Environmental impact and recovery at two dumping sites for dredged material in the North Sea

The environmental impact and recovery associated with the long and uninterrupted disposal of large volumes of moderately contaminated dredged material from the port of Rotterdam was studied at nearby dumping sites in the North Sea. Observations were made on sediment contamination, ecotoxicity, biomarker responses and benthic community changes shortly after dumping at the 'North' site had ceased and at the start of disposal at the new dumping site 'Northwest'. During the period of dumping, very few benthic invertebrates were found at the North site. Concentrations of cadmium, mercury, polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs) and tributyltin (TBT) in the fine sediment fraction (<63 microm) from this site were 2-3 times higher than at the reference site. In four different bioassays with marine invertebrates the sediments showed no acute toxic effects. In tissue (pyloric caeca) of resident starfish Asterias rubens, residual levels of mercury, zinc, PCBs and dioxin-like activity were never more than twice those at the reference site. Four different biomarkers (DNA integrity, cytochrome P450 content, benzo[a]pyrene hydroxylase activity and acetylcholinesterase inhibition) were used on the starfish tissues, but no significant differences were found between North and the reference site. Minor pathological effects were observed in resident dab Limanda limanda. One year after dumping had ceased at the North site, a significant increase in the species richness and abundance of benthic invertebrates and a concomitant decrease in the fine sediment fraction of the seabed were observed. After 8.2 million m3 of moderately contaminated dredged material had been dumped at the new dumping site Northwest, the species richness and abundance of benthic invertebrates declined over an area extending about 1-2 km eastwards. This correlated with a shift in sediment texture from sand to silt. The contamination of the fine sediment fraction at the Northwest location doubled. It is concluded that marine benthic resources at and around the dumping sites have been adversely affected by physical disturbance (burial, smothering). However, no causal link could be established with sediment-associated contaminants from the dredged spoils.     

莫桑比克的海洋生物学研究:过去、现在及未来

本文概述了莫桑比克包括渔业在内的海洋生物学研究的发展情况.莫桑比克的海岸线约为3000km,海洋的生物资源在莫桑比克的社会中起着重要的作用,主要是作为人们的蛋白质来源以及收入和出口创汇的来源.     

Incest avoidance and bonding between siblings in gerbils

Summary Social and sexual preferences for siblings versus non-siblings have been investigated in Mongolian gerbils (Meriones unguiculatus) in a series of laboratory and outdoor enclosure (100 m²) studies. When first social contact took place at pairing in adulthood full siblings and nonsiblings did not differ with respect to onset of reproduction. Correspondingly, both siblings and non-siblings paired at weaning age had a delayed onset of reproduction. Thus, no effect could be established in either case, related to the individuals' relatedness, but the importance of social exposure was clear. Non-siblings paired when 2 months old had a delayed onset of reproduction, which did not differ statistically from the onset in siblings, raised together, and housed pairwise since the same age. When sexually mature animals were paired at 3 months of age, siblings were found to start reproducing later than non-siblings (Ågren 1981). Following an initial delay in both siblings and nonsiblings paired when 5 months old, all non-sibling pairs reproduced before any sibling pair. At pair formation, at least the females in both groups were known to be sexually immature. These results indicate that for sibling-bonding to occur social exposure may be delayed until the animals are old enough, or somatically developed, to mature sexually. Thus, social exposure before weaning age during the period for primary socialization seem not to be crucial, nor the actual maturational state, sexually, in older females. To study the stability of the social bonds between siblings and non-siblings, animals kept pairwise in the laboratory were released in large outdoor enclosures. Pairs brought together before the age of sexual maturity did not remain stable, whether or not the former cagemates were siblings. Non-sibling pairs formed after this age, which had also reproduced successfully in the laboratory, did remain stable. Social and sexual interactions were studied within and between two mixed-sex sibling groups of four. The sibling groups had the possibility to establish group territories before being exposed to each other. Although the sibling groups remained stable, the females still preferred non-sibling males as sexual partners. However, socially dominant brothers copulated more frequently than subordinant brothers. This rank difference was not evident in non-siblings.     

Tissue retention and metabolism of 2,3,4,3′,4′-pentachlorobiphenyl in mink and mouse

2,3,4,3′,4′-Pentachlorobiphenyl was retained as the unmetabolized parent compound in liver and fat from mouse and mink. In contrast, in mouse plasma - 4-hydroxy-2,3,5,3′,4′-pentachlorobiphenyl - was present in concentrations 15 times higher than that of the parent chlorobiphenyl. In mink plasma the parent compound and the 4-hydroxylated metabolite were present in similar concentrations. Faeces was the major excretion pathway in both animals. Both the mouse and the mink excreted mainly the parent compound accompanied by trace amounts of hydroxylated metabolites but the mink also excreted significant amounts of hydrophilic metabolites, that gave hydroxylated products after acidic hydrolysis. Five hydroxylated metabolites, 4-hydroxy-2,3,5,3′,4′-pentachlorobiphenyl, 4-hydroxy-3,5,2′,3′,4′-pentachlorobiphenyl, 2-hydroxy-3,4,2′,3′,4′-pentachlorobiphenyl, 5-hydroxy-3,4,2′,3′,4′-pentachlorobiphenyl and 5-hydroxy-2,3,4,3′,4′-pentachlorobiphenyl, were identified in excreta of mink and mouse.     

