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

摘要

ABSTRACT: The aim of the present study was to investigate the influence of food availability on reproduction by comparing the response of reproductive biomarkers of a deposit-feeding amphipod Monoporeia affinis in 2 Swedish lentic environments (Lake Vänern and Lake Vättern) differing in eutrophication level, during the period between 1995 and 2002. In ultraoligotrophic Lake Vättern, 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 Vättern in 2001 showed significantly lower concentrations of lipids—mainly triacylglycerols (TAG)—and of fatty acids (FAs) than amphipods collected in the more eutrophic Lake Vänern. Dramatically increased spring bloom diatom abundance in Lake Vättern resulted in increased fecundity and lipid and fatty acid concentrations (namely monounsaturated fatty acids, MUFA) and decreased embryo aberrations. A significant relationship between fecundity and diatom biovolume in Lake Vänern and total algal biovolume in Lake Vättern was found. No other alga taxa influenced the fecundity. In Lake Vättern 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 environmental 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.