Pergamon Marine Pollution Bulletin, Vol. 36, No. 8, pp. 631-642, 1998 Crown Copyright © 1998 Published by Elsevier Science Ltd. All rights reserved Printed in Great Britain PII: S0025-326X(98)00051-4 0025-326X/98 $19.00+0.00 Assessment of Water Quality in Estuarine and Coastal Waters of England and Wales Using a Contaminant Concentration Technique M. F. KIRBY**, M. A. BLACKBURN§, J. E. THAIN* and M. J. WALDOCK* *The Centre for Environment, Fisheries and Aquaculture Science*, Remembrance Avenue, Burnham-on-Crouch, Essex CMO 8HA, U.K. §Sanofi Research Centre, Willowburn Avenue, Alnwick, Northumberland NE66 2JH, UK Water samples were taken from over 40 estuarine, nearshore and offshore sites in the U.K. during two CEFAS research cruises in 1993. The samples were processed using a bulk hexane extraction and concen- tration procedure and bioassayed using the marine harpacticoid copepod Tisbe battagliai. This process allowed the toxic effects of non-polar organic contami- nants to be measured at all sites, expressed as the concentration factor required to elicit a 48 h median lethal response. Total hydrocarbons (THC) and polycyclic aromatic hydrocarbons (PAH) were also quantified to estimate their contribution to sample toxicity. Extracted contaminants were concentrated <10-300-fold for estuarine sites, 100-600-fold for nearshore sites and 350- > 1000-fold for offshore sites before toxicity was observed. A tentative water contamination ranking of the studied estuaries was established as Tees > Wear > Mersey > Tyne > Blyth, Peele Harbour, Southampton Water > Ribble, Dee, Lune. Chemical analysis revealed a weak but statis- tically significant correlation (- 0.36 to -0.43) between total hydrocarbon concentrations in water and the concentration factor required to elicit a median lethal response. There was no correlation between a control determinand, algal fluorescence and toxicity. The results indicate that hydrocarbons may make a significant potential contribution to the toxicity of estuarine and coastal waters with a selected 10 PAH compounds estimated to be responsible for up to 18% of the total toxicity at one specific site. However, the cause of the majority of the toxic response remains unidentified. Although the technique is based on an acute endpoint, the high concentration factors *Corresponding author. Email: m.f.kirby@cefas.co.uk +Previously, the MAFF Directorate of Fisheries Research. required at near and offshore sites suggest that hexane extractable contaminants were not present at chron- ically toxic concentrations in the untreated seawater. However, at some estuarine sites, low concentration factors (<200-fold) suggested that these waters may be exhibiting chronic biological effects that are not always demonstrated by conventional bioassaylbased monitoring. Crown Copyright © 1998 Published by Elsevier Science Ltd. All rights reserved Keywords: Bioassay; toxicity; pollution monitoring; PAH; Tisbe battagliai; estuary. There are very few well documented examples of causal relationships between environmental concentra- tions of synthetic or persistent organic chemical contaminants and adverse biological effects in U.K. coastal waters. In the 1980s the effects of tributyltin (TBT) were described (Waldock et al., 1987) and there is evidence to suggest that polychlorinated diphenyls (PCBs) have affected the reproductive capacity of cetaceans (Helle et al., 1976). However, these appear to be exceptional cases and in general marine contami- nants appear to be well below toxicity thresholds, and even when considered to act in combination might not give rise to biological effects. Chemical analysis of potentially hazardous contaminants in U.K. coastal waters and complementary bioassay data collected by The Centre for Environment, Fisheries and Aquacul- ture Science (CEFAS, formerly MAFF, Directorate of Fisheries Research) broadly supports this statement (MAFF, 1995; Matthiessen et al., 1993), although bioassays of some estuarine waters and sediments frequently reveal acute toxicity (Matthiessen et al., 1998) which cannot be attributed to individual contaminants. 631