• Growth and survival of Spisula solidissima similis larvae fed different rations of Tahitian strain Isochrysis species

      Hurley, D.H.; Walker, R.L.; O'Beirn, F.X. (National Shellfisheries Association, 1997)
      Laboratory-spawned veliger-stage larvae of the southern Atlantic surfclam, Spisula solidissima similis (Say 1822), were reared to late pediveliger stage on five different cell concentrations of Tahitian strain Isochrysis species (T-Iso) to determine an optimal food ration for this subspecies. Larvae were fed daily 0, 50,000, 100,000, 200,000, or 300,000 cells/mL of T-Iso. Day-old veliger larvae were stocked in 150 (1-L) replicate flasks at mean densities of 0.7 or 0.8 larvae/mL for trials A and B, respectively. Larval growth and survival were assessed every 2 days over the 14-day trial penods. Significantly greater growth and survival of larvae occurred in both trials in the lower food rations of 50,000 and 100,000 cells/mL. A reduction in larval growth rate and survival was observed at the higher ration treatments. A decline in overall larval health may be associated with the deliterious effects of surplus ration degradation.
    • Culture of surfclams Spisula solidissima sp., in coastal Georgia: nursery culture

      O'Beirn, F.X.; Walker, R.L.; Hurley, D.H.; Moroney, D.A. (National Shellfisheries Association, 1997)
      Growth of the Atlantic surfclam, Spisula solidissima solidissima, was compared with that of the southern Atlantic surfclam, Spisula solidissima similis. All experimental animals were reared in upweller units at 20°C and fed cultured algae on a daily basis. Over the 14 wk of the study, the Atlantic surf clams grew markedly better (8.9-mm increase in shell length and a 1,103% increase in biomass) than the southern Atlantic surfclams (6.6-mm increase in shell length and 573% mcrease in biomass). Mortality for both groups was negligible. The mean shell lengths attained for the Atlantic surfclams (15.3 mm) and the southern Atlantic surfclams (13 mm) at the conclusion of the study were large enough to ensure good growth and survival on relocation to a field growout environment. The growth patterns obtained under similm growth conditions further highlight some basic life history differences between these subspecies, which were apparent from other studies.
    • 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.
    • Assessment of the risk of introducing harmful marine organisms by shipping to Bantry Bay

      Minchin, D. (1997)
      The main shipping activity in Bantry Bay is centred at Leahill, a site where there is aggregate extraction with direct transmission to bulk carriers at a dedicated pier. The size of vessels ranges from 250 to7,800mtNRT but with the majority of vessels being of 700 to l,800mtNRT. Ballast water from these vessels is required to be deposited at sea before entering the Bay should these vessels becoming from outside of Ireland. If this is done the risk of introducing dinoflagellate species present in those ports in Atlantic France and Spain will be reduced. Vessels from Irish ports are not required to discharge ballast before entering the Bay. The main risk to Bantry Bay, albeit small - because the amount of ballast discharged is small, is from inoculations of the toxic dinoflagellate Alexandrium tamarense from ships that have ballasted in Cork Harbouror Belfast Lough. It would be prudent for vessels ballasting in these sea inlets not to do so in the region and during the time of the toxic algal bloom events. Although vegetative stages of A. tamarense have been identified from the plankton of Bantry Bay and Alexandrium sp. cysts have been found in fine sediments it is not known whether further inoculations of A. tamarense either in its vegetative or cyst state could result in a PSP event within the Bay. The development of a management plan for ships' ballasting in Cork Harbour and Belfast Lough based on cyst distributions and the distribution of algal bloom events could greatly reduce the risk of a transfer. In the meantime discoloured water in Cork Harbour and Belfast Lough should not be ballasted. The Cork Harbour Commissioners will be advised when algal bloom events take place so that basic precautions.
    • Management and control of proliferative kidney disease (PKD) in a freshwater Atlantic salmon (Salmo salar L.) farm in Ireland: a case history

