Bioavailability of heavy metals in drilling muds

Experimental work on uptake of metals from sediments spiked with barite, ilmenite and hematite were performed using the ragworm Nereis diversicolor and the netted dog whelk Hinia (Nassarius) reticulata as test organisms. The present report also provides a brief review of recent litterature on biological effects of metals in drill cuttings, including relevant results from the UKOOA Drill Cuttings Initiative - an international research programme completed in December 2001. The review suggest low to moderate bioaccumulation and toxicity of metals in drill cuttings to marine organisms. The experimental work was performed in a standard test set-up at Solbergstrand Marine Research Station. The test determines enrichment ratios in exposed vs control organisms. Ratios of 67 and 76 for the respective species showed significant uptake of barium from marine sediments spiked with barite. Similarly, significant uptake of titanium were observed in organisms exposed to ilmenite. All other elements (Al, Li, Fe, Zn, Hg, Cd, Pb, Cu, Cr and Ni) showed no significant uptake and ratios within the range 0,6-1,5. This result was partly explained by anomalous low concentrations of Pb in the barite test substance, partly by the presence in several test substances of major fractions of Cr, Ni, Zn and Cu insoluble in standard nitric acid digestion (NS4770). Toxic effects of metals strongly bound in particulate mineral fractions are not expected.Norbar Minerals A

A long-term perspective on the Chrysochromulina bloom on the Norwegian Skagerrak coast 1988: a catastrophe or an innocent incident?

The long-term effects of the 1988 algal bloom (Chrysochromulina polylepis Manton et Parke) along the Norwegian Skagerrak coast are evaluated and discussed on the basis of several monitoring programmes. Effects on individual growth and survival of coastal cod and its population dynamics are analysed. Cod suffered a high mortality from June until November, and the 1988 yearclass was strongly reduced. Growth was only slightly affected. Furthermore, the effects at the community level are evaluated for the coastal fish community and the benthic communities. These communities were strongly affected on a short time scale, but recovered surprisingly fast. Populations of most organisms had recovered within months, and after 1 yr few traces of the toxic bloom could be observed; after 4 to 5 yr all communities had essentially recovered. As part of the review we also discuss to what extent harmful blooms are likely to reoccur, and conclude that blooms have reoccurred and will continue to do so. However, nothing can be concluded about the toxicity of such blooms. We expect that even large perturbations are unlikely to leave any profound long-lasting effects. The effects of the 1988 bloom are discussed within a theoretical framework including stability, resilience and inertia. In conclusion we emphasise the importance of long-term monitoring data; without such data the analyses reported in this paper would have been impossible

Biological geography of the European seas: results from the MacroBen database

This study examines whether or not biogeographical and/or managerial divisions across the European seas can be validated using soft-bottom macrobenthic community data. The faunal groups used were: all macrobenthos groups, polychaetes, molluscs, crustaceans, echinoderms, sipunculans and the last 5 groups combined. In order to test the discriminating power of these groups, 3 criteria were used: (1) proximity, which refers to the expected closer faunal resemblance of adjacent areas relative to more distant ones; (2) randomness, which in the present context is a measure of the degree to which the inventories of the various sectors, provinces or regions may in each case be considered as a random sample of the inventory of the next largest province or region in a hierarchy of geographic scales; and (3) differentiation, which provides a measure of the uniqueness of the pattern. Results show that only polychaetes fulfill all 3 criteria and that the only marine biogeographic system supported by the analyses is the one proposed by Longhurst (1998). Energy fluxes and other interactions between the planktonic and benthic domains, acting over evolutionary time scales, can be associated with the multivariate pattern derived from the macrobenthos datasets. Third-stage multidimensional scaling ordination reveals that polychaetes produce a unique pattern when all systems are under consideration. Average island distance from the nearest coast, number of islands and the island surface area were the geographic variables best correlated with the community patterns produced by polychaetes. Biogeographic patterns suggest a vicariance model dominating over the founder-dispersal model except for the semi-closed regional seas, where a model substantially modified from the second option could be supported