• Preliminary recruitment studies of the eastern oyster, Crassostrea virginica, and their potential applications, in coastal Georgia

      O'Beirn, F.X.; Heffernan, P.; Walker, R.L. (Elsevier, 1995)
      Oyster recruitment was monitored in Wassaw Sound, Georgia from April through October, 1991. The study was initiated to determine precise recruitment patterns of oysters over the 7 month spawning season. One of the goals was to determine the most suitable time for the collection of natural spat for maricultural, fisheries and recreational purposes. Three sites of varying hydrographic characteristics were chosen in Wassaw Sound. The sites varied in terms of temperature and salinity regimes and in their exposure to wind and wave action. Within each site, oyster recruitment was estimated at three tidal heights; subtidally, at mean low water and intertidally, approximately 2 h above the mean low water mark. Sampling took place so as to measure net recruitment over biweekly (BW), monthly (M) and seasonal ( S) periods. The results indicated that the recruitment of oysters in this region of coastal Georgia is protracted, lasting 6 months (May through October). The levels of recruitment were very high relative to other regions on the east coast of the USA, with peak recruitment for the entire study area (x = 2800 spat m- 2 for BW and x = 3020 spat m- 2 for M) occurring between July and September. The intensity of recruitment varied significantly among the three sites. The most sheltered site in terms of wave exposure experienced the highest recruitment (x =4380 spat m- 2 BW; x = 6260 spat m -2 M). This site also had higher overall water temperatures as well as greater daily temperature fluctuations. The least sheltered site had the lowest numbers of young oysters (x = 1000 spat m- 2 BW; X. = 686 spat m- 2 M), as well as having the most stable temperature regime. The biweekly samples generally experienced higher recruitment subtidally at the three sites. The monthly samples had higher numbers of oyster spat at the mean low water mark while the seasonal samples showed significantly higher recruitment intertidally (up to x =7353 spat m-2 ). The shift in recruitment patterns over time is partially attributed to increased subtidal predation pressure on the recruits. The collection of natural spat in relation to the natural fishery, potential maricultural activity and the recreational fishery is discussed.
    • Preliminary results from a survey of oyster production areas in Ireland for norovirus

      Keaveney, S.; Flannery, J.; Guilfoyle, F.; Doré, J. (2007)
      A survey of 18 oyster production areas in Ireland for norovirus (NoV) contamination was initiated in August 2006. The findings presented are the preliminary results from the first seven months of the survey. Prior to the survey commencing, a simple desk bask sanitary survey of each area was undertaken. This provided an assessment enabling each site to be ranked into 3 categories (low, medium and high) on the basis of the risk of NoV contamination. Samples were collected on a monthly basis and tested for the presence of NoV using semi-quantitative real-time PCR allowing relative quantitation of NoV levels. A correlation was observed between occurrence and levels of NoV detected and the risk categories ascribed to each production area. To date NoV was detected in 60.7, 30.0 and 2.5 percent of samples from the high, medium and low risk categorised areas, respectively. A strong seasonal bias towards increased winter contamination was observed with NoV detected in 15.5 and 50 % of samples in August and February, respectively. The preliminary results from this survey indicate that it may be possible to predict the relative risk of NoV contamination in a shellfish harvesting area. This in conjunction with targeted NoV monitoring using real-time PCR could aid the further development of risk management procedures in shellfisheries.
    • Prevalence of Perkinsus marinus in the eastern oyster, Crassostrea virginica in relation to tidal placement in a Georgia tidal creek

      O'Beirn, F.X.; Dean, C.C.; Walker, R.L. (Marine Environmental Sciences Consortium of Alabama, 1994)
      This experiment was designed to evaluate the effects tidal zonation and bottom placement of the eastern oyster, Crassostrea virginica, have on the prevalence and intensity of the oyster parasite, Perkinsus marinus a suspected causative agent for subtidal oyster mortalities experienced in the coastal waters of Georgia. Twelve growout bags (1 m x 0.5 m; 12.7 mm mesh), each containing 200 oysters, were placed in Jointer Creek, Georgia In March 1992. Bags (3 replicates each) were placed lntertidally and subtidally on the creek bottom and offbottom. Ten oysters per bag were removed monthly for twelve months beginning March 1992, and were inspected for prevalence and intensity of Perkinsus marinus, using the thioglycollate method. Oyster mortality and shell length data were also evaluated. Neither prevalence (p = 0.3505) nor intensity levels (p = 0.2993) of Perkinsus marinus in oysters were significantly different among the treatments. Although there were no significant differences In prevalence or intensity of the pathogen among treatments, the intertidal offbottom treatment had the lowest values most frequently. Perkinsus marinus was present in all replicates every month. Prevalence and intensity of infection followed the typically observed pattern of maximum values in summer and fall and minimum levels in winter. Subtidal bottom oysters experienced higher mortalities (p = 0.0022), but the prevalence and intensity of Perklnsus marinus in oysters were not significantly different between treatments. It appears therefore, that the oyster parasite, Perkinsus marinus is not the discerning factor in the higher mortalities witnessed in oysters placed subtidally on the bottom in the southeastern U.S. coastal waters.
    • Proceedings of the 8th Irish Shellfish Safety Workshop

