Cadee g c (21 Ergebnisse)

Assemblages of fossil brachiopods are often characterized by the absence af juvenile specimens. This absence may be due for instance to method of collection, transport by currents, mechanical destruction, diagenetic solution, predation, factors that all may work selectively on small specimens. In some instances, where it was ass…

During the last few decades nutrient concentrations in the Dutch coastal waters have increased significantly. Values observed for rates of primary production as well as for concentrations of chlorophyll and for particulate organic matter have been higher during recent years than estimates from earlier periods. Thus more food wil…

A large sample rich in empty Bithynia tentaculata (Linnaeus, 1758) was collected in a drift-line along Lake IJssel, The Netherlands. Of 400 adult Bithynia shells 62 (15.5%) showed repair of a damaged outer lip, most probably due to failed attacks by predators. The roach Rutilus rutilus (Linnaeus, 1758) was probably its main shel…

Bivalves and gastropods dropped by hooded crows (Corvus corone cornix) show - not surprisingly - a similar fragmentation as those dropped by herring gulls (Larus argentatus). Both bird species drop the shells from some height to crack them. Bivalves have one or both valves fragmented, but the valves still hold together by the li…

Rissoa membranacea disappeared from the Dutch Wadden Sea together with the large subtidal stands of eelgrass Zostera marina L. in the early 1930s, due to a still not completely understood 'Wasting disease' in Zostera. A small population of R. membranacea survived together with Zostera marina in an inland brackish water 'de Bol'…

A mass stranding of hundreds of cuttlebones of Sepia orbignyana occurred on the coast of Texel, the Netherlands, in July 2002. Up to now usually only low numbers were found on the Dutch coast. S. orbignyana does not live in the North Sea. Accompanying drift material such as thong weed Himanthalia elongata indicates a SW origin f…

Littorina littorea shells found broken on a cycle-track next to where they lived, are thought to be broken by shell-dropping birds. Shells broken experimentally by dropping them from 6 m height on a concrete floor showed very similar damage: a hole in the last whorl, whereas the aperture rim remained intact. Examples from the li…

In this paper we report on oystercatchers feeding on Corbicula fluminea, a recent invader in the river Rhine. Oystercatchers are specialised molluscivores. They could reach these freshwater bivalves during low river level in the summer of 2003 and in the end of March 2004. The shell remains after consumption have a characteristi…

Kuiper, H.: De Nederlandse Malacologische Vereniging, vijfenzeventig jaar. Coomans, H. E. & Moolenbeek, R. G.: Het Zoölogisch Museum Amsterdam en de Nederlandse Malacologische Vereniging. Gittenberger, E.: 's Rijks Museum van Natuurlijke Historie, het Nationaal Natuurhistorisch Museum, Naturalis, en de Nederlandse Malacologische…