Comparison of Benthic Assemblages in Native vs. Invading Seagrass Beds

Undergraduate #221
Discipline: Ecology Environmental and Earth Sciences
Subcategory: Geosciences and Earth Sciences

Lauren Arnold - University of the Virgin Islands

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Halophila stipulacea is a non-native seagrass, which was introduced into the Caribbean at Grenada in 2002 from the Western Indian Ocean. Since then it has been recorded in many Eastern Caribbean islands including St. Thomas. One study concluded that this invading seagrass could outcompete the native seagrasses. Syringodium filiforme and Halodule wrightii are seagrasses native to the Caribbean Sea and found in the shallow waters of Brewers Bay. The purpose of this research was to determine some impacts of this invasion by examining the possible differences in the benthic fauna in the native and invading seagrasses. We suction sampled 0.1m2 areas haphazardly in 10 native, invading and mixed seagrass beds. In the lab, the samples were thoroughly examined; the organisms and seagrasses were extracted. The organisms were identified by major taxonomic group. The seagrasses were identified by species and separated into detritus ‘brown’ and live ‘green’, the dry weights of each sample were taken. There was no significant difference in the number of organisms and the faunal diversity in the different seagrass habitats. Fauna included clams, crabs, shrimp, worms, fish, snails, and many more. There was more detritus in Halophila beds than in Syringodium beds. Sampled fauna still need to be more precisely classified. The effects of H. stipulate on turtle grass Thalassia testudinum, bare sand patches and deeper areas need to be studied.

Funder Acknowledgement(s): This research was supported in part by the National Science Foundation’s Virgin Islands Experimental Program to Stimulate Competitive Research (VIEPSCoR award #1355437) and the Center for Marine and Environmental Studies at the University of the Virgin Islands. NSF HBCU-UP Grant #1137472.

Faculty Advisor: Stephen Ratchford,