Marine Pollution Bulletin xxx (2015) xxx–xxx
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Editorial
The English Channel and its catchments: Status and responses to contaminants 1. Introduction According to the International Hydrographic Organisation (IHO, 1953) the western boundary of the English Channel (La Manche) is defined by a line from Ushant (Ouessant) to the Scilly Isles and the eastern boundary by a line across the Dover Strait from a point near Calais to one near Dover (Fig. 1). The English Channel covers an area of 77,000 km2 and it has a combined population of 3.5 million people living on the coastlines making it one of the world’s busiest sea areas. The coastal waters have a relatively high tidal range and the overall flow of seawater is from west to east, with a water replacement time of approximately 500 days. The total fluvial discharge from adjacent catchments is of the order 715 m3 s 1, of which 86% originates from rivers along the French coast between Calais and Brest, and is dominated by the Seine and its tributaries (Fig. 2). The estuaries are macro-tidal and systems on both sides of the Channel are contaminated by groundwaters, agriculture, domestic discharge, current and relict industrial inputs, although some estuaries, such as the Canche (France) and Fowey (UK), are regarded as fairly pristine. There are additional coastal impacts from intense maritime transport (including ports and dockyards), dredging and associated disposal of sediment, tourism, nuclear re-processing (including, between 1950 and 1963, the dumping of radioactive waste in the Hurd Deep), thermal discharges, and development of offshore structures (including renewable energy). This extensive human utilisation of the region implies that various species of riverine, estuarine and marine organisms, and their habitats, are under considerable pressure. Environmental sustainability is particularly important when considering that fish landings in 2010 for 12 UK ports along the south coast amounted to 59,000 tonnes, according to the Marine Management Organisation. Aquaculture (shellfish and algal products) is also an important economic and social element at a local level. Therefore, methods to assess impacts and coherent plans for the protection of the marine environment from hazardous substances (such as metals, persistent organic compounds and radionuclides), physical damage and biological threats (from microbes to invasive species) are required. The scientific building blocks for strategic planning are only now beginning to bear fruit as a result of collaborative projects conducted by partnerships on the north and south coasts of the English Channel, notably under the aegis of UK-France INTERREG programmes. Even though the English Channel is an important biological and physical resource, there has been little in respect of holistic publications on key scientific aspects over the past 20 years. Three decades ago the 17th European Marine Biology Symposium on http://dx.doi.org/10.1016/j.marpolbul.2015.02.004 0025-326X/Ó 2015 Elsevier Ltd. All rights reserved.
‘‘Fluctuation and Succession in Marine Ecosystems’’ was held in Brest and a special volume of Oceanologica Acta was published (Cabioch et al., 1983), although not all papers were devoted to the English Channel. In 1993, the North Sea Task Force compiled a quality status report (QSR) on the physical, chemical and biological conditions in the English Channel (Reid et al., 1993), together with an assessment of human impact. Arguably, this was the most comprehensive assessment at that time and remains so to the present day. However, since 1993 substantial strides have been made in techniques for assessing man’s impact on marine ecosystems, particularly in the waters of the English Channel. Subsequently, the EU funded a major research programme, named ‘‘Flux manche’’, concerned with the transport of metals, radionuclides, suspended particles and organic matter from the eastern English Channel into the North Sea (Statham et al., 1999). Updating and re-evaluation of the English Channel QSR was undertaken by Tappin and Reid (2000) in a book devoted to ‘‘Seas at the Millennium’’, where particular emphasis was given to contaminants and their effects. Gibbard and Lautridou (2003) also produced a special volume of the Journal of Quaternary Science, which considered geological aspects of the English Channel. More significant, is the publication of the Quality Status Report 2010 (OSPAR, 2010) in which the English Channel is integrated into Region II, that is the Greater North Sea. The problem with the OSPAR approach to the compartmentalisation of its sea areas is that insufficient prominence is given to the English Channel because of a greater focus on the North Sea and its coastlines. This lack of attention to the English Channel further supports the need to have the most up-to-date information published in a dedicated volume, rather than being dispersed in various journals. It is also important to give a platform to alternative methodologies, outside the confines of the statutory assessments which form the mainstay of Quality Status Reports. A catchment-based view is considered worthy of pursuit in this context, given the moves
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Editorial / Marine Pollution Bulletin xxx (2015) xxx–xxx
Fig. 1. The English Channel. The dashed line between Ushant and the Scilly Isles represents the western boundary and the dashed line across the Dover Straits the eastern boundary (IHO, 1953). Some of the key features and locations described in this editorial are displayed.
Fig. 2. English Channel Catchments dominated by inputs from rivers along the French coast, notably the Seine and its tributaries.
towards river-basin management by national and regional agencies. Priority is also given to new and integrated approaches which address the biological consequences of exposure to contaminants, as these are pertinent to European Directives and emerging strategies aimed at improved environmental protection (encompassed, for example, in the requirement to achieve Good Ecological Status under the EU Water Framework Directive and Good Environmental Status under the Marine Strategy Framework Directive, 2000/60/EC and 2008/56/EC, respectively).
