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Relationships among benthic green macroalgae, infaunal invertebrates, and dissolved sulfides in sediment pore waters, Yaquina Estuary, Oregon, USA
Citation:
YOUNG, D. R., J. O. LAMBERSON, AND R. S. Caldwell. Relationships among benthic green macroalgae, infaunal invertebrates, and dissolved sulfides in sediment pore waters, Yaquina Estuary, Oregon, USA. Presented at Poster Conference: , Moscow, RUSSIA, June 23, 2010.
Impact/Purpose:
Relatively high abundances of benthic green macroalgae (Ulva spp.) have been measured in Yaquina Estuary on the central coast of the State of Oregon, USA.
Description:
Relatively high abundances of benthic green macroalgae (Ulva spp.) have been measured in Yaquina Estuary on the central coast of the State of Oregon, USA. Band transects (30 meters in width) from the lower to the upper intertidal zone were established at two sites (Idaho Point and Coquille Point), on opposite sides of the main channel of the estuary and separated by about 1 km. Accumulations of the macroalgae were monitored within these transects between years 1999 and 2003. Surficial sediment (0-5 cm) pore water concentrations of dissolved sulfides were measured at both sites in year 2000; average values within native eelgrass beds (Zostera marina) at Idaho Point were 700 times those at Coquille Point (224 and 0.3 micromoles per liter, respectively), although corresponding average summer (July to October) macroalgae abundances were almost identical (142 and 139 grams dry weight per square meter, respectively). Substantially lower abundances of infaunal shrimp and amphipods, important components of the estuarine food web, were measured along most of the Idaho Point transect. In year 2001, sediment cores were collected from the eelgrass beds at the latter transect only. Owing to the high variability obtained, a comparison of normalized 0-5 cm values of dissolved sulfides indicated no significant differences between the two years. However, there was approximate agreement between the changes measured in macroalgae and dissolved sulfides at Idaho Point. In year 2001 the average values for macroalgae and dissolved sulfides decreased by factors of 2.9 and 2.6, respectively, from the averages measured in year 2000. Also, the percentage of fine sediment (grain size < 0.063 mm) at Idaho Point was approximately twice that at Coquille Point (30% and 15%, respectively). This difference in substrate composition may have contributed to the much higher levels of dissolved sulfides measured at Idaho Point. There, the average pore water concentration for year 2000 in eelgrass was four times the 48-hour threshold of toxicity reported in the literature for two benthic marine amphipods (50 micromoles per liter).