      McMahon, T.; Deegan, B.; Silke, J.; Ó Cinneide, M. (Marine Institute, 2008)
      This document outlines the proceedings of the 8th Irish Shellfish Safety Scientific Workshop. This event was organised by the Marine Institute, the Food Safety Authority of Ireland and Bord Iascaigh Mhara to discuss the methods and advances of food safety with respect to shellfish health.
    • Proceedings of the 9th Irish Shellfish Safety Scientific Workshop

      Gilmartin, M.; Silke, J. (Marine Institute, 2009)
      The 9th Irish Shellfish Safety Workshop was held on the 20th March, 2009, in Kenmare, County Kerry. The Workshop was co-sponsored by the Marine Institute, Bord Iascaigh Mhara, the Food Safety Authority of Ireland, and the Sea Fisheries Protection Authority, with support from IFA Aquaculture. The topics addressed at the workshop included an update on the National Biotoxin monitoring programme, and a number of research projects with Irish participation and international perspectives on toxin detection. Finding mechanisms to improve our product was a common theme with presentations on improving food safety, increasing productivity, providing easily applied test methods, and research in support of the shellfish industry. The focus of the three Workshop sessions was on a review of the year, research and legislation.
    • Real-time PCR detection of Dinophysis species in Irish coastal waters

      Kavanagh, S.; Brennan, C.; O’Connor, L.; Moran, S.; Salas, R.; Lyons, J.; Silke, J.; Maher, M. (Springer Verlag, 2010)
      Diarrhetic shellfish toxin-producing Dinophysis species occur in Irish coastal waters throughout the year. Dinophysis acuta and Dinophysis acuminata are the most commonly occurring species and are responsible for the majority of closures of Irish mussel farms. This study describes the development of a qualitative real-time polymerase chain reaction (PCR) assay for identification of D. acuta and D. acuminata in Irish coastal waters. DNA sequence information for the D1-D2 region of the large ribosomal sub-unit (LSU) was obtained, following single-cell PCR of D. acuta and D. acuminata cells isolated from Irish coastal locations. PCR primers and hybridization probes, specific for the detection of D. acuta, were designed for real-time PCR on the LightCycler™. The LightCycler™ software melt curve analysis programme determined that D. acuta was identified by a melt-peak at 61°C, while D. acuminata cells produced a melt peak at 48°C. The limit of detection of the real-time PCR assay was determined to be one to ten plasmid copies of the LSU D1-D2 target region for both species and one to five D. acuminata cells. Lugol's preserved water samples were also tested with the assay. The real-time PCR assay identified Dinophysis species in 100% of samples found to contain Dinophysis species by light microscopy and had a greater than 90% correlation with light microscopy for identification of D. acuta and D. acuminata in the samples. The assay can identify and discriminate D. acuta and D. acuminata at low numbers in Irish waters and has the potential to add value to the Irish phytoplankton monitoring programme.
    • REDRISK: reduction of the virus risk in shellfish harvesting areas