Hydroxylated PCB metabolites in nonhatched fulmar eggs from the Faroe Islands

Thirty-six polychlorinated biphenylols (OH-PCBs) congeners were characterized in Fulmar (Fulmarus glacialis) eggs collected from the Faroe Islands. The seven most abundant congeners were quantified in 19 samples, and the sigmaOH-PCB concentrations ranged between 0.92 and 4.0 ng g(-1) fresh weight (f.w.). These eggs constitute a part of the traditional diet for at least a part of the population on the Faroe Islands and may contribute to the high levels of these contaminants found in the blood of pregnant Faroese women. Because the metabolites are present in the nonhatched fulmar egg, it is concluded that the OH-PCBs are transferred to the egg before laying. High levels, 3300-18,000 ng g(-1) l.w., of sigmapolychlorinated biphenyls (PCB) were determined in the fulmar eggs, which are a considerable source for human exposure. The high PCB levels are a source for metabolic formation of hydroxylated PCBs.     

Microbial metagenomics in the Baltic Sea: Recent advancements and prospects for environmental monitoring

Metagenomics refers to the analysis of DNA from a whole community. Metagenomic sequencing of environmental DNA has greatly improved our knowledge of the identity and function of microorganisms in aquatic, terrestrial, and human biomes. Although open oceans have been the primary focus of studies on aquatic microbes, coastal and brackish ecosystems are now being surveyed. Here, we review so far published studies on microbes in the Baltic Sea, one of the world’s largest brackish water bodies, using high throughput sequencing of environmental DNA and RNA. Collectively the data illustrate that Baltic Sea microbes are unique and highly diverse, and well adapted to this brackish-water ecosystem, findings that represent a novel base-line knowledge necessary for monitoring purposes and a sustainable management. More specifically, the data relate to environmental drivers for microbial community composition and function, assessments of the microbial biodiversity, adaptations and role of microbes in the nitrogen cycle, and microbial genome assembly from metagenomic sequences. With these discoveries as background, prospects of using metagenomics for Baltic Sea environmental monitoring are discussed.     

Downward Migration of Dense Bottom Currents

The focus of this paper is on the dynamics of a dense current flowing along the continental slope, and the frictionally induced downward motion it experiences. In particular, the movement of the lateral boundaries where the isopycnals meet the bottom are considered. The current is taken to be wide compared to the Rossby radius, which is in accordance with observations and makes the dynamics quasigeostrophic. The time development of the plume thickness is studied, using three different parameterisations for the bottom friction.Independently of the choice of parameterisation, the following results are obtained: In the central part of the plume friction acts as a diffusive process to minimise the curvature of the upper surface of the plume. At the upper edge the plume quickly approaches a state with small slope, i.e. small geostrophic velocity and small frictionally induced downward flow. At the lower edge a tongue of dense water shoots out creating a widening layer. The thickness of the migrating layer is approximately equal to the boundary layer depth and its downward speed is comparable to the along-slope geostrophic velocity. The downslope end of the migrating layer may form a steep front which requires some precautions in the numerical procedure.     

Urban Geochemistry: A Multimedia and Multielement Survey of a Small Town in Northern Europe

The concentrations and distributions of chemical elements (Ag, Al, As, Au, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ga, Hg, K, La, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Sc, Se, Sr, Te, Th, Ti, Tl, U, V, W and Zn) were studied in till, humus and urban soil in Jakobstad, a small town (20,000 inhabitants) in W. Finland. The analyses were performed with ICP-MS after aqua regia leaching of till (n = 37), urban topsoil (n = 32) and subsoil (n = 32), and HNO3 leaching of humus (n = 37). The till and humus samples, collected at the same sites, were divided into urban and rural samples. The urban till was not significantly enriched in metals. In contrast, a majority of the elements occurred in higher concentrations in the urban than the rural humus samples. Statistical and spatial interpretations of the humus data revealed that traffic (Pb, V and Ni), metal industry (Pb, Zn, Bi, Sb and Cr), an abandoned shooting range (Pb and Sb) and other sources contribute to higher metal levels in the urban humus. The urban soil samples were collected at parks, yards, abandoned industrial sites, roadsides, etc. The topsoil samples were enriched in most elements, also by elements not enriched in the urban humus (e.g. Cd). At several sites, the concentrations far exceeded the limit concentrations for contaminated soils in Finland. A large variety of sources were identified or indicated.