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Distribution of macroalgae and sediment chlorophyll A along salinity and elevation gradients in Oregon tidal marshes
Citation:
JANOUSEK, C. N. AND C. FOLGER. Distribution of macroalgae and sediment chlorophyll A along salinity and elevation gradients in Oregon tidal marshes. Presented at Phycological Society of America meeting, Seattle, WA, July 13 - 16, 2011.
Impact/Purpose:
Algae contribute to trophic and biogeochemical processes in tidal wetlands.
Description:
Algae contribute to trophic and biogeochemical processes in tidal wetlands. We investigated patterns of sediment pigment content and macroalgal abundance and diversity in marshes in four Oregon estuaries representing a variety of vegetation types, salinity regimes, and tidal elevation. Common macroalgae included Ulva, Rhizoclonium, Vaucheria, Fucus, and Porphya. Macroalgal abundance and diversity was strongly linked to tidal elevation, with lower marshes containing more macroalgal species and greater algal cover. Vascular plant diversity, in contrast, increased with tidal elevation. Soil salinity measurements were coupled with elevation data to determine envelopes of environmental tolerance for common macroalgal taxa. As with macroalgal abundance, sediment chlorophyll a concentrations were much higher in lower tidal marshes. Qualitative observation of sediments suggested a diversity of diatoms and cyanobacteria were present which contributed to chlorophyll a content. Estimates of pheopigment concentrations usually exceeded chlorophyll a concentrations, probably because of substantial plant detritus in sediments. Understanding the spatial distribution of micro- and macroalgae in marshes will aid in quantification of ecosystem processes and prediction of marsh function with future sea level rise.