Influence of sea level on the growth and composition of intertidal oyster reefs Public Deposited

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  • March 21, 2019
Creator
  • Ridge, Justin
    • Affiliation: College of Arts and Sciences, Department of Marine Sciences
Abstract
  • Oyster reefs play an important role in the estuarine landscape but have been globally decimated over the past century from overharvesting, deteriorating water quality, and disease. Expanding our knowledge of how these habitats are responding to anthropogenic and climate driven changes will help improve management strategies. This work explored the growth and composition of intertidal oyster reefs in the euhaline estuaries of North Carolina using high-resolution mapping (terrestrial lidar), density sampling, and cores of reefs. The first chapter examined mature, constructed patch reefs (isolated on sandflats) to elucidate that oyster reef growth is strongly linked to specific elevation ranges within the intertidal zone. Building upon these findings, the second chapter determined this pattern holds true on marsh-fringing reefs, and as the reefs transgress the marsh with sea-level rise (SLR) they also protect carbonaceous marsh sediment from erosion. The third chapter observed reefs of varying age, both constructed and natural, over five years to discover that oyster reefs are in a dynamic equilibrium with sea level, responding rapidly (< 1 year) to fluctuations in sea level. Similarly, examining oyster reefs across time scales, from ancient reefs (~4,000-2,000 years old) to extant natural reefs (150 years old) and recently constructed reefs (5-10 years old), chapter four provided evidence that oyster reefs exhibit catch-up and keep-up growth phases tied to SLR, which was first described for coral reefs. Within this context, reefs experience exceptional rates of shell production and organic carbon accumulation while catching up to sea level, but these values are at least a magnitude less in reefs that are keeping up with sea level. Burial of ancient reefs is likely a result of estuarine changes related to the migration of adjacent barrier islands, indicating oyster reefs existing near the limits of suitable conditions could be fatally impaired by estuarine modifications, either anthropogenic (inlet and river dynamics) or climate driven (storms).
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  • In Copyright
Advisor
  • Piehler, Michael
  • Rodriguez, Antonio
  • McKee, Brent
  • Grabowski, Jonathan
  • Fodrie, F. Joel
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2017
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