Distribution patterns of marine debris along the Delaware coastline and impacts on shoreline organisms
Date
2024
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Publisher
University of Delaware
Abstract
Understanding the source, fate, and transport of shoreline debris is critical due to its ecological impacts and propensity to accumulate on coastlines, where it negatively affects the intertidal ecosystem through direct ingestion by organisms and bioaccumulation. Furthermore, macroplastic, which constitutes much of this debris from both land- and water-based sources, contributes to microplastic accumulation in waterways. Therefore, determining the spatial and temporal distribution of macroplastic debris and gleaning more information on the impacts to organisms is of the utmost importance. ☐ Analyzing data from International Coastal Cleanup events from 2016-2021 along the Delaware Bay coastline, I assessed the spatial and temporal distribution of marine debris, focusing on total weight and item count. To measure item size and polymer composition, I used data from clean-ups at Augustine Beach, Port Mahon, and Lewes Beach in fall 2021 and spring 2022. I measured the length and polymer composition of 100 plastic debris items from these locations, assigned a characteristic size and polymer to each category, and applied these findings to define a shoreline debris gradient in the Delaware Bay. Results suggest greater size, weight, and item count in up-estuary locations compared to down-estuary ones. However, polymer type and buoyancy were consistent throughout the coastal locations along the Delaware Bay shoreline. Additionally, the total weight and abundance of marine debris remained consistent over the study period from 2016-2021. ☐ Additionally, I conducted a behavioral assay of the wrack-associated amphipod Platorchestia platensis at the three locations to investigate the correlation between plastic body burden and scototaxis response, using µFTIR to confirm the presence of plastic particles. Platorchestia platensis behavioral responses mirrored spatial patterns observed on the Delaware Bay coastline, with stronger responses in down-estuary locations and weaker responses in up-estuary locations where marine debris abundance is higher. However, no correlation was observed between plastic body burden and amphipod behavioral response. ☐ On shorelines, where the characteristics of marine debris and macroplastic are highly variable, the impacts on the ecosystem are expected to increase. Although the direct impact of short-term microplastic ingestion on amphipods in their natural environment remains unclear, the presence of marine debris still appears to have significant impacts. Understanding the spatial distribution of debris can further enhance the effectiveness of management practices, and continued efforts to understand and manage marine debris are essential for protecting coastal ecosystems.
Description
Keywords
Delaware Bay coastline, Macroplastic debris, Platorchestia platensis, Scototaxis, Coastal ecosystems