Daly, K. L. National Science Foundation, kdaly@nsf.gov
Hofmann, E. L. Old Dominion University, hofmann@ccpo.odu.edu
Fraser, W. R. Montana State University, ubiwf@montana.edu
Ribic, C. A. US Department of Interior, caribic@facstaff.wisc.edu
Ainley, D. G. H.T. Harvey and Associates, harveyecology@att.net
Hopkins, J. L.. University of South Florida, jtorres@marine.usf.edu
Torres, . J. University of South Florida, jtorres@marine.usf.edu

 
DIRECT AND INDIRECT EFFECTS OF PREDATOR-PREY INTERACTIONS: COUPLING FIELD OBSERVATIONS AND A SPATIALLY-DEPENDENT MODEL
 
Predation is an important factor influencing the behavior of individuals and may play a central role in governing the structure and dynamics of marine populations. Here we examine the impact of predators on the Antarctic krill, Euphausia superba, in the Scotia-Weddell marginal ice zone ecosystem during autumn, winter, and spring. Twenty-six predators of larval krill and forty-two predators of juvenile and adult krill were identified based on observed or published accounts of gut contents of predators. The seasonal predation on different life-history stages of krill will be assessed using a model which incorporates the observed predator and krill distributions and predator consumption rates derived from bioenergetic requirements and seasonal diet composition and feeding behavior. Preliminary results indicate that the risk of predation for krill was highest during winter near the ice edge and that the highest spatial overlap between krill and predators occurred along the ice edge and not across the marginal ice zone. Predators also appeared to indirectly influence the behavior of krill. Swarming behavior by juvenile and adult krill increased in the presence of higher predator abundance. Larval krill that remain on the undersurface of ice floes during winter may experience a lower risk of predation.
 
Day: Wednesday, Feb. 3
Time: 02:45 - 03:00pm
Location: Hilton of Santa Fe
 
Code: SS20WE0245H