Hurricane impacts on oyster reef habitat in a large, wind-driven estuary

Coastal ecosystems vary in their resistance and resilience to the frequency, intensity, structural characteristics, and path of tropical cyclones. The successive passages of Hurricanes Florence and Dorian, and Tropical Storm Michael during the 2018 and 2019 hurricane seasons coincided with long-term monitoring of water quality and oyster reefs in Pamlico Sound, North Carolina, USA, providing a unique opportunity to examine storm impacts on estuarine ecosystems. Storm characteristics, reef depth, and reef structure strongly influenced outcomes. Deep-water reefs (~4.5–7 m) experienced degraded water quality, heavy sediment burial, and substantial oyster mortality, whereas shallow reefs (~1.5–3 m) in protected embayments exhibited minimal changes in water quality, limited sedimentation, and only minor impacts to oyster density and size structure. Hurricane Florence, a slow-moving, precipitation-heavy storm, caused widespread sediment burial, hypoxia, and near-total loss of oysters on deeper reefs. In contrast, Hurricane Dorian was fast-moving, with strong winds that mixed the water column and minimized oxygen depletion but resuspended sediments that buried low-relief reefs. Management and restoration strategies aimed at resilience to tropical cyclones should explicitly account for reef setting and structure. Deep areas of Pamlico Sound, which naturally accumulate sediment, are particularly vulnerable to storm-driven sediment resuspension that can bury nearby oyster reefs and should be avoided for restoration. Oyster reefs located in relatively shallow depths and embayments sheltered from high wind fetch may provide relatively stable reef structure in response to tropical cyclones. Reef heights are also critical: low-relief reefs are highly susceptible to burial, whereas maintaining a vertical relief of at least 20 cm improves long-term persistence. Continued monitoring and adaptive management are essential as changing storm regimes under climate change increase risks to oyster populations. Incorporating storm vulnerability into restoration planning, preserving no-harvest sanctuaries, and prioritizing resilient reef settings will be key to sustaining oyster populations in dynamic estuarine environments under increasing tropical storm frequency and intensity.