AB prepress abstract  -  doi: 10.3354/ab00048

ABSTRACT: The aim of this study was to investigate the influence of food availability on the reproduction by comparing the reproductive biomarkers response of a deposit-feeding amphipod Monoporeia affinis in two 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) was found and severe embryo aberrations in terms of undifferentiated eggs (% per female), dead eggs (% per female) and % females with dead broods were recorded. A significant negative correlation between fecundity and undifferentiated eggs and dead eggs and broods were obtained in both lakes. Amphipods collected in Lake Vättern 2001 showed significantly lower concentrations of lipids, mainly triacylglycerols (TAG), and fatty acids than amphipods collected in the more eutrophic Lake Vänern. Dramatic 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. Significant relationship between fecundity and diatom biovolume in Lake Vänern and total algae biovolume in Lake Vättern was found. No other algae taxa influenced the fecundity. In Lake Vättern total algal biovolume was negatively related to undifferentiated eggs. MUFA and saturated fatty acids (SFA) seem to be important for vitellogenesis and oogenesis and also constitute fuel during embryogenesis. Other environmental variables i.e. oxygen, pH and temperature in bottom waters and sediment organic content did not influenced the reproduction variables. Our findings strongly point to a relationship between embryo aberrations (e.g. undifferentiated eggs and dead broods) and low food resources.