CS39B Zooplankton - Community Dynamics
Date: Wednesday, June 12, 2002
Time: 9:30:00 AM
Location: Sidney
 
Mazzocchi, M, G, Stazione Zoologica, Napoli, Italy, grazia@alpha.szn.it
PaffenhoferGA, Skidaway Institute of Oceanography, Savannah, USA, cmp@skio.peachnet.edu
 
THE EPIPELAGIC TROPICAL OPEN OCEAN: WHICH VARIABLES GOVERN COPEPOD ABUNDANCE AND CO-EXISTENCE
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The tropical open ocean is characterized by highly diversified copepod assemblages in the epipelagial. The objective of our project in the tropical Atlantic is to determine the variables which allow so many species to co-occur in the upper water column. Our first step was to quantify the vertical distribution of juveniles and adults in the 0-100m layer(8 strata), using 63 and 200 micron mesh. Oithona,Oncaea,Calocalanus,Clausocalanus,Paracalanus,Microsetella,Mecynocera occurred in rank order, representing on average 88% of total abundance with 63 micron mesh. Concen= trations of total nauplii, and copepodids and adults of Oncaea and Calocalanus increased with depth, whereas those of Oithona did not. Two taxa strictly avoided the upper 30 to 40m: Mecynocera clausii and Oncaea spp. Very low mean abundances of nauplii(below 0.8 individuals per liter), and copepodids and adults(below 1.5 individuals per liter), scarce occurrence of predators plus behavioral data lead us to hypothesize that feeding habits and vertical partitioning more than predation is governing co-existence of the numerous species.