No Slide Title

G. Nolan 1, K.Lyons1, S.Fennell1, T. Mc Grath1, D.Guihen2, C.Cusack1, C. Lynam3

Variability in the physical structure, ocean chemistry, plankton ecology and commercial fish species of the seas surrounding Ireland between 1997 and 2010ICES/NAFO Decadal Symposium, Santander11th May 201119/04/07

Water mass overview

Biogeographical provinces: Niall Mc Ginty et al., (Poster 78)May 2011

Trends in sea surface temperature (1890 - 2007)

Recent intense warming in the NE Atlantic attributed in part to the AMO (Atlantic Multidecadal Oscillation), and in part to global warming.Sub-polar gyre cooled over the 1955-2003 period, consistent with predominantly positive NAO Local temperature anomalies extracted from HadSST2. Malin head data is overlain in red (Note apparent 60 year cycle in N. Atlantic)

Cannaby H, Husrevoglu YS (2009) The influence of low-frequency variability and long-term trends in North Atlantic sea surface temperature on Irish waters. ICES J Mar Sci:fsp062Annual mean SST anomalies (green bars), averaged over the region [45-60N, 3-20W], extracted from the HadSST2 dataset (Rayner et al., 2006) and overlain by a 5 year running mean (black line) for the period 1850-2008. AVHRR satellite derived SST anomalies for the period 1986-2006 are overlain in blue and the Malin Head coastal SST time series from 1958-2006 in red. Anomalies are calculated relative to the 1961-1990 mean for the case of HadSST2 and Malin Head datasets and relative to the time series climatology f.or the case of the AVHRR dataset19/04/077

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AVHRR: SST anomaly from 1985-2006 mean

Annual mean anomalies of SST (Deg C) derived from level-3 processed AVHRR satellite data and calculated relative to the 1985 to 2006 climatology. Data are presented at 7 year intervals from 1985 to 2006.19/04/079

Porcupine BankStation depth= 3000m

SAIW 2010MEDW 2007

19/04/07

Development of suitable growth conditions in Spring using SST as an indicator1959 2005 (47 years daily SST data).Timing of Spring in Julian Days1: Interannual variations on the date SST reaches 10 C

2: General Trend in coastal waters that it is arriving earlier

3: Abiotic conditions important in spring (water column structure and nutrient availability)

15 April05 JuneSpring Bloom timing2006-2007 Winter:Land vegetation greening occurred 10 days earlier than the average over the past three decades (Geophs. Res. Lett. 2008) Maignan et al.Phytoplankton colour and HAB species

The percentage occurrence of Karenia mikimotoi during the winter months has increased since 2000

Total annual abundance of harmful and toxic species varies greatly between yearsAn increase in phytoplankton biomass is evident in the northern Celtic Sea, based on Continuous Plankton Recorder (CPR) data, since 2000Increases in the annual numerical abundance of diatoms and dinofl agellates are evident in all coastalregions since 1998.

Diatom abundance has increased in numerical abundance earlier in the year since the late 1990s in allcoastal regions; an expansion of the growth season.19/04/0717Zooplankton changes:Beaugrand view of whole regionSpecific look at warm water species in Irish waters (on the increase)

Warm >>>>>>>>>> coldThe abundance of a common warm water species (Calanus helgolandicus) has increased to the southeast of Ireland

mean abundance in Celtic Sea : AnnualMarchp < 0.05Spatial patterns in the biodiversity of calanoid copepods have changed in response to warming with general movement north of warm water species and retreat of cold water species.

A possible phenological shift suggests that production of this common warm water species (Calanus helgolandicus) begins earlier in the year.

In oceanic areas, depth >200 m, gelatinous zooplankton abundance is higher during warm years, which arethought to improve prey availability.

