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Event Type
Research Presentation
Academic Department
Biology
Location
Dana Science Building, 2nd floor
Start Date
14-4-2023 1:30 PM
End Date
14-4-2023 3:00 PM
Description
Under the direction of Dr. Renee Godard
The introduction of Halophila stipulacea, an invasive sea grass species, has impacted grass bed composition in the Caribbean, reducing the presence of the native turtle grass, Thalassia testudinum. These changes in grass bed composition could have impacts on grazers such as Chelonia mydas, green turtles, who in turn could modulate grass bed structure through their foraging behavior. In June 2022, we sampled the composition of grass beds and foraging sites of green turtles in five bays (Francis, Maho, Salt Pond, Great Lameshur and Waterlemon) located on St. John (U.S. V.I.). Photo transects taken across each grass bed were compared to the exact foraging locations of all juvenile and sub-adult Chelonia mydas. While grassbed transects were dominated by Halophila, foraging transects had significantly higher abundance of the three native sea grass species. When foraging transects of juvenile turtles were compared to those of the sub-adults, we found that juvenile foraging transects had significantly less turtle grass and significantly more manatee grass than did the sub-adults. In addition, Halophila was more common in juvenile turtle transects, though this difference was not significant. Our results are similar to those found in other regions of the Caribbean and could indicate that turtles may act as an agent to increase the abundance of the invasive grass (enemy release hypothesis). However, the differences in foraging choices made by juvenile and sub-adult turtles is intriguing and may indicate the potential for juvenile turtles to acquire a taste for the non-native invader.
Foraging patterns of juvenile and sub-adult green turtles (Chelonia mydas) in sea grass meadows dominated by an invasive seagrass
Dana Science Building, 2nd floor
Under the direction of Dr. Renee Godard
The introduction of Halophila stipulacea, an invasive sea grass species, has impacted grass bed composition in the Caribbean, reducing the presence of the native turtle grass, Thalassia testudinum. These changes in grass bed composition could have impacts on grazers such as Chelonia mydas, green turtles, who in turn could modulate grass bed structure through their foraging behavior. In June 2022, we sampled the composition of grass beds and foraging sites of green turtles in five bays (Francis, Maho, Salt Pond, Great Lameshur and Waterlemon) located on St. John (U.S. V.I.). Photo transects taken across each grass bed were compared to the exact foraging locations of all juvenile and sub-adult Chelonia mydas. While grassbed transects were dominated by Halophila, foraging transects had significantly higher abundance of the three native sea grass species. When foraging transects of juvenile turtles were compared to those of the sub-adults, we found that juvenile foraging transects had significantly less turtle grass and significantly more manatee grass than did the sub-adults. In addition, Halophila was more common in juvenile turtle transects, though this difference was not significant. Our results are similar to those found in other regions of the Caribbean and could indicate that turtles may act as an agent to increase the abundance of the invasive grass (enemy release hypothesis). However, the differences in foraging choices made by juvenile and sub-adult turtles is intriguing and may indicate the potential for juvenile turtles to acquire a taste for the non-native invader.