|Tim Verslycke, Endocrine Disruption in the estuarine invertebrate Neomysis integer (Crustacea: Mysidacea), 2003|
The aim of this doctoral study was to investigate endocrine disruption in an ecologically relevant invertebrate test species, the mysid shrimp Neomysis integer (Crustacea: Mysidacea), through laboratory and field research. More specifically, the steroid and energy metabolism of N. integer were explored as endpoints to evaluate environmental endocrine disruption.
The thesis consists of 12 chapters, starting with an introduction to the environmental endocrine hypothesis and the conceptual framework of the study. Next, a global assessment is given of the state-of-the-science on endocrine disruption in mysid shrimp. In the third chapter, a new methodology (cellular energy allocation, CEA) to assess the energy budget was adopted for N. integer. In chapter 4, the CEA methodology was evaluated following acute exposure to the antifoulant tributyltinchloride (TBTCl). In chapter 5, the responses of N. integer following exposure to environmentally realistic concentrations of the organophosphate pesticide chlorpyrifos were compared using the CEA and scope for growth (SFG) assays. In chapter 6, testosterone metabolism by N. integer was assessed to obtain initial data on the metabolic capacity. In chapter 7, the effects of TBTCl on the phase I and phase II testosterone metabolism of N. integer were evaluated. In chapter 8, a diverse set of reference compounds suspected of having an endocrine-disrupting mode of action were tested for acute toxicity. In addition, the short-term sublethal effects of methoprene and nonylphenol on the energy and steroid metabolism of N. integer were evaluated. In chapter 9, sediment and mysids (N. integer) from the Scheldt estuary, one of the largest and most polluted estuaries in Western Europe, were analyzed for a number of endocrine disruptors. In chapter 10, the seasonal and spatial patterns in cellular energy allocation of N. integer were investigated in the Scheldt estuary over a 2-year period. In chapter 11, the applicability of the testosterone metabolism assay in N. integer was investigated under field conditions in the Scheldt estuary. In chapter 12, general conclusions and future perspectives of this doctoral study were formulated.
This doctoral study demonstrated that hormone-regulated processes in N. integer can be disrupted by acute exposure to chemicals at environmentally relevant concentrations. http://hdl.handle.net/1854/295