Report: ‘Muschel benches: History and Ecology Norderney (1949-1987)»
Description
The present study on the long-term changes in the mussel population in the catchment area of the Norderney Seagate consists of two parts:
1. Distribution and expansion of mussel benches are presented for different times, based on stocktakings in 1949, 1951, 1973 – 1975 and 1987.
2. In 1976, a permanent station was established in an unfished mussel bank of Norderneyer Watts to study the population dynamics of Mytilus edulis, the long-term fluctuations in its abundance and biomass, and the stock changes in its accompanying forms.
The situation of the benches initially showed a consistent pattern of distribution over decades. The clam stocks themselves, on the other hand, were subject to extraordinarily strong density fluctuations, due to the tendency of Mytilus edulis to fall mass at irregular intervals and their susceptibility to stochastic events such as ice ducts, storm surges and parasite epidemia. In the mid-1980s, such a persistent decline in the population occurred that a number of banks completely disappeared. The cause was probably a particular accumulation of stock-reducing factors: increased pressure from eider ducks since the end of 1983 and 1984 and three consecutive ice periods in 1985, 1986 and 1987. The mussel population has not yet recovered from its critical condition.
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Tags
- miesmuschelbestände-miesmuschelbänke-mytilus-edulis-bestandsaufnahme-geschichte-ökologie-nlwkn
- norderney-norderneyer-seegat