With these considerations in mind the current issue of Marine Pollution Bulletin is a collection of contemporary, research-oriented papers on crucial aspects of the status and impacts of contaminants in the catchments, estuaries and marine ecosystems of this vital regional sea area. Many stem from integrated research projects hosted by the EU INTERREG IVA programme, including DIESE (‘‘Determination of Indicators for Environmental monitoring: a Strategy for Europe’’) and CHRONEXPO (‘‘Studies of the Effects of CHRONic EXPOsure of Marine Organisms to Contaminants from Industry in the English Channel’’). Other France-UK projects from
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which contributions are drawn include AQUAMANCHE/RISKMANCHE, CLIMAWAT, MARINEXUS, PANACHE, SETARMS, WATER and VALMER which collectively address cross-border issues such as sources and effects of pollution, strategies to reduce or mitigate impacts and approaches to improved management of the system. THE CHANNEL CATCHMENT CLUSTER (3Cs) and a further consortium aimed at Promoting the Effective Governance of the Channel Ecosystem (PEGASEAS) have subsequently evolved from these projects in order to capitalise on the outcomes. The broad objectives of the common programme being promoted through the 3Cs cluster are (a) identification and mapping of bio-active contaminants, microbes and invasive fauna, (b) development of techniques, including advanced methods in molecular biology, to evaluate the impact of chronic exposure of relevant organisms to a range of contaminants (metals, persistent organic compounds and radionuclides) and (c) development of new approaches for the management of the aquatic environment. Our purpose here is to communicate the information arising from 3Cs and the INTERREG lVA programme to fellow scientists, regulators and stakeholders and to demonstrate the potential benefits of collaborative investments. Workshops and symposia staged jointly in Plymouth and Le Havre, in September 2014 have helped to reinforce these messages. 2. Composition of the special issue Contaminant status of transitional and coastal waters: Contributions to this dedicated volume are introduced by an overview of established information on the hydrographical features, catchments, anthropogenic influence and the status of chemical contamination in the Channel by Tappin and Millward. This review is based primarily on results of statutory monitoring programmes. The need for better loadings data (for source apportionment and trend analysis) is an obvious requirement highlighted by the authors. For those contaminants where data is robust, body burdens in marine biota seem to be declining or unchanged (exceptions being Cd, Hg and HBCDD); however, there are a large number of emerging contaminants, such as pharmaceuticals and micro-plastics, for which information is scarce. Radionuclides, largely emanating from the La Hague nuclear re-processing plant near to Cherbourg, are detected along the French coastline and in sediments and marine biota from Alderney, Guernsey and Jersey. However, direct comparison of activity concentrations is hampered by differences in methodologies. Nutrient-induced proliferation of algae and associated toxins (eutrophication) is probably the most visible and widespread threat to ecosystem function and shellfisheries in transitional and near-shore waters, though the authors point out the dearth of observations on ecotoxicological impacts for most hazardous contaminants. The need for innovative, crossdisciplinary/cross-border approaches (of the type promoted by INTERREG) to address this knowledge gap is evident. Contaminants and their biological activity in indicator species. Several contributions (Alvarez-Munoz et al., Langston et al., Pope et al., Dupuy et al.) describe non-statutory studies of spatial and temporal trends in contamination and biological activity in a variety of environmental compartments. Langston et al., present encouraging evidence of declining levels of the antifouling biocide TBT in water, sediment and biota in estuarine and coastal waters of the Channel which are related to successful legislative efforts to stem inputs. However, residual effects in biota such as dogwhelks Nucella lapillus and clams Scrobicularia plana are still evident more than 25 years after measures were first introduced. The legacy and persistence of TBT in sediments (half-times up to 30 years) is partly responsible for the delayed recovery of mollusc populations near major Channel ports. There are important lessons to be learned (for surveillance strategy, sediment dredging and disposal options,
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and policy development regarding other legacy contaminants) by continuing such time series on the recovery of impacted ecosystems in relation to regulatory and management efforts. Sediments are a sink for a wide range of contaminants besides TBT and, in addition to reflecting historic inputs and pollution events, can also act as a source – by releasing bound chemicals back into pore-water and the overlying water column. However, site-specific characteristics can influence this process, confounding regional comparisons and predictions of contaminant behaviour and risk. Based on an investigation at a number of Channel sites with different pollution histories, sediment properties – including organic content, grain size, metal concentration, leachability and pore-water composition – have been shown by Pini et al. to influence metal bioavailability and bioaccumulation in the polychaete Nereis virens. Biological factors were also shown to be an important consideration in modifying bioaccumulation, highlighted by the ability of N. virens to regulate tissue burdens of Cu and Zn. Though potentially a relevant choice of marker of sediment quality in the Channel, the value of N. virens as a bioindicator of these metals is therefore questionable, as environmental contamination would tend to be underestimated by analysis of these worms. Understanding dose–response relationships and physiological behaviour are, clearly, critical considerations in the choice of indicator species and when comparing pollution effects at different sites – often only unravelled by a combination of field observation and laboratory experimentation. Identification of TBT effects, notably masculinization of female dogwhelks, has heralded growing apprehension over the wider threat of endocrine disruption (ED) in rivers, estuaries and coastal waters of the Channel region. This concern has initiated research to study the distribution and effects of feminising/de-masculinizing (oestrogenic and anti-androgenic) compounds in Channel catchments, using sediments, molluscs and fish as indicators. BadoNilles et al. have shown the Bullhead Cottus sp. to be a relevant and ubiquitous fish species for monitoring responses to environmental stress in European freshwaters though, in fact, immune functions (leucocyte distribution, cellular mortality, respiratory burst, phagocytosis) were found to be easier biomarkers to interpret in the context of environmental quality of rivers than the rather unpredictable (site-specific) reproductive profile of bullhead populations. Temperature-induced (seasonal) factors mediate the complex reproductive cycle of Bullhead strongly (immune function to a lesser extent), contributing to the customary difficulty of separating inherent (natural) and anthropogenic drivers of physiological response. The variations and interactions in reproductive and immune system responses in this study demonstrate how important it is to factor-in confounding environmental and biological features when defining best practice in bio-monitoring. Using another ubiquitous European freshwater fish Rutilus rutilus as a model, Gerbron et al. have illustrated the importance and complexity of interactions between contaminants, in terms of interpreting the net impact on endocrine disruption. The feminising effect of the natural hormone 17-b oestrodiol on oestrogenic endpoints such as vitellogenin synthesis (both at the mRNA and protein level) and expression of steroid (estrogen/androgen) receptors, was shown to be compromised in vivo and in vitro by the antioestrogenic properties of another chemical linked to reproductive impairment in vertebrates, the widely-used pollutant metal, Cd. The observation that the non-essential metal Cd could impinge on male and female responses to hormones demonstrates the potential intricacy in the regulation of gender balance. Interactive effects of environmental chemicals such as this, at the protein and transcriptional levels, highlight the difficulties in the interpretation of endocrine disruption and its causes in the field. Whilst it is clear that chemical contaminants with estrogen receptor agonist or androgen receptor antagonist activity are
