The use of respiratory enzymes as biomarkers of petroleum hydrocarbon exposure in Mytilus edulis planulatus

Biological effects of dumped chemical weapons in the Baltic Sea: A multi-biomarker study using caged mussels at the Bornholm main dumping site

After World War II, thousands of tons of highly toxic chemical warfare agents (CWA) were deposited in the Baltic Sea, the main dumping site locating in the Bornholm Basin. In the present study, Baltic mussels (Mytilus trossulus) were transplanted in the area in cages at two hotspot sites and a reference site at the depths of 35 and 65 m for 2.5 months to study bioaccumulation and biological effects of CWA possibly leaking from the corroding warfare materials. No traces of degradation products of the measured phenylarsenic CWA could be detected in the tissues of mussels. Nevertheless, several biochemical and histochemical biomarkers, geno- and cytotoxicity indicators, and bioenergetic parameters showed significant responses. The Integrated Biomarker Index calculated from the single biomarkers also showed a higher total response at the two hotspot areas compared to the reference site. Although no direct evidence could be obtained confirming the responses being caused specifically by exposure to CWA, the field exposure experiment showed unambiguously that organisms in this sea area are confronting environmental stress affecting negatively their health and this is likely related to chemical contamination, which is possibly connected to the sea-dumped CWA.

Comparative and Interactive Biochemical Effects of Sub-Lethal Concentrations of Cadmium and Lead on Some Tissues of the African Catfish (Clarias gariepinus)

Cadmium is a strong toxic heavy metal which presents in paints and liquid wastes and causes oxidative stress in fish. On the other hand, lead is widely used for different purposes, e.g. lead pipes, it targets vital organs such as liver and kidney causing biochemical alterations. The present study evaluates the effects of 60 days exposure to Cd and Pb either single or combined together in African catfish. Sixty-four fishes were divided into 3 groups and exposed to CdCl2 (7.02 mg/L) or PbCl2 (69.3 mg/L) or a combination of them along with control group. Activities of acid phosphatase (ACP), lactate dehydrogenase (LDH) and glucose-6-phosphate dehydrogenase (G-6-PDH) were estimated. Moreover, gill, liver and kidney were assayed for activities of superoxide dismutase (SOD), catalase (CAT) and levels of glutathione (GSH) and malondialdehyde (MDA). Individual exposure showed that both Cd and Pb significantly decreased LDH activity and SOD activity in the kidney. Pb significantly increased G-6-PDH activity and decreased GSH level in the gill. CAT activity in liver and kidney elevated significantly on Cd exposure while lead caused a significant depletion in the liver and significant elevation in the kidney. Both Cd and Pb significantly increased MDA levels in liver and kidney while Pb increased its level in gills. The combined exposure resulted in normalization of LDH, G-6-PDH activity, and CAT activity in liver and kidney as well as GSH level in both tissues and MDA in gill and kidney. The combination increased SOD activity and MDA level in liver and decreased SOD activity in kidney and GSH level in gills. In conclusion, the antioxidant system of African catfish was adversely affected by prolonged exposure to Cd and Pb. The combined exposure caused less damage than individual exposure and returned most parameters to those of controls.

Multibiomarker interactions to diagnose and follow-up chronic exposure of a marine crustacean to Hazardous and Noxious Substances (HNS)

Integrated compensatory responses of physiological systems towards homeostasis are generally overlooked when it comes to analysing alterations in biochemical parameters indicative of such processes. Here an hypothesis-driven multivariate analysis accounting for interactive multibiomarker responses was used to investigate effects of long-term exposure of Carcinus maenas to Hazardous and Noxious Substances (HNS). Adult male crabs were exposed to low and high post-spill levels of acrylonitrile (ACN) or aniline (ANL) for 21d. Bioaccumulation, feeding behaviour, and biomarkers related to mode-of-action (MoA) (detoxification, neurotransmission and energy production) were evaluated over time. Distinct temporal patterns of response to low and high exposure concentrations were depicted, with a main set of interactive multibiomarker predictors identified for each HNS (five for ACN and three for ANL), useful to follow coupled evolvement of biomarker responses. ACN caused peripheral neurotoxic effects coupled with enhanced biotransformation and significant oxidative damage particularly relevant in gills. ANL elicited alterations in central neurotransmission affecting ventilation coupled with very low levels of oxidative damage in gills. Results indicate chronic toxicity data are determinant to improve HNS hazard assessment if the aim is to obtain reliable risk calculations, and develop effective predictive models avoiding overestimation but sufficiently protective. Accounting for multibiomarker interactions brought otherwise overlooked information about C. maenas responses and MoA of ACN and ANL.

