Food-particle size and selection by bivalve larvae in a temperate embayment

Epifluorescence microscopy was used to analyze the stomach contents of bivalve larvae collected in the Baie des Chaleurs (western Gulf of St. Lawrence, Canada) in order to document food-particle sizes, compare feeding among taxa, and compare the diet with the in situ phytoplankton community. Stomach contents were mainly composed of small autotrophic flagellates (<5 μm) and cyanobacteria (<2 μm), reflecting the microbial food web which characterizes these waters. More than half (55%) of all veligers examined contained algal cells of 5 to 15 μm, whereas only 3% had cells of 15 to 25 μm. Differences in the size ranges of ingested algal cells among similar-sized larvae of different species suggests that veligers actively selected food particles. Among the smallest veligers (185 to 260 μm), scallops (Placopecten magellicanus) and mussels (Mytilus edulis) ingested more <5 μm and 5 to 15 μm algae than clams (Mya arenaria). Among larger veligers (261 to 405 μm), clams contained significantly more <5 μm cells than mussels, whereas mussels contained significantly more 5 to 15 μm algae than clams. Algal cells of 15 to 25 μm were preferentially ingested by mussel veligers. Feeding also differed between different-sized veligers within taxa, i.e. the smallest clam veligers ingested fewer of 5 to 15 μm algae than the larger size classes. Mussel veligers ingested significantly more 15 to 25 μm and fewer <5 μm cells as their size increased. The dominance of ultraplankton in the nearshore waters of Baie des Chaleurs and in the stomach contents suggests that veliger larvae may be an important export path for carbon produced by small phytoplankton. Received: 17 July 1996 / Accepted: 20 September 1996     

Adaptation to Climate Variability and Change: Methodological Issues

The Intergovernmental Panel on Climate Change (IPCC) convened a Workshop on Adaptation to Climate Variability and Change in Costa Rica in 1998 that involved more than 200 expects and incorporated views from many research communities. This paper summarizes the recommendations from the Workshop and profiles the contributions to the advancement of methodologies for adaptation science.     

Untersuchungen zur Charakterisierung von Brandrauch

The aim of this work is to clarify if there is a correlation between fuel and its organic combustion products. To acquire homogenous data sets for our investigations, we analysed only the measurements of the “Forschungsstelle für Brandschutztechnik” at the University of Karlsruhe. All compounds with a similar structure were grouped and structural indices were ascribed to them. This also made it possible to obtain information about the frequency of occurrence of a set of substances in fire smoke. The kind of analytical measurements used by this institute provided no or only little information about inorganic compounds, highly volatile substances like acrolein or vinyl chloride, and very poorly volatile substances (e.g. polycyclic aromatic hydrocarbons). We found that benzene, methylbenzene, ethenylbenzene and ethylbenzene are always present in fire smoke. The formation of these typical compounds is described by a model. Aside from these compounds which are typically related to the smoke from fires, substances are always observed which are typical for a distinct fuel. Many compounds which are expected to be in the smoke are highly carcinogenic. Therefore, it is necessary for people with a high exposure to the smoke of fires, e.g. firemen, to protect themselves efficiently. In order to obtain more information about the risks to health of fire smoke, toxicological investigations will be necessary.     

Fate of hexachlorobenzene-14C in wheat plants and soil under outdoor conditions

Residues of hexachlorobenzene-¹⁴C were found in all parts of wheat plants grown from treated seeds or in contaminated soil. Besides the parent compound and bound residues in plants and soil, very small amounts of soluble acidic metabolites were present in plants, which were characterized and determined quantitatively.     

Auf zu neuen Ufern — Postgraduale Weiterbildung mit dem zertifizierten Abschluss Fach?kotoxikologin/e SETAC/GDCh beginnt 2005

Ohne Zusammenfassung     

Effect of agricultural antibiotics on the persistence and transformation of 17beta-estradiol in a Sequatchie loam

A laboratory incubation study was conducted to investigate the effect of agricultural antibiotics (sulfamethazine, tylosin, and chlortetracycline) on the persistence and transformation of 17beta-estradiol in Sequatchie loam. We measured concentrations of 17beta-estradiol and its primary metabolite (estrone) in soils spiked with antibiotics and 17beta-estradiol. Dehydrogenase activity (DHA) was also measured as an indicator of the total microbial activity of the soils. The presence of antibiotics significantly decreased transformation of 17beta-estradiol to estrone. There was a positive correlation between the DHA and the concentrations of estrone in soil spiked with 17beta-estradiol only, implying that the reaction is mainly catalyzed by dehydrogenases. However, the positive correlation was weakened in soil spiked with 17beta-estradiol and antibiotics together. We recommend that any study evaluating the fate and transport of estrogenic hormones in soil should include the effect of agricultural antibiotics because antibiotics and estrogenic hormones are commonly excreted together in environmental samples.