Revealing the extent of sea otter impacts on bivalve prey through multi-trophic monitoring and mechanistic models.

Autor: Leach CB; Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado, USA., Weitzman BP; U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, Alaska, USA., Bodkin JL; U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA., Esler D; U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA., Esslinger GG; U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA., Kloecker KA; U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA., Monson DH; U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA., Womble JN; Southeast Alaska Inventory and Monitoring Network, National Park Service, Juneau, Alaska, USA.; Glacier Bay Field Station, National Park Service, Juneau, Alaska, USA., Hooten MB; Department of Statistics and Data Sciences, The University of Texas at Austin, Austin, Texas, USA.
Jazyk: angličtina
Zdroj: The Journal of animal ecology [J Anim Ecol] 2023 Jun; Vol. 92 (6), pp. 1230-1243. Date of Electronic Publication: 2023 Apr 20.
DOI: 10.1111/1365-2656.13929
Abstrakt: Sea otters are apex predators that can exert considerable influence over the nearshore communities they occupy. Since facing near extinction in the early 1900s, sea otters are making a remarkable recovery in Southeast Alaska, particularly in Glacier Bay, the largest protected tidewater glacier fjord in the world. The expansion of sea otters across Glacier Bay offers both a challenge to monitoring and stewardship and an unprecedented opportunity to study the top-down effect of a novel apex predator across a diverse and productive ecosystem. Our goal was to integrate monitoring data across trophic levels, space, and time to quantify and map the predator-prey interaction between sea otters and butter clams Saxidomus gigantea, one of the dominant large bivalves in Glacier Bay and a favoured prey of sea otters. We developed a spatially-referenced mechanistic differential equation model of butter clam dynamics that combined both environmental drivers of local population growth and estimates of otter abundance from aerial survey data. We embedded this model in a Bayesian statistical framework and fit it to clam survey data from 43 intertidal and subtidal sites across Glacier Bay. Prior to substantial sea otter expansion, we found that butter clam density was structured by an environmental gradient driven by distance from glacier (represented by latitude) and a quadratic effect of current speed. Estimates of sea otter attack rate revealed spatial heterogeneity in sea otter impacts and a negative relationship with local shoreline complexity. Sea otter exploitation of productive butter clam habitat substantially reduced the abundance and altered the distribution of butter clams across Glacier Bay, with potential cascading consequences for nearshore community structure and function. Spatial variation in estimated sea otter predation processes further suggests that community context and local environmental conditions mediate the top-down influence of sea otters on a given prey. Overall, our framework provides high-resolution insights about the interaction among components of this food web and could be applied to a variety of other systems involving invasive species, epidemiology or migration.
(© 2023 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.)
Databáze: MEDLINE
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