Feeding behavior of newly settled winter flounder (Pseudopleuronectes americanus) on calanoid copepods

Field and laboratory investigations were conducted to examine feeding by ne wly settled winter flounder (Pseudopleuronectes americanus) on two co-occur ring calanoid copepods, Eurytemora affinis and Acartia hudsonica. During th e spring, these prey are present when winter flounder initiate their demers al lifestyle in estuaries of the northeastern United States. Epibenthic zoo plankton were collected concurrently with winter flounder in the Navesink R iver estuary, NJ, in May 1998 and 1999. Although both calanoid species were in the estuary during the 2-year survey, E. affinis was consumed nearly to the exclusion of A. hudsonica by newly settled winter flounder. Annually, E. affinis and A. hudsonica had similar size distributions in field collect ions, indicating that species choice was not size selective. However, when preying on E. affinis, winter flounder preferred the larger sized organisms . In single species laboratory experiments, E. affinis and A. hudsonica wer e consumed equally by newly settled winter flounder (19-23 mm TL), but ther e were more strikes made toward E. affinis. Despite the lower catch efficie ncy, E. affinis was selected over A. hudsonica when the prey species were o ffered together in equal numbers. The selection for E. affinis over A. huds onica by newly settled winter flounder may be the result of behavioral and/ or morphological differences in the prey species. (C) 2001 Elsevier Science B.V. All rights reserved.