Malcolm B. Jones

A multibiomarker approach to environmental assessment.

Incorporation of ecologically relevant biomarkers into routine environmental management programs has been advocated as a pragmatic means of linking environmental degradation with its causes. Here, suites of biomarkers, devised to measure molecular damage, developmental abnormality and physiological impairment, were combined with chemical analysis to determine exposure to and the effects of pollution at sites within Southampton Water (UK). Test species included a filter feeder, a grazer, and an omnivore to determine the sensitivity of organisms occupying different trophic levels. Linear regression confirmed a significant association between incidence of intersex in Littorina littorea and tributyltin (TBT) concentrations (R2 = 0.954) and between PAH metabolites in Carcinus maenas urine and PAHs in sediments (R2 = 0.754). Principal component analysis revealed a gradient of detrimental impact to biota from the head to the mouth of the estuary, coincident with high sediment concentrations of heavy metals, PAHs, and biocides. Multidimensional scaling identified C. maenas as the organism most sensitive to contamination. Carboxylesterase activity, metallothionein and total haemolymph protein were the most discriminating biomarkers among sites. This holistic approach to environmental assessment is encouraged as it helps to identify the integrated impact of chemical contamination on organisms and to provide a realistic measure of environmental quality.

Application of biomarkers for improving risk assessments of chemicals under the Water Framework Directive : A case study

To answer the requirement of the European Commissions Water Framework Directive (WFD) for biological-effects endpoints to classify the ecological health of aquatic ecosystems, we propose the biomarker response index (BRI). The BRI, based on a suite of biomarkers at different levels of biological response at the individual level, provides an integrated relative measure of the general health status of coastal invertebrates. Using the BRI, the health of mussels (Mytilus edulis) from 10 estuaries classified by the Environment Agency of England and Wales under the WFD was compared. Eight sites were healthier than predicted and two showed a similar health status to that of the predicted point-source pollution risk classification. Results indicate that the BRI offers a potential measure of organism health that can be used in monitoring under the WFD as an additional aid to reduce uncertainty in defining risk classification and to provide better evidence of existing impact.

Effects of the model PAH phenanthrene on immune function and oxidative stress in the haemolymph of the temperate scallop Pecten maximus.

Phenanthrene, a major component of crude oil, is one of the most abundant PAHs in aquatic ecosystems, and is readily bioavailable and toxic to a range of marine invertebrates. Within bivalves, the haemolymph acts as a transfer medium for these pollutants and their metabolic products, leaving haemocytes susceptible to deleterious effects. Using a suite of biological endpoints, this study determined the sublethal (7-d exposure to 50, 100 and 200microgL(-1)) effects of phenanthrene on several oxidative stress and immunological parameters in the haemolymph of the commercially-important scallop Pecten maximus. Phenanthrene exposure (200microgL(-1)) resulted in immune modulation with significant reductions in cell membrane stability (P<0.05) and phagocytosis (P<0.05), and a significant increase in the number of total haemocytes (P<0.05). Oxidative stress was also observed with a significant decrease in total glutathione (P<0.05) and significantly increased levels of lipid peroxidation in the haemolymph (P<0.05). Changes in the cellular and biochemical endpoints observed in this study illustrate their potential use in assessing the subtle effects of contaminant exposure. Whilst previous reports have suggested a link between free radical generation and immune suppression in vertebrates, this is the first instance where oxidative stress and immune function have been measured together in the haemolymph of a bivalve mollusc, demonstrating a possible link between PAH-induced oxidative stress and the subsequent inhibition in haemocyte immune function.

The ups and downs of benthic ecology: considerations of scale, heterogeneity and surveillance for benthic–pelagic coupling

Dave Raffaelli*, Elanor Bell, Guntram Weithoff, Asako Matsumoto, Juan Jose Cruz-Motta, Pete Kershaw, Ruth Parker, Dave Parry, Malcolm Jones Environment Department, University of York, Heslington, York YO10 5DD, UK b Institute for Biochemistry and Biology, University of Potsdam, Maulbeerallee 2, 14469 Potsdam, Germany Marine Ecosystems Research Department, Japan Marine Science and Technology Centre, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan Centre for Research on Ecological Impacts of Coastal Cities, Marine Ecology Laboratories, University of Sydney, Sydney NSW 2006, Australia The Centre for Fisheries, Environment and Aquaculture Science, Lowestoft Laboratory, Pakefield Road, Lowestoft NR33 0HT, UK Plymouth Environmental Research Centre, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK

