Composition of the plankton community and its contribution to the particle flux in the Sargasso Sea

The ‘biological pump’, the photosynthetically mediated transformation of dissolved inorganic carbon into particulate and dissolved organic carbon in surface ocean waters and its subsequent export to deep water, is a significant driver of the atmospheric carbon uptake by the oceans. It is driven by the activity of planktonic organisms in the surface layer of the ocean, their growth as well as grazing. In an earlier NSF-Biological Oceanography project (“Composition of the Plankton Community and Its Contribution to Particle Flux in the Sargasso Sea”) we studied the phytoplankton communities in the water column and in sinking particles collected by shallow surface tethered traps from May 2008 till April 2010 at the Bermuda Atlantic Time-Series Station (BATS) in the Sargasso Sea. We used a combination of traditional (epifluorescence microscopy, flow cytometry, HPLC) and novel molecular approaches (rRNA gene based Clone Libraries and DGGE fingerprints) in this research The emergence of molecular methods in marine ecological research provides us with the unique opportunity to not only study the diversity of phytoplankton in the water column, but also the microscopically “invisible” plankton contained in the detritus or fecal pellets collected by the traps (see references below).

 


We are currently funded by NSF-Biological Oceanography for a project entitled “Plankton Community Composition and Trophic Interactions as Modifiers of Carbon Export in the Sargasso Sea”, in short “Trophic BATS” (in collaboration with Dr. Tammi Richardson from the University of South Carolina, USC, Dr. Mike Lomas from the Bermuda Institute of Ocean Sciences, BIOS, and Dr. Rob Condon from the Dauphin Island Sea Lab in Alabama). In this project we are studying the contribution of phytoplankton groups to the carbon export at the Bermuda Atlantic Time-Series Station in the context of the food web process in the upper ocean, with a particular focus on mesoscale cyclonic and anticyclonic eddies in the region. These are large circular oceanic features several 10’s of kilometers across that can either suppress or stimulate the activities of the plankton communities. In addition to studying the contribution of plankton organisms to particle flux, we are also measuring taxon specific growth and grazing rates using the dilution method to relate the importance of plankton organisms in the upper water column to their role in particle export. Read more about the first cruise in the trophic BATS project hereand this blog about the science and life onboard the ship written on the third cruise written by Doug Bell at BIOS (now at USC).

References:

Amacher J., S. Neuer and M. Lomas. 2013 DNA-based molecular fingerprinting of eukaryotic protists and cyanobacteria contributing to sinking particle flux at the Bermuda Atlantic Time-series Study. Deep-Sea Research II.

Amacher J., C.Baysinger and S. Neuer. 2011. Biases associated with DNA-based molecular studies of marine protist diversity. Journal of Plankton Research 33, 1762-1766.

Amacher J., S. Neuer, I. Anderson and R. Massana. 2009. Molecular approach to determine contributions of the protist community to particle flux. Deep-Sea Research 1. 56, 2206-2215. Doi:10.1016/j.dsr.2009.08.007.