      Guilfoyle, F.; Keaveney, S.; Flannery, J.; Doré, B. (Marine Institute, 2006)
      Filter feeding bivalve shellfish can accumulate human pathogenic bacteria and viruses if grown in sewage-contaminated waters. Current consumer protection legislation relies on classification of harvesting areas based on their sanitary quality, using E coli as an indicator of sewage contamination. Advances in viral monitoring have shown that E coli can underestimate the extent of the contamination. The most common cause of gastroenteritis associated with shellfish is norovirus, commonly known as winter vomiting virus. The REDRISK project was undertaken to investigate the main environmental factors that cause viral contamination in shellfish. The REDRISK project is part of a EU research pillar with parallel research being undertaken in the UK, France and Spain. A recently developed technique to quantify norovirus in shellfish, real-time PCR, has been used in the REDRISK project. Clew Bay, in Co. Mayo was chosen as the study area in Ireland. The bay is generally considered to have good water quality but with certain areas subject to intermittent sewage contamination. The cooperation of local producers and organisations such as the Clew Bay Marine Forum and the Native Oyster Co-op greatly helped the project. The project was divided into a two-phased approach. Phase one involved the identification of contamination sources impacting the bay through a sanitary survey and selection of appropriate sites for further study. Results of the first phase of this study were presented previously at this forum (Keaveney, et al 2006) and the characteristics of the sites selected for study and locations within the bay are shown in table 1 and figure 1 respectively. The second phase of the project focused on monitoring environmental conditions and microbiological levels in shellfish to identify environmental conditions leading to viral contamination. This paper reports the finding of this monitoring.
    • Report on analysis of shellfish samples for the presence of Yessotoxins (YTX)

      Marine Institute (Marine Institute, 2001)
      In order to determine the cause of the positive mouse bioassay results obtained in mussel samples from several shellfish production areas (including Bantry Bay, Kenmare Bay, Cromane and Lough Foyle), samples were sent in December 2000 and January 2001 for analysis. Positive mouse bioassay results were obtained, using the Yasumoto (1978) assay, in the EU Reference Laboratory and using the Yasumoto (l 984) assay in the Italian Reference Laboratory. ASP toxins, Azaspiracid, Okadaic acid and DTXs were not detected. Yessotoxin, homoYessotoxins and analogues of Yessotoxins were not detected in the samples sent to the EU Reference Laboratory or the Italian Reference Laboratory. Prof. Yasumoto detected the presence of Yessotoxin and 45-hydroxyYessotoxin at the Japan Food Research Laboratory. 45-hydroxyYessotoxin is a shellfish metabolite of Yessotoxin, which occurs with time as the YTX is oxidised by the shellfish. The shellfish samples in which Yessotoxin and 45-hydroxy Yessotoxin were detected were taken from Bantry Bay, Roaring Water Bay (Summer 2000) and Mulroy Bay. If the initial detection of Yessotoxin and 45-hydroxyYessotoxin is confirmed in other samples, the Irish biotoxin management regime and the production cycles for shellfish (in particular mussels) will have to be adapted to encompass YTX.
    • Report on the incidence and implications of phytoplankton blooms on the East Coast and particularly Wexford Harbour, Summer 1984

      Doyle, J.; Dunne, T. (1984)
      The Fisheries Research Centre had a number of reports of discoloured water between Brittas Bay Co. Wicklow and Wexford Harbour and south to Kilmore Quay. Samples of water received from Dr. David Jeffrey, Department of Botany TCD, collected from Penny-come-quick beach, co. Wicklow on June 17th and examined by Tom Dunne in the Laboratory contained dense colonies of Phaeocystis pouchetii - a microscopic algae. Subsequent samples collected by Miss Ann Kiley, Wexford County Council, traced the extent of the bloom as far south as Neamstown near Kilmore Quay. A sample taken at Cullenstown west of Kilmore Quay was clear. Also associated with this bloom were large numbers of needlelike diatoms (Nitzschia spp. More seriously, blooms of another microscopic alga (Prorocentrum minimum) began to develop in early July during the later phase of the Phaeocystis bloom.
    • Reproductive biology and parasite (Perkinsus marinus) prevalence in the eastern oyster, Crassostrea virginica, within a Georgia tidal river

      O'Beirn, F.X.; Walker, R.L.; Jansen, M.L. (Elisha Mitchell Scientific Society, 1997)
      Recruitment, in 1992, of the eastern oyster, Crassostrea virginica, at one site (Flume Dock) within the Sapelo Island National Estuarine Research Reserve (SINERR) was lower than other sampling sites. Recruitment allied with gametogenesis and parasite (Perkinsus marinus) prevalence within the oysters was examined in 1993, in an attempt to explain the differences observed the previous year. Sampling occurred at three sites (Marsh Landing, Jack Hammock, and Flume Dock) along the Duplin River within the SINERR. Oyster recruitment in 1993 was reduced in all sites within the SINERR. No oyster recruitment was recorded at the Flume Dock site during any monthly collections or on collectors deployed for the duration of the sampling study. Oysters developed gametogenically and spawned at the Marsh Landing site two weeks prior to their occurrence at the Jack Hammock site. Gametogenic development in oysters at the Flume Dock site was retarded a further two weeks where the males appeared to spawn six weeks after the females, which could account for reduced recruitment levels at this site. Approximately, twice as many females as males occurred in all sites. Monthly sampling of prevalence and intensity of Perkinsus marinus (Dermo) revealed high levels of both parameters. Smaller oysters did display lower prevalences of Dermo than larger forms.
    • Reproductive Failure of Landlocked Atlantic Salmon from New York's Finger Lakes: Investigations into the Etiology and Epidemiology of the “Cayuga Syndrome”

