Effects of zinc on the life-cycle, growth and reproduction of the marine amphipod Corophium volutator

The effects of zinc concentrations on the life-history, growth and reproduction of Corophium volutator (Pallas, 1766) were investigated. Amphipods were exposed for 100 d to 4 sublethal zinc concentrations (0.2, 0.4, 0.6 and 0.8 mg l(-1)). Except for the highest concentration tested, zinc exposure did not affect the life-span of C, volutator, although the number of surviving amphipods decreased with increasing concentrations. Life expectancy at the end of the experiment differed at the various zinc exposure concentrations (p < 0.001). Zinc concentrations higher than 0.6 mg l(-1) reduced longevity up to 20% in comparison with controls. Growth was also impaired. The degree of reduction in growth rate increased with increasing metal concentration. Amphipods exposed to 0.2 mg Zn I-I exhibited a reduction of 6.4% in the specific growth rate (SGR), while those grown at 0.4, 0.6, and 0.8 mg Zn l(-1) exhibited reductions in SGR of 8, 9 and 24.6%, respectively. The length of mature amphipods was also reduced following zinc exposure (p < 0.05). Sex ratio was unaffected (p = 0.44), however maturation rates were slightly reduced and fertility was greatly impaired. Survival of ovigerous females and fertility were also affected by zinc when mature amphipods were exposed to these concentrations. The relationship between growth and reproduction as well as the use of growth as an endpoint in ecotoxicological studies is discussed.