculated (m2 * d) and mapped showing areas where ships stay longer thus increasing

risks. This can be elaborated further including biological parameters of target species, seasonal biological

changes (i.e. spawning periods), port of origin, time since docking and other risk characteristics.

Recommendation 2:

Monitoring of NIS in hot spots may be considered, this being industrial harbours, marinas, STS areas, port

of refuge and bunkering locations. The surveillance could be in combination with samples that is already

required in connection with dredging and hull cleanings, i.e. samples used for determination of metal or

biocide concentrations. A useful and cost effective solution to this monitoring could be the eDNA

technique.

Recommendation 3:

The responsibilities for managing in-water cleaning outside of port areas should be clarified and a uniform

monitoring guidance for this and port in-water cleaning developed for the municipalities to use. This may

include an updated BAT.

Recommendation 4:

Two communication initiatives: One directed towards the recreational craft owners and towards the local

marinas to increase awareness of the problem also among private actors and inform on BAT. Another

effort towards the shipowners, service suppliers and local municipalities regarding BAT relevant for in-

water hull cleaning, i.e. collection and treatment of waste and wastewater.


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Appendices

Appendix 1 Draft indicative list of non-indigenous species in Danish marine waters .. 55

Appendix 2 Summary of methods for removing biofouling from merchant vessels ..... 64

Appendix 3 Invasive Marine Species Risk Assessment and Management Options Flow

Chart ...................................................................................................... 68


Appendix 1 Draft indicative list of non-indigenous species in Danish marine waters

The following table is from Appendix 1 in Stæhr & Thomsen (2012). A project during winter 2015/2016 will update the table (Stæhr, 2015). For macro algae, benthic

invertebrates and zooplankton, the frequency of occurrence is presented in % (individual species/total species × 100). Dispersal history of individual species as well as

quantitative estimates when available can be found in the references of Stæhr & Thomsen (2012). A question mark "?" represents unknown information.

Taxa Art Oprindelse Sprednings-

vektor

Ankomst

Danmark

Hyppighed &

udvikling

Kommentarer Referencer

Blomster-plante Spartina anglica

(Engelsk vadegræs)

N. Amerika /

England

Udplantning 1930-40

Vadehavet

Danner tætte

bestande i tide-

vandszonen (~

10%)

I vækst

Veletableret i Vadehavet.

fjorde i Kattegat og

Bælthavet

Nehring & Adsersen 2006

Randløv 2007

Makroalge

(rødalge)

Aglaothamnion

halliae

Muligvis V.

Atlanterhav

Muligvis

Skibsskrog

2003?

I Norge i

1980erne, i

Sverige i 2003

Ukendt Samme som

Callithamnion halliae,

Aglaothamnion

westbrookiae

http://www.frammandearter.se

Makroalge

(rødalge)

Bonnemaisonia

hamifera Hariot

(Krogalge)

V. Stillehav Skibsskrog 1900

Avg: 1%

Max:1.8%

Stagneret

Kun tetrasporophyter

Nordsøen, Skagerak,

Kattegat

Thomsen et al. 2007

Thomsen et al. 2008b

Makroalge

(rødalge)

Dasya baillouviana

(S. G. Gmelin)

(Dusktang)

Middelhavet Østers?

skibsskrog?

1961

Nyborg

Avg: 0.4%

Max: 1%

Stagneret

Stigende forekomst de

seneste år

Kattegat, Bælthavet,

Østersøen

Thomsen et al. 2007




vektor

Ankomst

Danmark

Hyppighed &

udvikling


Makroalge

(rødalge)

Gracilaria

vermiculophylla

(Ohmi) Papenfuss

(Gracilariatang)

V. Stillehav Østers 2003

Horsens Fjord

Avg: 0.02%

Max: 0.10%

I vækst

Stigende forekomst de

seneste år

Nordsøen, Kattegat

Thomsen et al. 2007


Makroalge

(rødalge)

“Heterosiphonia

japonica”

Stillehavet Østers?

skibsskrog?

2005

Limfjorden

Avg: 0.13%

Max: 0.13%

I vækst

Samme som Dasysiphonia

sp.? Normal i Norge

Kattegat

Thomsen et al. 2007


Makroalge

(rødalge)

Neosiphonia harveyi

(J. Bailey) Kim, Choi,

Guiry & Saunders

Stillehavet/NV

Atlanterhav

Epifyt? 1986

Ukendt

Avg: 0.006%

Max: 0.10%

I vækst

Samme som Polysiphonia

harveyi. Forveksles nemt

med andre Polysiphonia-

arter

Kattegat

Thomsen et al. 2007


Makroalge

(brunalge)

Colpomenia

peregrina Sauvageau

(Østerstyv)

Vestlige

Stillehav

Østers 1939

Limfjorden

Avg: 0.02%

Max: 0.15%

Stagneret

Forekommer mest om

foråret og overses derfor

nemt i sommer-

kortlægningen.

