Importance of Feeding, Direct Uptake from Seawater, and Transfer from Generation to Generation in the Accumulation of an Organochlorine (p,p′-DDT) by the Marine Planktonic Copepod Calanus finmarchicus

Abstract
The accumulation of an organochlorine by the marine copepod Calanus finmarchicus, through feeding on contaminated phytoplankton, 14C-p,p′-DDT labeled Thalassiosira weisflogii, was measured. At "normal" densities, ≈ 60 μg C/L, the copepod retained 60–70% of the DDT ingested following gut egestion, but under "bloom" conditions, ≈ 600 μg C/L, retained as little as 10%. These results enable us to incorporate feeding and generation transfer terms into an earlier model of DDT flux between seawater and planktonic crustaceans. Model simulations indicate that it is not necessary to invoke direct uptake from seawater to arrive at published levels of ΣDDT in copepods, even when our lowest experimental DDT feeding efficiencies are used. We predict that the potential for rapidly developing Calanus to accumulate DDT from generation to generation will reach an equilibrium concentration after 12 generations but that an alternating equilibrium of generations will occur within four generations in a two-season temperature environment.Key words: p,p′-DDT, uptake, clearance, feeding, assimilation, copepods, Calanus finmarchicus

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