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present in wastewater effluents, and that steroidal estrogens and possibly anti-androgens are causing feminization of fish in some rivers, a major unresolved question surrounds impacts on marine biota, particularly invertebrates (which make up 95% of all organisms). Using a reporter gene assay, Alvarez-Munoz et al. describe the contamination of estuarine and coastal Channel sediments with anti-androgens (AA), with the aim of clarifying their involvement in endocrine disruption in bivalve molluscs. Some 90% of UK sites and 45% of French sites sampled exhibited androgen receptor antagonist activity in surface sediment extracts – highest in the Southampton and Poole area (UK) and the port of Le Havre (France) – and were a function of sediment properties notably organic and silt content. In clams (S .plana) from Southampton sites a considerable amount of AA activity was due to PAHs (oil-derived) implying association with port activities and the petrochemical industry (including spillage), though pyrogenic contributions cannot be ruled out. Interestingly, compared with female S. plana, a high level of androgen receptor agonist activity was detectable in male clams, attributable to dihydrotestosterone – implying a possible role for steroid androgens in these bivalves (one of the few such demonstrations in an invertebrate). However, although a range of AA activity was found in sediments – with the potential for ED – no clear relationship with effects on sexuality in clams have emerged as yet; synergistic or antagonistic effects, for example with (xeno)oestrogens or organotins, could be influential and merit further investigation. There is also a need to refine mollusc-based receptor screening tools to help characterise exposure to EDC in marine environments. Pope et al. have capitalised on the excellent bio-indicator potential of S. plana (widespread occurrence and abundance, salinity tolerant, central to ecosystem functioning, inherent gonochoristic sexuality) to describe the incidence of intersex (feminisation – occurrence of oocytes among normal testicular tissues) in estuaries throughout the entire Channel (108 sites of which 58% displayed intersex). As a deposit feeder, S. plana is likely to be exposed to many different EDCs in sediment. Causes of the observed range in intersex severity remain speculative (up to 50% males affected at some Channel sites, with an overall mean value of 8.6%), as highlighted also by the investigations with anti-androgens described above; nevertheless, this is an important model for future monitoring. In addition to providing an indication of the pervasive nature of ED, and impacts on shellfish, this study serves to illustrate that Channel-wide perspectives on water, sediment and ecological quality can be obtained by the appropriate choice of indicator and strategy. Regional and national barriers can be overcome to deliver Channel-scale opportunities for better integration and improved management. In future it would be constructive to explore more openings at this scale. Emerging biomarker protocols for assessing pollutant impacts and biological threats. A Channel-wide perspective on monitoring should extend to the use of state-of-the-art biomarker applications, including molecular approaches which might provide sensitive indicators of environmental impact. For example, examination of cellular pathways affected by endocrine disruption, using gene isolation methods and comparison of normal and toxicant-induced genomes, have proved a viable and novel part of the assessment of intersex causes and consequences in S. plana populations. Ciocan et al. screened intersex-associated transcripts, (previously identified by suppressive subtractive hybridisation), to describe their differential expression in ‘normal’ male clams sampled from UK and French Channel coasts. Transcripts involved in testicular development, energy production, intracellular signalling, ferritin and egg yolk precursor protein were differentially regulated at selected sites with varying intersex incidence and contaminant burdens. Sex ratios were correlated with oestrogenic activity, as opposed to anti-androgenic activity, of sediments (measured using
a steroid receptor transcription assay). The results provide an indication of the mode of action for intersex and potentially, molecular ‘early-warning’ biomarkers of the condition and perhaps more general stress indicators. Multiple biomarker application to assessing ecosystem health – in a ‘weight of evidence approach’ – is favoured over single biomarker use, as argued by Jha and Dallas in their critical evaluation of the application of biological effects tools, focused on the Tamar Estuary in SW England. The emphasis on guiding the reader through the benefits and drawbacks of this approach will help to promote the use of such tools to environmental managers and statutory bodies. This is an essential requirement in the context of complying with recent regulatory frameworks (WFD, MSFD) with their emphasis on evaluating pollution as a function of impacts on biological quality and ecological status (alongside contaminant levels) rather than traditional reliance on chemical monitoring alone. Many of the 24 sub-lethal biochemical and molecular responses reviewed (including carcinogenic, mutagenic and reprotoxic effects) have added-value in providing early-warning that damage may be occurring at tissue, whole organism and population levels; the requirement for more integrated studies to confirm these links is clearly presented. The Tamar Estuary, though parochial, is confirmed as an ideal environment in which to examine applications of these biological tools, given its conservation importance and combination of pressures (e.g. domestic discharges, agriculture, historical mining and other industry, port activity, low level nuclear waste) which are representative of those seen in transitional waters throughout the Channel. Given the wealth of information on the Tamar system It is also an excellent platform to examine future perspectives and challenges in the application of biomarker-style surveillance, including new ‘omics’ technologies (e.g. gene expression profiles) and to clarify more basic requirements such as appropriate choice of indicator organism, reference site and contextual chemistry. A practical illustration of the importance of the multiple biomarker philosophy, including gene expression, is provided in the multiparametric study by Dupuy et al. of juvenile flounder Platichthys flesus in three contrasting Channel estuaries: the Canche (clean), the Tamar (combination of pressures including metals) and the Seine (heavily polluted by diffuse contamination). This catadromous flatfish uses estuaries as a nursery and has often been advocated a bio-indicator of estuarine water and sediment quality. Condition (growth rate, composition of otoliths) and several biomarkers of the immune system, antioxidant enzymes, energy metabolism and detoxification process were investigated in (0+) group and one-year-old (1+) flounder, as a function of contamination (metals). Differences between the Canche and the Seine estuaries were highlighted by the multi-biomarker approach – notably responses in modulation of the immune system, raised cytochrome-c oxidase activity and up-regulation of betaine homocysteine S-methyltransferase (enzymes involved in detoxification and oxidative stress response) and a lower condition index. Moderate responses in juvenile flounder from the Tamar were linked to the intermediate levels of contamination (metals) present in this estuary. Numerous correlations between individual biomarker responses were evident for the polluted Seine fish (particularly in immune and detoxification processes). Together, these molecular, cellular and biochemical markers are becoming accepted, increasingly, as a viable means of estimating the quality of estuarine waters and the health status of aquatic populations; nevertheless, interpretation is not without interference from confounding environmental and biotic factors and the type (and combination) of contamination in question. At the molecular level, proteomics have been used by Galland et al. to detect contaminant responses in P. flesus following experimental exposure to dietary mixtures of PAHs and PCBs – at
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concentrations representative of the River Seine, and an order of magnitude higher. Protein identification in this novel ‘omics’ approach indicated perturbation of oxidative stress proteins, glutathione metabolism and possibly other pathways of adaptation to oxidative stress (betaine demethylation and methionine metabolism) in livers of PAH/PCB-exposed fish. These, and similar changes, promise to be valuable future markers in diagnosing pollution-impacted populations and identifying mechanisms of effect. In nature, deleterious effects are unlikely to be caused by single stressors in isolation. Using juvenile P. flesus as a test species, Lavergne et al. demonstrated at the gene transcription level, the importance of considering synergistic effects, showing that chemical contamination could influence tolerance to other pressures, such as thermal stress (e.g. from power stations or climate change). Temperature tolerance was compared in fish from the densely populated and polluted Seine Estuary with that of the less-contaminated Vilaine Estuary, using expression of genes related to energy metabolism as a marker of impact. A decrease in expression of the ribosomal 12S gene (a proxy for mitochondrial density and energy metabolism) in livers of P. flesus, in response to temperature, was observed in the more contaminated Seine fish, along with a drop in condition index, which implies that the chemical burden accumulated in these flounder reduces their tolerance of thermal stress and potentially reduces fitness to cope with other