Estuarine intertidal sandflat benthic microalgal responses to in situ and mesocosm nitrogen additions |
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Authors: | Michael F Piehler Carolyn A Currin |
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Institution: | a UNC-CH Institute of Marine Sciences, 3431 Arendell Street, Morehead City, NC 28557, United States b NOAA NOS, Center for Coastal Fisheries and Habitat Research, 101 Pivers Island Road, Beaufort, NC 28516, United States |
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Abstract: | Benthic microalgal communities are important components of estuarine food webs and make substantial contributions to coastal materials cycling. Nitrogen is generally the limiting factor for marine primary production; however other factors can limit benthic primary producers because of their access to the additional nutrients found in sediment porewater. Field and laboratory experiments were conducted to test the hypothesis that water column nitrogen supply affects estuarine sandflat benthic microalgal community structure and function. Our field and mesocosm experiments assessed changes at both the population and functional group levels. Simulated water column nitrogen additions increased maximum community photosynthesis in most cases (Pbmax from photosynthesis vs. irradiance curves). Additional changes that resulted from nitrogen additions were decreases in porewater phosphate, increases in porewater ammonium, shifts in community composition from N2 fixing cyanobacteria toward diatoms, and detectable, though not statistically significant increases in biomass (as chlorophyll a). Results from field and laboratory experiments were quite similar, suggesting that laboratory experiments support accurate predictions of the response of intertidal benthic microalgae to changes in water column nutrient conditions. |
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Keywords: | Benthic microalgae Nitrogen Intertidal flat Eutrophication Primary productivity Microphytobenthos |
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