      Fisher, J.P.; Spitsbergen, J.M.; Rodman, G.; symula, j. (American Fisheries Society, 1995)
      We describe a disease syndrome that afflicts larval, landlocked Atlantic salmon Salmo salar from Cayuga Lake, one of central New York's Finger Lakes. Mortality associated with the “Cayuga syndrome” is 98–100%. Death usually occurs between 650 and 850 centigrade degreedays after fertilization, approximately 2–4 weeks before yolk resorption is complete. Although there is minor temporal variation in the onset of the Cayuga syndrome in progeny from individual females, all sac fry eventually succumb. Incubation of embryos and sac fry under constant, ambient, or reduced temperature regimens slightly alters the degree-day timing of syndrome onset, but does not improve survival. Based on mortality rate, manifestation of the Cayuga syndrome has not changed in the past 10 years, even though incubation waters of varying chemistry and temperature have been used. Mortality of the negative control stocks used for these studies never exceeded 10% from hatching to first feeding. Findings from reciprocal crossbreeding experiments indicate the problem is associated with ova only. A noninfectious etiology is indicated by the lack of consistently identifiable fish pathogens from syndrome-afflicted sac fry and by the failure to transmit the condition horizontally. Suspect contaminants were eliminated as potential causative factors. Epidemiological studies on the viability of other Finger Lakes stocks indicate that Atlantic salmon from Keuka and Seneca lakes are also afflicted (100% mortality). yet those from Skaneateles Lake are not. The cause of this syndrome appears to be nutritional.
    • Review of phytoplankton monitoring 2005

      Moran, S.; Silke, J.; Salas, R.; Chamberlain, T.; Lyons, J.; Flannery, J.; Thornton, V.; Clarke, D.; Devilly, L. (Marine Institute, 2006)
      A national phytoplankton monitoring programme, has been in operation in Ireland since 1986, and fulfils requirements of the EU Council Directive 91/492/EEC. This programme provides an important part of the baseline data in the overall integrated shellfish monitoring programme. The analysis of samples received on a regular basis from a site can provide very important information in assembling a population profile for the area. This helps in crucial decisions, for example in Management Cell Decisions - conducted by representatives from the industry, MI, FSAI and DCMNR - when borderline toxin results are present. Phytoplankton monitoring is also hugely important in the Water Framework Directive, which all EU countries must follow, in developing an index of water quality in Ireland and Europe. The Irish Monitoring programme also gives valuable public health information to County Councils, Environmental Health Officer’s and the public during times of bloom events. This paper provides an overview of phytoplankton sampling, analysis and reporting in 2005. The occurrence of potentially toxic and harmful phytoplankton found in Irish coastal and shelf waters in 2005 is also reviewed and the quality scheme in operation is described.
    • Review of phytoplankton monitoring 2006

      Moran, S.; Silke, J.; Salas, R.; Chamberlain, T.; Lyons, J.; Shannon, S. (Marine Institute, 2007)
      This paper provides an overview of phytoplankton sampling, analysis and reporting in 2006. The occurrence of potentially toxic and harmful phytoplankton found in Irish coastal and shelf waters in 2006 is compared with the previous year. The succession of phytoplankton blooms in Bantry is described and environmental data that may explain the onset of toxic species is described.
    • Review of phytoplankton monitoring programme and research activities

      Salas, R.; Chamberlain, T.; Lyons, J.; Hynes, P.; Silke, J. (Marine Institute, 2008)
      This paper provides a review of the activities of the Phytoplankton Unit in the Marine Institute as part of the National Monitoring Programme for 2007 and compares the findings with those recorded during 2005 and 2006., It also presents an overview of the research activities carried out by the phytoplankton team during the year with a focus on culturing phytoplankton and the introduction of real time PCR techniques for phytoplankton identification.
    • Review of the phytoplankton monitoring programme and research activities in 2008

