Peter Donkin

Physiological and biochemical responses of bivalve molluscs to exposure to air

Abstract 1. 1. Aerial rate of oxygen consumption by Mytilus edulis and M. galloprovincialis is 4–17% of the aquatic rate. 2. 2. For Cardium edule and Modiolus demissus the aerial rate of oxygen uptake is between 28 and 78% of the aquatic rate. 3. 3. These species differences are related to the degree of shell gape during air exposure. 4. 4. All species show an apparent oxygen debt after exposure to air, the extent of which is not simply related to either the level of aerobic respiration or the degree of anaerobiosis during exposure. 5. 5. Anaerobic end-products accumulate in the tissues of Mytilus during aerial exposure, but not in Cardium. 6. 6. The relative energy yields by aerobic and anaerobic means in M. edulis are discussed.

Responses Of Mytilus-Edulis On Exposure To The Water-Accommodated Fraction Of North-Sea-Oil

Individuals of Mytilus edulis L., collected from the Erme estuary (S.W. England) in 1978, were exposed to low concentrations (7 to 68 μg l-1) of the water-accommodated fraction (WAF) of North Sea crude oil. The pattern of accumulation of petroleum hydrocarbons in the body tissues was affected by the presence of algal food cells, the period of exposure, the hydrocarbon concentration in seawater, the type of body tissue and the nature of the hydrocarbon. Many physiological responses (e.g. rates of oxygen consumption, feeding, excretion, and scope for growth), cellular responses (e.g. lysosomal latency and digestive cell size) and biochemical responses (e.g. specific activities of several enzymes) were significantly altered by short-term (4 wk) and/or long-term (5 mo) exposure to WAF. Stress indices such as scope for growth and lysosomal latency were negatively correlated with tissue aromatic hydrocarbons.

Seasonal distribution of dissolved pesticides and polynuclear aromatic hydrocarbons in the Humber Estuary and Humber coastal zone

The distribution of atrazine, 2-methylthio-4-tert-butyl-amino-6-cyclopropylamino-s-triazine (Irgarol 1051), lindane, malathion, fluoranthene and pyrene dissolved in the water column of the Humber Estuary and adjacent coastal zone was determined. Atrazine concentrations declined from the head (35–53 ng l−1) to the mouth (5–11 ng l−1) of the estuary; the highest concentrations were found in June. Lindane concentrations also declined through the estuary, although elevations were observed near a sewage outfall, especially in June and September. Irgarol concentrations typically peaked in April, then decreased in June before increasing again in September. The patterns of variation of fluoranthene and pyrene were similar to each other, suggesting common sources. Levels were similar throughout the estuary, with an exceptionally large elevation at a sewage outfall in June. Malathion concentrations were generally very low (<1–9 ng l−1). The concentrations of all compounds were lower off-shore than in the estuary, suggesting that the Humber catchment is a major source of organic micropollutants to the Humber coastal zone. Concentrations of atrazine and lindane were also elevated at stations close to the Wash, suggesting a contribution from rivers into the Wash.

Role Of Physiological Energetics In Ecotoxicology

1. The role of physiological energetic measurements combined with chemical analyses of contaminants in body tissues of mussels in fundamental toxicological studies and pollution monitoring programmes is outlined. 2. Important features of this toxicological approach are briefly reviewed, including aspects of bioaccumulation, sensitivity, quantitative concentration-response relationships, QSARs, mechanistic interpretation, ecological relevance, integration of the consequences of multiple mechanisms of toxicity and effects of contaminant mixtures and application to laboratory and field studies. 3. This review focuses particularly on recent advances in understanding and predicting the effects of complex mixtures of contaminants.