      Quigley, D.T.G.; McArdle, J.F. (Fish Veterinary Society, 1998)
      During July 1992, an acute clinical outbreak of proliferative kidney disease (PKD) was experienced in two strains (‘Irish’ and ‘Norwegian’) of juvenile (age 0+) Atlantic salmon (Salmo salar L.) held at two adjacent freshwater sites on the River Lee in southern Ireland. Various management strategies (including reduced stocking densities, handling, feeding rates and increased oxygenation), and treatment regimes (involving malachite green and fumagillin DCH) were used to control the disease. A total of 1·3 million juveniles died during the PKD outbreak, representing 61·6% and 54·6% of the Norwegian stock at the two farms respectively. The Irish stock appeared to be more resistant to the disease and only 15·6% died. The weekly prevalence of PKD fluctuated throughout the summer but seemed to disappear by mid-August. Although PKD was detected again during 1993, no clinical outbreak occurred. In conjunction with the management strategies adopted in 1992, seven consecutive weekly prophylactic bath treatments with malachite green (1·6 ppm for 40 minutes) administered prior to mid-July appeared to control the disease. During August 1993, a ten day course of fumagillin (6 mg/kg bodyweight per day) reduced the prevalence of the PKD parasite in a trial batch of juveniles from 24% to zero. The results of this study demonstrated the effectiveness of various management strategies and treatment regimes in controlling PKD.
    • Developments in analysis and toxicology of toxaphene compounds

      de Geus, H-J.; Besselink, H.; Brouwer, A.; Klungsøyr, J.; MacGovern, E.; MacHugh, B.; Nixon, E.; Rimkus, G.G.; Wester, P.G.; de Boer, J. (1998)
      Over the last 50 years toxaphene has been produced and used as a pesticide extensively. The US Environmental Protection Agency banned it in 1982. In the early 1990s the presence of toxaphene in marine fish in Europe caused concern with regard to human health in relation with consumption. This paper gives a brief overview of recent developments in the analytical and toxicological research on toxaphene.
    • Survival and growth of juvenile freshwater mussels (Unionidae) in a recirculating aquaculture system

      O'Beirn, F.X.; Neves, R.J.; Steg, M.B. (American Malacological Union, 1998)
      An indoor recirculating aquaculture system was constructed to provide suitable conditions to culture juvenile freshwater mussels. In the first of three growth trials, Villosa iris (I. Lea, 1829) juveniles were cultured for 22 wk, and grew from an initial mean length of 0.4 mm to 2.7 mm. Survival was 26.8% overall. In the second trial, growth and survival were compared between juveniles of V. iris held in sediment and without sediment. The initial mean length of both groups was 2.7 mm, and this experiment ran for 17 wk. The juvenile mussels in sediment grew to a mean length of 5.7 mm with 85% survival, significantly greater (p < 0.01) than juveniles held without sediment (4.5 mm, 74% survival). In the third trial, two cohorts of juvenile Lampsilis fasciola Rafinesque, 1815, increased in length from I.I mm and 1.4 mm to 3.3 mm and 4.1 mm, respectively, with comparable survival (78.7% versus 64.5%). Results of these trials demonstrate that juvenile mussels can be reared successfully within recirculating systems. One of the factors deemed important in successful culture is continuous feeding of an appropriate food source. In this study, a unialgal culture of Neochloris oleabundans Chantanachat and Bold, 1962, was used throughout. Regular cleaning of the system and water replacement also was important. Finally, the culture of juveniles in sediment appears to be an important factor in ensuring good growth and survival. This phenomenon could be related to pedal feeding behavior, proper orientation of the mussels for filtering efficiency, or stability from physical disturbance.
    • The implications of Alexandrium tamarense resting cysts in an area of shellfish aquaculture in Ireland