Disruption of swimming in the hyperbenthic mysid Neomysis integer (Peracarida: Mysidacea) by the organophosphate pesticide chlorpyrifos

Mysids are used routinely by regulatory authorities for conducting 96 h LC50 toxicity tests to evaluate the potential hazards of pollutants to aquatic ecosystems. Data from these acute tests suggest that the European estuarine mysid Neomysis integer (Peracarida: Mysidacea) is comparatively sensitive to trace metals and organophosphate pesticides, and may be a suitable alternative to the frequently-used sub-tropical American mysid Americamysis (≡Mysidopsis) bahia for testing the toxicity of chemical contaminants to European estuarine biota. There is, however, growing demand for the development of toxicity tests which are more representative of the effects of toxic contaminants on natural populations, and which provide results that are more readily extrapolated to natural ecosystems, than acute tests. Behavioural disruption, particularly of swimming ability, is used increasingly in laboratory toxicity studies as a sensitive endpoint for assessing the effects of contaminants on aquatic biota. This paper describes a sensitive laboratory technique, using an annular flume, to determine the effects of an organophosphate pesticide on the swimming behaviour of N. integer. Following 7-day exposure to 0.038 μg chlorpyrifos l−1, mysids became hyperactive and more swam forward into a slow current (3 cm s−1) than control mysids. Despite this hyperactivity, pesticide-exposed mysids were unable to swim faster than 15 cm s−1, whereas control mysids were able to swim faster than 18 cm s−1. Other changes in swimming behaviour following pesticide exposure included fewer mysids maintaining position, and more mysids swimming with the current at high current velocities (18 cm s−1), than control individuals. These responses of chlorpyrifos-exposed N. integer are predicted to cause reduced ability of N. integer to maintain position in the natural estuarine habitat. Furthermore, the swimming behaviour of N. integer was affected at pesticide concentrations below the 7 day LC50 (0.084 μg chlorpyrifos l−1), highlighting the importance of using sub-lethal toxicity studies for predicting environmental consequences of pollutant discharge.

Immunotoxicity and oxidative stress in the Arctic scallop Chlamys islandica: Effects of acute oil exposure

With increasing oil exploration in Arctic regions, the risk of an accidental oil spill into the environment is inevitably elevated. As a result, concerns have been raised over the potential impact of oil exposure on Arctic organisms. This study assessed the effects of an acute oil exposure (mimicking an accidental spill) on the immune function and oxidative stress status of the Arctic scallop Chlamys islandica. Scallops were exposed to the water accommodated fraction of crude oil over 21 d (maximum SigmaPAH 163 microg l(-1)) and immune endpoints and oxidative stress parameters were measured. Mortalities were recorded during the exposure and reductions in immunocompetence were observed, with significant impairment of phagocytosis and cell membrane stability. Scallops were also subjected to oxidative stress, with a significant reduction in glutathione levels and induction of lipid peroxidation. After the acute oil exposure had subsided, no recovery of immune function was observed indicating potential for prolonged sublethal effects.

Bioturbation as a mechanism for setting and maintaining levels of diversity in subtidal macrobenthic communities

Over 2 years, experiments were conducted tocompare the effects of sediment disturbance by different bioturbating, macrofaunal organisms on the diversity and structure of the associated infaunal community. The four species investigated were the bivalves Nuculoma tenuis (Montagu, 1808) and Abra alba (Wood, 1802), the heart urchin Brissopsis lyrifera (Forbes, 1841), and the burrowing decapod Calocaris macandreae (Bell, 1846). These organisms were chosen to allow assessment of the effects of contrasting feeding activities and body sizes of the bioturbating species on the diversity of the macrobenthic communities. Bioturbation by the sub-surface deposit feeders N. tenuis and B. lyrifera promoted higher levels of α and β diversity in treatments exposed to intermediate levels of disturbance. Whilst no such ‘intermediate response’ was demonstrated for A. alba or C. macandreae, it was evident that changes in the associated fauna were influenced by the feeding type of the bioturbating organism responsible. It was also shown that different elements of the associated community responded differently to biotic disturbance. The results indicate that the variability in density and distribution of such bioturbators are important factors in structuring infaunal communities, and in setting and maintaining levels of diversity in apparently homogeneous areas.