Kattegat

Thomsen et al. 2007


Makroalge

(brunalge)

Dictyota dichotoma

(Hudson) J.V.

Lamouroux

(Tvedelt bændel-alge)

Atlanterhavet Østers?

Naturlig?

1939

Limfjorden

Avg: 0.6%

Max: 1.2%

Aftagende

Kan være hjemmehørende

Skagerak, Limfjorden

Thomsen et al. 2007




vektor

Ankomst

Danmark

Hyppighed &

udvikling


Makroalge

(brunalge)

Fucus evanescens C.

Agardh

(Langfrugtet

klørtang)

Nordatlanten Skibsskrog?

Naturlig?

1948

Øresund

Avg: 0.08%

Max: 0.24%

Aftagende

Muligvis hjemmehørende.

Kan forveksles med andre

Fucus-arter - især små

individer

Skagerrak, Kattegat,

Limfjorden, Bælthavet

Thomsen et al. 2007


Makroalge

(brunalge)

Sargassum muticum

(Yendo) Fensholt

V. Stillehav Østers? 1984

Limfjorden

Avg: 2%

Max: 6%

Stagneret?

Meget hyppig i Limfjorden

Nordsøen, Skagerrak,

Limfjorden, Kattegat

Thomsen et al. 2007


Makroalge

(grønalge)

Codium fragile ssp.

tomentosoides (van

Goor) P.C. Silva

(Gaffelgrenet

plysalge)

V. Stillehav Østers?

skibsskrog?

1919

Hirsholmene?

Avg: 0.2%

Max: 0.6%

Aftagende

Codium-underarter er

svære at skelne

morfologisk og behandles

derfor som en art i

overvågningsprogrammet

Nordsøen, Skagerrak,

Limfjorden, Kattegat,

Bælthavet

Thomsen et al. 2007


Fytoplankton

(dinoflagellat)

Prorocentrum

minimum

? ? 1981

Op til > 50 mio

celler/L

Aftagende?

Dannede specielt i

1980’erne og 1990’erne

meget kraftige

opblomstringer i mange

danske fjorde. Er siden år

2000 forekommet i lavere

koncentrationer

Bjergskov et al. 1990



vektor

Ankomst

Danmark

Hyppighed &

udvikling


Fytoplankton

(dinoflagellat)

Karenia mikimotoi

(=”Gyrodinium

aureolum”, =

”Gymnodinium

mikimotoi”)

? ? 1968

Op til > 10 mio

celler/L

Aftagende?

Er med sikkerhed set i

specielt Nordsøen,

Skagerrak, Kattegat (inkl.

Limfjorden) - og i få

tilfælde i Bælthavet og

Øresund.

Bjergskov et al. 1990

Fytoplankton

(dinoflagellat)

Gymnodinium

chlorophorum

? ? 1999?

Op til > 7,8 mio

celler/L

I vækst

Dannede massiv

opblomstring i Skagerrak-

Kattegat i det sene

efterår/vinter 2009. Arten

er i modsætning til de

fleste andre dinoflagellater

grøn, hvilket ikke kan ses i

lugolfikserede prøver. Det

kan derfor ikke med

sikkerhed siges, at den

ikke har været i danske

farvande tidligere.

Hansen et al. 2000

Fytoplankton

(dictyocho-

phyceae)

Pseudochattonella

verriculosum

? ? 1998

Op til > 19 mio

celler/L

I vækst

Første opblomstring

forekom i Kattegat-

Skagerrak-Nordsøen i

vinter-forår 1998.

Opblomstringen medførte

massiv fiskedød. Siden da

er denne art blevet en

næsten årligt tilbage-

vendende del af

forårsfytoplankton.

Markager et al. 1999



vektor

Ankomst

Danmark

Hyppighed &

udvikling


Fytoplankton

(raphidophyceae

= flagellat)

Heterosigma

akashiwo

? ? 1988

Limfjorden

Op til ca. 2 mio

celler/L

Observeret i Kattegat Bjergskov et al. 1990

Pelagisk

makroinvertebrat

(ribbegoble)

Mnemiopsis leidy

(”Dræbergoble”)

V. Atlanterhav Ballast vand 2007

Lille- og

Storebælt

Op til ca. 600

indv./m3

Stagneret?