Gelatinous zooplankton in the Northeast Atlantic show cyclic changes in population sizes that differbetween oceanic and shelf areas. However, since 1997 they have been increasing simultaneously in shelfand oceanic waters.19/04/0718Poor cod distributions 2003/4 vs 2006/7(possible indicator species)

Poor cod and lesser spotted dogfish have increased to the north of Ireland and decreased to the south and are suitable candidate climate indicator speciesClimate change may lead to the decline of traditional fisheries (e.g. cod) and the emergence of new fisheries (e.g. boarfish). However, given the high value of many boreal species the economic effect may be negative.

The Irish Exclusive Economic Zone (EEZ) supports major fisheries worth 500 million to the international fleets.

The fishing industry makes a significant contribution to the economic and social fabric of coastal communities.

Climate change and anthropogenic impacts act in tandem to alter marine ecosystems, such that species responses to climate change cannot be considered in isolation.

Many, but not all, warm water species, including sprat, anchovy, pilchard and blue-mouth, have increased in abundance to the north of Ireland and in the Celtic Sea.

Climate change may lead to an increase in the Lusitanian fish community. However, fishery effects must be considered and long-term data is required to detect such change.

Overexploited stocks display stronger responses to climatic fluctuations.

Natural variability is high in the marine environment and whether or not important changes seen in thegyre circulation are due to global warming or natural variation is unclear.

Many exotic species are being sighted in Irish and United Kingdom waters. There appears to be anincrease in such sightings.

19/04/0719 Decline in cold-water species of fish and increase in warm-water species (Kendall tau plot) eg. Boarfish

Fishery effects must be considered and long-term data is required to detect such changeRed= expected distribution Blue= actualIn general, the abundance of marine fish has decreased in the Celtic Sea (1999-2007).

Both Lusitanian (warm water) and boreal (cold water) communities appear stable to the north of Ireland (2002-2007).

There is some suggestion of an increase in the Lusitanian community to the west of Ireland (2002-2007).19/04/0720Pipefishes (Syngnthidae) related to seahorsesA symptom of major ecosystem changes?Possibly linked to SST rises?Largely absent from samples 1958-2001 Increase in catch in 2003, 2004, 2005

The increase in the distribution of pipefish may reduce the survival of seabird chicks.19/04/0721

Migratory fish speciesSalmon

declining marine survival since the 1970sSea trout

stock collapse in 1980s, with adult returns still at a low levelKey biological processes in freshwater are controlled by environmental variables, (e.g. temperature, sunlight and rainfall). These play a fundamental role in controlling primary production, food web energetics and critical life stage processes in animals, such as hatching and survival in fish and smoltification and migration in salmonids. Possible changes in Irelands climate are likely to impact on the growth and survival of many species.

Diadromous fish species (having both a freshwater and marine element to their life cycle) are an important sentinel species in climate change research. The migrations of these species could have significant implications for understanding a broader set of biogeographical and ecological questionsacross a wide range of spatial and temporal scales.

The main three species of Irish diadromous fish have shown a decline in numbers and marine survivalover the past three decades, thought to be at least partly related to the interactive effects of changing climatic and oceanic conditions, along with human impacts. Data from the Marine Institutes experimentalcatchment in Burrishoole, Co. Mayo shows:

Salmon declining marine survival since the 1970s.Sea trout stock collapse in 1980s, with adult returns still at a low level.European eel sharp fall in recruitment since the 1980s, in line with similar declines throughout Europe.

Freshwater temperatures from the Burrishoole catchment have been increasing significantly from the 1970s to the present day. This change is likely to have strong knock on effects on the survival and development of juvenile fish populations.19/04/0722Nutrient analysis: water mass definition

May 2011

Higher surface nutrients in more recent cruises

AABW signalHigher phosphate values on WOCE cruises

19/04/0724ConclusionsWarming trend with AMO signal apparent at Malin HeadLSW (freshened between 2004 and 2009 and then increased salinity in 2010 and 2011)Changes in temperature are mirrored in biological data setsIncreases in the annual numerical abundance of diatoms and dinoflagellates are evident in all coastal regions since 1998.Warm water fish species more prevalentDecline in migratory fish returnsSome differences in nutrient concentrations when comparing WOCE data with 2008-2010 data