Dublin Bay - Ecology 2003 - EPAboth North and South Dublin Bay, including the Bull Wall Sands portion of the Liffey Estuary. 3. METHODOLOGY As part of the Environmental Impact Statement

Dublin Bay Power Plant

Monitoring of Estuarine Ecology

INTEGRATED POLLUTION CONTROL

LICENCE REGISTER NUMBER: 486

LICENSEE: SYNERGEN LIMITED

June 2003

Report P04E312A – R2

Stephen Court, 18/21 St. Stephen's Green, Dublin 2, Ireland.

Telephone: +353-1-7038000 Fax: +353-1-7037186 In association with:

Ecological Consultancy Services Ltd (EcoServe) B19 KCR Industrial Estate

Kimmage Dublin 12

Eleanor Mayes, Ecological Consultant Old Post Office

Ashford Co Wicklow

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Monitoring of Estuarine Ecology IPC Licence Reg. No. 486

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Table of Contents

1. INTRODUCTION ..............................................................................................................2

2. CONSERVATION DESIGNATIONS ................................................................................2

3. METHODOLOGY .............................................................................................................2

3. 1 LITTORAL SURVEY....................................................................................................................... 3

3. 2 SUBLITTORAL SURVEY................................................................................................................. 3

4. RESULTS .........................................................................................................................3

4. 1 LITTORAL SURVEY....................................................................................................................... 3

Upstream of outfall............................................................................................................3

Adjacent to the outfall .......................................................................................................4

Downstream of the outfall .................................................................................................4


Upstream of outfall............................................................................................................4

Adjacent to the outfall .......................................................................................................4

Downstream of the outfall .................................................................................................4

5. DISCUSSION....................................................................................................................5

5. 1 LITTORAL SURVEY....................................................................................................................... 5


5. 3 THE EFFECTS OF RESIDUAL CHLORINE ON RECEIVING WATERS................................................ 7

5. 4 THE EFFECTS OF THERMAL DISCHARGE ON RECEIVING WATERS.............................................. 8

6. RECOMMENDATIONS ....................................................................................................9

7. REFERENCES .................................................................................................................9

APPENDIX 1: MAPS.................................................................................................................11

APPENDIX 2: LITTORAL AND SUBLITTORAL FLORA AND FAUNA..................................11

APPENDIX 3: PHOTOGRAPHS...............................................................................................19

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1. INTRODUCTION Dublin Bay Power Plant at Pigeon House Road, Ringsend, Dublin was fully commissioned in May 2002. As part of Condition 6.11 of Integrated Pollution Control (IPC) Licence Reg. No. 486 issued by the Environmental Protection Agency (EPA) the station is required to undertake a biological survey of the Liffey estuary upstream and downstream of the cooling water channel outfall in order to monitor the effect on the receiving environment.

ESB International was commissioned to undertake the necessary study and this report outlines the results of investigations undertaken.

2. CONSERVATION DESIGNATIONS As part of the Environmental Impact Statement (EIS) for the power station in October 1998, a baseline study of the estuarine ecology was carried out by Environmental Consultancy Services (EcoServe), B19 KCR Industrial Estate, Kimmage, Dublin 12.

There have been some changes in conservation designations applying to areas in the vicinity of Dublin Bay Power Station since the EIS was prepared. The entire intertidal area of South Dublin Bay was listed as a candidate Special Area of Conservation (SAC) under the Habitats Directive in 1999. Changes have also been proposed to the boundaries of the Special Protection Area (SPA) designations in both South Dublin Bay and North Dublin Bay, to include intertidal areas that are not in State ownership. In South Dublin Bay it is proposed that the SPA designation will cover the entire intertidal area west of Dun Laoghaire Pier. In North Dublin Bay, it is proposed that most of the intertidal area of the Liffey Estuary is included, with the exception of a minor area adjoining the Dublin Port navigation channel which is exposed only on low spring tides. Neither of these proposed SPA boundary changes have been confirmed (as of June 2003).

The boundary changes do not have any additional implications for the operation of Dublin Bay Power Station. The Bull Wall Sands portion of Liffey Estuary, which lies between the North Bull Wall and the Navigation Channel in the Liffey, is included in the extended SPA designation of North Dublin Bay, because of the internationally important numbers of wintering waterfowl that use it in addition to other intertidal areas of the bay.

There are only very limited areas of intertidal shore exposure in the immediate vicinity of the cooling water discharge from Dublin Bay Power Station, along the southern side of the Liffey Quays. These areas are used occasionally by small numbers of wintering waterfowl. The significant concentrations of waterfowl occur on the extensive areas of sand and mudflats in both North and South Dublin Bay, including the Bull Wall Sands portion of the Liffey Estuary.

