COS 181-3 - Seascape resiliency is a multi-scale process: Oysters-Chesapeake Bay example

Friday, August 11, 2017: 8:40 AM
E145, Oregon Convention Center
M. Jerry McCormick-Ray, Environmental Sciences, University of Virginia, Charlottesville, VA

The historical resiliency and structural stability of oyster beds have been lost from Chesapeake Bay’s changed benthos. Applying modern concepts of resiliency, natural history, and self-organization to the productive oyster reefs surveyed by Winslow in 1878 suggests that such seascape structures along tidal channels sustained estuarine dynamics, human extractions, and habitat destruction until 1890s when harvest production began a long term decline. That structural resiliency in the 1880s observed at multiple scales is attributed to biological processes of survival that created ecological order, captured and altered kinetic energy, bound materials and nutrients into ecological energy, and through adaptive self-organization processes withstood change. Analysis of Winslow’s spatial data indicates a collective self-organization of oysters into discrete hard bottom beds of variable sizes, arranged in complex spatial and topographic patterns surrounded by soft sediment. Diverse species seeking substrate, food, shelter and opportunity in these rugose seascapes attracted spatially distributed and temporally changing communities. The community and their progeny depend upon hydrodynamics for dispersion and recruitment, connecting with available substrates near and far.


Modern analysis of historical evidence suggests a multi-scale process in the extirpation of oyster reef structure. Results show that oyster communities are linked at local and watershed scales. At large scale, the oyster reef system absorbs long-term change in an adaptive response cycle undetected at smaller scales in complex behavior. Ecological, social and economic services of oysters have declined over an historical Chesapeake Bay timeline of harvest change. Biological thresholds were probably reached at different times and locations in a slow process of change that created uncertainty and surprise in human expectations. Exposure to periods of gradual change interspersed with periods of rapid change resulted in broken linkages and functionally unstable, disconnected oyster beds. Hence, more specifically, the Bay’s ecosystem has lost not only the coupling of pelagic and benthic ecosystems, water filtration and water clarity, it has lost the self organizing capacity of oyster resiliency that relates to changes in the Bay’s biodiversity, material cycling, and ecosystem services historically documented in records.