Guidelines for the Care and Welfare of Cephalopods in Research -A consensus based on an initiative by CephRes, FELASA and the Boyd Group

This paper is the result of an international initiative and is a first attempt to develop guidelines for the care and welfare of cephalopods (i.e. nautilus, cuttlefish, squid and octopus) following the inclusion of this Class of ∼700 known living invertebrate species in Directive 2010/63/EU. It aims to provide information for investigators, animal care committees, facility managers and animal care staff which will assist in improving both the care given to cephalopods, and the manner in which experimental procedures are carried out. Topics covered include: implications of the Directive for cephalopod research; project application requirements and the authorisation process; the application of the 3Rs principles; the need for harm-benefit assessment and severity classification. Guidelines and species-specific requirements are provided on: i. supply, capture and transport; ii. environmental characteristics and design of facilities (e.g. water quality control, lighting requirements, vibration/noise sensitivity); iii. accommodation and care (including tank design), animal handling, feeding and environmental enrichment; iv. assessment of health and welfare (e.g. monitoring biomarkers, physical and behavioural signs); v. approaches to severity assessment; vi. disease (causes, prevention and treatment); vii. scientific procedures, general anaesthesia and analgesia, methods of humane killing and confirmation of death. Sections covering risk assessment for operators and education and training requirements for carers, researchers and veterinarians are also included. Detailed aspects of care and welfare requirements for the main laboratory species currently used are summarised in Appendices. Knowledge gaps are highlighted to prompt research to enhance the evidence base for future revision of these guidelines.

Separating natural from anthropogenic causes of impairment in Zebra mussel (Dreissena polymorpha) populations living across a pollution gradient

The relationship between the reproductive stage, the total lipid content and eight broadly used biochemical stress responses were used to assess seasonal and pollutant effects across eleven different zebra mussel (Dreissena polymorpha) populations from the Ebro and Mijares river basin, Spain. Biochemical markers included superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione S transferase (GST), multixenobiotic transporter activity (MXR), lactate dehydrogenase (LDH), lipid peroxidation (LPO) and single strand DNA breaks. Principal component analyses of zebra mussel responses across an annual cycle, showed a marked gonad stage component in total lipid content and biochemical responses. The same response pattern was observed across the populations sampled along a broad geographical and pollution gradient. Population differences on the gonad developmental stage were highly correlated with most of the measured responses and unrelated with the pollution gradient. Conversely, bioaccumulation of organic and inorganic contaminant residues was more related to pollution sources than with the reproductive cycle. These results indicate that the reproductive cycle is the major factor affecting the temporal and spatial variation of the studied markers in D. polymorpha.

Behaviour and biomarkers as tools to assess the acute toxicity of benzo(a)pyrene in the common prawn Palaemon serratus

Benzo(a)pyrene (BaP) is considered an important marine environmental contaminant, given its recognised environmental persistence and toxicity. However, its effects in marine crustaceans are poorly studied, namely the accumulation and sub-cellular effects that might be linked to behavioural alterations and may lead to ecologically relevant consequences. This study aims to investigate behavioural and physiological responses of the common prawn (Palaemon serratus) after acute exposure to BaP and infer the potential effects for the population in the wild. The applied approach included the evaluation of swimming performance after exposure, and several biochemical biomarkers involved in biotransformation, oxidative damage, energy production and levels of BaP-type compounds in tissues (eye, digestive gland and muscle) in a 96 h acute bioassay with exposure to BaP (16-4096 μg/L). The objective was to establish a link between behaviour (swimming velocity) and biochemical responses in order to assess the ecological relevance of the effects induced by BaP in P. serratus and to select useful tools for environmental risk assessment. Results showed swimming velocity impairment (LOEC = 128 μg/L), lipid peroxidation (LPO) induction (LOEC = 4096 μg/L) and BaP-type compounds increase in eye (LOEC = 32 μg/L), digestive gland and muscle (LOEC = 512 μg/L) of prawn after exposure to BaP. This oxidative damage in lipids seems to be caused by the incapacity to activate detoxification and anti-oxidant enzymes, once glutathione-S-transferase (GST), catalase (CAT) and glutathione peroxidase (GPx) were not affected by the exposure. This could be also an explanation to the increased levels of BaP-type compounds observed in tissues. An inability to increase the activities of enzymes involved in the production of energy was also observed, which may help to explain the detoxification failure and consequent increased levels of lipid peroxidation. The inhibition of swimming velocity was negatively correlated with biochemical parameters, including the presence of BaP-type compounds in different tissues and LPO, and thus, these parameters might be used as ecologically relevant and early-warning tools to assess the effects of PAHs. This study also highlights the usefulness of the fixed wavelength fluorescence (FF) technique to quantify PAHs-type compounds in tissues as indicative of exposure of P. serratus to PAHs, namely the sensitivity of eyes, which might be used for monitoring purposes and in marine ecological risk assessment studies.