Observeret i samtlige

danske farvande i 2005-07

Næsten ingen

observationer i 2011

Tendal et al. 2007

Riisgård et al. 2010

Pelagisk

invertebrat

(vandloppe)

Acartia tonsa Indo-pacific Ballast vand? 1925?

Avg: <4%

Max: 19%

Aftagende

Kattegat og Østersøen

(Mest i Kattegat)

MADS

BSASD

Pelagisk

invertebrat

(dafnie)

Penilia avirostris Subtropiske og

tropiske

havområder

Ballast vand 2001 Avg:<0.5%

Max: 2%

Kattegat og Østersøen

(Mest i Kattegat)

MADS

Søndergaard et al. 2006

Parasit

invertebrat

(fladorm)

Pseudodactylogyrus

anguillae Yin &

Sproston

V. Stillehav Import af

Japanske ål?

1985 ?

?

Vært (ål), parasit

Kattegat, Bælthavet

Jensen et al. 2005

Køie 1988

BSASD

Parasit

invertebrat

(fladorm)

Pseudodactylogyrus

bini Kikuchi


Japanske ål?

1985

Esrum sø

?

?


Østersøen?

Jensen et al. 2005

Køie 1988

Parasit

invertebrat

(nematod)

Anguillicola crassa

Kuwahara, Niimi &

Itagaki


Japanske ål?

1985?

?

?

?



Østersøen

Jensen et al. 2005

Køie 1988

BSASD



vektor

Ankomst

Danmark

Hyppighed &

udvikling


Parasit

invertebrat

(copepod)

Mytilicola intestinalis

Steuer

Middelhavet Ballast vand?

Østers? På

skibsskrog?

1964 ?

?

Parasit i muslinger

Limfjorden

Jensen et al. 2005

Bentisk

makroivertebrat

(børsteorm)

Ficopomatus

enigmaticus Fauvel

Australia?

India?

Skibsskrog?

Naturlig?

1939

Marstal

?

Stagneret?

Fasthæftet, hårdbund,

epifauna, kan danne rev

på blødbund, filtrator

Kattegat

Jensen et al. 2005

Bentisk

makroivertebrat

(hydroid)

Cordylophora caspia

Pallas

Ponto -

Caspiske hav

Skibsskrog 1895

Ringkøbing

Fjord

?

?

Findes pt. i Ringkøbing

Fjord og Nissum Fjord

(Jensen og Knudsen 2005)

Bentisk

makroivertebrat

(børsteorm)

Marenzelleria viridis

Verril

NV Atlanterhav Ballast vand? 1990

Ringkøbing

Fjord

Avg: 0.5%

Max: 1.5%

I vækst

Samme art som M. wireni.

Muligvis flere arter (M

neglecta). Fasthæftet,

blødbund, infauna

På lavt vand (<5m).

Nordsøen, Kattegat,

Bælthavet

Jensen et al. 2005

BSASD

Thomsen et al. 2008b, 2009

Banta 2010 (i Thomsen og

Stæhr 2010)

Bentisk

makroivertebrat

(børsteorm)

Neanthes succinea

Frey og Leuckart

Nordamerika,

Øslige

Sydamerika, V.

Afrika

? 1940

Kattegat

Avg: 0.2%

Max: 0.9%

I vækst

Samme art som Nereis

succinea og Alitta

succinea. Lever på blødt

(og hårdt) substratrat,

både som in- og epifauna,

mobil predator

Isefjord, Limfjord

Jensen et al. 2005




vektor

Ankomst

Danmark

Hyppighed &

udvikling


Bentisk

Makroivertebrat

(snegl)

Crepidula fornicata

L.

NV

Atlanterhavet

Østers? 1934

Vadehavet og

Nissum

Bredning

Avg: 0.02%

Max: 0.1%

I vækst

Lever på hårdbund,

epifauna, filtrator


Vadehavet

Jensen et al. 2005


Bentisk

Makroivertebrat

(snegl)

Potamopyrgus

antipodarum (Gray)

New Zealand Ballast vand? <1914

Randers Fjord

Avg: 1%

Max: 7%

Aftagende

Lever på blødbund,

epifauna, substratæder.

Kattegat, Østersøen

Jensen et al. 2005


Bentisk

Makroivertebrat

(snegl)

Ocinebrellus

inornatus

(Østersboresnegl)

N. Stillehav På

Stillehavsøsters

2006

Nissum

Bredning

?

I vækst

Observeret i store dele af

Limfjorden

Lützen et al. (i Thomsen og

Stæhr 2010)

Bentisk

makroivertebrat

(musling)

Petricola

pholadiformis

Lamarck

NV

Atlanterhavet

Østers? 1905

Vadehavet

Avg: 0.03%

Max: 0.1%

Stagneret?