3. METHODOLOGY As part of the Environmental Impact Statement (EIS) for the power station in October 1998, a baseline study of the estuarine ecology was carried out by Environmental Consultancy Services (EcoServe), B19 KCR Industrial Estate, Kimmage, Dublin 12. Fieldwork for this investigation was also carried out by EcoServe, in April 2003, and was under the direction of Eleanor Mayes, Ecological Consultant, Old Post office, Ashford, Co Wicklow.

Sampling locations for the current monitoring study were selected to replicate, as closely as possible, those of the baseline survey to enable direct comparison between the two studies. This included an examination of the intertidal quay and sections of various structures in the

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estuary and a number of sublittoral grab samples, both upstream and downstream of the cooling water outfall channel.

3. 1 LITTORAL SURVEY

Littoral sampling was conducted on the 22nd April 2003, at low water spring tides. A total of 12 sites were examined for the baseline survey in 1998. However, four of these sites (L9 - L12) are no longer accessible, as they were located along the outfall channel of the power station, and two others (L5 and L6) were too shallow to access at the time of the survey.

A total of six sites were examined (Appendix 1, Figure 1, Appendix 2, Table 2.1). The sites were examined and lists of species and their relative abundance were recorded (Appendix 2, Table 2.3). Species that could not be identified in situ were preserved in 70 % Industrial Methylated Spirits (IMS) and returned to the laboratory for identification. Species were identified to the lowest taxonomic level possible and nomenclature followed Howson & Picton (1997). Abundances were applied following the six-point abundance scale in Hiscock (1996).

Photographs were taken to illustrate the littoral sites and the species present (Appendix 3, Plates 3.1 – 3.12).

3. 2 SUBLITTORAL SURVEY

Sublittoral sampling was conducted on the 22nd April 2003. The same eight sites that were examined in 1998 during the baseline survey were resurveyed for benthic fauna and flora (Appendix 1, Figure 1, Appendix 2, Table 2.2), ranging from immediately downstream of the East Link Toll Bridge to the South Wall Lighthouse. In 1998 a biological dredge (approximately 50 cm by 25 cm) with a 1 cm mesh bag was used. However, in the 2003 survey a van Veen grab (0.1 m2) was used as it was considered a more suitable method as the substrata consisted of soft mud and is quantitative.

The grab was deployed over the side of the boat, which was fitted with a pot-hauler for retrieval (Appendix 3, Plate 3.13). The samples were washed through a 1 mm mesh sieve and the material collected was sorted onboard. Species which could not be identified in situ were preserved in 70 % Industrial Methylated Spirits (IMS) and returned to the laboratory for identification. Specimens were identified to the lowest possible taxonomic level (Appendix 2, Table 2.4). The abundance of fauna was recorded and a voucher collection of representative specimens was retained. Species nomenclature follows Howson & Picton (1997). Where possible notes on the substratum type were taken.

Photographs were taken to illustrate the sublittoral sites and the species present (Appendix 3, Plates 3.13 – 3.15).

4. RESULTS


Upstream of outfall

The quay walls were examined upstream of the Ringsend power station outfall at sites L1 and L2 (Appendix 2, Table 2.3, Appendix 3, Plates 3.1-3.3). These sites were characterised by a zone of the ephemeral green algae, Enteromorpha spp. followed by a band of spiralled wrack Fucus spiralis with the green algae Enteromorpha spp. and barnacles. Below this was a zone

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of the red algae Rhodothamniella floridula with occasional patches of Porphyra sp., Enteromorpha spp., and the fucoid Fucus vesiculosus.

Adjacent to the outfall

Two sites, L3 and L4, adjacent to the Ringsend power station outfall were examined (Appendix 2, Table 2.3, Appendix 3, Plates 3.4-3.6). At L3 the steel pilings were covered with Enteromorpha spp. and barnacles with Fucus vesiculosus on top of the pilings. Small patches of Porphyra sp. and the limpet, Patella vulgata occurred below this. Cooling water was being discharged from the outfall at this point and had a scum on the surface. The water at site L4 also had scum on the surface. The fauna and flora were similar to sites L3 but the littorinid, Littorina saxatilis was present in the barnacle/limpet zone and the mussels Mytilus edulis occurred below this and were covered in a dense layer of silt. Sites L5 and L6 were too shallow to survey.

