SHALLOW MARINE BENTHIC COMMUNITIES OF THE SUNDANCE SEA: A POTENTIAL ANALOG FOR SEAFLOOR ECOSYSTEMS UNDER STRESS DRIVEN BY CLIMATE CHANGE

As climate change continues to stress Earth’s ecosystems, there is an emergent need for analyzing the effects on shallow marine systems, especially in ways that are not immediately apparent. Marine benthic communities potentially serve as an appropriate secondary biological indicator of climate change as they tend to be more resistant to changes in their ecosystems than organisms in more frequently studied reef environments. Modern analogs that showcase the long-term effects of climate change on benthic communities are not well studied, however the marine deposits of the Jurassic Sundance Formation (SF) serve as a potential paleo-analog for shallow marine benthic communities undergoing the stress of a rapidly changing climate. Ichnology and sedimentology were studied in several SF outcrops in Eastern and Central Wyoming. The shallow marine environments of the Upper Sundance Formation and Pine Butte Member of the SF include several instances of Ophiomorpha, ichnofossils which are agreed to have been created by crustaceans which require well-oxygenated waters. Ichnofossils of the Redwater Shale (RS), however, include trace fossils such as large Rhizocorallium and Bergaueria, but Ophiomorpha is absent. The presence of glauconite in the RS suggests warm seawater with minimal clastic input and the clear lack of Ophiomorpha is consistent with decreased oxygen in the sea, potentially caused by warmer temperatures. Abundant storm bed deposits in the RS also suggest an increase in storm activity driven by this increase in temperatures. These interpretations are supported by and bolster interpretations of increasing temperature derived from δ18O Paris Basin oyster shells. This research exhibits the importance of studying ancient benthic and infaunal communities to predict the effects of climate change on modern communities and shallow marine ecosystems.