Food ingestion and assimilation by Hyaie media (Dana, 1853) (Crustacea - Amphipoda)

Abstract

The feeding of Hyale media was analysed under laboratory conditions in winter and summer temperatures. The results showed that assimilation rates increased following food ingestion rates and decreased when egestion rates increased. In winter temperatures no significant differences were found in the assimilation rates among developmental stages and sexes. In summer temperatures assimilation rates for ovigerous and non-ovigerous females were higher than those found for adult and young males. Although not statistically analysed, mean assimilation efficiencies were highest among ovigerous females and adult males, in summer. The quantitative and qualitative variations found in the assimilation efficiency and rates were explained by the differential effect of temperature on the specific growth rate and in the physiological conditions of each growth stage concerned.