Reproduction disorders in the benthic amphipod Monoporeia affinis: an effect of low food resources

Abstract

The aim of the present study was to investigate the influence of food availability on repro- duction by comparing the response of reproductive biomarkers of a deposit-feeding amphipod Mono- poreia affinis in 2 Swedish lentic environments (Lake Vanern and Lake Vattern) differing in eutrophi- cation level, during the period between 1995 and 2002. In ultraoligotrophic Lake Vattern, a very low fecundity (living eggs female -1 ) was found and severe embryo aberrations in terms of undifferentiated eggs (% female -1 ), dead eggs (% female -1 ) and the percent of females with dead broods were recorded. A significant negative correlation between fecundity and (1) undifferentiated eggs and (2) dead eggs and broods were obtained in both lakes. Amphipods collected in Lake Vattern in 2001 showed signifi- cantly lower concentrations of lipids — mainly triacylglycerols (TAG) — and of fatty acids (FAs) than amphipods collected in the more eutrophic Lake Vanern. Dramatically increased spring bloom diatom abundance in Lake Vattern resulted in increased fecundity and lipid and fatty acid concentrations (namely monounsaturated fatty acids, MUFA) and decreased embryo aberrations. A significant rela- tionship between fecundity and diatom biovolume in Lake Vanern and total algal biovolume in Lake Vattern was found. No other alga taxa influenced the fecundity. In Lake Vattern total algal biovolume was negatively related to undifferentiated eggs. MUFA and saturated fatty acids (SFAs) seem to be important for vitellogenesis and oogenesis and also constitute fuel during embryogenesis. Other envi- ronmental variables in bottom waters (i.e. oxygen, pH and temperature) and sediment organic content did not influence the reproduction variables. Our findings strongly suggest a relationship between embryo aberrations (e.g. undifferentiated eggs and dead broods) and low food resources.