      Salas, R.; Lyons, J.; Hynes, P.; Chamberlain, T.; Silke, J. (Marine Institute, 2009)
      The National Monitoring programme for phytoplankton is a well established programme and this was shown through the improvement and refinement of Phytoplankton shellfish and finfish sites around the country. One important development in the last 2 years has been to increase the number of sentinel sites. A sentinel site is a designated sampling site where a total community Phytoplankton cell count and identification is carried out. The number of sentinel sites has increased from 11 in 2005 to 24 in 2008. This means a better coverage of all the bays around the country. The number of phytoplankton samples analysed in 2008 has seen an increase from the previous year.
    • Risk factors associated with increased mortality of farmed Pacific oysters in Ireland during 2011

      Clegg, T.A.; Morrissey, T.; Geoghegan, F.; Martin, S.W.; Lyons, K.; Ashe, S.; More, S.J. (Elsevier, 2014)
      The Pacific oyster, Crassostrea gigas, plays a significant role in the aquaculture industry in Ireland. Episodes of increased mortality in C. gigas have been described in many countries, and in Ireland since 2008. The cause of mortality events in C. gigas spat and larvae is suspected to be multifactorial, with ostreid herpesvirus 1 (OsHV-1, in particular OsHV-1 μvar) considered a necessary, but not sufficient, cause. The objectives of the current study were to describe mortality events that occurred in C. gigas in Ireland during the summer of 2011 and to identify any associated environmental, husbandry and oyster endogenous factors. A prospective cohort study was conducted during 2010–2012, involving 80 study batches, located at 24 sites within 17 bays. All 17 bays had previously tested positive for OsHV-1 μvar. All study farmers were initially surveyed to gather relevant data on each study batch, which was then tracked from placement in the bay to first grading. The outcome of interest was cumulative batch-level mortality (%). Environmental data at high and low mortality sites were compared, and a risk factor analysis, using a multiple linear regression mixed effects model, was conducted. Cumulative batch mortality ranged from 2% to 100% (median = 16%, interquartile range: 10–34%). The final multivariable risk factor model indicated that batches imported from French hatcheries had significantly lower mortalities than non-French hatcheries; sites which tested negative for OsHV-1 μvar during the study had significantly lower mortalities than sites which tested positive and mortalities increased with temperature until a peak was reached. There were several differences between the seed stocks from French and non-French hatcheries, including prior OsHV-1 μvar exposure and ploidy. A range of risk factors relating to farm management were also considered, but were not found significant. The relative importance of prior OsHV-1 μvar infection and ploidy will become clearer with ongoing selection towards OsHV-1 μvar resistant oysters. Work is currently underway in Ireland to investigate these factors further, by tracking seed from various hatchery sources which were put to sea in 2012 under similar husbandry and environmental conditions.
    • The role of Azadinium spinosum (Dinophyceae) in the production of azaspiracid shellfish poisoning in mussels

      Salas, Rafael; Tillmann, Urban; John, Uwe; Kilcoyne, Jane; Burson, Amanda; Cantwell, Caoimhe; Hess, Philipp; Jauffrais, Thierry; Silke, Joe (Elsevier, 2011)
      Azaspiracids (AZAs) are a group of lipophilic polyether compounds first detected in Ireland which have been implicated in shellfish poisoning incidents around Europe. These toxins regularly effect shellfish mariculture operations including protracted closures of shellfish harvesting areas for human consumption. The armoured dinoflagellate Azadinium spinosum Elbrächter et Tillmann gen. et sp. nov. (Dinophyceae) has been described as the de novo azaspiracid toxin producer; nonetheless the link between this organism and AZA toxin accumulation in shellfish has not yet been established. In August 2009, shellfish samples of blue mussel (Mytilus edulis) from the Southwest of Ireland were analysed using liquid chromatography–tandem-mass spectrometry (LC–MS/MS) and were found to be above the regulatory limit (0.16 μg g−1 AZA-equiv.) for AZAs. Water samples from this area were collected and one algal isolate was identified as A. spinosum and was shown to produce azaspiracid toxins. This is the first strain of A. spinosum isolated from Irish waters. The Irish A. spinosum is identical with the other two available A. spinosum strains from Scotland (3D9) and from Denmark (UTHE2) in its sequence of the D1–D2 regions of the LSU rDNA. A 24 h feeding trial of blue mussels (M. edulis) using an algal suspension of the Irish A. spinosum culture at different cell densities demonstrated that A. spinosum is filtered, consumed and digested directly by mussels. Also, LC–MS/MS analysis had shown that AZAs were accumulating in the shellfish hepatopancreas. The toxins AZA1 and -2 were detected in the shellfish together with the AZA analogues AZA3, AZA6, AZA17 and -19 suggesting that AZA1 and -2 are metabolised in the shellfish within the first 24 h after ingestion of the algae. The levels of AZA17 detected in the shellfish hepatopancreas (HP) were equivalent to the levels of AZA1 but in the remainder tissues the levels of AZA17 were four to five times higher than that of AZA1, only small quantities of AZA3 and -19 were present with negligible amounts of AZA6 detected after the 24 h period. This could have implications in the future monitoring of these toxins given that at present according to EU legislation only AZA1–AZA3 is regulated for. This is the first report of blue mussels’ (M. edulis) feeding on the azaspiracid producing algae A. spinosum from Irish waters.
    • Salmon Mortalities at Inver Bay and McSwyne’s Bay Finfish farms, County Donegal, Ireland, during 2003

