Report: Macrozoobenthos: Wesermündung Long-term Development (1982-1994)»
Description
Since 1968, investigations have been carried out in the Weser estuar to estimate the impact of wastewater from the titanium dioxide industry on the composition of the macrozoobenthos. This report presents the results of the investigation period 1982-1994. For the interpretation of long-term development, the values are compared with the data from 1976-1980. As part of the ongoing monitoring programme, 7 stations are sampled twice a year in the Eulitoral of the Weser estuary. The composition, density and biomass of macrozoobenthos, plant dyes in the sediment, the salinity of the soil water and some measures for the description of the sediment properties are recorded. The dynamics of the macrozoobenthos can be attributed in part to temporary changes in salinity. For example, in years with low overwater drainage, some marine species migrated to the estuary (Arenicola marina, Mytilus edulis). At the same time, the Limnodrilus Limnodrilus hoffmeisteri withdrew upstream from the study area. The brackish water spy Marenzelleria viridis has established itself as a permanent new settler in the Weser estuary since its immigration, first registration in 1986. Other brackish water species, Streblospio shrubsoli and Tubificoides heterochaetus, show pronounced fluctuations in their population density, the cause of which could not be clarified during the study. In part of the study area (Lunewatt), the total biomass of macrozoobenthos has declined sharply since 1983. The microphytobenthos is only sparsely developed in the Weser estuary with 40-80 mg of chloropyll/sqm. There is no evidence of a continuous accumulation of iron in the sediment. However, the iron binding capacity of the sediment may be exhausted. With regard to the grain size distribution in the sediments, there is a long-term decline in the fine-grain fraction throughout the study area. This development is particularly pronounced in Blexer Watt. The characteristics of a disturbed Benthos community, e.g. species poverty and high dominance of individual species, are typical of today’s image of the Weser estuary. How large the proportion of anthropogenic disorders is, and how much the titanium wastewater modifies the community, cannot be derived from the results of the routine examinations.
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Tags
- makrozoobenthos-terminstation-daueruntersuchung-eulitoral-besiedlungsdichte-abundanz-artenzusammensetzung-biomasse-nlwkn-blmp-kronos-titan-werk-mesohalinicum-langzeitentwicklung
- wesermündung-weser-weser-estuary