Downstream of the outfall

Two sites, L7 and L8, located downstream of the outfall were examined (Appendix 2, Table 2.3, Appendix 3, Plates 3.8-3.12). Site L7 on the North Bank Light consisted of wooden and concrete structures with a band of Enteromorpha spp. with a zone of barnacles with the small winkle Melarhaphe neritoides and mussels, Mytilus edulis in crevices. Below this zone the flora and fauna were covered in a fine layer of silt. Site L8 was situated on the lighthouse at the North Bull and had the highest number of species present. There was a wide band of dense barnacles with barnacle spat, small mussels, littorinids, limpets and red and green algae. Below this zone was a slightly narrower zone of abundant mussel seed, barnacles, limpets and green and red algae. Mussels Mytilus edulis occurred beyond the sublittoral fringe with Enteromorpha spp., Ceramium sp., Chondrus crispus, Ulva sp., Fucus serratus, Cladophora sp. and Laminaria digitata.


Upstream of outfall

Sites G7 and G8 were taken upstream of the outfall channel. The substratum at these sites consisted of very black anoxic mud with a small amount of leaf litter. The fauna at site G7 consisted of polychaetes and one bivalve. No fauna were recorded from site G8 (Appendix 2, Table 2.4).

Adjacent to the outfall

Three grabs were taken in the vicinity of the outfall channel (sites G4 – G6). Sites G5 and G6 were taken at the outfall and consisted of black anoxic mud. The fauna at G5 were predominantly made up of the polychaete family Arenicolidae and the fauna of site G6 were dominated by the polychaete family Spionidae (Appendix 3, Plate 3.15). Site G4 was taken on the opposite side of the river from the outfall and consisted of anoxic mud but with abundant polychaetes and the bivalve, Abra alba (Appendix 2, Table 2.4).

Downstream of the outfall

Three grab samples were taken downstream of the outfall channel (sites G1 - G3). All consisted of black anoxic mud smelling strongly of hydrogen sulphide. Site G3 had the highest number of species or higher taxa recorded in the sublittoral survey, with six families of

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polychaetes and two species of molluscs (Appendix 2, Table 2.4). Sites G1 and G2 consisted mainly of polychaetes.

5. DISCUSSION


It was only possible to resurvey six of the 12 littoral sites initially surveyed in 1998. Sites were accessed by boat and shallow water prevented access during low tides. However, it is considered that a comparison of the results of the current and previous investigations is not compromised by the lesser extent of the current investigation.

From the sites surveyed during the 2003 survey, a total of 23 species or higher taxa were recorded, compared to 38 from the same six sites in 1998. Of the 38 species recorded during 1998, 14 were recorded as only being present (P) in one or two sites, and none of these were recorded during the 2003 survey. Many of these were polychaetes, which are not typical of hard substrata littoral sites and were possibly washed in or seeking refuge in a small patch of soft substrata deposited on the structures surveyed or amongst the clumps of mussels.

In general, species and higher taxa recorded during both surveys were similar, although there were certain differences between sites. Species of sponges, hydroids, bryozoans and tunicates were absent in the 2003 survey. It is not possible to state that these differences are the result of any one activity or process change within an estuary that has a varying pollution load (physical, chemical and biological), or even that they are the result of anthropogenic influences rather than natural ecological cycles. The main issues that may arise from the power station outfall are the increased water temperature and residual chlorine to receiving waters. It is not possible to attribute the difference in species composition to these issues.

Possible explanations for differences in species compositions between the surveys could be due to seasonal variation. The survey in 1998 was conducted in October, while the 2003 survey was conducted in April. Other explanations could be in the natural and anthropogenic fluctuations within the estuary.

Site L1 had a similar species composition in both surveys, with barnacles, red, green and brown algae being dominant. Similarly, species diversity was comparable at site L2 in both surveys, although the sponges Halichondria panicea and Hymeniacidon perleve were both abundant in 1998 and notably absent in 2003.

Site L3 in 1998 had 21 species or higher taxa, however five of these were polychaete worms and two were sponges. Only five species or higher taxa were recorded from the 2003 survey. The majority of these were also recorded from the 1998 survey. As mentioned earlier, the polychaetes are predominantly soft substrata species and may have been recorded from clumps of mussels or in muddy patches.

Site L4 in the 2003 survey had nine species or higher taxa, and mainly consisted of the green algae, Enteromorpha spp. with a matrix of barnacles and limpets underneath. In 1998 the same site had 24 species or higher taxa associated with it, however four of these species were polychaete worms recorded from the mud that had accumulated on the wooden piles. Sponges and hydroids were notably absent from the 2003 survey and present in 1998.

In 1998 site L7 had 15 species or higher taxa in comparison to eight in the 2003 survey. Species composition during both surveys was fundamentally similar, with barnacles, mussels

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and red and green algae being the main characterising species. Additional species included sponges, hydroids and polychaetes.

