USING BERYLLIUM 7 TO DETERMINE SEASONAL SEDIMENT AND ORGANIC MATTER DEPOSITION IN A SEAGRASS BED ON THE NORTH CAROLINA COAST

Seagrasses are increasingly recognized for the ecological services they provide, including their role as blue‑carbon ecosystems. While much of the existing research has focused millennial‑scale sedimentary records, far less is known about short‑term sedimentation within these systems. Here, we use the short‑lived radioisotope Beryllium-7 (7Be) to quantify seasonal sediment dynamics in a seagrass meadow in Core Sound, North Carolina. Monthly cores were collected from one site and 7Be inventories were used to determine whether deposition or erosion occurred between samplings. Our results show that 7Be is an effective tracer for detecting short‑term changes in sediment supply, revealing that deposition within the bed is episodic in nature. Mass accumulation estimates produce a high estimation of annual deposition rate compared to nearby rates calculated with 210Pb radiometric dating. These findings demonstrate that seagrass beds can undergo significant short‑term sediment fluctuations, even in the absence of major storm events, and highlight thresholds of deposition and erosion relevant to meadow stability.