Effects on Benthic Macrofauna from Pumped Flows in Rincon Bayou

Decreased inflow due to damming of the Nueces and Frio Rivers has resulted in increasing salinity in Nueces Bay and caused Rincon Bayou to become a reverse estuary disturbing the overall hydrology of the adjacent Corpus Christi Bay. Adaptive management to perform hydrological restoration began in 1994 and continues today. The objectives of the present study are to determine to what extent salinity fluctuates within Rincon Bayou and what effects these fluctuations have on estuary health. Benthic macrofauna are ideal indicators of ecological effects because of their relative immobility and longevity in contrast with plankton of comparable size. Archived samples were analyzed as well as new samples collected from the upper Rincon Bayou near Corpus Christi, TX. One historical station (466C) was sampled biweekly. Conductivity, temperature, and salinity were monitored continuously. Additional water column measurements were taken during sampling events. Macrofauna biomass, abundance, and diversity were recorded and analyzed. High inflow reduces salinity and introduces nutrients. Large and haphazard salinity fluctuations result in an often disturbed system populated by pioneer species, such as chironomid larvae and Streblospio benedicti, during especially low and high salinity periods. These results indicate that further changes need to be made to the Rincon Bayou restoration and management programs in order to reestablish a reasonably undisturbed ecosystem.