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RELATIONSHIPS BETWEEN SEAGRASSES, BENTHIC MACROALGAE AND NUTRIENTS IN A PACIFIC NORTHWEST ESTUARY
Citation:
YOUNG, D. R., C. A. BROWN, D. T. SPECHT, P. J. CLINTON, H. LEE, II, R. J. OZRETICH, AND K. M. MARKO. RELATIONSHIPS BETWEEN SEAGRASSES, BENTHIC MACROALGAE AND NUTRIENTS IN A PACIFIC NORTHWEST ESTUARY. Presented at Estuarine Research Federation 2007 Biennial Conference, Providence, RI, November 04 - 08, 2007.
Impact/Purpose:
research presentation
Description:
Pacific Northwest estuaries are characterized by large tidal ranges (2-3 m) that routinely expose submerged aquatic vegetation (SAV) such as seagrass and benthic macroalgae. The dominant native seagrass in PNW estuaries is the eelgrass Zostera marina. However, in recent decades the non-indigenous dwarf eelgrass Z. japonica has become widely established in the region. Studies were conducted in Yaquina estuary between 1997 and 2007 on distributions of the two Zostera species and benthic green macroalgae (Ulva spp.), as well as inputs of nutrients to the estuary. The native eelgrass occurs mainly in the lower intertidal and subtidal zones, while the non-indigenous dwarf eelgrass occurs principally in the upper intertidal zone. This spatial separation aids in the mapping of these two species in this estuary via color infrared aerial photography. Temporal comparisons suggest an inverse relationship between the abundance (% cover and above-ground biomass) of native eelgrass and benthic macroalgae, and an expansion of distributions of the non-indigenous dwarf eelgrass over the last decade. Correlations between SAV distributions and coastal inputs of upwelled nutrients are explored.
