• Trace Metal and Chlorinated Hydrocarbon Concentrations in Shellfish from Irish Waters, 1997-1999

      McGovern, E; Rowe, A; McHugh, B; Costello, J; Bloxham, M; Duffy, C; Nixon, E (Marine Institute, 2001)
      In accordance with the monitoring requirements of Council Directive 79/923/EEC, on the quality required of shellfish waters, and Council Directive 91/492/EEC, laying down the health conditions for the production and placing on the market of live bivalve molluscs, the Marine Institute collected water and shellfish samples from major shellfish growing areas and analysed for physicochemical parameters, trace metal levels and chlorinated hydrocarbon concentrations. Since, with the exception of mercury, there are no currently applicable European standards for the concentration of these contaminants in shellfish, the levels were compared with the available standards and guidance values for human consumption, as compiled by the Oslo and Paris Commission (OSPAR) countries. As in previous years, the water quality from shellfish growing areas was good and conformed to the guidelines and requirements of the Directive. Petroleum hydrocarbons were not observed in any of the shellfish waters or as deposits on the shellfish. Chlorinated hydrocarbon levels were very low, evidence of the clean, unpolluted nature of Irish shellfish and shellfish producing waters. Trace metal levels were consistently low with the exception of cadmium in oyster tissue, which was slightly elevated in the 1999 samples from Clew Bay, Inner Tralee Bay, Aughinish Limerick and Kilkieran. However these levels did not exceed the Dutch human consumption standard value or the EU maximum limit of 1.0 mg/kg wet weight due to apply from 2002. This survey confirms previous studies which show Irish shellfish products are effectively free from trace metal and chlorinated hydrocarbon contamination.
    • Trace Metal and Chlorinated Hydrocarbon Concentrations in Various Fish Species Landed at Selected Irish Ports, 1997-2000

      Tyrrell, L; Glynn, D; Rowe, A; McHugh, B; Costello, J; Duffy, C; Quinn, A; Naughton, M; Bloxham, M; Nixon, E; McGovern, E (Marine Institute, 2003)
      The Marine Institute samples a range of finfish species landed at five major Irish ports on an annual basis, in accordance with the monitoring requirements of various European legislation designed to ensure food safety. During 1997 – 2000, a total of 112 samples from 23 different species of finfish were collected from five major Irish fishing ports and analysed for total mercury concentration in the edible. The concentration of mercury ranged from 0.03 to 0.18 mg/kg wet weight in 1997, <0.03 to 0.19 mg/kg wet weight in 1998, <0.03 to 0.29 mg/kg wet weight in 1999 and 0.03 to 0.33 mg/kg wet weight in 2000. These levels are well within the maximum limit of 0.50 mg/kg wet weight for mercury in fishery products set by the EC. This survey confirms previous studies, which show that Irish seafoods are effectively free from mercury contamination. Selected samples were also analysed for other trace metals and chlorinated hydrocarbons. Overall, the levels of lead and cadmium detected in the edible portion of the fish were low and well within the standard values of 0.20 and 0.05 mg/kg wet weight respectively, set by the EU. There are no internationally agreed standards or guidelines available for the remaining trace metals and chlorinated hydrocarbons in fishery products. Therefore results are compared with the strictest standard or guidance value for fish tissue, which are applied by contracting parties to OSPAR. The levels of these additional contaminants are well below the strictest values listed.
    • Winter Nutrient Monitoring of the Western Irish Sea – 1990 to 2000

      McGovern, E; Monaghan, E; Bloxham, M; Rowe, A; Duffy, C; Quinn, A; McHugh, B; McMahon, T; Smyth, M; Naughton, M; McManus, M; Nixon, E (Marine Institute, 2002)
      Winter nutrient concentrations in the western Irish Sea have been monitored annually from 1990 to 2000. Surface samples have been taken between Dundalk Bay and Carnsore Point and analysed for total oxidised nitrogen (TOxN), ortho-phosphate (ortho-P), silicate and salinity. More recently monitoring has been extended into the Celtic Sea. Data from this monitoring programme are presented in detail, along with comparisons to existing data sets. The spatial distribution of nutrients and salinity are presented for each year in contour or classed plots (depending on sample coverage for the particular year). Salinity values were representative of those expected in the Irish Sea and TOxN, ortho-P and silicate values were in general agreement with previous studies. A short summary of studies on nutrient levels in estuaries on the western Irish Sea is presented. In addition, riverine input data supplied by the Environmental Protection Agency (EPA) is used to evaluate the relative magnitude of nutrient inputs from riverine and oceanic sources. Nutrient concentrations are considered using an ecological quality objectives (EcoQOs) approach, proposed as part of the Oslo Paris Convention’s (OSPAR) ‘Common Procedure for Identification of the Eutrophication Status of the Maritime Area’, in partial consideration of the trophic status of the western Irish Sea. Although there is evidence for nutrient enrichment in some estuarine waters and possibly to a lesser extent in some coastal waters, there is little evidence for generally elevated nutrient levels in coastal and offshore waters in the western Irish Sea. Salinity regression curves were calculated for TOxN and ortho-P values in order to generate salinity-normalised concentrations for trend determinations. Regression and trend analysis were carried out on the sample area as a whole and also on regions defining the north, mid, and south western Irish Sea. Trend analysis has been performed, based on nutrient-salinity regressions, using Trend-Y-Tector. A decrease in TOxN over the study period (ranging from 4 to13%) is observed in all regions analysed with the exception of the south west Irish Sea, where a 5% increase was indicated. Analysis of trends in ortho-P concentration showing decreasing trends ranging from 20 to 33%. On visual examination, trends in TOxN are not as intuitively apparent as trends in ortho-P concentrations, therefore it may not be prudent to draw conclusions from them at this stage. Trend analysis of riverine inputs shows an increase in TOxN by 17% and no apparent trend in ortho-P levels. These trends are not consistent with trends observed in the Irish Sea. On the basis of this assessment, it is recommended that this monitoring be continued. The design of future nutrient monitoring surveys is considered, with a view to improving the efficacy of the monitoring regime.