Occurrence of the marine antifouling agent irgarol 1051 within the Plymouth Sound locality: Implications for the green macroalga Enteromorpha intestinalis

Abstract Water samples taken from the Plymouth Sound locality were analysed for the presence of the s-triazine herbicide Irgarol 1051, which is an ingredient of antifouling paints used on pleasure boats and ships. Irgarol 1051 was detected at all sampling sites within the Sound; the highest levels were found in close proximity to areas of high boat density, especially where water flow was restricted within marinas. Concentrations within the semi-enclosed Sutton Harbour were less than values predicted from leach rate data. The highest detected concentration of over 120 ng dm−3 significantly inhibited the growth of Enteromorpha intestinalis spores under laboratory conditions; the no effect concentration was 22 ng dm−3. Photosynthetic efficiency in the adult frond of E. intestinalis from Sutton Harbour marina was inhibited by Irgarol 1051 in the laboratory with an EC 50 (72 h) of 2.5 |Gmg dm−3. A small adverse impact on E. intestinalis reproduction within the harbour is therefore likely. More polluted sites identified elsewhere in Europe will suffer proportionally greater impact.

Fluoranthene and pyrene in the suspended particulate matter and surface sediments of the Humber Estuary, UK

Abstract As part of the UK-based Land-Ocean Interaction Study (LOIS) community programme, suspended particulate matter (SPM) and surface sediments have been collected from the Humber estuary, which is a large and complex estuarine system on the east coast of England fed by several rivers including the Trent and Ouse. The samples from four surveys were extracted and analysed to determine the levels of anthropogenic organic contaminants such as fluoranthene and pyrene. Their concentrations in SPM and surface sediments ranged from 44 to 1560 ng g −1 dry weight and 13–1969 ng g −1 dry weight, respectively, and displayed no strong seasonal variation. Mean fluoranthene and pyrene concentrations were higher in the Trent than in the Ouse for both SPM and sediment samples, and were elevated at a sewage outfall, suggesting a multiplicity of inputs for these two compounds. Fluoranthene and pyrene on SPM showed no correlation with salinity, although correlations with suspended solids concentrations (SSC) and particulate organic carbon (POC) have been confirmed.

The partition of fluoranthene and pyrene between suspended particles and dissolved phase in the Humber Estuary: a study of the controlling factors

Abstract Particle–water interactions are one of the most important mechanisms controlling the distribution and movement of hydrophobic organic chemicals such as polycyclic aromatic hydrocarbons (PAHs) in aquatic environments (e.g. estuaries and oceans). To accurately predict the transport and fates of hydrophobic contaminants in estuarine and coastal marine environments, the partition coefficient ( K p ) and organic carbon normalised partition coefficient ( K oc ) are widely used in various biogeochemical models. Such partition coefficients may be calculated from the so-called linear free energy relationships between K p , K oc and more easily measured parameters such as the octanol-water partition coefficient ( K ow ). However K p and K oc values measured for real environmental samples of water and particles obtained from seasonal field surveys in the Humber Estuary, UK deviated from such ideals. For example, K P values showed no correlation with the fraction organic carbon content of particles ( f oc ) and instead of being constant, K oc , values varied with f oc . Both K p and K oc were 1–3 orders of magnitude higher than those predicted from the simple equilibrium–partitioning model, but were in good agreement with several other recently published field studies. To improve our understanding of PAH partitioning, the soot carbon (SC) content of particulate samples was measured so that the simple partition model can be extended to incorporate SC. The partition coefficients derived from the extended partition model are very close to the field K p s. The results suggest that PAHs associated with particles are in fact present in the form of soot and soot-like particles that are not subject to particle–water equilibrations. In other words, the PAHs on soot-like particles are extremely strongly bound and not influenced by further partitioning between the particles and water. However, there are still limitations with the extended partition model as it failed to simulate the field K oc values. No correlation was found between the partition coefficients and salinity, which again we attribute to the non-equilibrium nature of the PAHs. However both K p and K oc generally decreased with increasing suspended solids concentrations (SSC) in the estuary. Such a relationship is probably due to the mixing of soot-like permanently suspended particles with resuspended estuarine sedimentary particles at the higher SSC values, and to the increased concentrations of dissolved organic carbon (DOC) associated with increase in SSC. However, it has been shown that DOC concentrations are not a suitable tool for correcting the SSC effect. There is therefore an urgent need to harmonise the laboratory and field approaches for K p measurements.

