Predation in Patchy Habitat

Humans-altered ecosystems often experience concurrent declines in keystone predators and the loss and fragmentation of habitat. Whether and how habitat and predator modification interact to affect ecosystem structure and function remains poorly studied. New theory merges island biogeography and food web ecology theory to predict diversity patterns in in patchy landscapes. In this study we empirically test trophic island biogeography theory to quantify how the independent and interactive effects of habitat loss, fragmentation, and predator-prey interactions affect the assembly of coral reef fish communities. Our results demonstrate strong, but independent effects of predation and habitat characteristics in driving reef fish community assembly. Predators (Cephalopholis argus) exhibited an oddity effect – disproportionately consuming rare prey species and reducing fish abundance and biodiversity by ~50%. Additionally, fragmentation caused a 50% increase in reef fish biodiversity. Our findings suggest two independent pathways (i.e., habitat or predator shifts) by which natural and/or anthropogenic processes can drive variation in fish biodiversity and community assembly.

This paper is led by: Adrian Stier (me) (NOAA) and coauthored by Kate Hanson (University of Hawaii), and Russ Schmitt, Sally Holbrook, and Andrew Brooks (all UCSB). Download the paper here on the ESA website or e-mail me (adrian.stier@gmail.com) for a copy of the manuscript.