environmental pressures. Clearly, this may be important, in ecotoxicological terms, in a warming world (climate change), or as a result of seasonal change, or where temperature variation increases due to direct human influence (thermal discharges). There is growing concern over the presence of herbicides and other chemicals from agricultural run-off into coastal waters, and their effects on non-target aquatic species. A multi-biomarker investigation by Mottier et al., this time in the laboratory, following chronic exposure of commercial oysters Crassostrea gigas to glyphosate, compared a variety of responses. These ranged from molecular (mRNA quantification) and biochemical endpoints (glutathione-S-transferase GST-detoxification); catalase activity (antioxidant); malondialdehyde content (lipid peroxidation marker) to whole organism response (gametogenesis and tissue alterations). Mortality, growth and histopathology in yearling oysters were not significantly affected by this widely-used, but little-studied class of pesticide, though individual biomarkers revealed effects. The levels of GST and metallothionein gene expression increased significantly in oysters exposed to the highest glyphosate concentration, whilst the expression of MXR mRNA (multi-xenobiotic resistance) increased at all concentrations. Results suggested an activation of defence mechanisms at the molecular level which, combined with low bioaccumulation potential, may tend to reduce overall toxicity of these herbicides, compared to more toxic alternatives such as organochlorine insecticides. Assays such as these are a useful means of identifying the most environmentally acceptable biocides. Several contributions in this volume introduce new biological effects techniques to measure the responses of marine organisms. Some are as yet in the experimental stage, including physiological perturbations in juvenile cuttlefish Sepia officinalis induced by sub-chronic exposure to dissolved zinc (Le Pabic et al.).These are important additions to the ecotoxicological literature, given that S. officinalis is a significant English Channel fisheries resource, characterised by inshore migration during summer spawning – yet little is known about contaminant impacts on cuttlefish physiology, particularly vulnerable eggs and juveniles. Again, an integrated biomarker approach (growth, predation behaviour, mortality, immune function and digestive enzymes) has been deployed to demonstrate sensitivity towards
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contamination (Zn). Despite evidence of growing tolerance to Zn during development, juvenile cuttlefish appear susceptible, in terms of mortality, compared with other aquatic organisms. Sublethal responses affected by Zn included growth, ability to capture prey, inhibitory impacts on acid phosphatase, cathepsin and trypsin activity (digestive enzymes), and phenoloxidases (immune function). Though these experiments were performed at high Zn concentrations it would be interesting to extend testing to other forms of contamination, given the susceptibility shown in juvenile cuttlefish. With the likely resurgence of nuclear power generation in Channel catchments, exploring effects on different biological endpoints, at different life stages, has obvious relevance in the context of evaluating and managing impacts from controlled releases of radionuclides. The assessment of physiological responses, genotoxicity and expression of stress-related genes in the Pacific oyster C. gigas has been evaluated following chronic exposure to ionising radiation, namely 137Cs, 241Am and 3H (Devos et al.). Growth rate and expression of nine target stress-response genes in larvae and spat were not significantly changed by internal or external exposure, even at levels much higher than those expected near nuclear plants. However, whilst clearance rate and transcription levels were unaffected, DNA damage was increased in haemocytes of two-year old oysters exposed to tritiated water, highlighting the potential for higher level consequences. This research is helping to fill a major gap in our understanding of how chronic doses may affect marine organisms, and how these responses relate to acute exposure. Of course not all sites are polluted and the work described here includes information on those areas which can be considered as near-pristine – valuable in the context of defining regional baselines. Likewise not all threats are chemical and the issue of invasions by non-native species is recognised as a widespread concern. Bishop et al. demonstrate how to assess and quantify such problems, rapidly and pragmatically. Based on studies in marinas on both sides of the Channel in 2010 and 2013 this contribution reveals surprising variation in occupancy trends for non-indigenous species (NIS) of sessile invertebrates. In Brittany, NW France, most of these invasive species occupied most sites in both years. In SW England occupancy was lower in 2010 but rapid colonisation was evident in 2013, implying that these recent introductions to NW Europe have spread northwards across the Channel after initially becoming established in French marinas. Management tools and socio-economic issues. It is crucial to capitalise on the scientific effort and investment in research projects encompassed within the INTERREG programme (and others like it), by bringing results to the attention of interested scientists, potential users, environmental managers and policy makers. This is one of the major objectives of the current ‘special edition’. Improvement in TBT-impacted systems described in the paper by Langston et al. highlights one specific example of the benefits in linking science and policy: reviews of the current status of contaminants in the English Channel, consequences of exposure and suggestions for improved management of biological resources are a sub-text in most other contributions. Broader discussion of the management tools and approaches in the English Channel and its catchments are given prominence in the paper by Glegg et al. which summarises the current legislative drivers, policies, socioeconomic issues and governance in the Channel, with its conflicting commercial and conservation interests. The lack of integration between countries and sectors (industrial, academic, legislative), is highlighted and the needs and benefits of a Channel-wide perspective (encompassed within the EU’s new marine management
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frameworks and supported by innovative science to understand ecosystem structure and functioning) is endorsed. Together, these crucial components should enhance future governance in the Channel, which must seek an appropriate balance of interests and values, and long term-support at national and European level if it is to be effective. The articles in this edition indicate how valuable the INTERREG program has been in taking forward our collective understanding of biological and chemical threats in the Channel –an important sea area in its own right, not merely an adjunct of OSPAR’s Region ll (The Greater North Sea). It is hoped that the novel insights and diverse approaches described here, will reap benefits in terms of better water/ecological quality assessment (and governance) by the time the next round of environmental evaluations of the Channel takes place. The majority of the outputs should also be of relevance to assessment of the condition of regional seas further afield. Acknowledgements The Guest Editors wish to thank the authors for their outstanding contributions and the referees for their diligent reviewing of the manuscripts for this ‘Special Issue’. The support and suggestions given by the Editor-in Chief of Marine Pollution Bulletin, Professor Charles Sheppard, and colleagues in the Elsevier production team (especially Ms Sara Bebbington and Ms Jun You) are gratefully acknowledged. The guest editors would also like to thank INTERREG for financial contributions towards much of the science described here and for supporting the 3Cs cluster which has enabled the production of this volume. It should be noted however that the views expressed in this Special Edition are those of the authors and not necessarily their host organisations and funding bodies.
References Cabioch, L., Glémarec, M., Samain, J.-F., 1983. Fluctuation and succession in marine ecosystems. In: Proceedings of the 17th European Symposium on Marine Biology. Oceanological Acta, Special Volume, 225 pp. Gibbard, P.L., Lautridou, J.P. (Eds.), 2003. The Quaternary History of the English Channel. J. Quatern. Res. 18, 195–199. IHO (International Hydrographic Organization), 1953. Limits of Oceans and Seas, Special Publication 23, third ed., 42 pp. OSPAR, 2010. Quality Status Report 2010. OSPAR Commission, London, 175 pp. Reid, P.C., Auger, C., Chaussepied, M., Burn, M., 1993. Quality Status Report of the North Sea 1993: Assessment Report on Sub-Region 9. North Sea Task Force, Ruislip, United Kingdom, 153 pp. Statham, P.J., Davies, P.A., Lafite, R., 1999. Introduction and dedication of the Fluxmanche II special issue. Continent. Shelf Res. 19, 1849–1850. Tappin, A.D., Reid, P.C., 2000. The English Channel. In: Sheppard, C.R.C. (Ed.), Seas at the Millenium: An Environmental Evaluation, vol. 1. Regional Chapters, Europe, The Americas and West Africa. Pergamon Press, Oxford, UK, pp. 65–82 (chapter 5).
