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BENTHIC MACROALGAE, DISSOLVED SULFIDES, AND AMPHIPODS IN SURFICIAL SEDIMENTS OF YAQUINA BAY ESTUARY, OREGON, USA
Citation:
YOUNG, D. R., R. S. CALDWELL, AND J. O. LAMBERSON. BENTHIC MACROALGAE, DISSOLVED SULFIDES, AND AMPHIPODS IN SURFICIAL SEDIMENTS OF YAQUINA BAY ESTUARY, OREGON, USA. Presented at Ninth International Poster Session Conference: Aquatic Ecosystems, Organisms, Innovations, Moscow State University, Moscow, RUSSIA, October 25 - 26, 2007.
Impact/Purpose:
the relationship between elevated accumulations of benthic macroalgae, elevated pore water sulfides, and decreased density of infaunal amphipods contributes to our understanding of possible ecological effects of eutrophication of Northeast Pacific estuaries.
Description:
Surveys of benthic green macroalgae at two sites in Yaquina Bay Estuary, Oregon, in 1999 showed that percent cover and biomass values in June were much higher at one site, Idaho Point, than at the other site, Coquille Point. The frequency of detectable hydrogen sulfide odor later in the summer also was much greater at Idaho Point. Therefore, the accumulation of benthic green macroalage, the concentration of dissolved sulfides in surficial sediment pore water, and the density of infaunal amphipods at the two sites were measured between June and December, 2000. At Idaho Point macroalgal accumulation was substantially greater in June, and by late August the maximum pore water concentrations of dissolved sulfides were about 2000 micromoles per liter (µM/L), compared to < 10 µM/L at Coquille Point. The reported threshold of toxicity of dissolved sulfides to infaunal organisms is ~ 75 µM/L. The abundance of infaunal amphipods also was substantially lower off Idaho Point, suggesting that the higher frequency of elevated pore water sulfides there may have contributed to the lower amphipod abundance. Although in this estuary the processes observed may be natural, nevertheless the relationship between elevated accumulations of benthic macroalgae, elevated pore water sulfides, and decreased density of infaunal amphipods contributes to our understanding of possible ecological effects of eutrophication of Northeast Pacific estuaries.