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SPATIAL AND TEMPORAL VARIABILITY AND DRIVERS OF NET ECOSYSTEM METABOLISM IN WESTERN GULF OF MEXICO ESTUARIES
Citation:
RUSSELL, M. J. AND P. A. MONTAGNA. SPATIAL AND TEMPORAL VARIABILITY AND DRIVERS OF NET ECOSYSTEM METABOLISM IN WESTERN GULF OF MEXICO ESTUARIES. Estuaries and Coasts. Estuarine Research Federation, Port Republic, MD, 30(1):137-153, (2007).
Impact/Purpose:
to assess spatial and temporal variability in Net ecosystem metabolism
Description:
Net ecosystem metabolism (NEM) is becoming a commonly used ecological indicator of estuarine ecosystem metabolic rates. Estuarine ecosystem processes are spatially and temporally variable, but the corresponding variability in NEM has not been properly assessed. Spatial and temporal variability in NEM was assessed in four western Gulf of Mexico shallow water estuaries. NEM was calculated from hjigh-frequency dissolved oxygen measurements. Interbay, intrabay, and water column spatial scales were assessed for NEM, gross primary production (GPP), and respiration (R) rate variability. Seasonal, monthly, and daily temporal scales in NEM, GPP, and R were also assessed. Environmental conditions were then compared to NEM to determine which factors were correlated with each temporal and spatial scale. There was significant NEM spatial variability on interbay, intrabay, and water column spatial scales. Significant spatial variability was emphemeral, so it was difficult to ascertain which environmental conditions were most influential at each spatial scale. Significant temporal variability in NEM on seasonal, monthly, and daily scales was found and it was correlated to temperature, salinity, and freshwater inflow, respectively. NEM correlated strongly with dissolved oxygen, temperature, and salinity, but the relationships were different ine ach bay. The dynamics of NEM on daily scales indicate that freshwater inflow events may be the main driver of NEM in the semiarid estuaries studied. The variable natue of NEM found here is further evidence that it is not valid to use single station monitoring deplooyments for assessment of whole estuarine ecosystem metabolic rates in large ecosystems. The relationship betwteen NEM and temperature, salinity, and freshwater inflow events could drive predictive models assessing the potential influence of projected climate change and watershed development scenarios on estuarine metabolic rates.