[Joint monitoring of the North Sea (North Sea Task Force, NSTF). MFO studies as a portion of the German contribution to the Quality Status Report (QSR)].
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Distribution of viral haemorrhagic septicaemia virus in wild fish species of the North Sea, north east Atlantic Ocean and Irish Sea.
A surveillance programme was initiated on the occurrence and distribution of viral haemorrhagic septicaemia virus (VHSV) in wild marine fish. Six research cruises were undertaken in an 18 mo period during 1997 and 1998, covering the North Sea, the Atlantic waters off the north and west coasts of Scotland and the Irish Sea. A total of 19,293 fish were sampled from 23 different species including cod, haddock, Norway pout, herring and sprat. Individual fish lengths were recorded and the fish were checked for lesions, haemorrhaging and other signs of disease. Pools of organ samples were taken for virus assay. The majority of fish sampled did not display clinical signs indicative of viral haemorrhagic septicaemia. A small number of cod were found with skin lesions and haddock with skin haemorrhaging. Of the 2081 organ and skin sample pools collected, 21 tested positive for VHSV by tissue culture and enzyme-linked immunosorbent assay. Seventeen of the isolates originated from Norway pout Trisopterus esmarkii, one from cod Gadus morhua (skin lesion), one from herring Clupea harengus, one from whiting Merlangius merlangus, and one from a previously unreported host species, poor cod Trisopterus minutus.
Animals↗
Norwegian monitoring programme on the inorganic and organic contaminants in fish caught in the Barents Sea, Norwegian Sea and North Sea, 1994-2001.
The results from part of a monitoring programme of contaminant levels in fish and other seafood products initiated by the Directorate of Fisheries in Norway in 1994 are presented. Concentrations of 22 elements (four are presented here: As, Cd, Hg and Pb) and HCB, HCH, PCB 28, 52, 101, 105, 118, 138, 153, 156, 180, pp-DDD, p-DDE, p-DDT, sum DDT and (137)Cs were determined in 17 species of fish caught in three sampling locations: the Barents Sea, the Norwegian Sea and the North Sea. The fish species analysed in the survey were limited to species of commercial importance for Norway with catching volumes of at least 10,000 metric tons year(-1). The survey started in 1994 and is expected to continue beyond 2010. The analyses were carried out on 25 individual fish from each species and each sampling location, and the locations were representative of commercial fishing grounds for the species in question. The concentrations of contaminants found were considerably lower than the maximum levels permissible in fish set by CODEX and the European Union for contaminants in seafood products.
Animals↗
Certified reference material for radionuclides in fish flesh sample IAEA-414 (mixed fish from the Irish Sea and North Sea).
A certified reference material (CRM) for radionuclides in fish sample IAEA-414 (mixed fish from the Irish Sea and North Seas) is described and the results of the certification process are presented. Nine radionuclides (40K, 137Cs, 232Th, 234U, 235U, 238U, 238Pu, 239+240Pu and 241Am) were certified for this material. Information on massic activities with 95% confidence intervals is given for six other radionuclides (90Sr, 210Pb(210Po), 226Ra, 239Pu, 240Pu 241Pu). Less frequently reported radionuclides (99Tc, 129I, 228Th, 230Th and 237Np) and information on some activity and mass ratios are also included. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in fish sample, for the development and validation of analytical methods and for training purposes. The material is available from IAEA, Vienna, in 100 g units.
Animals↗
Genetic population structure of turbot (Scophthalmus maximus L.) supports the presence of multiple hybrid zones for marine fishes in the transition zone between the Baltic Sea and the North Sea.
