GEOSPATIAL ANALYSIS OF ECOLOGICAL ASSOCIATIONS AND SUCCESSIONS IN MIDDLE DEVONIAN BIOHERMS OF THE GREAT LAKES REGION

Corals and stromatoporoids often built biohermal complexes, which preserve intrinsic and extrinsic controls, dictating reef development. Devonian bioherms from the Appalachian, Michigan, and Illinois Basins were evaluated to compare community compositions and detect similarities between successional buildups and localities. Species abundances, environmental parameters, and successional models described reef morphology and development within and between basins. Localities were analyzed by taking photographs, documenting environmental parameters, and identifying organisms to a species level. Photographs included 1m² quadrats, used in Coral Point Count with Excel extensions (CPCe) to acquire total percent of coral-stromatoporoid species as a proxy for abundances. Data matrices were created to run diversity indices, cluster analyses and multivariate techniques to interpret intrinsic and extrinsic controls affecting bioherms. Intrinsic factors, include species present and community interactions between organisms. Extrinsic controls such as lithology, grain size, and environmental energy, largely affect the construction of reefs. Cluster analyses demonstrate extrinsic controls such as biogenic carbonate texture and basin type dictate community composition. Ordination techniques revealed the importance of lithology, biogenic carbonate texture and substrate type as the driving forces during reef development. Investigation of bioherms in the Great Lakes region were used in a comparative approach to recognize spatial and temporal trends. Documentation of coral-stromatoporoid biohermal complexes provide a better understanding of reef ecology, biodiversity, and evolution during the supergreenhouse climate of the Middle Devonian.