      Silke, J.; McMahon, T. (1998)
      The Irish Marine Institute's Fisheries Research Centre carry out a monitoring programme for the detection of algal toxins in shellfish. This programme is carried out under EU Directive 91/492. During the course of this programme the North Channel area of Cork Harbour has been the only location in Ireland where toxins causing Paralytic Shellfish Poisoning (PSP) have been detected in shellfish above the regulatory limit. For short periods during each of the summers of 1996,1997 and 1998, PSP toxins were found in mussels{Mytilus edulis) from this area above the regulatory limit period necessitating a ban on harvesting. Oysters {Crassostrea gigas) from the same area remained below the regulatory threshold. The dinoflagellate Alexandrium tamarense, a known vector of PSP toxins, was observed in the area during each of the toxic events. The exact origin of the populations of A. tamarense was unknown. A. tamarense is known to produce a cyst stage as part of its life cycle. These cysts can remain viable in the sediments for several years. A survey of the distribution of cysts of A. tamarense in the surface sediments in Cork Harbour was carried out in order to determine if they were potentially seeding the area. They were detected in 6 sites, and successfully germinated to yield vegetative cells. The results of the survey are presented and discussed.
    • Environmental occurrence, analysis, and toxicology of toxaphene compounds

      de Geus, H.-J.; Besselink, H.; Brouwer, A.; Klungsøyr, J.; McHugh, B.; Nixon, E.; Rimkus, G.G.; Wester, P.G.; de Boer, J. (1999)
      Toxaphene production, in quantities similar to those of polychlorinated biphenyls, has resulted in high toxaphene levels in fish from the Great Lakes and in Arctic marine mammals (up to 10 and 16 microg g-1 lipid). Because of the large variabiliity in total toxaphene data, few reliable conclusions can be drawn about trends or geographic differences in toxaphene concentrations. New developments in mass spectrometric detection using either negative chemical ionization or electron impact modes as well as in multidimensional gas chromatography have recently led researchers to suggest congener-specific approaches. Several nomenclature systems have been developed for toxaphene compounds. Although all systems have specific advantages and limitations, it is suggested that an international body, such as the International Union of Pure and Applied Chemistry, make an attempt to obtain uniformity in the literature. Toxicologic information on individual chlorobornanes is scarce, but some reports have recently appeared. Neurotoxic effects of toxaphene exposure such as those on behavior and learning have been reported. Technical toxaphene and some individual congeners were found to be weakly estrogenic in in vitro test systems; no evidence for endocrine effects in vivo has been reported. In vitro studies show technical toxaphene and toxaphene congeners to be mutagenic. However, in vivo studies have not shown genotoxicity; therefore, a nongenotoxic mechanism is proposed. Nevertheless, toxaphene is believed to present a potential carcinogenic risk to humans. Until now, only Germany has established a legal tolerance level for toxaphene--0.1 mg kg-1 wet weight for fish.
    • MATT: Monitoring, Analysis and Toxicity of Toxaphene: improvement of analytical methods

      de Boer, J.; Klungsøyr, J.; Nesje, G.; Meier, S.; McHugh, B.; Nixon, E.; Rimkus, G.G. (1999)
      The European Research Project MATT (Investigation into the Monitoring, Analysis and Toxicity of Toxaphene) started in 1997 and had the objective to provide information on toxicological risks to the consumer of toxaphene residues in fish from European waters. This report includes information on the analytical block of the project, which comprised three studies.
    • Pea Crab, Pinna theres ostreum Say, 1817, in the eastern Oyster, Crassostrea virginica (Gmelin, 1791): prevalence and apparent adverse effects on oyster gonad development

