Caribbean seagrass beds are becoming increasingly populated by the invasive seagrass Halophila stipulacea that has negative impacts on native seagrass. Restoring herbivore populations, such as the sea urchin, Diadema antillarum, has significantly reduced nuisance algae on many coral reefs in Puerto Rico. D. antillarum can graze heavily on seagrass as well. However, culturing and restoring D. antillarum comes with challenges. In this study, another essential sea urchin, Tripneustes ventricosus, was released to seagrass beds to measure their grazing impacts on the benthic composition. The grazing behaviors of D. antillarum and T. ventricosus were studied in H. stipulacea seagrass beds of Isla Magueyes, Boqueron, and Laurel in Puerto Rico using closed cage systems. The D. antillarum and T. ventricosus were allowed to feed on the H. stipulacea for one month, with photoquadrats being used to record their herbivory once a week. Preliminary findings suggest that D. antillarum and T. ventricosus have the ability to graze H. stipulacea to bare sediment in three weeks. In addition to this, substrate percent cover increased after the inclusion of the herbivores while live Halophila cover decreased. Given the preliminary results of this study, D. antillarum and T. ventricosus may be effective herbivores for restoration efforts. Releasing D. antillarum and T. ventricosus may reduce the invasive seagrass, H. stipulacea, and other competitive algal species on coral reefs in Puerto Rico.

Primary Presenter: Hunter Howard, University of Puerto Rico Mayagüez (hunterbhoward@gmail.com)

Authors:

Hunter Howard, University of Puerto Rico, Mayagüez/ISER-Caribe  (hunterbhoward@gmail.com)

Manuel Olmeda, ISER-Caribe  (molmeda93@gmail.com)

Stacey Williams, ISER-Caribe  (stcmwilliams@gmail.com)

Juan Cruz-Motta, University of Puerto Rico, Mayagüez  (Juan.cruz13@upr.edu)