A preliminary assessment of the primary productivity, respiration rates,and organic carbon levels of a southeastern Texas estuary:findings correlated to a salinity gradient

 Allison Fong, Leah Hurley, and Dr. Daniel Roelke

With the anticipated divergence of surface water from the Guadalupe River to meet the needs of the growing San Antonio population, a study of the effects of freshwater inflow to the estuarine system downstream is in effect.  An overall increase is salinity can change the rate at which productivity occurs and to what extent existing autotrophs can contribute to the system as biomass.  Unlike phytoplankton, coastal macrophyte assemblages cannot adjust readily to changes in salinity and use energy, which would otherwise be used to create biomass, to compensate for the osmotic stress.  Therefore, the contribution of biomass from macrophytes would decrease as salinity increases.  Additionally, primary productivity in the water column and in the benthos may experience an enhanced opportunity to sequester labile nutrients and contribute a greater biomass overall to the system.  This adjustment would also reflect a change in the efficiency of respiration rates of the phytoplankton, thereby displaying correlations between primary productivity, respiration, and the contribution of organic carbon to the system along a salinity gradient.

As a preliminary study, with the use of multiprobe instrumentation, benthic chambers, and classic light/dark bottle experimentation, data was recorded to show high variability temporally and geographically within the sample area.  Definitive conclusions about possible trends would require a more extensive and intensive sampling regime in the future.  Thus, data and results presented here represent the natural variability within the system.

 Power Point Presentation: