Effect of freshwater inflow on macrobenthos in minor bays and river-dominated estuaries collected from 2000-10-04 to 2005-08-06, Texas

This dataset contains data showing the effect of freshwater inflow on macrobenthos in minor bays and river-dominated estuaries collected from 2000-10-04 to 2005-08-06 along the Texas coast. This study compared the impact of different freshwater inflow volumes on benthic communities and water column dynamics in different estuary classes. Benthic and water column spatial dynamics were contrasted in lagoons (with no direct inflow sources), tidal rivers that empty directly into the Gulf of Mexico, and bar-built estuary systems (with direct inflow sources and connections to the sea) along the Texas (USA) coast to determine the role of inflow in regulating ecosystem structure and function. Chlorophyll-a and nutrient concentrations were inversely correlated with salinity and were thus highest in the river systems, but lowest in lagoons. All Texas estuary types studied have conservative mixing for silicate and are sinks for nitrite plus nitrate and phosphate. In contrast, ammonium is produced in lagoons and lost in bays. Macrobenthic production (abundance and biomass) was lowest in rivers and highest in lagoons. Diversity was low in estuaries with salinities between 1 and 17, but increased with salinities of up to 30, before decreasing in hypersaline conditions. Macrofaunal community structure divided the estuaries into two groups. The first group represented polyhaline communities and contained lagoons (East Matagorda, Matagorda, Christmas and South Bays). The second group represented oligo-mesohaline community characteristics and contained the secondary bays (Lavaca Bay and Cedar Lakes) and rivers (San Bernard River, Brazos River, and the Rio Grande River). The implications of these results for managing freshwater flows are that altered hydrology can change the character of estuarine systems regardless of their classification as bays, lagoons, or tidal rivers.