Genetic population structure of turbot (Scophthalmus maximus L.) in the Northeast Atlantic was investigated using eight highly variable microsatellite loci. In total 706 individuals from eight locations with temporal replicates were assayed, covering an area from the French Bay of Biscay to the Aaland archipelago in the Baltic Sea. In contrast to previous genetic studies of turbot, we found significant genetic differentiation among samples with a maximum pairwise FST of 0.032. Limited or no genetic differentiation was found among samples within the Atlantic/North Sea area and within the Baltic Sea, suggesting high gene flow among populations in these areas. In contrast, there was a sharp cline in genetic differentiation going from the low saline Baltic Sea to the high saline North Sea. The data were explained best by two divergent populations connected by a hybrid zone; however, a mechanical mixing model could not be ruled out. A significant part of the genetic variance could be ascribed to variation among years within locality. Nevertheless, the population structure was relatively stable over time, suggesting that the observed pattern of genetic differentiation is biologically significant. This study suggests that hybrid zones are a common phenomenon for marine fishes in the transition area between the North Sea and the Baltic Sea and highlights the importance of using interspecific comparisons for inferring population structure in high gene flow species such as most marine fishes.
Animals↗
May organic pollutants affect fish populations in the North Sea?
The North Sea is a highly productive area with large fish populations that have been extensively harvested over the past century. North Sea fisheries remain important to the surrounding countries despite declining fish stocks over the past decades. The main reason for declining fish stocks is nearly certainly overfishing, but other environmental pressures also affect fish populations, such as eutrophication, climate change, and exposure to metals and organic pollutants, including polyaromatic hydrocarbons (PAHs), alkylphenols, and organochlorine compounds. There are three main sources of organic pollutants in the North Sea: atmospheric, land-based sources, and inputs from offshore gas and oil installations. All three sources contribute to elevated concentrations of organic pollutants in the North Sea compared to the Norwegian Sea. There is evidence that chlorinated organic contaminants were present in sufficiently high concentrations in the southern North Sea two decades ago, to alter embryonal development in fish. The results from extensive, long-term monitoring programs show that some diseases decreased whereas other increased in the southern North Sea and that, among other factors, contaminants may play a role in the temporal changes recorded in disease prevalence. Recent studies demonstrated that components in offshore effluents may affect fish reproduction and that tissues of fish near oil rigs are structurally different to tissues of fish from reference areas. Data on effluents from offshore activities have recently become available through an international workshop (BECPELAG) and follow-up studies.
Animals↗
Biochemical and histological responses in mussel (Mytilus edulis) exposed to North Sea oil and to a mixture of North Sea oil and alkylphenols.
Several environmental chemicals are suspected to be responsible for adverse health effects on the reproductive system in various organisms. During this work, environmentally relevant concentrations of North Sea oil were used alone or in combination with alkylphenols and additional PAH to study the effect on vitellogenin-like protein expression and gonadal development in mussels. North Sea oil (0.5 ppm) induced the expression of phospho-proteins in both sexes indicating that some compounds are oestrogen-mimics. This induction was not seen in samples dosed with the mixture but signs of toxic effects were observed in the gonads. Indeed, numerous degenerating ovarian follicles in females and foci, similar to vertebrate melanomacrophage centres, were observed in testes.
Animals↗
Volatiles released by a Streptomyces species isolated from the North Sea.
The North Sea Streptomyces strain GWS-BW-H5 was investigated by analyzing headspace extracts of agar-plate cultures (HE) or liquid cultures (LCE), obtained with a closed-loop stripping apparatus (CLSA), by GC/MS (Table 1). The volatile profile of the HE is dominated by the known volatiles (-)-geosmin (4) and 2-methyisoborneol (1). Small amounts of sesquiterpenes occur, which are present in a more-diverse structural variety and in higher quantities in the LCE. The different structures can be rationalized by few cationic intermediates along their biosynthetic pathway. The most-prominent difference between the two culture methods were the presence of the Me-branched gamma- and delta-lactones 31-38, not previously reported from nature, in the LCE. Major components were 10-methyldodecan-5-olide (34), 10-methyldodec-2-en-4-olide (36), and 10-methyldodec-3-en-4-olide (38). The structures of all new lactones were verified by synthesis. Furthermore, more volatiles in higher amounts were produced by the liquid culture than by to the agar plate culture. Since 36 showed inhibitory growth effects against strain GWS-BW-H5, growth inhibition against twelve other strains isolated from the same habitat was tested. Antagonistic activity against four of the strains was observed, with a slightly higher threshold level than found for penicillin G, which was used in control experiments (Table 2).
