Alteration of kairomone-induced antipredator response of the freshwater amphipod Gammarus roeseli by sediment type.

The importance of sediment type and of kairomones released by juvenile burbot (Lota Iota) on behavioral responses of the freshwater amphipod Gammarus roeseli was studied in laboratory experiments. In the absence of kairomones. G. roeseli preferred coarse substrates; the highest preference was shown for the most coarse sediment. In the presence of kairomones, the amphipods preferred the less-coarse substrate pebbles over gravel. This difference is an effective antipredator response; G. roeseli is able to hide efficiently in the interstices of the pebbles. Juvenile burbot have a low foraging efficiency on pebbles and preferentially forage in the interstices of coarser sediments. G. roeseli responded differently to kairmones in different sediment types. The amphipods decreased their activity only in pebbles. In gravel, the rate of exploration behavior increased, and on a bare surface, the area containing fish kairomones was avoided.