Site L8 at the Poolbeg lighthouse had the highest number of species during the 2003 survey. Sixteen species were recorded in comparison with seven during 1998. Species composition was similar with barnacles, mussels, limpets and kelp, Laminaria digitata in the sublittoral fringe.

There were no apparent differences between sites upstream and downstream of the power station in either the 1998 study or the 2003 study.

As with the baseline study in 1998, none of the species recorded during the 2003 survey were of specific nature conservation importance or interest. Although all the species and habitats recorded are typical of the east coast of Ireland (Picton & Costello, 1998), few of the species recorded would be characterised as typically estuarine.


A total of 12 species or higher taxa were recorded from the grab samples taken during the 2003 survey. This was significantly lower than the1998 survey when 42 species or higher taxa were recorded. However, the majority of the species were recorded at site D1 which had 25 species or higher taxa in comparison to three at site G1 during the 2003 survey. The remainder of the sites had similar numbers of species or higher taxa. Possible explanations for these differences could be the different sampling methods used, the routine dredging that occurs in the River Liffey, which has an effect on the substratum, and natural and anthropogenic fluctuations within the estuary.

The 2003 survey used a 0.1 m2 van Veen grab to obtain the sublittoral seabed samples. This grab collects a discrete bite from a single area of the seabed and everything in that bite is brought to the surface for sorting. The survey of 1998 used a biological dredge to obtain samples. The biological dredge was trawled on the seabed for a defined distance and thus is more likely to collect species from a variety of substrata within one sample. The 1 cm mesh size and greater area trawled allows for a more general sample but many of the smaller species can be lost. The use of the van Veen grab during the 2003 survey allows for greater repeatability of sampling in future years and is quantitative.

In addition, some species recorded during the 1998 survey were washed into the samples (e.g. Corophium sp. site D1), were drift (e.g. Sertularia argentea, site D1) or consisted of empty shells (e.g. Chamelea gallina at site D4), accounting in part to the higher species diversity.

The estuary adjacent to the outfall is heavily developed with port facilities and industry on both sides of the river. The Dublin Port fairway is extensively dredged every four years to maintain adequate navigation depth for shipping, with additional maintenance dredging every two years. Since 1998 maintenance dredging of the main channel has been conducted twice, the latest of which was in August - September 2002. The 1998 survey recorded a coarser substratum at sites D1 and D2, whereas the corresponding sites (G1 and G2) in the 2003 survey consisted of soft anoxic mud. Although dredging has been conducted twice since the survey in 1998, a build up of fine mud in this area is apparent.

The biggest difference in species richness between the 1998 and 2003 surveys was at site D1, which is also one of the areas where coarse substrata was recorded in 1998. Many of the species recorded at site D1 in 1998 are not generally found in soft mud substrata and some

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species such as the barnacles Elmius modestus and Balanus crenatus, and the hydroid species would be typical of hard substrata. It is likely that the accumulation of fine mud at this site (G1) has resulted in the loss of hard substrata species.

Site G2 had a similar number of species or higher taxa to site D2 (from the 1998 survey), although species composition was quite different. The species recorded from D2 were more characteristic of sandy substrata, such as the sand mason worm, Lanice conchilega. It is likely that the difference in species composition is due to the alteration of substratum at this site and the different sampling methods used.

Site G3 and D3 had a similar number of species or higher taxa, consisting mainly of polychaetes and bivalves. Abundance of species was slightly higher at site G3, although no crustaceans were recorded at this site.

In comparison to site G4, site D4 was relatively species poor. Although both sites had similar numbers of species or higher taxa, the abundance of species was much higher at site G4, with 150 polychaetes of the family Arenicolidae indet. recorded. This is most probably a reflection of the sampling method used, as the grab retained all the species in the sample which may have been lost through the biological dredge.

Four species or higher taxa were recorded at site G5 and none were recorded during the previous survey at site D5. The fauna mainly consisted of polychaetes and one brown shrimp, Crangon crangon. Similar to site D4 the polychaetes may have been lost through the dredge.

Sites G6 and G7 had similar numbers of species or higher taxa to sites D6 and D7. Both sites mainly consisted of polychaetes and bivalves, although abundance was much higher at sites G6 and G7, perhaps due to sampling techniques.

No species were recorded at site G8 in the 2003 survey, while three species were recorded in 1998 at the same site. However, these species consisted of the mites Cyrolaelapidae indet. and Erythracidae indet., which were most likely washed into the sample, and the barnacle Elminius modestus, which is presumed to have been recorded on a piece of shell or rock.

There were no apparent differences between sites upstream and downstream of the power station in either the 1998 study or the 2003 study.

As with the 1998 survey, none of the sublittoral species or habitats recorded during the 2003 survey is of nature conservation importance or interest. The habitats had few species reflecting the variable salinity and stressful estuarine environment. While there were changes between the ecology of the two surveys, these changes did not appear to be dramatic or negative.