      O'Beirn, F.X.; Walker, R.L. (California Malacozoological Society, 1999)
      Incidence of pea crab, Pinnotheres ostreum Say 1817, infestation in the eastern oyster, Crassostrea virginica (Gmelin, 1791), was recorded and related to oyster gametogenic activity over 18 months. Sampling occurred at twO tidal heights (high intertidal HI and low intertidal LI) at two sites (House Creek, HC and Skidaway River, SR) in Wassaw Sound, Georgia. Overall, incidence rates were 3% HC LI, 1 % HC HI, 8% SR LI, and 4% SR HI. At both tidal heights at HC, no differences were observed in gonad area between those oysters with and without pea crabs. At SR (where overall incidences were higher), oysters without pea crabs had significantly higher gonad area values than those oysters with pea crabs present. These results suggest that at higher incidences of pea crab infestation, oyster reproductive capabilities could be impacted, and support the claim that the pea crab/oyster relationship is a parasitic one.
    • Polychlorinated Biphenyls and Organochlorines in By-Caught Harbour Porpoises Phocoena phocoena and Common Dolphins Delphinus delphis from Irish Coastal Waters

      Smyth, M.; Berrow, S.; Nixon, E.; Rogan, E. (Royal Irish Academy, 2000)
      Concentrations of 11 organochlorine (OC) pesticides and 10 individual polychlorinated biphenyls (PCB) in blubber and liver from 12 harbour porpoise Phocoena phocoena and eight common dolphins Delphinus delphis incidentally caught in fishing nets in Irish waters are presented. Female harbour porpoises had highest concentrations of OC in blubber and male common dolphins in liver. Harbour porpoises had higher mean concentrations of lindane (121-154 ng/g extractable lipid), dieldrin (116-121 ng/g) and  BHC (54-128 ng/g) but common dolphins had greater overall concentrations of DDT (9444-3998 ng/g). The predominant DDT metabolite was pp-DDE and for the chlordanes was t-nonachlor. Concentrations of ICES 7 PCB (liver-blubber) were similar in both species (4075-7999 ng/g in harbour porpoise and 4076-8945 in common dolphins). The sum of ICES 7 PCB in porpoises ranged from 3041-12270 ng/g extractable lipid in the blubber of females and from 2911-10429 ng/g in males and 798-11074 ng/g in the blubber of female common dolphins and 1555-15883 ng/g in males. Contaminant levels were generally similar to those reported from Scotland but lower than reported from Scandinavia. Ratios of DDT to DDE suggests that there are limited new sources of DDT into the Irish marine environment. These results provide a baseline for monitoring of persistent pollutants in the Irish marine environment.
    • In vitro and in vivo tumor promoting potency of technical toxaphene, UV-irradiated toxaphene, and biotransformed toxaphene

      Besselink, H.T.; Nixon, E.; McHugh, B.; Klungsøyr, J.; Brouwer, A. (2000)
      Toxaphene, a complex mixture of polychlorinated camphenes, was first introduced in 1945 by Hercules Co. as Hercules 3965. Until the mid 1980s, it was mass produced and widely used as an insecticide, and was also used as a piscicide to control rough fish in various water systems. The lipophilic, persistent, and volatile nature of toxaphene has contributed to its global dispersion throughout the fresh water and marine environment. In addition to bioaccumulation in biota inhabiting these regions, it is also been detected in humans. Human exposure mainly occurs through the consumption of toxaphene contaminated fish. Information on the carcinogenicity and general toxicology of weathered and biotransformed TT would be of major interest. To mimic the weathered toxaphene found in fish, we developed a so-called 'realistic exposure' procedure for toxaphene. This procedure makes use of cod that were exposed to TT. Toxaphene residues that were extracted from cod liver (CLE), were then used in in vitro and in vivo studies to obtain information on its tumor promoting potency. Besides CLE, we also studied the tumor promoting properties of UV-irradiated toxaphene (UVT) and TT.
    • Survey of toxaphene concentrations in fish from European waters

      McHugh, B.; Nixon, E.; Klungsoyr, J.; Besselink, H.; Brouwer, A.; Rimkus, G.; Leonards, P.; de Boer, J. (2000)
      Toxaphene, a suspected carcinogen, is a broad spectrum chlorinated pesticide. The objective of this study was to provide information on the toxicological risks posed by toxaphene to the consumer of fish from European waters. The levels of 3 toxaphene congeners in various fish species from different geographical locations were determined. These data were then used to provide information on the exposure of toxaphene to the consumer of fish.
    • Toward design criteria in constructed oyster reefs: oyster recruitment as a function of substrate type and tidal height

