Epsilon Archive for Student Projects

Abstract

Risk of predation induces behavioural responses in prey, such as
decreased activity and avoidance of risky habitats. Sheltering by prey
in low risk habitat not only constrains the physical area but also the
accessibility of resources. Hence, variation in refuge availability
affects the performance of refuging individuals. In a large scaled
pond experiment I tested the effect of refuge availability on survival
and growth in young-of-the-year (YOY) arctic char (Salvelinus
alpinus), subject to predation from cannibalistic char. In addition, I
also studied the behaviour of YOY char in response to predation risk.
Results showed that predation decreased both survival and growth of
YOY char. Increasing refuge availability decreased the mortality of
YOY char, but had no effect on growth. Risk of predation restricted
the habitat use of YOY char to the protected near shore habitat.
There was also a density dependent resource depletion in the refuge
habitat when cannibals were present, induced by refuge availability
and habitat use of YOY char. The overall results suggest predation to
be the key factor limiting growth and survival in YOY char rather
than resource competition, and that both quality and density of
refuges affect the survival of YOY char.