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Estuarine water quality and plankton community responses in the Pensacola Bay Estuary
Citation:
Murrell, M., J. Nestlerode, Jim Hagy, B. Jarvis, D. Yates, J. Aukamp, AND D. Marcovich. Estuarine water quality and plankton community responses in the Pensacola Bay Estuary. CERF 24th Biennial Conference, Providence, RI, November 05 - 09, 2017.
Impact/Purpose:
The work presented here is in support of development of better indicators and endpoints will help improve quantitative relationships between nutrient pollution and support for human and aquatic life uses and, similarly, effects of nutrient pollution on ecosystem condition. The audience that would be interested in this presentation will include conference attendees (scientists and managers) from across the Gulf coast region.
Description:
Phytoplankton serve a centrally important role in estuaries forming the base of the food web. Thus factors that affect phytoplankton production and species composition cascades to higher trophic levels, ultimately affecting secondary production. Given their sensitivity to myriad natural and anthropogenic factors, measures of phytoplankton community composition can serve as an indicator of likely environmental stressors and/or the nature of the coupling between phytoplankton and their grazers. In conjunction with an ongoing Pensacola Bay study measuring water quality and sediment characteristics, we collected monthly phytoplankton samples from surface and bottom waters of the Escambia Bay sub-estuary over a 2-year period from Apr. 2014 to May 2016. In this region of the bay the water column is often strongly stratified; thus one goal of the study was to examine the potential for stratification to create unique niches, resulting in distinctive phytoplankton communities. We used two principal methods to examine the phytoplankton composition: 1) direct enumeration of pico-cyanobacteria via epifluorescence microscopy, and 2) enumeration of larger phytoplankton (>10 µm) via FlowCam® image analysis. Similar to earlier studies (e.g. Murrell and Lores 2004, Murrell and Caffrey 2005), preliminary results indicate very high abundances of pico-cyanobacteria (peak abundances >3 X 10^9 L-1) during summer months in the mesohaline portions of the bay. Flow Cam analysis on selected samples has yielded many recognizable phytoplankton and microzooplankton images. The abundance and biovolume of major taxonomic groups will be summarized for surface and bottom waters over a seasonal cycle and placed in in context with the prevailing physical environment.