Biomonitoring of pollution in harbours when multiple pollutants are present

This study compared the use of biomarkers to assess sub-lethal effects of pollutants alongside a standard toxicity test and sediment analysis within a harbour environment predominantly affected by TBT and PAHs, in Aberdeen, NE Scotland. Analysis of sediment sampled twice yearly showed few clear trends for metals, TBT or PAHs over a 8 year period from 1997-2005. At one sample site, (29) PAHs were seen to increase during the study period. This could potentially be linked to the Denburn storm overflow, which can release untreated waste water during periods of prolonged heavy rain. Levels of contamination were highest at sample sites located within the inner harbour, sites where sediment would accumulate and tidal flushing would be less effective at redistributing contaminants. The Corophium bioassay was used to assess temporal and spatial variation in the toxicity of harbour sediment. Significant differences were seen between sample sites located in the inner harbour areas and control sediment. In most cases, mortality did not correlate to any one individual contaminant, however when mortality was relatively low, correlations were seen with heavy metals such as Pb, Cd and Cr. A seasonal fluctuation in toxicity was evident at sample site 29, which could relate to seasonal fluctuations in water quality due to the Denburn overflow, since metals such as zinc also followed a seasonal fluctuation. By 2005, no sample sites showed a significant increase in mortality when compared to controls. At 7 sample sites, a significant improvement in Corophium survival was seen during the study period, which strongly suggests that bioavailable levels of contaminants are decreasing. Intersex in L. littorea was assessed on an annual basis to monitor the effects of TBT within the harbour. Again, a significant difference was found between the inner harbour and a control site, whilst intersex levels in the outer harbour area were comparable to the control site. At the inner harbour site, levels of intersex were sufficient to reduce reproductive capability individual periwinkles, but would not affect reproduction rates at the population level. Intersex ISI values suggest that water within Aberdeen harbour does not yet meet the UK EOS of 2 ngl-1. Again, a decrease in the degree of intersex was seen during the study period, this was not statistically significant, yet may indicate that the level of bioavailability pollutants is decreasing.EThOS - Electronic Theses Online ServiceGBUnited Kingdo