Lever i relativt hårdt

substrat (kalksten,

skiffer), infauna (borer),

filtrator

Vadehavet, Skagerak,

Limfjorden, Kattegat

Jensen et al. 2005


Bentisk

makroivertebrat

(musling)

Ensis americanus

Gould

NV

Atlanterhavet

Ballast vand? 1981

Vadehavet

Avg: 0.01%

Max: 0.1%

I vækst

Lever på blødbund,

infauna, filtrator

Vadehavet, Skagerrak,


Bælthavet

Jensen et al. 2005




vektor

Ankomst

Danmark

Hyppighed &

udvikling


Bentisk

makroivertebrat

(musling)

Crassostrea gigas

Thunberg

V. Stillehav Larvedrift og

akvakultur

1980

Vadehavet

?

?

Fasthæftet, lever på

hårdbund, epifauna, kan

danne rev på blødbund,

filtrator

Kattegat, Bælthavet

BSASD

Wrange et al. 2009

Bentisk

makroivertebrat

(musling)

Teredo navalis L Kinesiske hav I skibsskrog

eller

drifttømmer

1853

Kiel bugt

Nissum

Bredning

?

?

Lever på hårdt substrat

deposit feeder

Kattegat og Bælthavet

Jensen et al. 2005

BSASD

Bentisk

makroivertebrat

(musling)

Mya arenaria L. NV

Atlanterhavet

Importeret? <1200?

?

Avg: 3%

Max: 9%

Stagneret

Sandsynligvis intro-

duceret fra Nordamerika

af vikingerne. Diskuteres

om arten skal betragtes

som introduceret.


Østersøen

Jensen et al. 2005


Bentisk

makroivertebrat

(rur)

Balanus improvisus

Darwin

V. Atlanterhav I skibsskrog

eller

drifttømmer

1880

København

Avg: 0.1%

Max: 0.3%

Stagneret


hårdbund, epifauna,

filtrator

Almindelig i det meste af

Danmarks farvande

Jensen et al. 2005


Bentisk

makroivertebrat

(rur)

Elminius modestus

Darwin

Australien,

New Zealand?

Skibsskrog 1978

Vadehavet

?

?



filtrator

Vadehavet

Jensen et al. 2005



vektor

Ankomst

Danmark

Hyppighed &

udvikling


Bentisk

makroivertebrat

(krabbe)

Eriocheir sinensis

Milne-Edwards

V. Stillehav Ballast vand? 1927

Nordjylland

?

?

Lever på blødbund (i

banker), ses hovedsageligt

i ferskvand og brakvand


Østersøen

BSASD

Bentisk

makroivertebrat

(krabbe)

Rhithropanopeus

harrisii

(Østamerikansk

brakvandskrabbe)

Amerikanske

østkyst

Ballast vand? 1936

(i Østersøen)

?

I vækst?

Gammel gæst?

Østersøen

BSASD

Tendal (i Thomsen og Stæhr

2010)

Bentisk

makroivertebrat

(Søpung)

Styela clava

Herdman

NV stillehav Ballast vand?

Østers? På

skibsskrog?

1984

Limfjorden

Avg:<0.0001%

Max: 0.0001%

Stagneret



filtrator

Vadehavet, Limfjorden

Jensen et al. 2005


BSASD

Pelagisk vertebrat

(Fisk)

Neogobius

melanostomus

(sortmundet kutling)

Sortehavet og

Det Kaspiske

Hav

Ballastvand eller

via kunstige

kanaler

2008

Borneholm

Observeret

mindst 10

gange i 2009

I vækst

Eneste invasive fiskeart vi

har i Danmark.

Den eneste ikke

hjemmehørende

saltvandsfisk, som yngler i

dansk farvand.

Bælthavet og Østersøen

www.fiskeatlas.dk

Azour et al. (2011)

Pelagisk vertebrat

(Fisk)

Oncorhynchus mykiss

(Regnbueørred)

Nordamerika Dambrugsfisk 1894 Hyppig, især

nær dambrug

Yngler sporadisk.

Undslipper fra dambrug


Bælthavet, Østersøen

www.fiskeatlas.dk

http://www.fiskeatlas.dk/

http://www.fiskeatlas.dk/


Appendix 2 Summary of methods for removing biofouling from merchant vessels

The following table is from Inglis et al. (2013). All values are in New Zealand dollar, which in December 2015 is approximately 4.6 Danish krone.





Appendix 3 Invasive Marine Species Risk Assessment and Management Options Flow Chart

In the following flow chart from the company Woodside, IMSMP = Invasive Marine Species Management Plan and IMSMA = Invasive Marine Species Management Area

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