Distribution and summer diapause of Canthocamptus staphylinus (Jurine) (Copepoda: Harpacticoida) in Lake Ladoga
The spatial distribution of Canthocamptus staphylinus (Jurine) in Lake Ladoga was examined. C. staphylinus is one of the most numerous species of harpacticoids in the lake. It can dwell in almost all littoral biotopes. In profundal biotopes strongly exposed to anthropogenic influence (pollution and eutrophication) only this species of harpacticoid was found. A peculiarity of C. staphylinus biology is that in summer individuals are in the resting stage as cysts. In summer active individuals were found in littoral habitats at a water temperature of 20 °C, but their number was small in comparison with cold periods of the year. In the littoral zone the relative number of individuals in cysts was clearly related to water temperature. Twelve degrees temperature appears to be critical for development of littoral populations of C. staphylinus.
Lacustrine profundal meiobenthos as an environmental indicator
Organic loading and eutrophy is indicated at profundal depths by large numbers of resting copepodid stages of cyclopoid copepods, by the occurrence of the naidid oligochaete species, Amphichaeta leydigii and Specaria josinae, and the harpacticoid species Canthocamptus staphylinus, and by a low meiobenthos/macrobenthos biomass ratio. An oligotrophic environment is indicated by the occurrence of the aeolosomatid oligochaetes Aeolosoma quaternarium, A. hemprichi and Rheomorpha neiswestnovae, the naidid oligochaete Chaetogaster langi and the harpacticoid species Attheyella crassa and a high meiobenthos/macrobenthos biomass ratio.
Untersuchungen über Geschlechtsbestimmungsmechanismen bei Copepoden
Zusammenfassung1.Die genotypische Geschlechtsbestimmung von Megacyclops viridisJurine ist gekennzeichnet durch weibliche Heterogametie vom X-Y-Typ. Das Weibchen besitzt 2 n=10+XY, das Männchen 2 n= 10+XX. Es gelang eine experimentelle Beeinflussung der geschlechtsbestimmenden Reifeteilung.2.Acanthocyclops robustusSars hat in beiden Geschlechtern eine diploide Chromosomenzahl von 6 ohne strukturell differenzierte Geschlechtschromosomen.3.Acanthocyclops vernalisFischer ist im Weibchen digametisch mit 2 n=8+XY; das Männchen besitzt 2 n=8 Autosomen und 2 X-Chromosomen.4.Die Diploidzahl der Chromosomen von Macrocyclops fuscusJurine beträgt in beiden Geschlechtern 14 ohne cytologisch unterscheidbare Geschlechtschromosomen.5.Eucyclops serrulatusFischer ist im weiblichen Geschlecht heterogametisch mit 2 n=12+1 X-Chromosom, das Männchen besitzt 2 n=12+XX-Chromosomen.