BENTHIC FORAMINIFERA AS A TOOL FOR MONITORING ESTUARINE HEALTH: HOW SPATIAL AND TEMPORAL VARIATION IN FORAMINIFERAL ASSEMBLAGES RECORD HISTORY OF HUMAN ACTIVITIES WITHIN THE MATAGORDA BAY SYSTEM

The Lavaca-Colorado (Matagorda Bay) estuarine system has been impacted by regional water usage, human-mediated diversions of the Colorado River, agricultural runoff, and industrial contamination. To examine the spatial and temporal ecological consequences of these impacts, we analyzed fossils preserved in six sediment cores spanning the last ~100-200 years with attention to assemblage differences before and after ~1950 CE. Benthic foraminiferal fossil assemblages, comprised of the shelly remains of these single celled protists, successfully recorded environmental changes consistent with the location of the studies sites. The core nearest the diverted outflow of the Colorado River showed faunal changes consistent with freshening, the core nearest an EPA Superfund site had greatest abundance of stress-tolerant species, three sites impacted by agricultural runoff showed faunal shifts indicating changes in oxygen, and the most hydrologically isolated site showed no significant changes before and after 1950. These data show the utility of using benthic foraminifera assemblages to assess ecosystem health and as a spatially informative environmental monitoring tool in estuaries.

In future work, we plan to apply similar methodologies to understand ecosystem change in Chesapeake Bay driven by anthropogenic impacts. The Chesapeake Bay is the largest estuary in the United States and has been directly impacted by human activities for centuries, such as extensive industrial pollution, agricultural runoff, and associated seasonal hypoxia. In addition to assemblage analysis, we plan to test and apply geochemical proxies to create a more robust analysis of potential drivers of ecosystem health.