Metals in Zooplankton from the Baltic Sea, 1980-84

Between 1980 and 1984, plankton was collected for metal analysis during four expeditions in the Baltic Sea. for comparison, samples from adjacent areas of the northeastern Atlantic Ocean were also taken. the mixed net-plankton samples were analyzed by AAS for metals (Al, Cd, Co, Cr, Cu. Fe, Mn, Ni, Pb, and Zn). the results are discussed with regard to spatial and temporal trends and for comparison with data from other authors. Correlations among the contents of the different metals and between the metal contents and 'external factors' including salinity, season, percentage of co-collected phytoplankton, and concentration of dissolved and particulate metals in the water are considered.

There is a tendency for higher metal contents in plankton from the brackish Baltic Sea (Al, Mn and Hg), while other metals (e.g. Cd) show higher levels in samples taken from the marine environment. Except for mercury, no clear correlations could be found between the metal content in plankton and the dissolved concentration of the same metal in the ambient water. Otherwise, the contents of aluminium, iron, manganese and zinc in the suspended particulate matter and in the plankton seem to be partly related to each other.     

Heavy Metals in Littoral Deposits Off Havana City, Cuba

The content of Al, Cd, Co, Cu, Fe, Hg, Mn, Ni, Pb, Zn, C org and organic matter was investigated in sediment samples taken in the littoral zone off Havana City. the results revealed three areas affected by contamination: (a) Chivo Beach with a submarine sewage outfall, (b) the mouth of the Havana Bay and (c) the estuarine area of the Almendares River. the normalization of the heavy metals contents with respect to aluminium and organic matter combined with multivariate statistical methods was found valuable for a proper interpretation of the analytical results.     

Inhibition of phosphoenolpyruvate carboxykinase activity appears to be the key biochemical lesion in the acute toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin in rats

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) exerts its acute toxicity by inducing a gradually increasing voluntary feed refusal. However, this seems not to be caused by a direct effect on the central nervous system, as far higher concentrations of TCDD were found in the brain after intracerebroventricular (i.c.v.) than after lethal intravenous (i.v.) injections, but were not accompanied by a wasting syndrome. TCDD causes inhibition of several key enzymes of gluconeogenesis, with phosphoenolpyruvate carboxykinase (PEPCK) responding earliest and strongest to the insult. Responses of pyruvate carboxylase (PC) and glucose-6-phosphatase (G-6-Pase) are less pronounced and begin at later time points. Blood and brain levels of tryptophan increase following TCDD treatment with a lag period of about three days, shortly after the decrease of PEPCK activity becomes apparent. Since thi samino acid is the precursor of the appetite suppressant neurotransmitter serotonin, and since it is normally degraded via gluconeogenesis, a series of events can be suggested to explain the TCDD-induced wasting syndrome. By an as yet unrevealed mechanism TCDD decreases the activity of PEPCK to about 40 percent of normal, leading to a back-up of gluconeogenic substrates, among them tryptophan, which in turn can further inhibit PEPCK activity in vivo. This causes an increase in serotonin turnover in brain and possibly in other tissues. Increased serotonergic activity in turn is likely to play an important role in the increasing feed refusal of TCDD-treated rats which eventually leads to death.     

Evolutionary relationships among deep-sea mytilids (Bivalvia: Mytilidae) from hydrothermal vents and cold-water methane/sulfide seeps

A protein electrophoretic survey of mytilids inhabiting deep-sea hydrothermal vents and cold-water methane/sulfide seeps revealed electromorph patterns diagnostic of 10 distinct species. From hydrothermal vents located at sites on the Galápagos Rift, the Mid-Atlantic Ridge, and the Mariana Back Arc Basin, we detected four species of mytilids. Six additional species were detected from three cold-water seep sides in the Gulf of Mexico. The patchy distribution and temporal stability of seeps may provide a greater opportunity for mytilid diversification and persistence than vent sites Nei's genetic distances (D) between species were relatively large (range: 0.528 to ) both within and among habitat types. This pronounced degree of genetic differentiation suggests a relatively ancient common ancestor for the group. Phylogenetic trees were generated using distance Wagner and parsimony analyses of allozyme and morphological characters. The tree topologies obtained from both methods support: (1) the hypothesis that a seep ancestor gave rise to the deep-sea hydrothermal vent mytilids, (2) a historical progression from shallow-water to deep-water habitats, and (3) a co-evolutionary progression from external to internal localization of bacterial symbionts. Whether the seep mytilid taxa constitute paraphyletic or polyphyletic groups remains unresolved. Our phylogenetic hypotheses also provide a benchmark for the phylogeny of mytilid bacterial symbionts.     