Molecular Structure↗
Changes in the seasonal cycles of inorganic nutrients in the coastal zone of the southeastern North Sea from 1960 to 1997: effects of eutrophication and sensitivity to meteoclimatic factors.
A long-term analysis of seasonal cycles of inorganic nutrients by means of a seasonal index is presented for the German Bight and the southern Wadden Sea (SE North Sea). Multivariate analysis for the German Bight data series revealed dependence of ammonium and phosphate index time series on dissolved inorganic nitrogen concentrations and riverine nutrient loads. Both indices are assumed to reflect seasonal dynamics of remineralisation processes associated with increased supply of organic matter. Temporal analysis revealed breaks in nutrient dynamics in 1970/1972 and 1979/1980. After 1970/1972, an unprecedented increase in the summer concentrations of mineralisation endproducts with correspondingly low index values were observed, which further declined after 1979/1980. Further breaks for Wadden Sea data series were identified in 1985 and 1988/1989. The indicative value of the temporal breaks with respect to eutrophication is discussed against the background of changes in meteoclimatic factors and local environmental conditions. Collated information on eutrophication effects was consistent with the observed breaks. It is suggested that the break in 1970/1972 in the German Bight was the first sign of ecosystem response to eutrophication in the SE North Sea.
Climate↗
Efficiency of blue mussel (Mytilus edulis) spat collectors in highly dynamic tidal environments of the Lower Saxonian coast (southern North Sea).
Traditional mussel culture in the Wadden Sea, southern North Sea, is carried out by taking seed mussels of about 1-4 cm shell length from natural beds and transplanting them to permanently water covered sites. Besides the damage done to the natural beds, the ratio of seeded to harvested mussels is only about 1:1-1.3, i.e. about the same tonnage of mussels seeded is recovered. In addition, this technique relies exclusively on natural spat falls, which do not occur regularly. In order to overcome these difficulties spat collectors have been deployed in the Jade Bay, southern North Sea. These provided suitable settlement grounds for mussel larvae. Blue mussel weights reached weights of about 8-9 kg/m collector rope with maximum shell lengths of 4-5 cm within one growing season.
Animals↗
Thysanoessa inermis and T. longicaudata (Euphausiidae) as first intermediate hosts of Anisakis sp. (Nematoda: Ascaridata) in the northern North Sea, to the north of Scotland and at Faroe.
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Animals↗
Haemoglobin polymorphism of cod in the North Sea and the North Atlantic Ocean.
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Animals↗
[The North Sea climate and skin diseases. 20 years of dermatologic climatotherapy at the North Sea].
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Climate↗
Survival and air-sea rescue in North Sea oil operations.
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Accidents, Occupational↗
Isolation of viral haemorrhagic septicaemia virus (VHSV) from wild marine fish species in the Baltic Sea, Kattegat, Skagerrak and the North Sea.
In order to analyse the occurrence of viral haemorrhagic septicaemia virus (VHSV) in the marine environment surrounding Denmark, fish tissue samples were collected on four cruises with the research vessel H/S Dana in 1996 and 1997. The sampling comprised 923 samples totalling 7344 fish representing 29 different species. VHSV was isolated from 24 fish samples from the Baltic Sea, four samples from Skagerrak and three samples from the North Sea. The virus-positive host species included herring Clupea harengus (11 isolates), sprat Sprattus sprattus (eight isolates), cod Gadus morhua (six isolates), rockling Rhinonemus cimbrius (one isolate), Norway pout Trisopterus esmarkii (one isolate), blue whiting Micromesistius poutassou (one isolate), whiting Merlangius merlangus (two isolates) and lesser argentine Argentina sphyraena (one isolate). VHSV has previously been reported from cod and herring, but not from the other five species. A virus belonging to serogroup II of the aquatic birnaviruses was isolated from three samples of flounder Platichthys flesus and three samples of dab Limanda limanda and a virus preliminary identified as iridovirus (lymphocystis virus) was isolated from seven samples of long rough dab Hippoglossoides platessoides.
