Scott Thomas Eanes

Thesis Abstract

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The majority of Caribbean hawksbill sea turtle (Eretmochelys imbricata) research in the United States Virgin Islands (USVI) has centered around the island of St. Croix. However, on the island of St. Thomas in the northern USVI, there is a vital juvenile and sub-adult foraging habitat.  This foraging habitat extends between Brewer’s Bay and Hawksbill Cove, which was created by the extension of the Cyril E. King (CEK) airport runway. The runway extension project, completed in 1992, led to an artificial reef habitat that is both unique and a crucial developmental area for juvenile and sub-adult critically endangered Caribbean hawksbill sea turtles. In the Spring of 2014, benthic surveys examined two factors along the runway, composition of sessile benthic communities, and crevice size. Sessile benthic composition and crevice size being the two factors most responsible for linking hawksbill turtle hourly habitat usage to artificial reef. The CEK marine habitat was then divided into five sections and five acoustic receivers were placed around the artificial habitat to maximize acoustic coverage. Six hawksbill sea turtles were subsequently hand captured and acoustically tagged, with two turtles transmitting depth data. Animals were tracked for a minimum of 100 days. Analysis of crevice size and benthic sessile composition (BSC) concluded statistically larger crevices in runway sections with concrete dolos and BSC changing with depth. The calculated hourly habitat usage concluded a minimum of at least 3hrs/per day to a maximum of over 9hrs/per day along the CEK habitat. Turtles transmitting depth data had an average depth of three meters.  The overwhelming conclusion is juvenile hawksbill turtles along the CEK utilize sections with large concrete dolos.