      O'Beirn, F.X.; Luchenbach, M.W.; Nestlerode, J.A.; Coates, G.M. (National Shellfisheries Association, 2000)
      Restoration of degraded oyster reef habitat generally begins with the addition of substrate that serves as a reef base and site for oyster spat attachment. Remarkably, little is known about how substrate type and reef morphology affect the development of oyster populations on restored reefs. Three-dimensional, intertidal reefs were constructed near Fisherman's Island, Virginia: two reefs in 1995 using surfclam (Spisula solidissima) shell and six reefs in 1996 using surfclam shell, oyster shell, and stabilized coal ash. We have monitored oyster recruitment and growth quarterly at three tidal heights (intertidal, mean low water, and subtidal) on each reef type since their construction. Oyster recruitment in 1995 exceeded that observed in the two subsequent years. High initial densities on the 1995 reefs decreased and stabilized at a mean of 418 oyster/m2. Oyster settlement occurred on all reef types and tidal heights in 1996; however, postsettlement mortality on the surfclam shell and coal ash reefs exceeded that on the oyster shell reefs, which remained relatively constant throughout the year (mean = 935 oysters/m2). Field observations suggest that predation accounts for most of the observed mortality and that the clam shell and coal ash reefs, which have little interstitial space, suffer greater predation. Oyster abundance was consistently greatest higher in the intertidal zone on all reefs in each year studied. The patterns observed here lead to the preliminary conclusion that the provision of spatial refugia (both intertidal and interstitial) from predation is an essential feature of successful oyster reef restoration in this region. In addition, high levels of recruitment can provide a numerical refuge, whereby the oysters themselves will provide structure and increase the probability of an oyster population establishing successfully on the reef.
    • Small intestinal injuries in mice caused by a new toxin, Azaspiracid, isolated from Irish mussels

      Ito, E.; Satake, M.; Ofuji, K.; McMahon, T.; Silke, J.; James, K.; Yasumoto, T. (UNESCO, 2001)
      Pathological changes of the small intestine caused by a new toxin, azaspiracid, from Irish mussels were studied. Human poisoning cases included both diarrhetic shellfish and paralitic shellfish poisoning symptoms. The present paper focused on the former. Injuries were observed in the Upper part of the small intestine, where lamina propria in the villi became atrophied at the initial stage, followed by desquamation of epithelial cells and shortening of villi. The injuries were different from the DSP toxin okadaic acid; 1) they developed very slowly after a lag time of about 3 hr, 2) recovery was very late, 3) initial target and process were different.
    • Harmful phytoplankton events caused by variability in the Irish Coastal Current along the west of Ireland

      O'Boyle, S.; Nolan, G.; Raine, R. (UNESCO IOC, 2001)
      Frequent sampling in summer along the western and northwestern coasts of Ireland showed the rapid onshore development of blooms of potentially harmful phytoplankton species. In both 1998 and 1999, concentrations of Gyrodinium cf. aureolum rose by four orders of magnitude to over one million cells per litre in Donegal Bay(northwestern Ireland) in less than 10days. The rapid development of these populations was linked to advection resulting from unfavourable wind-forcing of the Irish Coastal Current (ICG) which runs northwards along the western Irish coast. Current measurements showed that after a particular sequence of changes in wind direction phytoplankton populations could be rapidly advected from areas of slack circulation on the shelf via the ICC into aquaculturally sensitive coastal zones such as Donegal Bay. The model presented is similar to one already demonstrated for the occurrence of toxic events in the bays of southwestern Ireland. Other historical harmful events along the west and northwest coasts relating to substantial losses in both finfish and shellfish culture could also be explained using the model. These include the G. aureolum bloom of 1992, the Prorocentrum balticum bloom in 1997.
    • 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.
    • Amnesic shellfish poisoning in the king scallop, Pecten maximus, from the west coast of Scotland