Impact of laboratory exposure to light Arabian crude oil, dispersed oil and dispersant on the gills of the juvenile brown spotted grouper (Epinephelus chlorostigma): a histopathological study

The present study investigated the impact of subchronic exposure of the water accommodated fraction (WAF) of light Arabian crude oil, dispersed oil and dispersant on the gills of the juvenile brown spotted grouper (Epinephelus chlorostigma), observing several histopathological lesions at different time points and different concentrations. Significant alterations, compared to the control groups (p < 0.05), in four health categories (circulatory, proliferative, degenerative and inflammatory) were identified. Evaluations of histopathological lesions in gill tissue were carried out following 3, 6, 9, 12, 15, 18 and 21 days of exposure. The main lesions observed were circulatory (lamellar aneurysms, vasodilatation and hemorrhage), degenerative (edema, lifting of lamellar and filamentary epithelium and epithelium necrosis), proliferative (hypertrophy and hyperplasia of epithelial, mucous and chloride cells, fusion of adjacent lamellae), and inflammatory (lymphocytic infiltration). These results provide a tool for evaluating reclamation initiatives, such as the use of dispersants, and lead to better risk evaluations and environmental health in natural and reclaimed systems.

Detecting benthic community responses to pollution in estuaries: a field mesocosm approach

Biological stress responses in individuals are used as indicators of pollution in aquatic ecosystems, but detecting ecologically relevant responses in whole communities remains a challenge. We developed an experimental approach to detect the effects of pollution on estuarine communities using field-based mesocosms. Mesocosms containing defaunated sediments from four estuaries in southeastern Australia that varied in sediment contamination were transplanted and buried in sediments of the same four estuaries for six weeks. Mesocosm sediment properties and metal concentrations remained representative of their source locations. In each estuary, fauna communities associated with sediments derived from the site with the highest metal concentrations were significantly different from other communities. This pattern was evident for some of the individual taxa, in particular the polychaete Capitella sp. Consistent responses across estuaries suggest numbers of individuals, and especially Capitella sp., could be used to identify contaminated sediments in estuaries with similar fauna and site characteristics.

Histopathological liver alterations in juvenile rabbit fish (Siganus canaliculatus) exposed to light Arabian crude oil, dispersed oil and dispersant

With the heavy transport of crude oil there is an increasing risk of a major oil spill in the Gulf waters; however, there have been few studies on the impact of oil spills and subsequent remedial action on Gulf fish. The aim of the experiment was to investigate the effects of acute exposure to water soluble fraction (WAF) of light Arabian crude oil, dispersed oil and dispersant on the liver of the juvenile rabbit fish (Siganus canaliculatus), observing several histopathological biomarkers of the liver at different time points and different doses. The concentrations used (3-100 percent WAF) simulated a range of possible oil pollution events. The main alterations observed in this study include hepatocyte swelling and cytoplasmic vacuolisation, megalocytosis, coagulative dispersed necrosis, lymphocytic infiltration, melanomacrophage aggregates, spongiosis hepatis, pericholangiitis, and bile stagnosis. Treated livers showed significantly higher total index values than the control group (p<0.01). According to the total liver index, liver exposed to WAF, dispersed oil or dispersant showed significant histopathologic alterations compared with the control fish (Mann-Whitney U-test; p<0.01). Components of the total liver index, (circulatory, degenerative, proliferative, and inflammatory changes) differed significantly from the control groups. There was a significant correlation between exposure time and the total liver index values and the different reaction pattern indexes of treated fish (Spearman correlation; p>0.05). The present study indicates that dispersed oil is not more toxic, to livers of juvenile rabbit fish, than crude oil or dispersant.

