12-1PM EST Monday January 27, 2014 NOAA Central Library, 2nd Floor SSMC3
MEASURING AT RELEVANT SCALES: HOW WHELKS RESPOND TO DIFFERING PREY LEVELS ACROSS REGIONS AND YEARS
Will Tyburczy, NOAA Policy, Planning and Integration
Many multi-species models assume that the reproduction and mortality of predators relate directly to their immediate feeding rate and local prey abundance. Similarly, many empirical investigations measure short-term feeding rates of predators and extrapolate reproductive consequences. However, for annually reproducing species, where predation and reproduction occur on very different timescales, the validity of these assumptions remains in question. From 2009-2012, I measured growth, survival, and reproduction of the predatory whelk, Nucella ostrina, both in caged manipulations across Oregon and Washington, and in naturally isolated populations in Washington. Whelks were exposed to a range of prey abundances. Analysis revealed an effect of barnacle abundance on whelk growth, and a correlation between growth and reproduction, but showed no discernable relationship between barnacle abundance and whelk reproduction. A literature search also revealed large regional variation N. ostrina survival rates. The results demonstrate the value of conducting research at larger spatial and temporal scales.