Discipline: Biological Sciences
Matthew Mullins - University of the Virgin Islands
The Virgin Islands have been impacted by an invasive seagrass (Halophila stipulacea) as well as two category five hurricanes. In Brewers Bay, St Thomas, VI, the hurricanes uprooted much of the native seagrasses, and H. stipulacea has spread across the sandy-bottomed bay. From a recent study, the invasive seagrass has lowered fish diversity in the bay. This summer we noticed large volumes of detached algae over the shallow Halophila and sandy bottom of the bay. In order determine the effect of this algae on juvenile fish, we compared the density of fish in the seagrass and the sand habitats to habitats impacted by the algae. Transects (30×2 meter) were laid at 13 nearshore locations to determine the amount of juvenile fish. Compared to the sand only, the algae that drifted above the sand quadrupled the abundance of juvenile fish and increased the diversity slightly. The algae that drifted over the H. stipulacea doubled the abundance of juvenile fish, but the diversity remained the same. The large amount of detached algae this summer has increased the abundance and diversity of juvenile fish living in it compared to normal habitats. The detached algae appears to be providing additional structural complexity, additional protection, and possibly a food source for juvenile fish allowing for a higher abundance of juvenile fish in these areas. Our next steps are to determine if there is detached algae and if it has an impact on other bays around St. Thomas and even other Caribbean islands.
Funder Acknowledgement(s): The National Science Foundation (NSF) and University of the Virgin Islands (UVI)
Faculty Advisor: Dr. Stephen Ratchford, email@example.com
Role: I conducted all of the research that was advised by my mentor. This means I conducted all of the field study by swimming the transects and counting the fish. I collected and then analyzed the data with the help of my mentor.