In recent decades, goals for the restoration of eastern oyster (Crassostrea virginica) populations along the eastern coast of the United States have shifted from increasing harvestable oyster fisheries to enhancing the range of ecosystem services provided by oyster reefs. By filtering large volumes of water and releasing nutrient-rich feces and pseudofeces, oysters can locally enhance sediment biogeochemical cycling compared to that of unstructured benthic environments. An ongoing restoration program in Mosquito Lagoon, FL was leveraged to assess the immediate impacts ( < 1 year) of restoration on sediment biogeochemical properties of oyster reefs. The first study measured both short-term and long-term pools of carbon, nitrogen and phosphorus on dead, natural and restored reefs periodically over one year. The second study investigated one of the contributions to sediment nutrient pools by comparing feeding and feces/pseudofeces nutrient content of juvenile and older oysters. Results show that inorganic nitrogen and phosphorus pools can change within weeks after restoration and total nutrient pools by 6 months post-restoration. Restored reefs experienced a 136 % increase in ammonium, 78 % increase in total nitrogen, 46 % increase in total phosphorus, and 75 % increase in organic matter concentrations after 12 months of restoration. These nutrient increases were all positively correlated with oyster density, shell length and reef height measured on each reef. When standardized to grams of dry tissue weight, juvenile oysters showed significantly higher rates of chlorophyll-a removal, release of ammonium, and biodeposits with higher concentrations of dissolved organic carbon, nitrite + nitrate, and ammonium. The short-term changes to biogeochemical cycling on eastern oyster reefs within the first year of restoration are important to managers seeking to monitor ecosystem service recovery and overall coastal ecosystem health.
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Master of Science (M.S.)
College of Sciences
Length of Campus-only Access
Masters Thesis (Campus-only Access)
Locher, Bryan, "Understanding Sediment Biogeochemistry and the Role of Juvenile Oysters on Recently Restored Eastern Oyster Reefs" (2019). Electronic Theses and Dissertations. 6523.