Quantitative Larvenanalyse des Rügenschen Frühjahrsherings in den Laichsaisons 1991 und 1992

Das bereits vom ehemaligen Institut für Hochseefischerei, Rostock, routinemäßig durchgeführte Heringslarvenprogramm im Greifswalder Bodden wird als Beitrag zur Bestandsschätzung des Rügenschen Frühjahrsherings (RFH) zunehmend unter ökologischen Gesichtspunkten im Institut für Ostseefischerei (IOR) in Kooperation mit der Universität Rostock (Fachbereich Biologie) weitergeführt. Die quantitative Larvenanalyse ermöglicht über den Anteil des aus dem Greifswalder Bodden stammenden Nachwuchses eine Voraussage über den Erfolg der in einem weitaus größeren Seegebiet (ICES SD 22+24) produzierten Nachwuchsjahresklassen. Vorliegende Publikation dokumentiert erste Ergebnisse hinsichtlich der Heringslarvenverteilung im Saisonverlauf 1991 und 1992.

Pond action: Promoting the conservation of ponds in Britain

Pond Action is an independent freshwater conservation project which was started in 1987. It is based in the School of Biological and Molecular Sciences in Oxford Polytechnic and has five full-time staff with two senior advisors. The main aim of Pond Action's work has been to promote the conservation of ponds by creating a sound, scientific basis for pond conservation. An essential aspect of this work is the need to make the results of scientific work available and understandable to everybody concerned with pond conservation.

Predation and selection in copepod populations of Alpine waters [Translation from: Bollettino di Zoologia 21 541-545, 1954]

Zooplankton was studied in four alpine lakes in Switzerland, France and Italy. The presence the presence of the invertebrate predator Heterocope in three lakes was stated. It is then discussed why in three of these four lakes, the copepod Arctodiaptomus denticornis is present in the absence of Arctodiaptomus bacillifer, and vice versa respectively in the second and first parts of the lacustrine summer.

Development of trophic state and phytoplankton in an oligo-mesotrophic reservoir (Kleine Kinzig) in Black Forest, Germany

Since 1989, intensive studies have been made on a relatively new (1983-84) oligotrophic reservoir and its pre-reservoir in the Black Forest. This paper briefly reports on the hydrochemistry, especially annual variations in phosphorus loadings, and the seasonal development of phytoplankton in 1989 and 1990.

Doses efficaces en glyphosate et en 2,4-D pour le contrôle chimique des laitue d'eau (Pistia stratiotes, Linn.) et toxicité du glyphosate vis-à-vis des tilapias (Sarotherodon melanotheron)

The toxic effects of two herbicides Round up (gliphosate) and 2,4-D (herbazol) were tested on Pistia stratiotes (Linn. Araceae) samples cultivated in glass aquariums. The gliphosate appears to be more toxic on Pistia Stratiotes than 2,4-D. It was then tested on tilapia Sarotherodon melanotheron juveniles. The lethal dose for tilapia (CL50 = 13.25 mg.l -1) is about 18, 37 and 74 times higher than the glyphosate toxic dose for plants at 1, 2 and 4 meters water depth respectively.