Beobachtungen über die Eientwicklung des Blaufelchens (Coregonus lavaretus wartmanni) im Bodensee-Obersee

Lake Constance whitefish (Coregonus lavaretus wartmanni) spawn in the water column. The demersal eggs develop at the mud-water interface at depths down to 250 m. Samples were taken by dredging areas of 100 m². Mortality, developmental stages and rate of malformations were determined. Incubation period lasts roughly from December to March. The percentage of dead eggs increased from 52% in January to 74% in February. Among living eggs deformations of the trunk raised from 4% to 31% during the same time. It is assumed that larvae with anomalities of the trunk will have no survival chances. Total losses were 91.7% in the average of all samples.      

Quantitative und theoretische Methoden in der stratigraphisch-sedimentologischen Analyse

The mathematical methods involved in sedimentary stratigraphy are reviewed. One can differentiate between an analytical and a theoretical approach. The former is particularly suitable for the analysis of facies patterns but theoretical considerations are more important in the study of vertical sections. The problem of stratigraphical correlation is only partly defined in mathematical terms and so-called methods of quantitative correlation should be treated with care.     

Gewässerfeindliche Wirkungen von Phosphaten in Flüssen und Bächen

Phosphates cause an increasing proliferation of submerged flowering plants or green filamentous and other algae types in surface waters. These tangles of growth impede the water flow, distort the flow rates calculated on the basis of the water level, disturb and disrupt bathers, shipping activities, fishing and fish breeding, power plant operations, the replenishment of the underground aquifer and the preparation of water for drinking. Primary and secondary wastewater treatment cannot offset the strong imbalance produced in surface waters. Protective measures are discussed.