Abstract Title

Session S-03A: Changes in Salish Sea Water Quality

Proposed Abstract Title

Changes in nutrient ratios drive changes in pelagic and benthic assemblages, and benthic-pelagic coupling in Puget Sound: A compelling hypothesis linking water quality and the benthos

Keywords

Marine Water Quality

Location

Room 6C

Start Date

1-5-2014 5:00 PM

End Date

1-5-2014 6:30 PM

Description

Analyses of Ecology’s long-term monitoring data indicate that despite abundant nutrients, shifts in nutrient ratios in the surface waters of Puget Sound may be driving changes in the cycling of organic material affecting phytoplankton, micro-zooplankton, and benthic communities. Changes in the nutrient balance can promote opportunistic species that affect the diatom-based food web through competition and grazing on diatom biomass in Puget Sound. Examples include highly visible, large-scale Noctiluca and dinoflagellate blooms and a decline of subsurface chlorophyll a levels. These species shifts in the lower trophic pelagic food web, and a documented wide-spread decline in benthic community and detritivore feeding guild abundances, corroborate a scenario where benthic animals are increasingly deprived of the planktonic food resource that rains down from the upper water column. The long-term continuing change has potential implications for marine food web structure, energy transfer, particle export, and higher trophic levels such as fish. Several lines of independent evidence are presented, supporting an hypothesis that changing water column nutrient ratios may result in shifting composition of both pelagic and benthic communities at lower levels of the Puget Sound food web.

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May 1st, 5:00 PM May 1st, 6:30 PM

Changes in nutrient ratios drive changes in pelagic and benthic assemblages, and benthic-pelagic coupling in Puget Sound: A compelling hypothesis linking water quality and the benthos

Room 6C

Analyses of Ecology’s long-term monitoring data indicate that despite abundant nutrients, shifts in nutrient ratios in the surface waters of Puget Sound may be driving changes in the cycling of organic material affecting phytoplankton, micro-zooplankton, and benthic communities. Changes in the nutrient balance can promote opportunistic species that affect the diatom-based food web through competition and grazing on diatom biomass in Puget Sound. Examples include highly visible, large-scale Noctiluca and dinoflagellate blooms and a decline of subsurface chlorophyll a levels. These species shifts in the lower trophic pelagic food web, and a documented wide-spread decline in benthic community and detritivore feeding guild abundances, corroborate a scenario where benthic animals are increasingly deprived of the planktonic food resource that rains down from the upper water column. The long-term continuing change has potential implications for marine food web structure, energy transfer, particle export, and higher trophic levels such as fish. Several lines of independent evidence are presented, supporting an hypothesis that changing water column nutrient ratios may result in shifting composition of both pelagic and benthic communities at lower levels of the Puget Sound food web.