Animals↗
Bioaccumulation and biomarkers in the sea star Asterias rubens (Echinodermata: Asteroidea): a North Sea field study.
During two North Sea field trips in March 1995 and September 1996 sea stars, Asterias rubens, were collected at various stations along pollution gradients in order to study the relation between biochemical markers and levels of accumulated contaminants. Biomarkers measured were: cytochrome P450 level, benzo[a]pyrene hydroxylase (BPH) activity, acetylcholinesterase (AChE) activity and DNA integrity. Accumulation levels of heavy metals, polychlorinated biphenyls, organochlorine pesticides and polycyclic aromatic hydrocarbons (PAHs) in the pyloric caeca of sea stars indicate different pollution gradients, influenced by rivers in The Netherlands, UK and Germany. For some contaminants, especially PAHs, relatively high levels were found in the central part of the North Sea (Dogger Bank). On the basis of multivariate statistics, stations near the mouth of the Elbe and the Rhine/Meuse were shown to have different patterns of biomarker responses. Sea stars from stations in coastal zones showed relatively high levels of cytochrome P450 and 'P418', another haemoprotein that is present in most marine invertebrates. The station nearest to the Elbe Estuary showed the lowest BPH and AChE activity. DNA integrity was lower especially in stations near the Dutch coast and in a station near the Tees/Tyne estuaries. Using these biomarkers as early warning signals of exposure and/or adverse effects, this type of monitoring can be used also in the future to study the spatial and temporal trends in the quality of coastal waters.
Acetylcholinesterase↗
Atmospheric concentrations and air-sea exchanges of nonylphenol, tertiary octylphenol and nonylphenol monoethoxylate in the North Sea.
Concentrations of nonylphenol isomers (NP), tertiary octylphenol (t-OP) and nonylphenol monoethoxylate isomers (NP1EO) have been simultaneously determined in the sea water and atmosphere of the North Sea. A decreasing concentration profile appeared following the distance increasing from the coast to the central part of the North Sea. Air-sea exchanges of t-OP and NP were estimated using the two-film resistance model based upon relative air-water concentrations and experimentally derived Henry's law constant. The average of air-sea exchange fluxes was -12+/-6 ng m(-2)day(-1) for t-OP and -39+/-19 ng m(-2)day(-1) for NP, which indicates a net deposition is occurring. These results suggest that the air-sea vapour exchange is an important process that intervenes in the mass balance of alkylphenols in the North Sea.
Adsorption↗
Bioaccumulation and effects of PCBs and heavy metals in sea stars (Asterias rubens, L.) from the North Sea: a small scale perspective.
Sea stars (Asterias rubens L.) were collected in different stations distributed in the Southern Bight of the North Sea. Concentrations of four heavy metals and six PCB congeners were measured in two body compartments (body wall and pyloric caeca). In order to assess the potential harm of these contaminants, two biochemical parameters were measured in sea stars, viz. reactive oxygen species (ROS) production by amoebocytes and cytochrome P450 immunopositive protein (CYP1A IPP) induction in pyloric caeca. Sea stars from stations located in the plume of the Scheldt river showed the highest contamination levels. Other stations, similarly located, displayed lower levels. No simple relationship could be established between ROS production by sea star amoebocytes and contaminant levels measured in sea star tissues. CYP1A IPP induction displayed more contrasted responses, and highly significant regressions were found between PCB concentrations measured in pyloric caeca and CYP1A IPP. Both biological parameters were found to vary significantly over the study area. On the whole, data indicated that contamination levels and subsequent effects in sea stars were comparable to those described in previous large-scale studies, but that working at a smaller scale highlighted the existence of patterns of contamination which can blur general trends due to major contamination sources like contaminated rivers.
Animals↗