Geoffrey E. Millward Marine Institute, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK Awadhesh N. Jha School of Biological Sciences, Plymouth University, Plymouth PL4 8AA, UK Christophe Minier National Agency for Water and Aquatic Environments (Onema), Le Nadar – Hall C, 5, Square Félix Nadar, 94300 Vincennes, France Nicholas D. Pope William J. Langston Marine Biological Association of the United Kingdom, Citadel Hill, Plymouth PL1 2PB, UK Available online xxxx
Contents lists available at ScienceDirect
Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul
Editorial
The English Channel and its catchments: Status and responses to contaminants 1. Introduction According to the International Hydrographic Organisation (IHO, 1953) the western boundary of the English Channel (La Manche) is defined by a line from Ushant (Ouessant) to the Scilly Isles and the eastern boundary by a line across the Dover Strait from a point near Calais to one near Dover (Fig. 1). The English Channel covers an area of 77,000 km2 and it has a combined population of 3.5 million people living on the coastlines making it one of the world’s busiest sea areas. The coastal waters have a relatively high tidal range and the overall flow of seawater is from west to east, with a water replacement time of approximately 500 days. The total fluvial discharge from adjacent catchments is of the order 715 m3 s 1, of which 86% originates from rivers along the French coast between Calais and Brest, and is dominated by the Seine and its tributaries (Fig. 2). The estuaries are macro-tidal and systems on both sides of the Channel are contaminated by groundwaters, agriculture, domestic discharge, current and relict industrial inputs, although some estuaries, such as the Canche (France) and Fowey (UK), are regarded as fairly pristine. There are additional coastal impacts from intense maritime transport (including ports and dockyards), dredging and associated disposal of sediment, tourism, nuclear re-processing (including, between 1950 and 1963, the dumping of radioactive waste in the Hurd Deep), thermal discharges, and development of offshore structures (including renewable energy). This extensive human utilisation of the region implies that various species of riverine, estuarine and marine organisms, and their habitats, are under considerable pressure. Environmental sustainability is particularly important when considering that fish landings in 2010 for 12 UK ports along the south coast amounted to 59,000 tonnes, according to the Marine Management Organisation. Aquaculture (shellfish and algal products) is also an important economic and social element at a local level. Therefore, methods to assess impacts and coherent plans for the protection of the marine environment from hazardous substances (such as metals, persistent organic compounds and radionuclides), physical damage and biological threats (from microbes to invasive species) are required. The scientific building blocks for strategic planning are only now beginning to bear fruit as a result of collaborative projects conducted by partnerships on the north and south coasts of the English Channel, notably under the aegis of UK-France INTERREG programmes. Even though the English Channel is an important biological and physical resource, there has been little in respect of holistic publications on key scientific aspects over the past 20 years. Three decades ago the 17th European Marine Biology Symposium on http://dx.doi.org/10.1016/j.marpolbul.2015.02.004 0025-326X/Ó 2015 Elsevier Ltd. All rights reserved.
‘‘Fluctuation and Succession in Marine Ecosystems’’ was held in Brest and a special volume of Oceanologica Acta was published (Cabioch et al., 1983), although not all papers were devoted to the English Channel. In 1993, the North Sea Task Force compiled a quality status report (QSR) on the physical, chemical and biological conditions in the English Channel (Reid et al., 1993), together with an assessment of human impact. Arguably, this was the most comprehensive assessment at that time and remains so to the present day. However, since 1993 substantial strides have been made in techniques for assessing man’s impact on marine ecosystems, particularly in the waters of the English Channel. Subsequently, the EU funded a major research programme, named ‘‘Flux manche’’, concerned with the transport of metals, radionuclides, suspended particles and organic matter from the eastern English Channel into the North Sea (Statham et al., 1999). Updating and re-evaluation of the English Channel QSR was undertaken by Tappin and Reid (2000) in a book devoted to ‘‘Seas at the Millennium’’, where particular emphasis was given to contaminants and their effects. Gibbard and Lautridou (2003) also produced a special volume of the Journal of Quaternary Science, which considered geological aspects of the English Channel. More significant, is the publication of the Quality Status Report 2010 (OSPAR, 2010) in which the English Channel is integrated into Region II, that is the Greater North Sea. The problem with the OSPAR approach to the compartmentalisation of its sea areas is that insufficient prominence is given to the English Channel because of a greater focus on the North Sea and its coastlines. This lack of attention to the English Channel further supports the need to have the most up-to-date information published in a dedicated volume, rather than being dispersed in various journals. It is also important to give a platform to alternative methodologies, outside the confines of the statutory assessments which form the mainstay of Quality Status Reports. A catchment-based view is considered worthy of pursuit in this context, given the moves
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Fig. 1. The English Channel. The dashed line between Ushant and the Scilly Isles represents the western boundary and the dashed line across the Dover Straits the eastern boundary (IHO, 1953). Some of the key features and locations described in this editorial are displayed.
Fig. 2. English Channel Catchments dominated by inputs from rivers along the French coast, notably the Seine and its tributaries.
towards river-basin management by national and regional agencies. Priority is also given to new and integrated approaches which address the biological consequences of exposure to contaminants, as these are pertinent to European Directives and emerging strategies aimed at improved environmental protection (encompassed, for example, in the requirement to achieve Good Ecological Status under the EU Water Framework Directive and Good Environmental Status under the Marine Strategy Framework Directive, 2000/60/EC and 2008/56/EC, respectively).