Fitness consequences of sexual cannibalism in female<Emphasis Type="Italic"> Argiope bruennichi</Emphasis>

The evolution of sexual cannibalism as the most extreme form of nuptial feeding is still poorly understood. Although increasing evidence suggests that female aggressiveness is related to other aspects of foraging behaviour, it is not clear whether the nutritional value of a male is sufficient to provide an adaptive significance for sexual cannibalism. A widely cited though rarely tested explanation is based on a paternal investment model, and predicts that consumption of a male results in increased female fecundity. The available evidence is either correlational or restricted to species with relatively large and potentially nutritious males, and different studies have come to different conclusions. Here we present a test of the paternal investment hypothesis using the very cannibalistic and highly size-dimorphic spider Argiope bruennichi. After a preset schedule, we had females consume none, one or two males independent of the female's cannibalistic behaviour. Consumption of male bodies did not result in any detectable fitness benefit for the female: neither the number of clutches, nor clutch size or hatching success were affected by consumption of males. The frequency of cannibalism was around 80%, independent of the female mating status. We did not observe male complicity, but cannibalism was associated with prolonged copulation. This suggests a sexually selected benefit of cannibalism for males. We conclude that the paternal investment hypothesis does not explain the existence of sexual cannibalism in A. bruennichi and probably not in other spider species with a pronounced sexual size dimorphism.Communicated by L. Simmons     

Relationships between effects of environmental temperature and seston on growth and mortality of Mytilus edulis in a temperate northern estuary

The growth and mortality of experimentally-rafted Mytilus edulis L. of known age at 7 locations in a northern estuary (Damariscotta River, Maine, USA) were related to environmental temperatures and to the presence or absence of various potential food sources. All particles were regarded as potential food substrates. Growth decreased appreciably at sites where water temperatures exceeded 20°C, but mussels survived a wide range of elevated temperature exposures, ranging from 0 to 149 degree-days in excess of 20°C. The maximum temperature was 25°C. Mortalities of mussels at all sites but did affect the extent of mortality, which increased abruptly in late summer, when water temperatures were declining. Differences in degree-days of exposure to elevated temperatures did not influence the timing of mortality, which occurred synchronously at all times, but did affect the extent of mortality, which ranged from 35 to 90%. The period of high mortality was preceded by a rapid decline in phytoplankton standing crop. Total particle concentrations decreased during this period, but the shift toward larger particles suggests that there was little, if any, decrease in total volume of material in the seston, at least through August. It is suggested that living phytoplankton provided the critical energy source for these mussels, and that the mortalities were caused by rapidly reduced ration at a time of metabolic stress. The role of temperature and the possible role of the gametogenic cycle are discussed. In addition, the feeding efficiency of M. edulis may have decreased during this period due to an increase in mean particle diameter. Chlorophyll was divided into a nannoplankton fraction (<-20 m) and a larger fraction (>20 m). A smaller size criterion for this distinction is proposed for future studies. The importance of nannoplankton to the primary production of this estuary and the role of nannoplankton and nannoplankton-sized particles in the diet of mussels in nature are discussed.     

Teil III: Die Verkehrsbilanz der Universität Osnabrück

One central aspect of the environmental management system for universities developed in Osnabrück is the environmental audit of universities, realized by an ecobalance. This article deals with modelling the material and energy flows caused by the University’s commuters (staff and students), and by the business trips of employees, using the software Umberto^®. The result is the University’s traffic balance. 10,000 MWh of energy are consumed yearly by the University’s traffic. 94% of the consumption is caused by commuters (1,300 employees and 11,500 students) and only 6% by business trips. Compared with the whole energy consumption of the University, the traffic’s share is 32% and therefore lies between the electricity’s share (25%) and that of heat (43%). Similarly related are the CO₂ emissions, caused by traffic (3,160 tons per anno). Compared with the whole CO₂ emissions of the University the traffic’s share is 31%, thus putting it between the heat’s share (27%) and that of electricity (42%). Although the average weekly distance the University’s commuters drive (79 km/student and 84 km/employer) is at the bottom of the range for other comparable universities, a transportation demand management for a further reduction of the traffic-caused CO₂ emissions should be implemented.