Metabolic and physiological responses in tissues of the long-lived bivalve Arctica islandica to oxygen deficiency

In Arctica islandica, a long lifespan is associated with low metabolic activity, and with a pronounced tolerance to low environmental oxygen. In order to study metabolic and physiological responses to low oxygen conditions vs. no oxygen in mantle, gill, adductor muscle and hemocytes of the ocean quahog, specimens from the German Bight were maintained for 3.5 days under normoxia (21 kPa=controls), hypoxia (2 kPa) or anoxia (0 kPa). Tissue levels of anaerobic metabolites octopine, lactate and succinate as well as specific activities of octopine dehydrogenase (ODH) and lactate dehydrogenase (LDH) were unaffected by hypoxic incubation, suggesting that the metabolism of A. islandica remains fully aerobic down to environmental oxygen levels of 2 kPa. PO(2)-dependent respiration rates of isolated gills indicated the onset of metabolic rate depression (MRD) below 5 kPa in A. islandica, while anaerobiosis was switched on in bivalve tissues only at anoxia. Tissue-specific levels of glutathione (GSH), a scavenger of reactive oxygen species (ROS), indicate no anticipatory antioxidant response takes place under experimental hypoxia and anoxia exposure. Highest specific ODH activity and a mean ODH/LDH ratio of 95 in the adductor muscle contrasted with maximal specific LDH activity and a mean ODH/LDH ratio of 0.3 in hemocytes. These differences in anaerobic enzyme activity patterns indicate that LDH and ODH play specific roles in different tissues of A. islandica which are likely to economize metabolism during anoxia and reoxygenation.

Effects of dietary benzo[a]pyrene on growth and hematological parameters in juvenile rockfish, Sebastes schlegeli (Hilgendorf)

Experiments were conducted to evaluate the effect of dietary benzo[a]pyrene (B[a]P) on the growth and hematological parameters of rockfish, Sebastes schlegeli, after they were fed with subchronic dietary B[a]P for 30 days. The weight growth rate of the rockfish was significantly different from that of the control group at dietary B[a]P concentration of 1.5 and 2.0 mg/kg. Significant reduction in red blood cells, hematocrit, and hemoglobin were observed during 30 days of exposure to the highest concentration. Over 30 days, serum AST increased at a B[a]P concentration of 1.5 mg/kg and LDH increased at a B[a]P concentration of 1.0 mg/kg concentration. However, no changes were observed in ALT, total protein, magnesium or calcium.

Biochemical responses of the marine mussel Mytilus galloprovincialis to petrochemical environmental contamination along the North-western coast of Portugal

Following the development of urban and industrial centres petrochemical products have become a widespread class of contaminants. The aim of this study was to investigate the effects of petrochemical contamination in wild populations of mussels (Mytilus galloprovincialis) along the NW Atlantic coast of Portugal by applying antioxidant and energetic metabolism parameters as biomarkers. For that, mussels were collected at five sampling sites presenting different petrochemical contamination levels. To evaluate the mussels' antioxidant status, enzymatic activities of catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glutathione S-transferases, as well as glutathione redox status were evaluated in gills and digestive glands of mussels collected from the selected sites. Lipid peroxidation was determined in the same tissues to quantify cellular oxidative damage. Furthermore, to investigate how energetic processes may respond to these contaminants, the activity of NADP(+)-dependent isocitrate dehydrogenase was determined in mussels' digestive glands, and octopine dehydrogenase was determined in mussels' posterior adductor muscle. Furthermore, the concentrations of aliphatic hydrocarbons, unresolved complex mixture and polycyclic aromatic hydrocarbons (PAHs) were quantified in mussels' tissue, and abiotic parameters were quantified in water samples collected at each site. Several biomarkers showed statistically significant differences among sampling sites. The redundancy analysis (RDA) used to perform the integrated analysis of the data showed a clear separation of the sampling sites in three different assemblages, which are in agreement with the PAHs levels found in mussels tissues. In addition, the RDA indicated that some of the selected biomarkers may be influenced by abiotic parameters (e.g. salinity, pH, nitrates and ammonia). The approach selected for this study seems to be suitable for monitoring petrochemical contamination.

