| Summary: | Euphausia superba is an Antarctic keystone species and its health has importance for the condition of the entire Antarctic ecosystem. Persistent organic pollutants (POPs) are transported to remote areas such as the polar regions by long range environmental transport. One such toxin is the notorious insecticide DDT, which use has been re-introduced in some southern hemisphere countries. p,p’-DDE is the most stable metabolite of DDT and was a dominant organohalogen contaminant in E. superba sampled across the Eastern Antarctic in 2006. Recently, the behavioural effects of aqueous exposure to p,p’-DDE were demonstrated in adult krill. Behavioural fitness is crucial for the survival of the early life stages of Antarctic krill. Eggs are laid in the surface layer and sink down to about 1km depth where they hatch out, then start ascending, and must reach the surface as they develop into their fourth larval stage calyptopis 1 when they finally start feeding. In this study, larvae of E. superba were exposed to aqueous p,p’-DDE (1-20ug/L nominal) for 10 days post hatching, from nauplius 1 through nauplius 2 to metanauplius. An increased proportion of unresponsive larvae was observed at concentrations as low as 1ug/L, and there was an indication of higher mortality in exposed larvae. Interestingly, upon termination of the experiment, surviving exposed larvae had reached the same larval stage as the controls, although developmental aspects need further examination. These preliminary findings are fundamental for understanding the toxic implications of early life stage exposure of an Antarctic keystone species to one of its main anthropogenic contaminant threats. This study further highlights the need to continue to explore the toxicity of POPs to all life stages of Antarctic krill.
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