J. Nieuwenhuize

Influence of temperature and polyaromatic contaminants on CYP1A levels in North Sea dab (Limanda limanda)

Abstract Mature specimens (n = 686) of male dab (Limanda limanda) were collected at several stations from the southern North Sea during two surveys in 1991 and 1992. Levels of CYP1A protein and 7-ethoxyresorufin O-deethylase (EROD) activity were measured in liver and heart. Elevated CYP1A levels were observed in dab collected from off-shore stations with low bottom water temperatures due to stratification of the water column. Considerably lower CYP1A levels were observed at stations with higher water temperatures. Multiple regression analyses with PCB concentrations in fish and water temperature as independent variables influencing EROD activity or CYP1A protein levels demonstrated significant correlations with both parameters. The water temperature was inversely related to CYP1A levels, whereas PCB concentrations showed a positive relation with CYP1A levels. The effect of water temperature dominated over the effect of PCB contamination. The relationship between water temperature and CYP1A levels was also examined in a laboratory study, where dab were acclimated to 8, 12 and 16 °C for 4 weeks. A three-fold increase in EROD activity in the group acclimated to 8 °C compared to the group acclimated to 16 °C was observed, whereas no differences were observed for CYP1A protein levels. Multiple regression analyses with PCB concentrations and condition factor of fish as independent variables influencing CYP1A levels also demonstrated significant correlations in the field. Thus, differences in water temperature and nutritional status of dab between sampling locations obscured the effects of contamination with polyhalogenated aromatic compounds on CYP1A levels. The results indicate that these factors have to be taken into account when employing CYP1A responses in dab as biomarkers for environmental contamination in the North Sea.

Spatial and seasonal differences in the PCB content of the mussel Mytilus edulis

Seasonal and spatial variation in the concentration of PCBs, fats (non-polar lipids) and total lipids and the condition of the mussel Mytilus edulis were assessed in three differing water bodies of the Dutch delta area. Highest concentrations of PCBs in the mussel were found in the Westerschelde estuary, with much lower concentrations in the Oosterschelde and the brackish lake Grevelingenmeer. Spatial differences were strongly related to salinity; lower concentrations were found at the more saline stations, pointing to freshwater inputs as being the origin of the PCBs in mussels. The PCB concentration in mussels, on the basis of dry or total weight, in general increased during summer, autumn and winter and decreased strongly during spring. The strong decrease is related to the spawning of gametes. Seasonal changes in the PCB concentration on the basis of the dry weight were not related to changes in the fat content or the condition of the animals. Only PCBs on a fat basis were negatively related to fat content, indicating a dilution of PCBs during seasonal fat accumulation and concentration of PCBs during fat utilization, in such a way that the total PCB concentration in the animal remains the same. It seems that, besides reproduction, equilibrium partitioning is the most probable mechanism that determines the PCB content of mussels.

Partitioning of organochlorines between water, particulate matter and some organisms in estuarine and marine systems of the Netherlands

Abstract The distributions of organochlorines in estuarine and marine systems, and in particular those of the individual PCB components have been analysed for the partitioning of these substances between water, particulate matter (seston), plankton, worms, shellfish, fish and some birds. The Kd concept, where Kd is the distribution coefficient in ml·g−1 units, has been used to investigate the distribution ratio between solid substrates and water. Additionally, an attempt has been made to determine the regression coefficient of Kds with a polarity index of the individual PCB components. Since the octanol-water partition coefficient (log Kow) is significantly proportional to the IUPAC Numbers of these components, this Kd-IUPAC Number regression has been carried out for samples from the Delta region, the North Sea and the Wadden Sea. For the latter two regions, existing concentrations from unpublished reports have been taken. Two major results have been obtained, while one important question remains to be answered: (i) Organochlorine (pesticides and ΣPCBs) concentrations in mussels can be successfully correlated to salinities of estuarine waters, if the sources of organochlorines are linked to the major fresh waters of the estuarine system. This correlation is independent of the seasonal changes in condition of these organisms by fat content, if the records is made for a period of two years. (ii) These results and those on Kd determinations demonstrate for aquatic organisms a degree of consistency in the Kd levels if concentrations in the organisms are calculated on fat basis. The Kd range for ΣPCBs is 105–106, independent of the area of investigation. The same is true for seston with a range of Kds of 104–105. (iii) A very interesting question involves the Kd-IUPAC Number regression coefficients and the value and sign (+ or −) of this coefficient. In general 60% of all correlations seem to be significant, but the different values and in particular the negative correlations are difficult to explain even when third-degree S-shape correlations are considered. A negative correlation implies a weaker adsorption of less-polar compounds (higher chlorinated PCBs with higher IUPAC Number), which cannot be explained by hydrophobic-hydrophylic reactions. An extended study on the true-dissolved organochlorines might be necessary to exclude errors which might be due to the methodology of filtration.

Relationship between PCB concentrations and reproduction in mussels Mytilus edulis

Abstract Changes in the concentrations of PCBs and fats were followed in mussels Mytilus edulis, transferred vice versa between a polluted estuary (Westerschelde) and a relatively low-pollution sea-arm (Oosterschelde). The concentrations in the mantle, which contains the gonads, were determined separately from the rest of the body. The fat content of the mantle increased 1 1 2 - to 2-fold during the observation period (autumn, winter) and remained constant in the rest of the body. Polychlorinated biphenyls (PCBs) in mussels transferred from the polluted to the less polluted area were not eliminated. In the mussels transferred to the polluted area the increase of the PCB content was 2- to 3-fold over a period of 3 months. PCBs in the mantle, and therefore in the gonads, can amount to more than 40% of the total PCB load in a mussel. It was concluded that during the spawning of gametes a substantial proportion of the PCBs may be shed.

