Aquatic Sciences Meeting, Albuquerque 2001

SS01 Submerged Aquatic Vegetation and the Water Column (Environmental Connections)

Date: Tuesday, February 13, 2001, Time: 4:00:00 PM

Location: Galisteo

Sullivan, G, , NRC/US EPA Coastal Ecology Branch, Newport, OR, USA, sullivan.gary@epa.gov

IMPACT OF GREEN MACROALGAE ON INTERTIDAL HABITATS WITHIN A PACIFIC NORTHWEST ESTUARY

Green macroalgae densities were manipulated within 2m x 2m x 0.5m enclosures in Yaquina Bay Estuary, Oregon to examine impacts on sediment and water column processes affecting habitats dominated by either Zostera marina, Upogebia pugettensis, Neotrypaea californiensis or areas without seagrass or shrimp. Algae was removed or added, with enclosure and non-enclosure controls. Algae biomass differed among habitats, with habitat-specific treatment differences developing among sites through time. Porewater NH4+ and PO4- increased with algae density in all habitats, while porewater NO2- and NO3- differed among habitats, but did not respond to algae density. Treatment differences within habitats in pH, sulfides and redox were strongly influenced by the presence of shrimp. Water column nutrient and oxygen concentrations within algae canopies differed from open water levels, but only oxygen concentrations responded to algae manipulations. Algae density affected seagrass populations, with algae additions reducing shoot density, and algae removals increasing shoot density relative to controls. Neither shrimp species was negatively affected by algae manipulations, but rather ameliorated impacts by burying algae, increasing carbon and nitrogen storage within the system.

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Aquatic Sciences Meeting, Albuquerque 2001

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