Asian Shore Crab Population Decline at a Marsh Restoration Site in Stratford, Connecticut
Leah Foito is Psychology Major with Neuroscience and Honors minors graduating in 2025.
Abstract
Invasive species like Asian shore crabs (Hemigrapsus sanguineus) can disrupt coastal ecosystems, including restoration efforts. However, comparatively little attention has been given to the effects of restoring habitats on invasive H. sanguineus populations. This study estimated changes in H. sanguineus population size at a restored marsh site in Stratford, Connecticut from 2019 to 2022. Based on previous predation studies, we hypothesized that the H. sanguineuspopulation would decrease as the restored marsh matured. We conducted mark-recapture studies on H. sanguineus at Stratford Point each July in 2019, 2021, and 2022 and measured smooth cordgrass (Spartina alterniflora) density in 2019, 2020, and 2021. We used three common population size equations (Lincoln-Petersen index unmodified and with Bailey and Jolly-Seber modifications for resampling and non-closed populations) to calculate H. sanguineus population size in each year. The H. sanguineus population declined by 24 – 25% over the study period according to all three population size equations, supporting our hypothesis. Cordgrass density increased over the same time span. Since H. sanguineusoccurs mainly in areas with substantial cobble or rock and marshes encourage sediment deposition that can bury rocks, the maturing marsh may be a less suitable habitat for these crabs, reducing their population over time.
Asian Shore Crab Population Decline at a Marsh Restoration Site in Stratford, Connecticut
Digital Commons & West Campus 2nd Floor University Commons
Invasive species like Asian shore crabs (Hemigrapsus sanguineus) can disrupt coastal ecosystems, including restoration efforts. However, comparatively little attention has been given to the effects of restoring habitats on invasive H. sanguineus populations. This study estimated changes in H. sanguineus population size at a restored marsh site in Stratford, Connecticut from 2019 to 2022. Based on previous predation studies, we hypothesized that the H. sanguineuspopulation would decrease as the restored marsh matured. We conducted mark-recapture studies on H. sanguineus at Stratford Point each July in 2019, 2021, and 2022 and measured smooth cordgrass (Spartina alterniflora) density in 2019, 2020, and 2021. We used three common population size equations (Lincoln-Petersen index unmodified and with Bailey and Jolly-Seber modifications for resampling and non-closed populations) to calculate H. sanguineus population size in each year. The H. sanguineus population declined by 24 – 25% over the study period according to all three population size equations, supporting our hypothesis. Cordgrass density increased over the same time span. Since H. sanguineusoccurs mainly in areas with substantial cobble or rock and marshes encourage sediment deposition that can bury rocks, the maturing marsh may be a less suitable habitat for these crabs, reducing their population over time.