Polychlorinated biphenyl equilibria in an estuarine system

The stability of the partition of polychlorinated biphenyl (PCB) congeners between water and the compartments of particulate matter (seston), surface sediment, net-plankton and mussels has been investigated for 1.5 years. Samples were regularly obtained from four stations, representing River Rhine, brackish and saline estuarine and stagnant saline conditions. In spite of the PCB gradients, from freshwater to seawater, and time variations in concentrations, the partition coefficients Kd (distribution coefficients) were very stable for each of the congeners. This demonstrates that the partition between water and the other compartments is due to processes which reach their equilibrium within weeks, independent of the local variations in concentrations. This confirms the non-foodchain accumulation concept of Schneider [1] for aquatic organisms.

Changes of sediment distribution patterns in Lake Grevelingen, an enclosed estuary in the SW Netherlands☆

Abstract Some basic sediment parameters from samples of 0 to 3 cm sediment depth have been investigated at 430 stations in the recently formed Lake Gervelingen. The results have been used to get some insight into the history of sediment deposition in Lake Grevelingen and the former Grevelingen estuary. A geographical trend exists for the sediment median grain size, with increasing Mdφ values towards the eastern part of the lake. This trend has been caused by sediment distribution processes under the former ebb and flood currents in the Grevelingen estuary. After enclosure of the estuary in 1971, much of the fine-grained sediment material has been transported towards the deeper gullies. A reflection of this may be seen in the recent sediment maps for mud content and organic carbon content of the upper 0–3 cm sediment layer in Lake Grevelingen.

Analysis of estuarine soil gradients in salt marshes of the southwestern Netherlands with special reference to the Scheldt estuary

Macro- and microgradients in salt-marsh soils of the Scheldt estuary have been studied. The soil parameters used are clay, carbonate, organic matter, pH, nitrogen, potassium and phosphate. The hypothesis that estuarine soil gradients can be reflections of similar aquatic gradients is affirmed for two gradients. Soil gradients of upstream increasing organic matter and phosphate contents have been found, relating significantly to corresponding aquatic gradients caused by river pollution. In the same direction gradients of decreasing nitrogen and potassium contents occur. A macrogradient in carbonate content was not found. Some microgradients in clay and carbonate contents are described, and relevant mutual relationships between the soil parameters are characterized.

Possible loss of polychlorinated biphenyls from migrating European silver eels: a 3 month simulation experiment

Abstract A 3 month experiment was set up to simulate the polychlorinated biphenyl (PCB) congener behavior in lipids during migration of silver eels, Anguilla anguilla , from river to sea. The thesis is that there should be loss of PCB contamination, to establish a new chemical equilibrium between the lipid and water compartments, where metabolism is the vehicle. Male and female eels collected in the River Rhine were placed separately, and in duplicate, in aquaria with running seawater of 5°C under starvation conditions for 91 days. Eels were sampled at regular intervals for the determination of eel-conditional parameters and PCB congener analysis. Also, water and particulate matter were analyzed for PCB congeners. Wet weight, lipid content, condition of organs such as heart, liver and spleen did not change throughout the experiment, at least not within the accuracy of the investigations and there was no indication of sexual maturation. This agrees with literature information and, for loss of weight, with theoretical calculation based on energy budget. The PCB congener chromatograms of eels showed little difference in time, and did not demonstrate any loss from the lipid compartment due to exposure to less contaminated seawater. The eel chromatograms showed the typical congener distribution with higher values at 2/3 of the chromatogram, also found earlier for mussels, and relative to that of water. The process of attaining a new partitioning equilibrium between the lipid compartment in gill-breathing aquatic organisms and that of water was not found. Neither were there changes in the PCB congener chromatograms due to selective metabolic activities. Using PCB congener No. 138 as reference, a congener that remained rather constant in the lipids of eels, only two congeners, Nos. 105 and 118, showed a significant increase with respect to No. 138. Starvation possibly retards metabolic activity and thus also inhibits loss of PCB congeners to the seawater compartment. Therefore, PCBs may remain as toxic contaminants in the lipids of fasting and migrating eels, which potentially may have noxious effects during migration and maturation. However, a noxious effect was not found during this experiment.

Polychlorinated biphenyls in oystercatchers (Haematopus ostralegus) from the oosterschelde (Dutch Delta area) and the Western Wadden Sea, that died from starvation during severe winter weather

Wintering oystercatchers (Haematopus ostralegus), charadriid shorebirds that chiefly feed on intertidal bivalves, suffered mass mortality in The Netherlands during severe frosts in 1986 and 1987. PCBs were analysed in liver and (partially) brain lipids of 96 birds to examine the influence of age (three categories), sex and wintering area (the Oosterschelde estuary versus the westernmost Wadden Sea) on levels, and the risk of intoxication due to starvation. Victims had lost nearly 40% of their normal winter weight. PCB-structures were similar in all age/sex categories, and in both areas. Sex did not affect total PCB-concentrations. First-winter Wadden birds had lower levels than subadults and adults, but an age-difference was absent in the Oosterschelde birds. Some juvenile outliers possibly originated from polluted breeding areas. Individual variation was considerable in most categories. Relevant ecological factors are discussed. Although a dam has considerably reduced the direct transport of PCBs into the Oosterschelde since 1969, contamination of local birds was hardly lower than in Wadden winterers. Influx of riverine PCBs into the Oosterschelde from coastal water may have been underrated. Starvation increased liver concentrations by a factor of 35; factors for the brain were 56 for juveniles and approximately 120 for older birds. Considering published lethal levels for other species, it is doubtful if PCBs contributed to this winter mortality.