With these considerations in mind the current issue of Marine Pollution Bulletin is a collection of contemporary, research-oriented papers on crucial aspects of the status and impacts of contaminants in the catchments, estuaries and marine ecosystems of this vital regional sea area. Many stem from integrated research projects hosted by the EU INTERREG IVA programme, including DIESE (‘‘Determination of Indicators for Environmental monitoring: a Strategy for Europe’’) and CHRONEXPO (‘‘Studies of the Effects of CHRONic EXPOsure of Marine Organisms to Contaminants from Industry in the English Channel’’). Other France-UK projects from
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which contributions are drawn include AQUAMANCHE/RISKMANCHE, CLIMAWAT, MARINEXUS, PANACHE, SETARMS, WATER and VALMER which collectively address cross-border issues such as sources and effects of pollution, strategies to reduce or mitigate impacts and approaches to improved management of the system. THE CHANNEL CATCHMENT CLUSTER (3Cs) and a further consortium aimed at Promoting the Effective Governance of the Channel Ecosystem (PEGASEAS) have subsequently evolved from these projects in order to capitalise on the outcomes. The broad objectives of the common programme being promoted through the 3Cs cluster are (a) identification and mapping of bio-active contaminants, microbes and invasive fauna, (b) development of techniques, including advanced methods in molecular biology, to evaluate the impact of chronic exposure of relevant organisms to a range of contaminants (metals, persistent organic compounds and radionuclides) and (c) development of new approaches for the management of the aquatic environment. Our purpose here is to communicate the information arising from 3Cs and the INTERREG lVA programme to fellow scientists, regulators and stakeholders and to demonstrate the potential benefits of collaborative investments. Workshops and symposia staged jointly in Plymouth and Le Havre, in September 2014 have helped to reinforce these messages. 2. Composition of the special issue Contaminant status of transitional and coastal waters: Contributions to this dedicated volume are introduced by an overview of established information on the hydrographical features, catchments, anthropogenic influence and the status of chemical contamination in the Channel by Tappin and Millward. This review is based primarily on results of statutory monitoring programmes. The need for better loadings data (for source apportionment and trend analysis) is an obvious requirement highlighted by the authors. For those contaminants where data is robust, body burdens in marine biota seem to be declining or unchanged (exceptions being Cd, Hg and HBCDD); however, there are a large number of emerging contaminants, such as pharmaceuticals and micro-plastics, for which information is scarce. Radionuclides, largely emanating from the La Hague nuclear re-processing plant near to Cherbourg, are detected along the French coastline and in sediments and marine biota from Alderney, Guernsey and Jersey. However, direct comparison of activity concentrations is hampered by differences in methodologies. Nutrient-induced proliferation of algae and associated toxins (eutrophication) is probably the most visible and widespread threat to ecosystem function and shellfisheries in transitional and near-shore waters, though the authors point out the dearth of observations on ecotoxicological impacts for most hazardous contaminants. The need for innovative, crossdisciplinary/cross-border approaches (of the type promoted by INTERREG) to address this knowledge gap is evident. Contaminants and their biological activity in indicator species. Several contributions (Alvarez-Munoz et al., Langston et al., Pope et al., Dupuy et al.) describe non-statutory studies of spatial and temporal trends in contamination and biological activity in a variety of environmental compartments. Langston et al., present encouraging evidence of declining levels of the antifouling biocide TBT in water, sediment and biota in estuarine and coastal waters of the Channel which are related to successful legislative efforts to stem inputs. However, residual effects in biota such as dogwhelks Nucella lapillus and clams Scrobicularia plana are still evident more than 25 years after measures were first introduced. The legacy and persistence of TBT in sediments (half-times up to 30 years) is partly responsible for the delayed recovery of mollusc populations near major Channel ports. There are important lessons to be learned (for surveillance strategy, sediment dredging and disposal options,
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and policy development regarding other legacy contaminants) by continuing such time series on the recovery of impacted ecosystems in relation to regulatory and management efforts. Sediments are a sink for a wide range of contaminants besides TBT and, in addition to reflecting historic inputs and pollution events, can also act as a source – by releasing bound chemicals back into pore-water and the overlying water column. However, site-specific characteristics can influence this process, confounding regional comparisons and predictions of contaminant behaviour and risk. Based on an investigation at a number of Channel sites with different pollution histories, sediment properties – including organic content, grain size, metal concentration, leachability and pore-water composition – have been shown by Pini et al. to influence metal bioavailability and bioaccumulation in the polychaete Nereis virens. Biological factors were also shown to be an important consideration in modifying bioaccumulation, highlighted by the ability of N. virens to regulate tissue burdens of Cu and Zn. Though potentially a relevant choice of marker of sediment quality in the Channel, the value of N. virens as a bioindicator of these metals is therefore questionable, as environmental contamination would tend to be underestimated by analysis of these worms. Understanding dose–response relationships and physiological behaviour are, clearly, critical considerations in the choice of indicator species and when comparing pollution effects at different sites – often only unravelled by a combination of field observation and laboratory experimentation. Identification of TBT effects, notably masculinization of female dogwhelks, has heralded growing apprehension over the wider threat of endocrine disruption (ED) in rivers, estuaries and coastal waters of the Channel region. This concern has initiated research to study the distribution and effects of feminising/de-masculinizing (oestrogenic and anti-androgenic) compounds in Channel catchments, using sediments, molluscs and fish as indicators. BadoNilles et al. have shown the Bullhead Cottus sp. to be a relevant and ubiquitous fish species for monitoring responses to environmental stress in European freshwaters though, in fact, immune functions (leucocyte distribution, cellular mortality, respiratory burst, phagocytosis) were found to be easier biomarkers to interpret in the context of environmental quality of rivers than the rather unpredictable (site-specific) reproductive profile of bullhead populations. Temperature-induced (seasonal) factors mediate the complex reproductive cycle of Bullhead strongly (immune function to a lesser extent), contributing to the customary difficulty of separating inherent (natural) and anthropogenic drivers of physiological response. The variations and interactions in reproductive and immune system responses in this study demonstrate how important it is to factor-in confounding environmental and biological features when defining best practice in bio-monitoring. Using another ubiquitous European freshwater fish Rutilus rutilus as a model, Gerbron et al. have illustrated the importance and complexity of interactions between contaminants, in terms of interpreting the net impact on endocrine disruption. The feminising effect of the natural hormone 17-b oestrodiol on oestrogenic endpoints such as vitellogenin synthesis (both at the mRNA and protein level) and expression of steroid (estrogen/androgen) receptors, was shown to be compromised in vivo and in vitro by the antioestrogenic properties of another chemical linked to reproductive impairment in vertebrates, the widely-used pollutant metal, Cd. The observation that the non-essential metal Cd could impinge on male and female responses to hormones demonstrates the potential intricacy in the regulation of gender balance. Interactive effects of environmental chemicals such as this, at the protein and transcriptional levels, highlight the difficulties in the interpretation of endocrine disruption and its causes in the field. Whilst it is clear that chemical contaminants with estrogen receptor agonist or androgen receptor antagonist activity are