5. 3 THE EFFECTS OF RESIDUAL CHLORINE ON RECEIVING WATERS

Cooling water at the power station is treated to control slime formation and to inhibit the settlement of shellfish larvae on the condenser tubes. Deposits result in significant heat transfer loss and restricted cooling water flow. These translate directly to a reduction in station efficiency and thereby lead to greater overall environmental emissions.

The residual chlorine concentration of 0.13 - 0.19 mg/l recorded during the first year of operation of the cooling water system at Dublin Bay Power Plant is well within the limits of 0.25 mg/l chlorine set by Schedule 2(i) – Emissions to Water of IPC Licence No. 486.

In the absence of dramatic changes to the ecology of the receiving waters, it cannot be stated that any differences in the marine fauna and flora between the baseline study and current

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survey were from any single factor in the estuary. It is probable that any changes are a result of numerous activities, both natural and anthropogenic. These include routine dredging in the estuary (or the absence of it), the overall fluctuating pollution load of the estuary (physical, chemical and biological) and the natural fluctuations and adaptations of ecological systems.

It is not possible to attribute the difference in species composition to treatment of cooling water at Dublin Bay Power Plant.

5. 4 THE EFFECTS OF THERMAL DISCHARGE ON RECEIVING WATERS

While it is accepted that thermal discharges do have ecological effects on aquatic systems, it is considered difficult to isolate changes caused by temperature from changes caused by other factors (Langford, 1983). In addition, temperature acts with other parameters to cause ecological effects and so should not be studied in isolation if change or potential change in an ecosystem is to be understood.

While taking the above into consideration, thermal discharges can have both direct and indirect effects on the receiving environment. Direct effects include changes in the temperature regime of the water column and seabed sediments and a reduction in the dissolved oxygen content of the water (UK Marine SAC, 2003) with subsequent lethal and sub-lethal responses from organisms and stimulation in productivity of some organisms.

There are a number of aspects of temperature that can affect the ecology of the receiving water. Mean temperature, which varies with distance from the outfall, is required if long-term change is to be predicted and understood. Maximum temperature is important as it can be related to the upper thermal lethal limit of organisms and also to sub-lethal effects such as an inhibition of reproduction. Temperature fluctuation should also be considered, especially in estuaries, where tidal flow affects available dilution and also the direction of the plume itself (Bamber, 1995, as cited on www.ukmarinesac.org.uk).

A thermal plume study undertaken in May 2003 maps the temperature plume resulting from the Dublin Bay Power Station cooling water outfall.

Lethal temperatures for algae are in the range of 28 °C for Fucus serratus, and 30 – 35 °C for Cladophora species. It is somewhat lower for the deeper living kelps, with lethal temperatures in the range of 23 °C for Laminaria digitata (Langford et al, 1998, as cited on www.ukmarinesac.org.uk). Thus, even when the receiving water is at its warmest ambient temperature, an increase in temperatures similar to those recorded during the May 2003 thermal plume survey should not push temperatures above the lethal limits of the seaweeds recorded during the ecological surveys. An increase of 5 - 7 °C above ambient temperature would see a decline in the fucoid populations (Langford 1990, as cited on www.ukmarinesac.org.uk). However, for the short portion of the tidal cycle when the plume is most evident at depths other than close to the surface, the warmest part of the plume appears to go towards the centre of the estuary where fucoids were absent. This is unlikely to cause significant adverse effects. In addition F. serratus, Cladophora sp., and L. digitata were only recorded at site L8, at the end of the North Bull Wall, away from the effects of the thermal plume.

The upper temperature limits for algal reproduction are significantly lower than lethal temperatures, at around 10 – 15 °C for many species. However, most species are able to reproduce over extended periods, which are not confined to the months when ambient temperatures are at their highest. It is likely that ambient temperatures would restrict

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reproduction of some species during the warmer times of year anyway. Thus, the thermal discharge is unlikely to adversely affect the reproduction of the recorded algal species significantly.

It is unlikely that the invertebrate species recorded on the quay walls and other hard substrata would be adversely affected by the the thermal plume. Under the current regime there is unlikely to be any significant effects on invertebrate species.

There is not enough information to comment reliably on the effect of the thermal discharge on the infauna of the estuary bed, although it is probable that the plume does not extend downwards to a significant area of seabed and there are likely to be few effects. No infauna of ecological conservation importance were recorded during the survey. As the thermal discharge is not likely to cause a complete thermal barrier across the whole estuary, it is unlikely to obstruct the passage of migratory fish.

