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Comparison of Nutrient Drivers and Response Metrics in Oregon Estuaries
Citation:
Brown, C., Jim Kaldy, M. Frazier, TChris MochonCollura, AND Pat Clinton. Comparison of Nutrient Drivers and Response Metrics in Oregon Estuaries. Presented at 22nd Biennial Conference of the Coastal and Estuarine Research Federation, San Diego, CA, November 03 - 07, 2013.
Impact/Purpose:
This presentation focuses on a cross-estuary comparison of nutrient sources, levels and biological responses for thirteen Oregon estuaries. The results may aid in the development of nutrient criteria by establishing expectations for causal (nutrient) and response metrics (algal blooms, chlorophyll a) for estuaries in Oregon.
Description:
With the goal of assessing sensitivity to nutrient enrichment, we present a cross-estuary comparison of nutrient sources, levels, and biological responses (phytoplankton and macroalgae) for thirteen Oregon estuaries. Nitrogen levels in the upstream portions of the estuaries are related to forest cover in the watershed, while in the marine-dominated portions of the estuaries nitrogen levels are dependent upon ocean conditions. Phosphorous levels are primarily determined by ocean input. Stable isotope data of macroalgae are useful for distinguishing oceanic, watershed and wastewater inputs of nitrogen along an estuary. Variations in water column chlorophyll a levels among estuaries appear to be related to the variations in freshwater inflow to the estuaries. Patterns of nutrient limitation of phytoplankton were variable among systems and appear to be related to watershed characteristics. Macroalgal blooms varied among systems and were concentrated in the marine-dominated portion of the estuary. These results will aid in determining the expectation of causal and response variables for the development of estuarine nutrient criteria in the region.