River Inflow Effects on Structure and Function of Two Texas Estuaries

River inflow and nutrient loading to an estuary contribute greatly to estuarine water quality and ecosystem health, and in some estuaries, poor health, reduced productivity, and even losses of coastal wetlands have been linked to modifications in freshwater input. Given the rapid development in Texas and the stateas plans for water diversion along the coast, an understanding of the importance of natural variation in freshwater inflow events to estuaries is needed. From 2005-2006 we conducted monthly samplings in the Guadalupe (i.e. San Antonio Bay) and Trinity-San Jacinto (i.e. Galveston Bay) estuaries to map water quality at a high spatial resolution and sample fixed stations along the estuarine gradient for nutrient content and water column productivity. Variations in river inflow conditions during this period yielded a range of spatial patterns in surface water quality with consistently strong negative correlation between CDOM and salinity and positive correlation between chlorophyll a and CDOM. We also observed strong river source signals of nitrogen and phosphorus from these different watersheds and consistent, net autotrophic conditions in the water column of both estuaries.