Effect of crude oil contaminated sediment exposure on cytochrome P450 enzymes in the Australian asteroid Coscinasterias muricata

Levels of cytochrome P450 enzymes were measured in pyloric caeca microsomes of the asteroid Coscinasterias muricata following exposure to sediment with nominal concentrations of 0, 0.1 or 2 ml crude oil kg(-1) (dry weight) and subsequent depuration. No significant differences were observed in total cytochrome P450 levels or cytochrome P418 levels following the exposure period. However after five days of depuration, levels of total P450 in the pyloric caeca of C. muricata exposed to the highest oiled sediment concentration were significantly lower than in specimens exposed to the other treatments. Cytochrome P418 levels were inversely related to total P450 levels following exposure and subsequent depuration. Preliminary results show that levels of CYP1A-like immunopositive protein (CYP1A-like IPP) in exposed asteroids exhibited a concentration response relationship following the exposure period. Variations in CYP1A-like IPP levels observed during the depuration period may be influenced by the sublethal toxicity of hydrocarbons within the crude oil.

Changes in oxygen consumption and respiratory enzymes as stress indicators in an estuarine edible crab Scylla serrata exposed to naphthalene

The sublethal effect of naphthalene was studied on the physiology of a mud crab Scylla serrata. The 96 h acute toxicity of naphthalene was determined and found to be 28 mg 1(-1) (LC100), 18 mg 1(-1) (LC50), 10 mg 1(-1) (LC0) respectively. The 30 days sublethal effect (LC0) 9 mg 1(-1), 8 mg 1(-1), 10 mg 1(-1), of naphthalene was investigated in the crab S. serrata with reference to oxygen consumption and changes in the activity of respiratory enzymes. The results indicated that naphthalene caused disturbance in the normal physiology of the crab. The bioaccumulation of naphthalene was also investigated in gills, hepatopancreas, haemolymph and ovary. The consumption of oxygen increased in the naphthalene medium when compared with that of the crabs exposed to naphthalene free medium. A decreased trend in the activity of respiratory enzymes such as lactate dehydrogenase (LDH), isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), alpha-ketoglutarate dehydrogenase (alpha-KDH) and glutathione (GSH) were recorded in the hepatopancreas, ovary and gills of S. serrata for all the tested concentrations of naphthalene and the results were analyzed for their significance.

Steroid levels and steroid metabolism in the mussel Mytilus edulis: the modulating effect of dispersed crude oil and alkylphenols

Significant amounts of oil and alkylphenols are released into the sea by petroleum installations as a result of discharges of produced water. Some of these pollutants elicit estrogenic responses in fish, but their effects on the endocrine system of molluscs are largely unknown. In this study, mussels Mytilus edulis were exposed to North Sea oil (O) and the mixture of North Sea oil+alkylphenols (OAP), and the effects on tissue steroid levels and steroid metabolism (P450-aromatase and estradiol-sulfotransferase) were monitored. Levels of free testosterone and free estradiol were much higher in gonad tissue than in peripheral tissue, whereas esterified steroids (released after saponification) were of the same order of magnitude in both tissues. Levels of free steroids determined in gonads were not affected by exposure, but esterified steroids significantly increased in OAP exposed mussels (up to 2.4-fold). The sulfation of estradiol was investigated as a conjugation pathway, and increased activities were observed in digestive gland cytosol of both O and OAP exposure groups (up to 2.8-fold). Additionally, increased P450-aromatase activity was determined in OAP exposed mussels (up to three-fold, both in gonad and digestive gland), but not in the O group. Altogether, the results indicate that North Sea oil leads to increased sulfation of estradiol, and that in combination with alkylphenols, additional alterations are observed: increased P450-aromatase, and increased levels of esterified-steroids in gonads. Nonetheless, mussels are able to maintain gonad concentrations of free steroids unaltered, possibly via homeostatic mechanisms such as the conjugation with fatty acid or the formation of sulphate conjugates.

Avoidance of crude-oil contaminated sediment by the Australian seastar, Patiriella exigua (Echinodermata: Asteroidea)

This study attempted to determine whether Patiriella exigua, an Australian seastar, could detect and/or avoid oiled sediment when given an equal choice of unoiled sediment. The sediment was spiked once to produce one of three concentrations of oiled sediment used in the test chambers versus unoiled sediment. Behavioral observations were repeated over a 32 day period to test the effects of aging the oiled sediment. Results show that Patiriella exigua was capable of detecting oiled sediment and/or an oiled environment. Seastars avoided oiled sediment, with significantly higher numbers choosing either to reside on the clean sediment (p<0.05) or to travel up the glass sides of the tanks (p<0.001). Avoidance of oiled sediment increased with increasing sediment oil concentrations. Aging the oiled sediment decreased the oil content of the sediment and increased the number of seastars able to inhabit it (p<0.001). A potential narcotic effect of exposure to oiled sediment was observed.