Abstract Title

Session S-01D: Pelagic Ecology in the Salish Sea I

Keywords

Species and Food Webs

Start Date

30-4-2014 10:30 AM

End Date

30-4-2014 12:00 PM

Description

Unicellular microscopic organisms are the interface between the marine chemical domain and the pelagic food web. Phytoplankton, bacteria, and archea transfer molecules to and from food webs, but can be limited by physical parameters such as insolation and temperature. A geographically extensive survey of Puget Sound in 2011 addressed patterns and relationships of the lower trophic levels of the pelagic food web. Chlorophyll a and fluorescence (primary production proxies) were positively associated with bacterial biomass and heterotrophic production, while all four of these biotic measures displayed strong inverse relationships with dissolved nutrients. These observations coupled with nitrate stable isotope results suggest microbes were effectively regulating inorganic nitrogen and phosphorous concentrations. The abundance of picophytoplankton was positively associated with cyanobacterial (Synecococcus spp.) abundance, the abundance of low nucleic acid bacterioplankton, silicic acid concentration, and pH across the six oceanographic basins surveyed, indicating coordinated fluctuations of microbial subsets and abiotic conditions. The structures of bacterial communities, which were characterized by DNA profiling, displayed convergent patterns between adjacent oceanographic basins over time, with highest similarities occurring in the fall. Hood Canal, however, was distinct from other basins in bacterial community structure and in concentration of dissolved inorganic nitrogen. Anthropogenic influences were measured by detection of human-sourced or bovine-sourced fecal indicators, which were observed most frequently at sites near urban centers or in basins with higher densities of dairy operations, respectively. These observations highlight the value of integrated measurements in evaluating lower trophic levels of pelagic food webs.

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Apr 30th, 10:30 AM Apr 30th, 12:00 PM

Patterns and relationships of lower trophic levels of Puget Sound's pelagic food web

Room 611-612

Unicellular microscopic organisms are the interface between the marine chemical domain and the pelagic food web. Phytoplankton, bacteria, and archea transfer molecules to and from food webs, but can be limited by physical parameters such as insolation and temperature. A geographically extensive survey of Puget Sound in 2011 addressed patterns and relationships of the lower trophic levels of the pelagic food web. Chlorophyll a and fluorescence (primary production proxies) were positively associated with bacterial biomass and heterotrophic production, while all four of these biotic measures displayed strong inverse relationships with dissolved nutrients. These observations coupled with nitrate stable isotope results suggest microbes were effectively regulating inorganic nitrogen and phosphorous concentrations. The abundance of picophytoplankton was positively associated with cyanobacterial (Synecococcus spp.) abundance, the abundance of low nucleic acid bacterioplankton, silicic acid concentration, and pH across the six oceanographic basins surveyed, indicating coordinated fluctuations of microbial subsets and abiotic conditions. The structures of bacterial communities, which were characterized by DNA profiling, displayed convergent patterns between adjacent oceanographic basins over time, with highest similarities occurring in the fall. Hood Canal, however, was distinct from other basins in bacterial community structure and in concentration of dissolved inorganic nitrogen. Anthropogenic influences were measured by detection of human-sourced or bovine-sourced fecal indicators, which were observed most frequently at sites near urban centers or in basins with higher densities of dairy operations, respectively. These observations highlight the value of integrated measurements in evaluating lower trophic levels of pelagic food webs.