Composition, productivity and nutrient chemistry of a coastal ocean planktonic food web

Verity, Peter G.; Yoder, James A.; Bishop, S. Stephen; Nelson, James R.; Craven, D. B.; Blanton, Jackson O.; Robertson, C.; Tronzo, Craig R.

doi:10.1016/0278-4343(93)90026-t

Cited by 56 publications

(28 citation statements)

References 67 publications

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“…3), respiration was most likely controlled by organic matter supply. The summertime offshore decrease in respiration rate is consistent with previous observations showing that allochthonous organic carbon inputs (Hopkinson et al 1989;Moran et al 1991;DeAlteris 2007) and primary production (Yoder et al 1993;Verity et al 1993) are highest nearshore where rivers and salt marshes are a strong influence. This is also consistent with the fact that interactions between water column and sediments help resuspension of more organic detritus shoreward of the CFZ (Pomeroy et al 1983;Pomeroy 1985), and the CFZ significantly diminishes cross-shelf exchange of both dissolved and particulate constituents (Blanton 1981).…”

Section: Processessupporting

confidence: 91%

Pelagic community respiration on the continental shelf off Georgia, USA

et al. 2009

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The South Atlantic Bight (SAB) has been a focus for the study of continental shelf ecosystem respiration during the past two decades. However, two questions concerning respiration in this area have yet to be answered. First, why do previous estimates of respiration in the SAB exceed measured carbon fixation rates by almost an order of magnitude? Second, considering that bacteria are responsible for most of the pelagic community respiration in the SAB, why is respiration almost uniform from the coastline to the shelf break, while bacterial production estimates decrease offshore? This study addresses these critical questions by presenting new pelagic community respiration data that were collected across the entire width of the continental shelf off Georgia, USA from June 2003 to May 2006. The respiration was calculated as in vitro changes of dissolved oxygen and dissolved inorganic carbon concentrations during deck incubations. The measured respiration rates ranged from 0.3(±0.1) to 21.2(±1.4) mmol m -3 day -1 . They followed a clear seasonal pattern, being lowest over the entire shelf in winter and reaching maxima in summer. Summertime respiration rates were highest on the inner shelf and decreased with distance offshore. Consistent with this trend, bacterial abundance measurements taken during the sampling month of July 2005 followed a pattern of seaward decline. The SAB organic carbon fluxes calculated from the respiration data are close to the estimates for primary production, which resolves a long-standing mystery regarding perceived carbon imbalance in the SAB.

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Section: Processessupporting

confidence: 91%

Pelagic community respiration on the continental shelf off Georgia, USA

et al. 2009

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“…Bacterial numbers also increase one order of magnitude in non-winter high-productivity events on the southeastern shelf, such as upwellings near the shelf break [33]. We will report elsewhere that bacterial production and respiratory rates, however, decline markedly in winter, although phytoplankton production is known not to change significantly [4,32,47]. Because the nonliving particulate substrate sources are also suitable as food for zooplankton and benthic invertebrates, the reduction of active bacterial utilization in winter on the southeastern shelf should permit a greater utilization of those product of phytoplankton production by metazoan consumers.…”

Section: Discussionmentioning

confidence: 99%

Evidence for an enhanced substrate requirement by marine mesophilic bacterial isolates at minimal growth temperatures

1993

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Bacterial isolates from the subtropical southeastern continental shelf were cultured in a matrix of temperature and substrate concentrations encompassing a range of temperature and substrate concentrations equal to and exceeding natural ones. At the annual minimum temperature, marine heterotrophic bacterial isolates required higher concentrations of dissolved substrates for active growth than are usually found in seawater. We show this to result from a nonlinear interaction of the combined effects of temperature and substrate concentration on bacterial growth and respiratory rate. As a result, bacterial and protozoan utilization of phytoplankton production during winter and early spring is low, permitting greater energy flow to zooplankton and benthic animals, while in late spring, summer, and fall, the microbial loop dominates energy flux and organic carbon utilization. Escherichia coli shows a similar nonlinear response to temperature at minimal substrate concentrations, albeit at a higher range of concentrations than were utilized by the marine isolates. Thus, bacteria from subtropical regions are shown to have a differential growth response near the minimum temperature for growth, depending on the concentration of available substrates.

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“…While the analysis performed in this study does not allow us an accurate characterization of the organisms present in the <10 µm POM, it is known that this fraction is mainly composed of bacteria, phototrophic and heterotrophic flagellates, diatoms and cyanobacteria (Lalli & Parsons 1997). In the SAB region, phototrophs account for 60 to 90% of the carbon biomass of pico-and nanoplankton, particularly diatoms that compose 30 to 70% of the phototrophic community (Verity et al 1993(Verity et al , 1996. In recent laboratory experiments, Leal et al (2014a) demonstrated that symbiotic O. arbuscula is able to feed on microalgae from 4 to 12 µm.…”

Section: Discussionmentioning

confidence: 99%