Scope for Growth and Levels of Contaminants in Mussels from the Wash - Phase 2 Dr
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EA-oI /516/3/A Scope for growth and levels of contaminants in mussels from the Wash - Phase 2 Dr. J. Widdows et al. Plymouth Marine Laboratory Dr. J. Widdows Dr. P. Donkin M. Brinsley S. Evans T.W. Fileman D.M. Lowe F. Staff Dr. J.L. Zhou Plymouth Marine Laboratory, Prospect Place, West Hoe, Plymouth, PL1 3DH. Publishing Organisation Environment Agency - Anglian Region Kingfisher House Goldhay Way Orton Goldhay Peterborough PE2 5ZR Tel: 01733 371811 Fax: 01733 231840 © Environment Agency 1996 Ail rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior permission of the Environment Agency. The views expressed in this document are not necessarily those of the Environment Agency. Its officers, servants or agents accept no liability whatsoever for any loss or damage arising from the interpretation or use of the information, or reliance upon views contained herein. Dissemination Status Internal: Limited Release External: Limited Release Statement of Use This report is restricted to Environment Agency Anglian Region staff only and is in connection with a previous PML report (DoE Contract, 1993). Research Contractor This document was produced by: Plymouth Marine Laboratory Prospect Place W est Hoe Plymouth PL1 3DH Tel: 01752 633100 Fax: 01752 633101 PML Project Leader The PML's Project Leader for OI Project 578 was: Dr. John Widdows Environment Agency’s Project Manager Mr. David Tester - Anglian Region Additional Copies Environment Agency staff wishing to purchase further copies of this document should contact their Regional R&D Coordinator. DFR - OI / 578 / 3 / A II CONTENTS Page 1 Introduction 1 1.1 The Wash system 1 1.2 Environmental quality 1 1.3 The use of mussels for assessing environmental quality 1 2 Materials and Methods 4 2.1 Measurement of physiological responses and scope for growth 5 2.2 Chemical analyses: Polyaromatic hydrocarbons 5 2.3 Tissue chemical residue fractionation and toxicology 5 3 Results and Discussion 10 3.1 Biological effects - Physiological responses and scope for growth 10 3.2 Bioaccumulation of contaminants: Polyaromatic hydrocarbons 13 3.3 Tissue chemical residue fractionation and toxicology 14 3.4. Chemical analysis of toxic fractions 18 4 Synthesis and Interpretation 20 5 Recommendations for further work 23 6 References I DFR - OI / 578 / 3 / A III Figures Figure 2.1 Map showing location of mussel sampling sites in the Wash. Figure 3.1 Scope for growth of mussels {Mytilus edulis) in July 1995. Figure 3.2 Mussel clearance rate assay to test toxicity of tissue fractions of mussels from Holy Island and Pandora Sand. Figure 3.3 Use of neutral red retention in blood cell lysosomes of Mytilus edulis to assess toxicity in selected tissue fractions of mussels from Holy Island and Pandora Sand. Figure 3.4 Mussel clearance rate assay to test toxicity of tissue fractions of mussels from Holy Island and Pandora Sand. Figure 3.5 Use of neutral red retention in blood cell lysosomes of Mytilus edulis to assess toxicity in selected tissue fractions of mussels from Holy Island and Pandora Sand. Figure 4.1 Residual transport in the Humber * Wash region of the North Sea (unpublished data from R.G. Wood, PML) Tables Table 2.1 Sampling sites for mussels {Mytilus edulis) Table 3.1 Physiological responses and the integrated scope for growth of mussels. Table 3.2 Concentration of 2 & 3 ring aromatic hydrocarbons in the body tissues o f mussels. DFR- 01/578/3 / A IV ACKNOWLEDGEMENTS We thank Colin Worrail of the Anglian Region NRA and staff of the Eastern Sea Fisheries Joint Committe for their help in collecting mussel samples. Also John and Geraldine Green (Blakeney Harbour Mussel Association) and Cyril Sutherland (Brancaster Fisherman’s Association) for their cooperation and help at Stiffkey and Brancaster. GLOSSARY CR Clearance rate or suspension feeding rate DoE Department of the Environment GC Gas chromatography GC-ECD Gas chromatography - electron capture detection GC-FID Gas chromatography - flame ionisation detection GC-MS Gas chromatography - mass spectrometry HPLC High performance liquid chromatography NR Neutral red retention in blood cells NRA National Rivers Authority PAH Polyaromatic hydrocarbons PCBs Polychlorinated biphenyls PML Plymouth Marine Laboratory SFG Scope for growth DFR - OI / 578 / 3 / A V EXECUTIVE SUMMARY • The Wash embayment is an important area both in terms of nature conservation (RAMSAR site and Special Protection Area) and commercial fisheries (mussels and cockles). However, during the past decade many studies, particularly those concerning assessment of shellfish stocks, bird populations and pollution impact, have highlighted possible environmental problems in the area. • The objectives of this study were: i) To quantify the degree of pollution impact in the Wash by measuring the scope for growth (SFG) of mussels {Mytilus edulis) collected from nine sites:- Stiffkey, Brancaster, Hunstanton, Pandora Sand, Great Ouse - Barrier