Examining Parasite Diversity as an Indicator of Ecosystem Restoration Success

Abstract

In oceans across the world, oyster reefs, ecosystems generated by a foundational species of mollusks, are an essential source of habitat where fauna such as fishes, birds, and crustacea depend both indirectly and directly on the organism’s habitat, food availability, and nursery capabilities for their offspring. Due to primarily anthropogenic effects, the Eastern oyster (Crassostrea virginica), found from the Gulf of St. Lawrence to the Gulf of Mexico, has been severely declining in numbers, resulting in impacts being felt across terrestrial and aquatic ecosystems. Because of their foundational role in providing habitat and protection for so many other species spanning multiple different taxa, the loss of these oyster reefs can have a ripple effect through communities. To accurately examine ecosystem health and biodiversity in oyster reef communities, researchers are now exploring an array of sampling schemes. One of these methods gaining in recognition is analyzing parasitic prevalence and diversity as a signal of ecosystem health post-restoration. In previous investigations, scientists have used parasites to examine predator and prey relationships, environmental issues, and coevolution. My study examined the abundance and diversity of crab hosts and the prevalence and diversity of parasites over time to determine whether there were changes in these biodiversity metrics post-restoration. Specifically, I investigated crab species that have been identified as known hosts for taxa-spanning endoparasites, including the Atlantic mud crab Panopeus herbstii, the white-fingered mud crab Rhithropanopeus harisii, the black-fingered mud crab Dyspanopeus sayi, the depressed mud crab Eurypanopeus depressus, and the stone crab Menippe mercenaria. These crabs were collected along Taylor’s Creek at Carrot Island, which is part of the Rachel Carson Reserve near Beaufort, NC. Oyster restoration occurred in late spring 2020, and host-parasite sampling began monthly in October 2020 until October 2021, as part of an ECU master’s thesis, and then continued seasonally through Spring 2024. After collection, crabs were examined in the lab at ECU: crab hosts were identified to species level and then dissected to measure parasite diversity using standard techniques. This project holds significance because global biodiversity is currently facing an unparalleled threat, and with species already reduced to a fragment of the abundance they once were, these ecosystems could be nearing a point of no return without restoring vital habitats like oyster reefs. My data will prove valuable to the scientific community because it can serve as a model for how parasite data can be informative of community biodiversity changes post-restoration, which can be applied in other systems outside of oyster reefs and estuarine environments. From my research, I have acquired an understanding that parasitic abundance can be efficient and accurate when used as another metric for surveying for community biodiversity in ecosystems. There are many challenges and limitations to evaluating community biodiversity and ecosystem health after a restoration attempt has been made; so, having a novel solution like using a highly quantifiable and investigable method of biodiversity surveying (such as parasite surveys from abundant hosts) would allow for results with stronger confidence and evidentiary support.