Using native food webs to reduce impacts of non-native predators and increase success of native Olympia oyster restoration

R/HCE-03
Start/End: February, 2018 to February, 2020

Ongoing restoration projects in California are working to restore oyster populations that have been reduced by overharvesting, loss of habitat, and non-native pests including predatory non-native whelks (oyster drills).  The goal of this project is increase restoration success by creating more complete food webs with increased populations of native cancrid crabs that may reduce oyster losses to whelks.

The specific aim of this project is to experimentally determine the most effective methods for enhancing the abundance of rock crabs around oyster restoration structures in San Francisco Bay.  Increased abundances of these large predatory crabs would can predation by whelks on native oysters, either indirectly by behaviorally restricting whelk predation on oysters, or directly by consuming whelks and reducing their predation.  

The project will experimentally test a range of possible restoration structures that could efficiently increase the abundances of cancrid crabs and, in the process, quantify both the direct and indirect effects of cancrid crabs on whelk predators of oysters and their impacts on oysters.

Results from the project will be used to refine an online tool for oyster restoration site selection. The information produced by this project will directly benefit oyster restoration practitioners and resource agency staff working to restore oysters in San Francisco Bay.

Co-principal Investigators