Critical-Evaluation Of Sediment Turnover Estimates For Callianassidae (Decapoda Thalassinidea)

Abstract Members of the decapod family Callianassidae influence sediment dynamics and ecosystem function via their bioturbation activities. The latter is currently assessed by measures of sediment turnover rates which are collected, calculated and expressed by different methods. Some estimates, particularly extrapolations which do not consider the influence of temperature, population structure and expulsion behaviour, are likely to be significantly over/under estimates of sediment turnover. Therefore, published values of sediment turnover by the Callianassidae need to be treated with caution and are not strictly comparable. In view of the need for assessing the relative importance of callianassid bioturbation, it is suggested that attempts should be made to standardize the measurement of sediment turnover rate to allow future comparisons to be made with confidence.

Biomarker responses and PAH uptake in Mya truncata following exposure to oil-contaminated sediment in an Arctic fjord (Svalbard).

Expanding industrial activity (notably oil and gas exploration) in the Arctic requires assessment of the potential impact of chemicals on marine organisms living in seawater at low temperature. The bivalve Mya truncata is common in Svalbard fjord (Norway) where it experiences low temperature throughout the year. To measure the impact of polycyclic aromatic hydrocarbons (PAH) on M. truncata, the responses of three biomarkers [total oxyradical scavenging capacity-assay (TOSC), plasma membrane stability of haemocytes and respiration rates] were investigated from bivalves exposed to sediment contaminated with a PAH mixture (crude oil). After two weeks of exposure to the contaminated sediment, TOSC showed no change. The high TOSC value (4010+/-1339 unit mg(-1) protein) of Mya truncata (control group) is thought to protect biomolecules with a low turnover rate efficiently in a low food availability environment. In the exposed bivalves, the haemocyte cellular membranes were significantly destabilised compared with controls (P<0.05). Respiration rate of control and PAH-exposed individuals (0.055+/-0.020 mg O(2) dw(-1) h(-1)) was similar and relatively low as is typical for polar bivalves, reflecting a strategy to minimise energy expenditure to cope with 9 months of starvation. Bioaccumulation of PAH by M. truncata was also low, due probably to a combination of low metabolic rate and reduced solubility of the oil compounds at low temperature. Data indicated an uptake of mainly low molecular weight compounds (two and three ring molecules). A good correlation of logBAF(lipid) (bioaccumulation factor) and logK(ow) (octanol/water partitioning coefficient) was shown (r(2)=0.87). Tissue sensitivity and/or functional differences (digestive gland vs. haemocytes), PAH uptake route (dietary vs. gills), the low metabolic rate of M. truncata and the low environmental temperature (reducing the bioavailability of PAH) are factors that help explain these findings.

Total oxyradical scavenging capacity and cell membrane stability of haemocytes of the Arctic scallop, Chlamys islandicus, following benzo(a)pyrene exposure.

Industrial activities, notably oil and gas industries, are expanding in the Arctic. Most of the biomarkers were developed using temperate organisms living at temperatures above 10 degrees C. Little is known about the biomarker responses of organisms living between -1.88 and 5 degrees C. Therefore, assessment of the toxicity of chemicals to cold-water adapted species is required. In this study, the Arctic scallop, Chlamys islandicus, was selected as a key species for bio-monitoring because of wide distribution in Arctic waters and its commercial value. Test animals, stored in seawater at 2 degrees C, were injected with benzo(a)pyrene (diluted in cod liver oil 5 mg ml(-1)) in the adductor muscle every 24 h for four days giving a final dose of 0, 74 and 90.6 mg kg(-1) wet weight for control, low and high dose, respectively. The biomarkers used were total oxyradical scavenging capacity (TOSC) in the digestive gland and cell membrane stability of haemocytes. TOSC values were significantly reduced (ca. 30%) in exposed groups (P < 0.05), indicating a depletion in oxyradical molecular scavengers. The antioxidant defences appeared to be overwhelmed by the reactive oxygen species as the plasma membranes of haemocytes were destabilised (P < 0.05) probably due to lipid peroxidation. These data indicate that reactive oxygen species (ROS) were produced by Arctic scallops via the metabolisation of benzo(a)pyrene at 2 degrees C.