There is an urgent need for a greater understanding of the impacts of endocrine disrupting chemicals (EDCs) at the population level. This project will examine reproductive, genetic and population- level consequences of endocrine disruption in fish. The main objective will be to determine for the first time the dynamics of individual reproductive fitness in a group-spawning fish and the impact of endocrine disruption on this breeding system. Naturally breeding populations of wild-type zebrafish will be used in the laboratory as an experimental model.

The distribution of fitness between individuals will be determined in highly replicated group- spawning scenarios by measuring the number, paternity and survival of the offspring. Paternity will be analyzed using DNA fingerprinting. Fish exposed during earlier sensitive developmental periods will be used to assess the impact of EDCs on reproductive fitness in competitive group- spawning scenarios.