A. Bucklin, E. Ünal, P.H. Wiebe, and N.J. Copley
During 1997, 1998, and 1999, the hydrography of the Gulf of Maine changed dramatically, lagging the precipitous 1996 drop in the NAO index. The presence of cold fresh Labrador Sea water throughout much of 1998 coincided with low abundances of fall diapausing C. finmarchicus. Since population growth of C. finmarchicus in the Gulf of Maine each spring results both from copepods migrating up from deep basin habitats where they overwinter and from transport of newly-emerged adults from adjacent regions, year-to-year variation in abundance may be reflected in the species' population genetic diversity. DNA sequences of genes encoding metabolic enzymes were determined for C. finmarchicus samples during these years. Temporal and spatial patterns of population genetic diversity may help distinguish far-field (principally NAO-driven advective pathways) and near-field (predator-prey and recruitment) processes in causing year-to-year variation in C. finmarchicus abundances in the Gulf of Maine.