6. RECOMMENDATIONS When conducting future monitoring on the fauna and flora in the vicinity of the power station, it will be important to use a similar method to the 2003 study (0.1 m2 van Veen grab) so that future data can be directly compared in terms of species and abundance.

As there are no specific bioindicators of chlorine pollution, future monitoring of water and sediment quality in conjunction with benthic fauna may be a more effective method of estimating the impacts of residual chlorine in the estuarine environment.

7. REFERENCES Hiscock, H, Ed. 1996, Marine Nature Conservation Review, rationale and methods. Joint Nature Cinservation Committee, Peterborough

Howson, C. M. & Picton, B. 1997. The species directory of the marine fauna and flora of the British Isles and surrounfing seas. The Ulster Museum, Northern Ireland and the Marine Conservation Society, Ross-on-Wye

Picton, B. E. and Costello M. J. 1998. The BioMar biotope viewer: a guide to marine habitats, fauna and flora in Brirain and Ireland, environmental Sciences unit, trinity College, Dublin.

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APPENDIX 1: MAPS

Figure 1: Map showing the locations of the littoral sites (L1-L4, L7-L8 blue dots) and the grab sample sites (G1-G8 orange dots) of the current survey. Sampling locations of the 1998 littoral sites are illustrated as red stars (L1-L12) and dredge samples (D1-D8 green dots).

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APPENDIX 2: LITTORAL AND SUBLITTORAL FLORA AND FAUNA Table 2.1: Site locations and details of littoral sites, April 2003.

Site no.

Latitude Longitude Location

L1 53º20.63 N 06º12.96 W Vertical concrete wall beside the boat club

L2 53º20.56 N 06º12.28 W Vertical concrete wall near the chimney stacks

L3 53º20.53 N 06º11.82 W Vertical steel pilings just before the cooling water outfall at Ringsend Power

Station

L4 53º20.51 N 06º11.43 W Vertical wooden pilings on a wooden pontoon in channel (north facing side)

L5 53º20.48 N 06º10.92 W Vertical steel pilings just west of the Poolbeg Power Station cooling water and

sewage treatment works outfall

L6 53º20.52 N 06º10.66 W Vertical steel pilings just east of the Poolbeg Power Station cooling water and

sewage treatment works outfall

L7 53º20.70 N 06º10.56 W Vertical wood and concrete pilings at the North Bank Light

L8 53º20.66 N 06º08.88 W Vertical concrete and stonework

Table 2.2: Site locations and details of sublittoral grab sites, April 2003.

Site no.

Latitude Longitude Depth (m) BSL

Substratum

G1 53º20.636 N 06º09.056 W 8 Black anoxic mud, smelling strongly of hydrogen

sulphide.

G2 53º20.646 N 06º09.720 W 9 Black anoxic mud. A few polychaetes were recorded

by very little species present.

G3 53º20.610 N 06º10.618 W 8.8 Black anoxic mud with some polychaetes and

bivalves.

G4 53º20.634 N 06º11.497 W 8.8 Black anoxic mud with abundant polychaetes and the

bivalve, Abra alba.

G5 53º20.543 N 06º11.693 W 7 Black anoxic mud. Very sticky with some leaf litter. Polychaetes recorded.

G6 53º20.553 N 06º11.800 W 8.6 Black anoxic mud with a few polychaetes.

G7 53º20.636 N 06º12.320 W 8 Very black anoxic mud. Some polychaetes recorded.

G8 53º20.729 N 06º13.536 W 6 Very black anoxic sediment with a small amount of

leaf litter. No flora or fauna recorded.

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Table 2.3: Abundance of flora and fauna recorded during the present littoral survey. P=Present; O=Occasional, F=Frequent; C=Common; A=Abundant, after Hiscock (1996).

Species L1 L2 L3 L4 L5 L6 L7 L8

Crustaceans

Elminius modestus F - - - - - - -

Semibalanus balanoides F - - A - - F A

Chthamalus sp. - - - - - - A A

Cirripedia indet. - P P A - - - -

Isopoda indet. - P - O - - - -

Molluscs

Patella vulgata - - O O - - - F

Littorina saxatilis - - - O - - - F

Melarhaphe neritoides - - - - - - O P

Mytilus edulis - - - - - - O F

Rhodophycota (red algae)

Unidentified red algae - P - - - - O C

Porphyra umbilicalis O O P O - - O O

Chondrus crispus - - - - - - - O

Rhodothamniella floridula O F - C - - - -

Ceramium sp. - - - - - - - F

Ectocarpus indet. - C - - - - - -

Chromophycota (brown algae)

Laminaria digitata - - - - - - - O

Fucus serratus - - - - - - - O

Fucus spiralis F F - F - - - -

Fucus vesiculosus F F P - - - - -

Chlorophycota (green algae)

Scytosiphon lomentaria - - - - - - - P

Enteromorpha sp. C F A A - - F O

Ulva lactuca - O - - - - O C

Cladophora rupestris - - - - - - - O

Total no. of species or higher taxa 7 9 5 9 0 0 8 16

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June 2003 13/21

Table 2.4: Abundance of flora and fauna recorded during the present sublittoral survey. P=Present, after Hiscock (1996).

