Genin, A. Steinitz Marine Biology Laboratory, The Hebrew University, amatzia@vms.huji.ac.il
Jaffe, J. MPL, Scripps Institution of Oceanography, jules@mpl.ucsd.edu
Ayalon, I. Steinitz Marine Biology Laboratory, inbal@vms.huji.ac.il
Ohevia, M. Steinitz Marine Biology Laboratory, moty@vms.huji.ac.il
Lindell, D. Steinitz Marine Biology Laboratory, The Hebrew University, debbie@vms.huji.ac.il

 
ZOOPLANKTIVORY BY CORAL-REEF FISH INVESTIGATED WITH TRADITIONAL NETS AND A NEW DUAL-HEAD SONAR: FLUX-DEPENDENCY, SIZE SELECTIVITY AND COMMUNITY EFFECTS
 
Most of the diurnal zooplanktivorous fish in coral reefs are quasi-stationary, feeding on prey advected in with the flow. Rates of zooplankton predation were measured in situ, from the level of a single fish to the whole community, using both stationary and towed nets and a novel dual-head sonar. While samples taken with nets typically integrate over large time intervals and spatial scales, use of the sonar permitted a precise measurements of instantaneous rates of predation over a large range of prey densities and flow speeds. Using both techniques, individual rates of predation were measured by deploying the nets or the sonar immediately upstream and downstream of fish groups. The results showed that about 50% of the zooplankton passing through the fishes' reactive volume were consumed, exhibiting a nearly-linear relationship between predation rates and prey flux. About 25% of the zooplankton was removed every 0.5 hr from water parcels flowing over the reef slope. The fish were highly selective for large prey resulting in sharp gradients of decreasing zooplankton abundance and smaller body size going from the open sea toward the reef. Zooplanktivory by fish accounts for a major flux of carbon and nutrients into the coral-reef ecosystem.
 
Day: Thursday, Feb. 4
Time: 09:45 - 10:00am
Location: Hilton of Santa Fe
 
Code: SS22TH0945H