181Two Lineages Within Griffithsia (Ceramiaceae, Rhodophyta) Based on Plastid Protein-Coding psaA, psbA and rbcL Genes

"Green tides" or blooms of ulvoid green algae are frequent in Yaquina Bay estuary on the central Oregon coast, USA. Measurements of their biomass were made from late spring to early winter in 1999 at six intertidal sites in the estuary, and were continued through the winter of 2002 at two sites that showed the greatest accumulation. The dominant blooming species were the Enteromorpha linza complex, Ulva fenestrata, E. flexuosa , and E. intestinalis . Red and brown algal abundance was negligable. Nutrients in the central channel were monitored, along with incident light and water column absorbence, and sediment temperature. The abundance of benthic amphipods was negatively correlated with the concentration of dissolved sulfides in porewater. However, dissolved sulfide levels were not correlated with green macroalgae biomass. Additional correlations were sought between the variables measured in an effort to suggest or negate major cause and effect relationships. This research is relevant to discerning the effects of eutrophication as a stressor on estuarine processes and could contribute toward an understanding of anthropogenic impacts on biological communities in coastal ecosystems.