Quantitative structure-activity relationships for the effect of hydrophobic organic chemicals on rate of feeding by mussels (Mytilus edulis)

Abstract The effect of hydrophobic organic chemicals on the rate of feeding by mussels ( Mytilus edulis ) was investigated. The effect was expressed as the toxicant concentration in water required to reduce feeding rate by 50% (WEC 50 ). A quantitative structure-activity relationship (QSAR) was derived in which WEC 50 was negatively correlated with log 10 octanol-water partition coefficient (log K ow ) and positively correlated with aqueous solubility, indicating that hydrophobicity has a major influence on toxicity. QSARs calculated between bioconcentration factor, and log K ow and aqueous solubility showed, that hydrophobicity influences toxicity largely through its effect on bioconcentration. This observation was confirmed by expressing toxicity as the toxicant concentration in mussel tissue required to reduce feeding rate by 50% (TEC 50 ). For the compounds tested which have log K ow values 50 was relatively constant, irrespective of molecular structure. Compounds with log K ow values > 5 could be accumulated to much greater concentrations before feeding rate was affected, indicating that there is a ‘molecular weight cut-off’ in the toxicological response. These observations are characteristic of a non-specific narcotic mode of toxic action. The application of the reported QSARs to interpreting results derived from combined chemical contamination and biological effects environmental monitoring studies with mussels is discussed.

Responses of the mussel Mytilus edulis to copper and phenanthrene: Interactive effects

Most investigations of the responses of marine organisms to xenobiotics have concentrated on single contaminants and little is known of possible interactive effects of different classes of xenobiotics. As these latter seldom occur in environmental isolation, it is important to understand any interactions (synergistic or antagonistic) which may occur. This problem has been approached in the mussel Mytilus edulis by exposing estuarine mussels to copper (20 μg litre−1) and phenanthrene (100 μg litre−1) both individually and in combination, and measuring cytochemical subcellular and physiological responses after 3 days exposure and 3 days and 12 days recovery period. Results showed that mussels accumulated both xenobiotics during 3 days exposure. Depuration of copper was complete in 3 days recovery period, while loss of phenanthrene ranged from 30% to 70% of the concentration reached after 3 days exposure. There were no interactive effects on depuration. Both copper and phenanthrene reduced lysosomal hydrolase latency in digestive cells, and copper appeared to have a synergistic effect in preventing recovery of latency of lysosomal N-acetyl-β-hexosaminidase during the recovery period. There was evidence, in the digestive cells, of an antagonistic effect of copper on stimulation of activity of the microsomal respiratory chain (measured as NADPH-neotetrazolium reductase) by phenanthrene. Stimulation of this system by phenanthrene persisted after 12 days recovery period. There was a synergistic interaction of copper and phenanthrene on elevation of oxygen consumption and ammonium excretion. Clearance rates and scope for growth (physiological condition) were depressed by copper but not by phenanthrene after 3 days exposure. These findings are discussed in terms of known effects of copper and phenanthrene and the interactions are considered in terms of environmental effects measurements.

Occurrence of the antifouling herbicide, Irgarol 1051, within coastal-water seagrasses from Queensland, Australia

Abstract The s-triazine herbicide Irgarol 1051 is now widely distributed throughout European coastal waters. In Australia, the compound is not registered for use as a biocide in antifouling paints. To investigate contamination, seagrasses were sampled from the east coast of Queensland and within the Great Barrier Reef Marine Park. A green alga was also sampled from the Outer Barrier Reef. Tissues were analysed for the presence of Irgarol 1051 using solvent extraction followed by quantification with GC-MS and confirmation by GC-MS-MS. Irgarol 1051 was detected at nine of the ten locations sampled. Concentrations of up to 118 ng g−1 wet weight leaf tissue were recorded in samples from the Gold Coast (near Brisbane) which is the highest plant tissue concentration yet reported. Antifouling paint purchased within Australia was analysed by GC-MS (full scan) and found to contain Irgarol 1051. The concentrations of Irgarol 1051 reported within the Australian coastal environment are potentially toxic and the possible consequences for long-lived herbivores (such as the dugong) and for endosymbiotic algae of corals, are discussed.