      Campbell, D.A.; Kelly, M.S.; Busman, M.; Bolch, C.J.S.; Wiggins, E.; Moeller, P.D.R.; Morton, S.L.; Hess, P.; Shumway, S.E. (National Shellfisheries Association, 2001)
      The king scallop, Pecten maximus, is a valuable economic resource in the UK. The industry relies on supplying premium "roe-on" processed scallops to the continental market. In July 1999, king scallops harboring the amnesic shellfish poisoning (ASP) toxin, domnic acid (DA), in gonadal tissue at levels above the regulatory limit (20 μg DA g-1) were detected across a wide area of northern and western Scotland. In response, a survey of the southern extent of the closed harvest areas was initiated to describe variability of ASP toxin levels over varying spatial scales (<5 m to >5 km); determine the anatomical distribution of the toxin, and identify, isolate, and culture causative Pseudo-nitzschia species. Toxin analysis was conducted using a liquid chromatography-tandem mass spectroscopy (LC-MS/MS) procedure. The DA content of tissues followed the predictable rank order: all other tissue -1 gonad -1 adductor. The toxin levels within all other tissue (95% Cl = 580-760 μg DA g-1, n = 170) consistently accounted for 99% of the total individual toxin burden. DA levels in the gonad (95% CI = 8.2-11.0 μg DA g- 1, n = 170) were an order of magnitude below levels in all other tissue and contributed to less than 0.5% of the total individual toxin burden, although levels above the regulatory limit were detected in individual gonad samples. Adductor muscle tissue contained the lowest concentration of DA (95% Cl = 0.38-0.82 μg DA g- 1, n = 170), and was typically within two to three orders of magnitude below levels in all other tissue. None of the scallops examined had DA toxicities in adductor muscle tissue exceeding the regulatory limit. Toxin variability among individuals and sites was high (range of coefficients of variation (CV) in all other tissue = 29&-l20% and gonadal = 45%-85%). The results do give an indication of the scale on which microhabitat differences may influence ASP toxicity in P. maximus populations, because significant differences were found in all other and gonadal tissue toxin levels between groups of individuals only 25-m apart. In total, seven species of Pseudo-nitzschia were identified from west coast waters. A suspected causative species, P. australis, was found to produce high levels of DA, in culture. The high individual variation in toxicities and the occurrence of DA in the gonad at levels above the regula1ory limit clearly demonstrate the complexity of managing the king scallop fishery during ASP events.
    • Use of LC-MS testing to identify lipophilic toxins, to establish local trends and interspecies differences and to test the comparability of LC-MS testing with the mouse bioassay: an example from the Irish biotoxin monitoring programme 2001

      Hess, P.; McMahon, T.; Slattery, D.; Swords, D.; Dowling, G.; McCarron, M.; Clarke, D.; Gobbons, W.; Silke, J.; O'Cinneide, M. (Conselleria de Pesca e Asuntos Maritimos da Xunta de Galicia and Intergovernmental Oceanographic Commission of UNESCO, 2003)
      During 2001, the Marine Institute has extended its range of chemical tests to include the analysis of DSP toxins by Liquid Chromatography coupled to Mass Spectrometry (LC-MS). Thus the range of compounds determined extends from domoic acid over DSP compounds (okadaic acid and DTXs) to azaspiracids (AZAs). These tests complement the mouse bioassay, which is the current reference method for lipophilic toxins within the European Community. The development and performance characteristics of the LC-MS method are discussed. Isomer patterns and interspecies differences are discussed as well as local trends in time and variability at one production site at a given time. Comparison of the LC-MS results with the results from the mouse bioassay showed good agreement (93%), and a small but significant number of discrepancies (7%). Overall, the chemical testing has proven to be an invaluable tool in the assessment of shellfish toxicity in Ireland. Lacks of standards and reference materials are discussed as well as the need for further research into the equivalence of methods.