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present in wastewater effluents, and that steroidal estrogens and possibly anti-androgens are causing feminization of fish in some rivers, a major unresolved question surrounds impacts on marine biota, particularly invertebrates (which make up 95% of all organisms). Using a reporter gene assay, Alvarez-Munoz et al. describe the contamination of estuarine and coastal Channel sediments with anti-androgens (AA), with the aim of clarifying their involvement in endocrine disruption in bivalve molluscs. Some 90% of UK sites and 45% of French sites sampled exhibited androgen receptor antagonist activity in surface sediment extracts – highest in the Southampton and Poole area (UK) and the port of Le Havre (France) – and were a function of sediment properties notably organic and silt content. In clams (S .plana) from Southampton sites a considerable amount of AA activity was due to PAHs (oil-derived) implying association with port activities and the petrochemical industry (including spillage), though pyrogenic contributions cannot be ruled out. Interestingly, compared with female S. plana, a high level of androgen receptor agonist activity was detectable in male clams, attributable to dihydrotestosterone – implying a possible role for steroid androgens in these bivalves (one of the few such demonstrations in an invertebrate). However, although a range of AA activity was found in sediments – with the potential for ED – no clear relationship with effects on sexuality in clams have emerged as yet; synergistic or antagonistic effects, for example with (xeno)oestrogens or organotins, could be influential and merit further investigation. There is also a need to refine mollusc-based receptor screening tools to help characterise exposure to EDC in marine environments. Pope et al. have capitalised on the excellent bio-indicator potential of S. plana (widespread occurrence and abundance, salinity tolerant, central to ecosystem functioning, inherent gonochoristic sexuality) to describe the incidence of intersex (feminisation – occurrence of oocytes among normal testicular tissues) in estuaries throughout the entire Channel (108 sites of which 58% displayed intersex). As a deposit feeder, S. plana is likely to be exposed to many different EDCs in sediment. Causes of the observed range in intersex severity remain speculative (up to 50% males affected at some Channel sites, with an overall mean value of 8.6%), as highlighted also by the investigations with anti-androgens described above; nevertheless, this is an important model for future monitoring. In addition to providing an indication of the pervasive nature of ED, and impacts on shellfish, this study serves to illustrate that Channel-wide perspectives on water, sediment and ecological quality can be obtained by the appropriate choice of indicator and strategy. Regional and national barriers can be overcome to deliver Channel-scale opportunities for better integration and improved management. In future it would be constructive to explore more openings at this scale. Emerging biomarker protocols for assessing pollutant impacts and biological threats. A Channel-wide perspective on monitoring should extend to the use of state-of-the-art biomarker applications, including molecular approaches which might provide sensitive indicators of environmental impact. For example, examination of cellular pathways affected by endocrine disruption, using gene isolation methods and comparison of normal and toxicant-induced genomes, have proved a viable and novel part of the assessment of intersex causes and consequences in S. plana populations. Ciocan et al. screened intersex-associated transcripts, (previously identified by suppressive subtractive hybridisation), to describe their differential expression in ‘normal’ male clams sampled from UK and French Channel coasts. Transcripts involved in testicular development, energy production, intracellular signalling, ferritin and egg yolk precursor protein were differentially regulated at selected sites with varying intersex incidence and contaminant burdens. Sex ratios were correlated with oestrogenic activity, as opposed to anti-androgenic activity, of sediments (measured using
a steroid receptor transcription assay). The results provide an indication of the mode of action for intersex and potentially, molecular ‘early-warning’ biomarkers of the condition and perhaps more general stress indicators. Multiple biomarker application to assessing ecosystem health – in a ‘weight of evidence approach’ – is favoured over single biomarker use, as argued by Jha and Dallas in their critical evaluation of the application of biological effects tools, focused on the Tamar Estuary in SW England. The emphasis on guiding the reader through the benefits and drawbacks of this approach will help to promote the use of such tools to environmental managers and statutory bodies. This is an essential requirement in the context of complying with recent regulatory frameworks (WFD, MSFD) with their emphasis on evaluating pollution as a function of impacts on biological quality and ecological status (alongside contaminant levels) rather than traditional reliance on chemical monitoring alone. Many of the 24 sub-lethal biochemical and molecular responses reviewed (including carcinogenic, mutagenic and reprotoxic effects) have added-value in providing early-warning that damage may be occurring at tissue, whole organism and population levels; the requirement for more integrated studies to confirm these links is clearly presented. The Tamar Estuary, though parochial, is confirmed as an ideal environment in which to examine applications of these biological tools, given its conservation importance and combination of pressures (e.g. domestic discharges, agriculture, historical mining and other industry, port activity, low level nuclear waste) which are representative of those seen in transitional waters throughout the Channel. Given the wealth of information on the Tamar system It is also an excellent platform to examine future perspectives and challenges in the application of biomarker-style surveillance, including new ‘omics’ technologies (e.g. gene expression profiles) and to clarify more basic requirements such as appropriate choice of indicator organism, reference site and contextual chemistry. A practical illustration of the importance of the multiple biomarker philosophy, including gene expression, is provided in the multiparametric study by Dupuy et al. of juvenile flounder Platichthys flesus in three contrasting Channel estuaries: the Canche (clean), the Tamar (combination of pressures including metals) and the Seine (heavily polluted by diffuse contamination). This catadromous flatfish uses estuaries as a nursery and has often been advocated a bio-indicator of estuarine water and sediment quality. Condition (growth rate, composition of otoliths) and several biomarkers of the immune system, antioxidant enzymes, energy metabolism and detoxification process were investigated in (0+) group and one-year-old (1+) flounder, as a function of contamination (metals). Differences between the Canche and the Seine estuaries were highlighted by the multi-biomarker approach – notably responses in modulation of the immune system, raised cytochrome-c oxidase activity and up-regulation of betaine homocysteine S-methyltransferase (enzymes involved in detoxification and oxidative stress response) and a lower condition index. Moderate responses in juvenile flounder from the Tamar were linked to the intermediate levels of contamination (metals) present in this estuary. Numerous correlations between individual biomarker responses were evident for the polluted Seine fish (particularly in immune and detoxification processes). Together, these molecular, cellular and biochemical markers are becoming accepted, increasingly, as a viable means of estimating the quality of estuarine waters and the health status of aquatic populations; nevertheless, interpretation is not without interference from confounding environmental and biotic factors and the type (and combination) of contamination in question. At the molecular level, proteomics have been used by Galland et al. to detect contaminant responses in P. flesus following experimental exposure to dietary mixtures of PAHs and PCBs – at
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concentrations representative of the River Seine, and an order of magnitude higher. Protein identification in this novel ‘omics’ approach indicated perturbation of oxidative stress proteins, glutathione metabolism and possibly other pathways of adaptation to oxidative stress (betaine demethylation and methionine metabolism) in livers of PAH/PCB-exposed fish. These, and similar changes, promise to be valuable future markers in diagnosing pollution-impacted populations and identifying mechanisms of effect. In nature, deleterious effects are unlikely to be caused by single stressors in isolation. Using juvenile P. flesus as a test species, Lavergne et al. demonstrated at the gene transcription level, the importance of considering synergistic effects, showing that chemical contamination could influence tolerance to other pressures, such as thermal stress (e.g. from power stations or climate change). Temperature tolerance was compared in fish from the densely populated and polluted Seine Estuary with that of the less-contaminated Vilaine Estuary, using expression of genes related to energy metabolism as a marker of impact. A decrease in expression of the ribosomal 12S gene (a proxy for mitochondrial density and energy metabolism) in livers of P. flesus, in response to temperature, was observed in the more contaminated Seine fish, along with a drop in condition index, which implies that the chemical burden accumulated in these flounder reduces their tolerance of thermal stress and potentially reduces fitness to cope with other environmental pressures. Clearly, this may be important, in ecotoxicological terms, in a warming world (climate change), or as a result of seasonal change, or where temperature variation increases due to direct human influence (thermal discharges). There is growing concern over the presence of herbicides and other