Exploration of interstitial habitats by the phytophilous Ostracod Cypridopsis vidua (O.F. Müller) : experimental evidence

Abstract

Cypridopsis vidua, interstitial habitat. vidua (O.F.M.) lives within dense stands of Chara fragUis Desv. in Mondsee. The species develops fast and is very voracious, feeding on the « Aufwuchs » of the Chara stems. Under experimental conditions, C. vidua acti- vely explores the interstitial of a fine gravel sediment. The ostracodes are also able to find their way out of the interstitial labyrinth. The limited colonisation of deep groundwater habitats by C. vidua (e.g. in the Danube and the Rhône valleys the species lives in superficial alluvial sediments located near the bottom of surface waters) is presumably due t o its high energetic requirements. C. vidua recognises the chemical alarm signals of predators such as the fish Abramis brama (L.) ; th e ostracods react by drecreasing their motility in both the surface and the interstitial habitat.