NCEAS Project 9861

Physiological limits on realized patch structure and trophic coupling from krill to diving seabirds

  • James R. Lovvorn

ActivityDatesFurther Information
Sabbatical Fellow5th January 2006—4th January 2007Participant List  

As marine food webs are increasingly altered by climate change and human exploitation, it is often desirable to estimate the amount of prey at one trophic level that is needed to sustain higher trophic levels. Critical to such estimates is the tightness of trophic coupling, or the fraction of prey that are effectively available and eaten by predators. For example, small diving seabirds are limited in dive depth, so that even abundant prey like krill are unavailable unless they come near the surface. Thus, physiological constraints on these predators can make the realized patch structure of available prey quite different from that of the entire prey population. Availability of pelagic prey is also determined by prey behavior, with diel vertical movements that can vary temporally and spatially with bathymetry, light levels, and tides. Overall prey availability may vary predictably with these factors at large scales (fronts) -- however, smaller-scale features (eddies) that concentrate prey into profitable densities are far less predictable, and may not be detected without costly exploratory dives. As a result, much of the prey is never exploited. In this research, I will link models of the foraging energetics of auklets to variations in 3-dimensional dispersion of krill prey over a time series of months and years. In particular, I will explore mechanisms and develop predictive models of how physiological limits on prey availability can control and weaken trophic coupling. Resulting concepts and models will have broad utility in foodweb approaches to marine ecosystem management, for both quantifying prey stocks needed to support top predators, and determining the location and extent of viable foraging habitat.

TypeProducts of NCEAS Research
Journal Article Doak, Daniel F.; Estes, James A.; Halpern, Benjamin S.; Jacob, Ute; Lindberg, David R.; Lovvorn, James R.; Monson, Daniel H.; Tinker, M. Timothy; Williams, Terrie; Wootton, J. Timothy; Carroll, Ian; Emmerson, Mark C.; Micheli, Fiorenza; Novak, Mark. 2008. Understanding and predicting ecological dynamics: Are major surprises inevitable?. Ecology. Pages 952-961.
Data Set Grebmeier, Jacqueline M. 2008. Bivalves in northern Bering Sea. (Online version)
Journal Article Lovvorn, James R.; Grebmeier, Jacqueline M.; Cooper, Lee W.; Bump, Joseph K.; Richman, Samantha E. 2009. Modeling marine protected areas for threatened eiders in a climatically changing Bering Sea. Ecological Applications. Vol: 19(6). Pages 1596-1613.
Journal Article Lovvorn, James R. 2010. Modeling profitability for the smallest marine endotherms: Auklets foraging within pelagic prey patches. Aquatic Biology. Vol: 8. Pages 203-219. (Online version)