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Sediment diatom species and community response to nitrogen addition in Oregon (USA) estuarine tidal wetlands
Citation:
Hankin, S., C. Weilhoefer, Jim Kaldy, AND Ted DeWitt. Sediment diatom species and community response to nitrogen addition in Oregon (USA) estuarine tidal wetlands. WETLANDS. The Society of Wetland Scientists, McLean, VA, 32:1023-1031, (2012).
Impact/Purpose:
Sediment microalgae play an important role in nutrient cycling and are important primary producers in the food web in Pacific Northwest estuaries. This study examines the effects of nitrogen addition to benthic microalgae in tidal wetlands of Yaquina Bay estuary on the Oregon coast, USA. We examined changes in diatom species and community parameters in response to nitrogen addition in early and late summer 2010 after 2 years of nitrogen additions. Liquid nitrogen fertilizers were added to plots and intended to mimic anthropogenic increases in water column nutrient availability. Nitrogen addition (N) to plots had a significant effect on species composition and community parameters. Increased N availability decreased diatom species diversity and richness which could lead to alterations in the algal food web. Our results suggest the microalgal communities are limited by nitrogen levels and therefore may be susceptible to changes in nitrogen loading to these systems.
Description:
Sediment microalgae play an important role in nutrient cycling and are important primary producers in the food web in Pacific Northwest estuaries. This study examines the effects of nitrogen addition to benthic microalgae in tidal wetlands of Yaquina Bay estuary on the Oregon coast, USA. Liquid nitrogen fertilizers (0, 0.2, 0.5, and 1.0 gN/m2/wk during the first year of the study, and increased to 0, 15.6, 62.5, and 156 gN/m2/wk during the second year of the study) were applied weekly to four salt marshes in Yaquina Bay for two summers (2009 and 2010). Diatom species and community parameters were analyzed in response to nitrogen addition in early and late summer 2010. Nitrogen addition (N) had a significant effect on species composition and community parameters. Amphora spp. and Nitzschia palea were more dominant with higher N], while Navicula gregaria and Navicula phyllepta were more dominant with lower N. Species diversity and richness were significantly higher (p < 0.05) with lower [N] (3.1 ±0.1; 40.0 ±3.3) compared with higher N (2.4 ±0.5; 34.5 ±3.0). NMDS ordination displayed shifts in overall diatom assemblage with time and with N. Results suggest the microalgal communities are limited by nitrogen levels and therefore may be susceptible to changes in nitrogen loading to these systems.
