The Environmental Relevance of Laboratory Measured Toxicity Threshold Concentrations of P,p’-Dde in Antarctic Krill (euphausia Superba); A Modeling Assessment Based on Measured Environmental Levels

2. This discrepancy of many orders of magnitude ostensibly suggests that there exists little likelihood of observing toxic effects of p.p’-DDE in wild populations of krill in Antarctica. Modelling persistent organic pollutants (POPs) such as DDE in plankton populations in the natural environment poses particular problems due to seasonal changes in population sizes. The strong seasonal variation in photosynthetically available radiation (PAR) experienced by coastal marine ecosystems in polar regions induces the largest variations in phytoplankton biomass on the planet, and consequently grazer populations such as krill experience large seasonal fluctuations in biomass. Rigorous modelling of DDE and other POP distributions in Antarctic marine biota therefore requires careful treatment of ‘growth dilution’ and ‘digestive concentration’ processes. Here we use a mass-conserving dynamic fugacity model of POP movement in Antarctic marine plankton ecosystems 3 to simulate the distribution of p,p’-DDE in Antarctic food webs. We assess the likelihood of wild krill populations accumulating p,p’-DDE in their lipid to levels associated with toxic responses in Antarctic krill under laboratory conditions. Abiotic environmental p,p’-DDE data is limited to one publication from McMurdo Sound, Antarctica, where relatively high levels of p.p’-DDE (4 x 10