Wall, Gat Sand, Roger Sand, Witham - Tabs Head, and Holy Island (an established 'clean reference' site); ii) To analyse the concentration of specific organic contaminants in the mussel tissues (i.e. aromatic hydrocarbons); iii) To provide a toxicological interpretation of the tissue residue data based on established relationships between tissue concentrations of aromatic hydrocarbons and the stress response SFG; iv) To extract, fractionate, and toxicity test fractions derived from tissues of Pandora Sand and Holy Island mussels; and v) To analyse the most toxic fractions by GC and GC-MS. • Sampling and measurement of mussels was carried out in July 1995. The results of this study show that the SFG values of mussels living in the Wash are significantly lower than mussels inhabiting open coastal sites receiving minimal contamination. This reduction in SFG is primarily due to inhibitory effects on the ciliary feeding rate. • Mussels from sites near the mouth of the two major rivers entering the Wash (Great Ouse and Witham) had the lowest SFG values and were the most stressed (i.e. Barrier Wall, Pandora Sand and Tabs Head). SFG measurements of mussel populations along the eastern coast of the Wash showed a gradual improvement in water quality (i.e. increase in SFG) from the Great Ouse - Barrier Wall, Hunstanton, Brancaster to Stiffkey. Mussels living in the central part of the Wash (e.g. Gat Sand and Roger Sand) had intermediate SFG values between those severely stressed populations living near the mouths of Great Ouse and Witham rivers and those on the north Norfolk coast. The wider ecological consequences of low SFG may include reduced egg / larval quality, poor recruitment and growth, all of which will hinder recovery and sustainability of resources when combined with any possible over-fishing of mussel stocks. • The SFG data for July 1995 were consistent with the results recorded in a pilot Wash study in July 1994 and an earlier North Sea mussels programme (July 1990). • The aromatic hydrocarbon data for July 1995 were also in close agreement with the earlier Wash study (July 1994) and the North Sea mussels survey (July 1990). Measured values are approximately 5-fold higher than background levels in open ocean waters (e.g. Shetland Islands), but 50-fold less than the levels typical of the major urbanised / industrialised UK estuaries. Toxicological interpretation of the hydrocarbon concentrations in the mussels indicates that these levels can explain a significant but a relatively small proportion of the recorded decline in SFG. • Mussel tissues from Pandora Sand and Holy Island were extracted / fractionated and the fractions were toxicity tested using two assays (clearance rate o f small mussels and neutral DFR - OI / 578 / 3 / A VI red retention by mussel blood cells). These results confirmed the 1994 pilot study and indicated that mussels from both Pandora Sand and Holy Island contain a complex and physicochemically diverse mixture of ‘potentially toxic’ chemicals (biogenic and anthropogenic) and that these were more evident in mussels from Pandora. Selected fractions have been analysed by HPLC, GC-FID and GC-ECD. These demonstrate the presence of higher levels of some compounds in the Pandora fractions compared with Holy Island. Attempts to confirm the identity of these compounds by GC-MS met with only limited success due to the low levels of the individual chemicals present, and in some cases to their likely polar and involatile nature rendering them unsuitable for direct GC-MS analysis. • The spatial changes in both SFG and hydrocarbon contaminant levels in mussels from the Wash sites reflect the hydrographic data and the input of contaminants via the Great Ouse and the Witham. The output of a hydrodynamic model illustrates that water enters the Wash along the central channel and circulates away from the central region (Gat Sand) and out along the north-western and south-eastern coastlines. Therefore any contaminants entering the Wash via the Great Ouse will be transported out, along the north Norfolk coastline in the following sequence (Barrier Wall > Pandora Sand > Hunstanton > Brancaster > Stiffkey). • The SFG results and the complexity of the tissue residue chemistry data are not inconsistent with the hypothesis that the adverse effects are related to the complex sewage inputs via the major rivers entering the Wash. This is supported by evidence from the literature which indicates that sewage inputs can have significant adverse effects on the SFG of mussels. • Recommendations for further work are outlined. This includes using SFG to examine the possible improvement and recovery in environmental quality following the upgrading of a sewage treatment works on the Great Ouse in the autumn of 1996; as well as the further refinement and application of the important investigative approach to ‘Environmental Diagnostics’ which involves tissue extraction / fractionation / toxicity testing / chemical analysis. Keywords:- Wash, Mussels, Mytilus edulis, Pollution, Contaminants, Hydrocarbons, Sewage.