8/15/2012 12 th International Coral Reef Symposium, July 2012 Key - PDF document

8/15/2012 12 th International Coral Reef Symposium, July 2012 Key interactions on coral reefs Algal growth and coral recruitment: distinguishing fish and urchin effects Wendy A. Cover, Donald C. Potts University of California Santa Cruz Fagatele Bay National Marine Sanctuary indirect effect herbivory competition Key interactions on coral reefs Key interactions on coral reefs indirect indirect effect effect herbivory herbivory competition competition Hawaiian Archipelago The details specific roles relative importance strength of interactions 1

8/15/2012 Midway The primary “herbivores” Atoll protected intact high-latitude How do fishes and urchins differ in their effects on How do fishes and urchins differ in their effects on macroalgal growth and coral recruitment? macroalgal growth and coral recruitment? ? ? vs. Methods Factorial design deployed for 11 mo. Algal biomass Algal species composition Coral recruitment 2

8/15/2012 Fish grazing prevented macroalgal growth Higher urchin densities remove more macroalgae Higher coral recruitment with fish Higher coral recruitment despite higher sediment Direct, negative relationship between macroalgae and Summary coral recruitment p = 0.018 3

8/15/2012 Conclusions Acknowledgments Funding: Fishes are the dominant herbivores on Midway U.S. Fish and Wildlife Service, Midway Atoll Mitsubishi Corporation (Tokyo) – Global Coral Reef Conservation Project EEB Department Fish grazing indirectly promotes coral recruitment National Fish and Wildlife Foundation CDELSI Packard Foundation Every little bit helps: any reduction in macroalgal cover should GANN allow for more coral recruitment UCSC Center for Remote Sensing Lawrence Livermore National Labs Field, Lab, and Analysis help: Kate Schoenrock, Kristin McCully, Anne Warner, Mike Richardson, Thomas Omolo, Mark Carr, Jim Estes, Mike Graham, Pete Raimondi 4