Species or higher taxa G1 G2 G3 G4 G5 G6 G7 G8

Polychaetes (worms)

Polychaete fragments indet P P P P P P P -

Arenicolidae indet. - 1 20 150 28 15 14 -

Aphroditodea indet. - - 1 - - - - -

Ampharetidae indet. - - 11 1 - - - -

Spionidae indet. 5 1 4 43 7 120 - -

Cirratulidae indet. 1 1 - - - - - - Tharyx marioni

- - 1 - - - - -

Nephtys sp. - 2 4 - - - - -

Glyceridae indet. - 1 - - - - - -

Terebellidae indet. - - - 1 - - - -

Crustacea (crabs, barnacles and amphipods) Crangon crangon

- - - - 1 - - -

Mollusca (snails and bivalves) Angulus squalidus

- - 2 - - - - - Abra alba

- 1 18 27 - 3 1 -

Total no. of species or higher taxa 3 7 9 6 4 4 3 0

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Table 2.5: Abundance of littoral flora and fauna recorded during 1998. P=Present; O=Occasional, F=Frequent; C=Common; A=Abundant, after Hiscock (1996).

Species L1 L2 L3 L4 L5 L6 L7 L8 L9 L10 L11 L12

Chironomidae - - - 2 - - P - - - - -

Porifera (sponges)

Halichondria panicea - A A F - - - F - - - -

Hymeniacidon perleve - A C F - - F F - - - -

Cnidarians (hydroids and sea anemones)

Obelia dichotoma - - - P - - P - - P - -

Obelia geniculata - - P P - - - - - - - -

Metridium senile - - - - O - C - - - - -

Nematodes

Nematoda indet. - - - P - - - - - - - -

Polychaetes (worms)

Polychaeta indet.1 - - P - - - - - - - - -

Pholoe sp. - - - P - - - - - - - -

Phyllodoce sp. - - P - - - - - - - - -

Syllidae sp.2 - - P - - - - - - - - -

Syllis gracilis - - P - - - - - - - - -

Neanthes virens - - - - - - - - P - - -

Spionidae indet. - - - P - - - - - - - -

Cirratulus cirratulus - - - - - - - - A - - -

Capitella sp. - - P A - - P - - - - -

Arenicola marina - - - - - - - - O - - -

Fabricia sabella - - - P - - - - - - - -

Pomatoceros triqueter - - - - - - - - O P - P

Spirorbis sp. - - - - - - - - - P - -

Crustaceans (crabs, barnacles and amphipods)

Elminius modestus - C C A A C - C - O - -

1 Juveniles 2 Washed in

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June 2003 15/21


Semibalanus balanoides O O C C A O A C - C - P

Balanus crenatus - - - - P - - - - - - -

Rissoides desmaresti3 - - - 1 - - - - - - - -

Corophium acherusicum - - 3 - - - - - - - - -

Carcinus maenas - - 1 1 - - - - O - - P

Molluscs (snails and bivalves)

Acanthochitona fascicularis - - - - - - - - 1 - - -

Patella sp. - - - O - - O O - - - P

Littorina littorea - - - - - - - - O - - P

Littorina obtusata - - - - - - - - - - - P

Melarhaphe neritoides - - - - - - A - - - - -

Mytilus sp.2 - - 2 15 - - 1 - - - - -

Mytilus edulis - - O O S - S - O - P P

Cerastoderma edule - - - - - - - - O - P -

Bryozoans (sea mats)

Bryozoan crusts indet. - - P - - - - - - - - -

Bowerbankia sp. - - - - - - - - - P - -

Tunicata (sea squirts)

Ciona intestinalis - - - O - - - - - - - -

Pisces (fish)

Gobius paganellus - - - - - R - - - - C -

Rhodophycota (red algae)

Porphyra umbilicalis O O O O O - O - O - - -

Chondrus crispus - O O - - - F - O C - P

Ceramium sp. O O - - - - - - - - - -

Chromophycota (brown algae)

Ectocarpus indet. - O - - - - - - - - - -

Laminaria digitata - - - - - - - O - - - -

3 Larvae

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Laminaria saccharina - - - - - - - F - - - -

Ascophyllum nodosum - - - - - - - - - O - -

Fucus serratus C - O O - - - - O A - P

Fucus spiralis C C - - - - - - - - - -

Fucus vesiculosus C O F O O - - - - - - P

Chlorophycota (green algae)

Enteromorpha sp. - O C O - O F - O A - P

Ulva lactuca C C C C C - F - O A - P

Cladophora rupestris O O - O - - F - O - - P

No. of species recorded 8 13 21 24 8 4 15 7 15 11 3 13

Table 2.6: Abundance of sublittoral flora and fauna recorded during 1998. P=Present; O=Occasional, F=Frequent; C=Common; A=Abundant, after Hiscock (1996).

