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Event Type
Research Presentation
Academic Department
Biology, Environmental Studies
Start Date
5-4-2021 12:00 AM
End Date
8-4-2021 12:00 AM
Description
Sea grass meadows are critical foraging habitat for sub-adult and adult green turtles (Chelonia mydas). Until recently, seagrass meadows in St. John (STJ), USVI were dominated by three native Caribbean seagrasses: Thalassia testudinum, Syringodium filiforme, and Halodule wrightii. An invasive sea grass species was introduced to the Caribbean in 2002 and first appeared in STJ in 2010. We evaluated the extent of the invasion of H. stipulacea by sampling grassbed composition at regular intervals along a transect line in five different seagrass meadows in STJ in January 2020. Snorkelers took a 25 cm2 photo of the grassbed along the transect line as well as at identified foraging sites of turtles in each of the five bays. Each photo transect was evaluated separately by four individuals who identified and counted each blade of grass and an average abundance of each species was calculated. H. stipulacea accounted for more than half of all seagrass blades/transect in three of the five bays and was at least 30% of blades in the other two bays. However, H. stipulacea was significantly less common in the foraging sites when compared to transect sites, and native grasses were more abundant in foraging sites than in transect sites. Our results indicate that H. stipulacea has rapidly colonized multiple seagrass meadows in STJ and that the foraging preferences of green turtles may facilitate the expansion of the invasive species in the future.
Green Turtles (Chelonia mydas) prefer foraging locations with reduced abundance of the invasive sea grass, Halophila stipulacea
Sea grass meadows are critical foraging habitat for sub-adult and adult green turtles (Chelonia mydas). Until recently, seagrass meadows in St. John (STJ), USVI were dominated by three native Caribbean seagrasses: Thalassia testudinum, Syringodium filiforme, and Halodule wrightii. An invasive sea grass species was introduced to the Caribbean in 2002 and first appeared in STJ in 2010. We evaluated the extent of the invasion of H. stipulacea by sampling grassbed composition at regular intervals along a transect line in five different seagrass meadows in STJ in January 2020. Snorkelers took a 25 cm2 photo of the grassbed along the transect line as well as at identified foraging sites of turtles in each of the five bays. Each photo transect was evaluated separately by four individuals who identified and counted each blade of grass and an average abundance of each species was calculated. H. stipulacea accounted for more than half of all seagrass blades/transect in three of the five bays and was at least 30% of blades in the other two bays. However, H. stipulacea was significantly less common in the foraging sites when compared to transect sites, and native grasses were more abundant in foraging sites than in transect sites. Our results indicate that H. stipulacea has rapidly colonized multiple seagrass meadows in STJ and that the foraging preferences of green turtles may facilitate the expansion of the invasive species in the future.
Comments
Under the direction of Renee Godard and Morgan Wilson.