A review of protist grazing below the photic zone emphasizing studies of oxygen-depleted water columns and recent applications of in situ approaches
Medina, Luis E.
Taylor, Craig D.
Pachiadaki, Maria G.
Edgcomb, Virginia P.
MetadataShow full item record
KeywordOMZ; Phagotrophy; In situ technology; Incubation studies; ETSP; Eastern Tropical South Pacific OMZ
Little is still known of the impacts of protist grazing on bacterioplankton communities in the dark ocean. Furthermore, the accuracy of assessments of in situ microbial activities, including protist grazing, can be affected by sampling artifacts introduced during sample retrieval and downstream manipulations. Potential artifacts may be increased when working with deep-sea samples or samples from chemically unique water columns such as oxygen minimum zones (OMZs). OMZs are oxygen-depleted regions in the ocean, where oxygen concentrations can drop to <20 μM. These regions are typically located near eastern boundary upwelling systems and currently occur in waters occupying below about 8% of total ocean surface area, representing ~1% of the ocean's volume. OMZs have a profound impact not only on the distribution of marine Metazoa, but also on the composition and activities of microbial communities at the base of marine food webs. Here we present an overview of current knowledge of protist phagotrophy below the photic zone, emphasizing studies of oxygen-depleted waters and presenting results of the first attempt to implement new technology for conducting these incubation studies completely in situ (the Microbial Sampling- Submersible Incubation Device, MS-SID). We performed 24-h incubation experiments in the Eastern Tropical South Pacific (ETSP) OMZ. This preliminary study shows that up to 28% of bacterial biomass may be consumed by protists in waters where oxygen concentrations were down to ~4.8 μM and up to 13% at a station with nitrite accumulation where oxygen concentrations were undetectable. Results also show that shipboard measurements of grazing rates were lower than rates measured from the same water using the MS-SID, suggesting that in situ experiments help to minimize artifacts that may be introduced when conducting incubation studies using waters collected from below the photic zone, particularly from oxygen-depleted regions of the water column.
© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Marine Science 4 (2017): 105, doi:10.3389/fmars.2017.00105.
Suggested CitationFrontiers in Marine Science 4 (2017): 105
The following license files are associated with this item:
Showing items related by title, author, creator and subject.
Fluid mechanics applied to the study of atmospheric circulations. I. A study of flow patterns with the aid of isentropic analysis. Rossby, Carl-Gustaf; Namias, Jerome; Simmers, Ritchie G. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1938-12)This paper constitutes Part I of a report on certain investigations which have been in progress at the Massachusetts Institute of Technology during the past few years and which have been supported in part with funds ...
Wettlaufer, John; Buhler, Oliver (Woods Hole Oceanographic Institution, 2016-11)Stochastic Processes in Atmospheric & Oceanic Dynamics was the theme at the 2015 GFD Program. Professors Charlie Doering (University of Michigan) and Henk Dijkstra (University of Utrecht) were the principal lecturers. ...
Rosenfeld, Leslie K.; Signell, Richard P.; Gawarkiewicz, Glen G. (Woods Hole Oceanographic Institution, 1984-02)A series of four hydrographic cruises at three-month intervals was undertaken in Buzzards Bay in 1982-83. Buzzards Bay is located on the southern coast of Massachusetts, west of Cape Cod. Listings and vertical profiles ...