Species D1 D2 D3 D4 D5 D6 D7 D8

Chironomidae indet.

Cyrtolaelapidae indet.1 - - - - - - - 2

Erythracidae indet. - - - - - - - 1

Cnidarians (hydroids and sea anemones)

Hydrallmania falcata P - - - - - - -

Sertularia argentea2 P - - - - - - -

Obelia dichotoma - - - - - P - -

Obelia longissima P? - - - - - - -

Metridium senile 1

Polychaetes (worms)

Harmothoe sp. - - 1 - - - - -

Eteone sp. 1 - - - - - - -

Anaitides maculata 8 - - - - - - -

Trypanosyllis coeliaca 4 - - - - - - -

1 Washed in 2 Drift

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Sphaerosyllis sp. 3 - - - - - - -

Nephtys sp. - - - - - - 1 -

Nephtys caeca? - - 20 - - - - -

Nephtys longosetosa - - - 6 - 1 - -

Spionidae indet. - - 2 - - - - -

Chaetopterus variopedatus

1 - - - - - - -

Ampharete grubii - - 1 - - - - -

Lanice conchilega P P 1 - - - - -

Fabricia sabella - - - - - - - -

Pomatoceros triqueter P - - - - - 2 -

Crustaceans (crabs, barnacles and amphipods)

Elminius modestus P - - - - - - 4

Balanus crenatus P - - - - - - -

Apherusa jurinei 1 - - - - - - -

Aora gracilis 1 - - - - - - -

Corophium sp.3 1 - - - - - - -

Crangon crangon 3 24 9 - - 2 - -

Pagurus bernhardus - 10 - 1 - - - -

Macropodia? Linaresi 1 - - - - - - -

Carcinus maenas 8 5 8 1 - 1 - -

Molluscs (snails and bivalves)

Juvenile bivalves 2 - 1 - - - - -

Buccinum undatum 1 1 - - - - - -

Mytilus sp.3 P - - - - - - -

Cerastoderma edule - - - - - - 3 -

Pharus legumen - - 1 - - - - -

Chamelea gallina4 - - - 1 - - - -

Bryozoans (sea mats)

Bryozoan crusts indet. - - - - - - P -

Alcyonidium parasiticum P - - - - - - -

3 Washed in 4 Empty shell

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Bugula plumosa P - - - - - - -

Echinoderms (starfish)

Ophiura albida 1 - - - - - - -

Ophiura ophiura 4 - - - - - - -

Pisces (fish)

Pleuronectes platessa - 1 - - - - - -

Solea solea - 1 - - - - - -

No. of species recorded 25 7 9 5 0 4 4 3

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APPENDIX 3: PHOTOGRAPHS

Plate 3.1: Site L1, the quay wall on the south side of River Liffey, showing vertical

zonation of the flora and fauna.

Plate 3.2: Close up of site L1, highlighting Enteromorpha spp. and Fucus spiralis

zones.

Plate 3.3: Site L2, quay wall on south side of the River Liffey, showing Enteromorpha

spp. and Fucus spiralis.

Plate 3.4: Site L3, Vertical steel pilings just before the cooling water outfall at

Ringsend Power Station.

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June 2003 20/21

Plate 3.5: Site L4, vertical wooden pilings on a wooden pontoon in the channel of the

R. Liffey.

Plate 3.6: Close up of site L4, showing Enteromorpha spp. and barnacles.

Plate 3.7: Vertical steel pilings at the site of the cooling water outflow.

Plate 3.8: Site L7, North Bank Light.

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June 2003 21/21

Plate 3.9: Close up of Site L7, showing barnacle growth.

Plate 3.10: Site L8, Poolbeg Lighthouse.

Plate 3.11: Close up of mussel seed at site L8, Poolbeg Lighthouse.

Plate 3.12: Close up of barnacles and juvenile barnacles at site L8.

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Documents

Dublin Bay - Ecology 2003 - EPAboth North and South Dublin Bay, including the Bull Wall Sands portion of the Liffey Estuary. 3. METHODOLOGY As part of the Environmental Impact Statement