Hess, N. A.. University of Wisconsin - Madison, nahess@students.wisc.edu
Ribic, C. A.. USGS BRD, caribic@facstaff.wisc.edu
Biggs, D. C.. Texas A&M University, dbiggs@ocean.tamu.edu

 
DISTRIBUTION AND RELATIVE ABUNDANCE OF SEABIRDS IN RELATION TO HYDROGRAPHY AND PRODUCTIVITY IN THE NORTHERN GULF OF MEXICO
 
Cyclonic and anticyclonic rings and their edges have been shown to affect nutrient concentrations and plankton communities, but little work has been conducted to assess their effect on upper-level predators. Our objective was to relate biological productivity to physical processes by investigating the distribution of piscivorous seabirds in the northern Gulf of Mexico. We compared the distribution and relative abundance of several seabird species to hydrographic data from shipboard seabird surveys conducted during October 1996, August 1997 and August 1998 in the northern Gulf of Mexico. We compared seabird presence and absence in strip transects to oceanographic data including: sea surface temperature, sea surface salinity, dynamic height, magnitude of geostrophic flow, and bathymetry. We developed multiple generalized additive models incorporating chemical properties of the sea surface, bathymetry, dynamic topography, indicators of productivity, and surface debris (flotsam and sargassum) to identify which aspects of the marine environment best explain patterns of seabird distribution. We found that seabirds, as mobile marine predators, respond to varied levels of productivity created by cyclonic and anticyclonic rings, the edges of the rings and the plume of the Mississippi River.
 
Day: Thursday, Feb. 4
Time: 11:00 - 11:15am
Location: Hilton of Santa Fe
 
Code: SS04TH1100H