Behaviour and microhabitat of early life stages of Cobitis taenia

The present study investigates the mobility and phototactic behaviour of ea rly life stages of spined leach in order to define the microhabitat of the different ontogenetic phases. The eggs were placed by the spawning adults i nto dense vegetation. Since the embryos did not show any mobility until eye pigmentation, they face the same microhabitat as the eggs. After eye pigme ntation, they became negatively phototactic. In the field, the light gradie nt would lead them beneath the centre of the vegetation. With the beginning of exogenous feeding, phototaxis changed into a positive reaction. This wo uld lead the larvae towards the lighter marginal areas under the vegetation . Afterwards, the spontaneous mobility of the larvae increased and the phot otactic behaviour lost its importance. When early life stages of Cobitis we re exposed to 13 invertebrate and vertebrate predators, they showed a high vulnerability to predation. Therefore, the dense vegetation acts as a shelt er for predation.