Interactions between members of the microbial loop in an estuary dominated by microzooplankton grazing (2009-2011)

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Quantifying the linkages between primary production and higher trophic levels is necessary to understand why particular regions can support high fisheries production. Modified dilution experiments were employed to characterize microbial communities in surface waters at four sites from within a bay to the shelf in the northern Gulf of Mexico (nGOM). Inshore surface waters were more variable than shelf surface waters due to the strong influence of river discharge. Phytoplankton (Chl a) and prokaryote biomass were both significantly higher inshore than on the shelf, with phytoplankton significantly higher than prokaryotes inshore. Virus and heterotrophic nanoflagellate abundances, however, did not differ between inshore and shelf waters. Samples were amended with nutrients (N + P) to examine the impact of nutrient limitation. Prokaryotes were nutrient limited in 14 (28%) of the experiments, while phytoplankton were nutrient limitated in 26 (52%) of the experiments. When phytoplankton were nutrient limited, prokaryote growth rates were significantly altered. A similar impact on phytoplankton growth rates occurred when prokaryotes were nutrient limited, suggesting that the two groups are in competition for resources. Grazing was detected in the majority of experiments, while viral lysis was only detected in 24% of phytoplankton and 12% of prokaryote experiments. Growth and grazing rates for both phytoplankton and prokaryotes were tightly coupled inshore and on the shelf, with significantly more phytoplankton and prokaryotes grazed inshore (average = 106% and 75%, respectively) than on the shelf (average = 55% and 57%). These findings indicate that surface waters across the estuary are highly productive, with microzooplankton grazing transferring the majority of the microbial production to higher trophic levels.

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Author Alice Ortmann
Maintainer data@disl.org
Last Updated July 23, 2022, 03:05 (UTC)
Created July 23, 2022, 03:05 (UTC)
Access_Constraints Permission to access these data must be given by Dr. Alice Ortmann of the Dauphin Island Sea Lab.
ISO 19115 Topic Categories biota, inlandWaters, oceans
Place Keywords Dauphin Island Sea Lab, DISL, Mobile Bay, Alabama, Gulf of Mexico
Theme Keywords growth, production, grazing, viral lysis, microbial loop, phytoplankton, chlorophyll a, prokaryote, microzooplankton, virus, protist, heterotrophic nano-flagellate
Use_Constraints Acknowledgment of the Dauphin Island Sea Lab (DISL), Fisheries Oceanography of Coastal Alabama (FOCAL) program, and the Alabama Department of Conservation and Natural Resources is required in products developed from these data, and such acknowledgment as is standard for citation and legal practices for data source is expected by users of these data. Users should be aware that comparison with other data sets for the same area from other time periods may be inaccurate due to inconsistencies resulting from changes in mapping conventions, data collection, and computer processes over time. The distributor shall not be liable for improper or incorrect use of these data, based on the description of appropriate/inappropriate uses described in the metadata document. These data are not legal documents and are not to be used as such.
dc.coverage.placeName Dauphin Island Sea Lab DISL Mobile Bay Alabama Gulf of Mexico
dc.coverage.t.max 201112T
dc.coverage.t.min 200907T
dc.coverage.x.max -88.0113
dc.coverage.x.min -88.2116
dc.coverage.y.max 30.4374
dc.coverage.y.min 29.79887
dc.creator Alice Ortmann
dc.date Unpublished material
dc.description Quantifying the linkages between primary production and higher trophic levels is necessary to understand why particular regions can support high fisheries production. Modified dilution experiments were employed to characterize microbial communities in surface waters at four sites from within a bay to the shelf in the northern Gulf of Mexico (nGOM). Inshore surface waters were more variable than shelf surface waters due to the strong influence of river discharge. Phytoplankton (Chl a) and prokaryote biomass were both significantly higher inshore than on the shelf, with phytoplankton significantly higher than prokaryotes inshore. Virus and heterotrophic nanoflagellate abundances, however, did not differ between inshore and shelf waters. Samples were amended with nutrients (N + P) to examine the impact of nutrient limitation. Prokaryotes were nutrient limited in 14 (28%) of the experiments, while phytoplankton were nutrient limitated in 26 (52%) of the experiments. When phytoplankton were nutrient limited, prokaryote growth rates were significantly altered. A similar impact on phytoplankton growth rates occurred when prokaryotes were nutrient limited, suggesting that the two groups are in competition for resources. Grazing was detected in the majority of experiments, while viral lysis was only detected in 24% of phytoplankton and 12% of prokaryote experiments. Growth and grazing rates for both phytoplankton and prokaryotes were tightly coupled inshore and on the shelf, with significantly more phytoplankton and prokaryotes grazed inshore (average = 106% and 75%, respectively) than on the shelf (average = 55% and 57%). These findings indicate that surface waters across the estuary are highly productive, with microzooplankton grazing transferring the majority of the microbial production to higher trophic levels.
dc.language en
dc.subject growth production grazing viral lysis microbial loop phytoplankton chlorophyll a prokaryote microzooplankton virus protist heterotrophic nano-flagellate
dc.title Interactions between members of the microbial loop in an estuary dominated by microzooplankton grazing (2009-2011)
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