      Cronin, M.; Cusack, C.; Geoghegan, F.; Jackson, D.; McGovern, E.; McMahon, T.; O'Beirn, F.X.; Ó Cinneide, M.; Silke, J. (Marine Institute, 2004)
      This report details the investigations into a major mortality of farmed salmon at Inver Bay and McSwyne’s Bay, Co. Donegal in July 2003. Previous reports were provided on 29th July 2003 and on 11th August 2003. The information is based upon analysis and research by MI scientists, a review of environmental data, survey reports by external consultants, inputs from veterinary practitioners who visited the site, reports from DCMNR staff in Killybegs, and site visits made by DCMNR / MI inspectors. Following a review meeting of the principal investigators on the 9th October, 2003, MI proceeded to carry out further scientific investigations. DCMNR also commissioned Kirk McClure Morton Consulting Engineers (KMM) to carry out a parallel investigation of the mortalities at Inver Bay and McSwynes Bay salmon farms. MI provided support as required to the KMM study, the report for which was furnished to DCMNR and MI on 11 February 2004. (KMM, 2004) MI wishes to acknowledge the high level of co-operation and assistance that it received from the owners and staff of Creevin Fish Farm Ltd, Eany Fish Products Ltd and Ocean Farms Ltd. It also wishes to acknowledge the assistance of veterinary practitioners, DCMNR staff and others in the course of this investigation.
    • A sensitive liquid chromatography/tandem mass spectrometry method for the determination of natural and synthetic steroid estrogens in seawater and marine biota, with a focus on proposed Water Framework Directive Environmental Quality Standards

      Ronan, J.; McHugh, B. (Wiley, 2013)
      RATIONALE: Trace levels of natural and synthetic steroid estrogens estrone (E1), 17b-estradiol (E2) and 17a-ethynyl estradiol (EE2) have been demonstrated to exert adverse effects in exposed organisms. E2 and EE2 have been proposed for inclusion in the Water Framework Directive (WFD) list of priority pollutants; however, the detection and accurate quantification of these compounds provide significant challenges, due to the low detection limits required. METHODS: A sensitive method combining ultrasonication, solid-phase extraction (SPE) and liquid chromatography/tandem mass spectrometry, with electrospray ionisation in negative mode (LC/ESI-MS/MS), capable of determining E1, E2 and EE2 at concentrations between 0.07 and 60 ng/L for seawater and between 0.4 and 200 ng/g wet weight in Mytilus spp. is reported. Recoveries at the limit of quantification (LOQ) ranged from 95 to 102% and 88 to 100% for water and tissue, respectively. Salinity (12 to 35%) and typical marine particulate matter loadings (between 10 and 100 mg/L) were not found to affect analyte recoveries. RESULTS: The first detection of E1 by LC/MS/MS in Irish marine waters (Dublin Bay, at 0.76 ng/L) is reported. Steroids were not detected in Galway Bay, or in any mussel samples from Dublin, Galway and Clare. The level of E2 detected in the dissolved water phase was below the proposed WFD Environmental Quality Standard (EQS) in other surface waters. CONCLUSIONS: The proposed method is suitable for the detection of E1, E2 and EE2 at biologically relevant concentrations and, due to the specificity offered, is not subject to potential interferences from endogenous E1 and E2 which often complicate the interpretation of estrogenic biomarker assays.