chemicals from agricultural run-off into coastal waters, and their effects on non-target aquatic species. A multi-biomarker investigation by Mottier et al., this time in the laboratory, following chronic exposure of commercial oysters Crassostrea gigas to glyphosate, compared a variety of responses. These ranged from molecular (mRNA quantification) and biochemical endpoints (glutathione-S-transferase GST-detoxification); catalase activity (antioxidant); malondialdehyde content (lipid peroxidation marker) to whole organism response (gametogenesis and tissue alterations). Mortality, growth and histopathology in yearling oysters were not significantly affected by this widely-used, but little-studied class of pesticide, though individual biomarkers revealed effects. The levels of GST and metallothionein gene expression increased significantly in oysters exposed to the highest glyphosate concentration, whilst the expression of MXR mRNA (multi-xenobiotic resistance) increased at all concentrations. Results suggested an activation of defence mechanisms at the molecular level which, combined with low bioaccumulation potential, may tend to reduce overall toxicity of these herbicides, compared to more toxic alternatives such as organochlorine insecticides. Assays such as these are a useful means of identifying the most environmentally acceptable biocides. Several contributions in this volume introduce new biological effects techniques to measure the responses of marine organisms. Some are as yet in the experimental stage, including physiological perturbations in juvenile cuttlefish Sepia officinalis induced by sub-chronic exposure to dissolved zinc (Le Pabic et al.).These are important additions to the ecotoxicological literature, given that S. officinalis is a significant English Channel fisheries resource, characterised by inshore migration during summer spawning – yet little is known about contaminant impacts on cuttlefish physiology, particularly vulnerable eggs and juveniles. Again, an integrated biomarker approach (growth, predation behaviour, mortality, immune function and digestive enzymes) has been deployed to demonstrate sensitivity towards
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contamination (Zn). Despite evidence of growing tolerance to Zn during development, juvenile cuttlefish appear susceptible, in terms of mortality, compared with other aquatic organisms. Sublethal responses affected by Zn included growth, ability to capture prey, inhibitory impacts on acid phosphatase, cathepsin and trypsin activity (digestive enzymes), and phenoloxidases (immune function). Though these experiments were performed at high Zn concentrations it would be interesting to extend testing to other forms of contamination, given the susceptibility shown in juvenile cuttlefish. With the likely resurgence of nuclear power generation in Channel catchments, exploring effects on different biological endpoints, at different life stages, has obvious relevance in the context of evaluating and managing impacts from controlled releases of radionuclides. The assessment of physiological responses, genotoxicity and expression of stress-related genes in the Pacific oyster C. gigas has been evaluated following chronic exposure to ionising radiation, namely 137Cs, 241Am and 3H (Devos et al.). Growth rate and expression of nine target stress-response genes in larvae and spat were not significantly changed by internal or external exposure, even at levels much higher than those expected near nuclear plants. However, whilst clearance rate and transcription levels were unaffected, DNA damage was increased in haemocytes of two-year old oysters exposed to tritiated water, highlighting the potential for higher level consequences. This research is helping to fill a major gap in our understanding of how chronic doses may affect marine organisms, and how these responses relate to acute exposure. Of course not all sites are polluted and the work described here includes information on those areas which can be considered as near-pristine – valuable in the context of defining regional baselines. Likewise not all threats are chemical and the issue of invasions by non-native species is recognised as a widespread concern. Bishop et al. demonstrate how to assess and quantify such problems, rapidly and pragmatically. Based on studies in marinas on both sides of the Channel in 2010 and 2013 this contribution reveals surprising variation in occupancy trends for non-indigenous species (NIS) of sessile invertebrates. In Brittany, NW France, most of these invasive species occupied most sites in both years. In SW England occupancy was lower in 2010 but rapid colonisation was evident in 2013, implying that these recent introductions to NW Europe have spread northwards across the Channel after initially becoming established in French marinas. Management tools and socio-economic issues. It is crucial to capitalise on the scientific effort and investment in research projects encompassed within the INTERREG programme (and others like it), by bringing results to the attention of interested scientists, potential users, environmental managers and policy makers. This is one of the major objectives of the current ‘special edition’. Improvement in TBT-impacted systems described in the paper by Langston et al. highlights one specific example of the benefits in linking science and policy: reviews of the current status of contaminants in the English Channel, consequences of exposure and suggestions for improved management of biological resources are a sub-text in most other contributions. Broader discussion of the management tools and approaches in the English Channel and its catchments are given prominence in the paper by Glegg et al. which summarises the current legislative drivers, policies, socioeconomic issues and governance in the Channel, with its conflicting commercial and conservation interests. The lack of integration between countries and sectors (industrial, academic, legislative), is highlighted and the needs and benefits of a Channel-wide perspective (encompassed within the EU’s new marine management
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frameworks and supported by innovative science to understand ecosystem structure and functioning) is endorsed. Together, these crucial components should enhance future governance in the Channel, which must seek an appropriate balance of interests and values, and long term-support at national and European level if it is to be effective. The articles in this edition indicate how valuable the INTERREG program has been in taking forward our collective understanding of biological and chemical threats in the Channel –an important sea area in its own right, not merely an adjunct of OSPAR’s Region ll (The Greater North Sea). It is hoped that the novel insights and diverse approaches described here, will reap benefits in terms of better water/ecological quality assessment (and governance) by the time the next round of environmental evaluations of the Channel takes place. The majority of the outputs should also be of relevance to assessment of the condition of regional seas further afield. Acknowledgements The Guest Editors wish to thank the authors for their outstanding contributions and the referees for their diligent reviewing of the manuscripts for this ‘Special Issue’. The support and suggestions given by the Editor-in Chief of Marine Pollution Bulletin, Professor Charles Sheppard, and colleagues in the Elsevier production team (especially Ms Sara Bebbington and Ms Jun You) are gratefully acknowledged. The guest editors would also like to thank INTERREG for financial contributions towards much of the science described here and for supporting the 3Cs cluster which has enabled the production of this volume. It should be noted however that the views expressed in this Special Edition are those of the authors and not necessarily their host organisations and funding bodies.
References Cabioch, L., Glémarec, M., Samain, J.-F., 1983. Fluctuation and succession in marine ecosystems. In: Proceedings of the 17th European Symposium on Marine Biology. Oceanological Acta, Special Volume, 225 pp. Gibbard, P.L., Lautridou, J.P. (Eds.), 2003. The Quaternary History of the English Channel. J. Quatern. Res. 18, 195–199. IHO (International Hydrographic Organization), 1953. Limits of Oceans and Seas, Special Publication 23, third ed., 42 pp. OSPAR, 2010. Quality Status Report 2010. OSPAR Commission, London, 175 pp. Reid, P.C., Auger, C., Chaussepied, M., Burn, M., 1993. Quality Status Report of the North Sea 1993: Assessment Report on Sub-Region 9. North Sea Task Force, Ruislip, United Kingdom, 153 pp. Statham, P.J., Davies, P.A., Lafite, R., 1999. Introduction and dedication of the Fluxmanche II special issue. Continent. Shelf Res. 19, 1849–1850. Tappin, A.D., Reid, P.C., 2000. The English Channel. In: Sheppard, C.R.C. (Ed.), Seas at the Millenium: An Environmental Evaluation, vol. 1. Regional Chapters, Europe, The Americas and West Africa. Pergamon Press, Oxford, UK, pp. 65–82 (chapter 5).
Geoffrey E. Millward Marine Institute, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK Awadhesh N. Jha School of Biological Sciences, Plymouth University, Plymouth PL4 8AA, UK Christophe Minier National Agency for Water and Aquatic Environments (Onema), Le Nadar – Hall C, 5, Square Félix Nadar, 94300 Vincennes, France Nicholas D. Pope William J. Langston Marine Biological Association of the United Kingdom, Citadel Hill, Plymouth PL1 2PB, UK Available online xxxx
