Calbet, A. University of Hawaii, acalbet@soest.hawaii.edu
Landry, M. University of Hawaii, landry@soest.hawaii.edu
Scheinberg, R. University of Hawaii, rebeccas@soest.hawaii.edu

 
COPEPOD INGESTION RATES IN A SUBTROPICAL BAY: SPECIFIC RESPONSES TO A MIDSUMMER INCREASE IN THE NANOPLANKTON STANDING STOCK
 
Ingestion rates of four small copepod species were assessed in Kaneohe Bay, Hawaii during a midsummer increase of the pico- and nanoplankton community. None of the copepods (Oithona simplex, O. nana, Acrocalanus inermis and Parvocalanus crassirostris) fed significantly on picoplankton. However, all responded behaviorally to variations in the concentration (0.01 to 0.05 ug C/ml) and size spectrum (relative increase of > 5 um cells) of nanoplankton. The copepods behaved as opportunistic particle feeders, showing higher consumption rates upon the most abundant cells (2-5 um nanoplankton). Maximum ingestion rates were similar for the two calanoids and O. nana (around 80,000 cells/cop/day) and lower for O. simplex (around 40,000 cells/cop/day), but when converted to specific rates (per unit of biomass) O. simplex and P. crassirostris surpassed the rates of the other species. At the highest nanoplankton concentrations, the ingestion rates of copepods were saturated, the daily ration ranging from 35% body C/d for A. inermis to 110 % body C/d for O. simplex and P. crassirostris. These values are low for such small species at high temperature (26-27 degrees C) suggesting that ingestion might be held below potential by the inefficient handling of small cells rather than the physiological constraints of food ingestion.
 
Day: Tuesday, Feb. 2
Time: 02:00 - 02:15pm
Location: Hilton of Santa Fe
 
Code: SS23TU0200H