Amphiura filiformis (Ophiuroidea: Echinodermata) in the North Sea: Distribution, present and former abundance and size composition
Duineveld, G.C.A.; Künitzer, A.; Heyman, R.P. (1987). Amphiura filiformis (Ophiuroidea: Echinodermata) in the North Sea: Distribution, present and former abundance and size composition. Neth. J. Sea Res. 21(4): 317-329
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579; e-ISSN 1873-1406, meer
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| Auteurs | | Top |
- Duineveld, G.C.A., meer
- Künitzer, A.
- Heyman, R.P.
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| Abstract |
During the North Sea Benthos Survey undertaken by the ICES Benthos Ecology Working Group in spring 1986, a synoptic inventory was made of the benthos in the southern, central and part of the northern North Sea. The present paper deals with the status of the population of the infaunal ophiuroid Amphiura filiformis on the basis of measurements from 150 stations. A. filiformis was found at all the offshore muddy stations, but densities were generally highest in the shallow area south of the Dogger Bank. Stations with more than 1000 ind·m-2 were mainly situated near the frontiers between turbid and summer-stratified water masses, viz. along the southern border of the Oyster Ground, the southern slope of the Dogger Bank and in the northern part of the Pleistocene Elbe river valley. The size-distributions of A. filiformis show that juveniles were generally scarce at stations with high numbers of adults, whereas highest numbers of juveniles occur at stations with few adults. An unequivocal relation between adults and juveniles was, however, absent. This stresses the importance of other factors involved in recruitment. Comparison between the present and former (1938 and 1950) density of A. filiformis suggests that density has increased in the shallower parts but has remained stable in the deeper northern North Sea. An increase of A. filiformis in the shallow part of the North Sea could point to an enhanced food supply for the benthos, which may have some relation to the eutrophication in nearshore areas. |
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