Project: Plankton Community Composition and Trophic Interactions as Modifiers of Carbon Export in the Sargasso Sea

Acronym/Short Name:Trophic BATS
Project Duration:2010-10 - 2014-09
Geolocation:Sargasso Sea, BATS site

Description

Fluxes of particulate carbon from the surface ocean are greatly influenced by the size, taxonomic composition and trophic interactions of the resident planktonic community. Large and/or heavily-ballasted phytoplankton such as diatoms and coccolithophores are key contributors to carbon export due to their high sinking rates and direct routes of export through large zooplankton. The potential contributions of small, unballasted phytoplankton, through aggregation and/or trophic re-packaging, have been recognized more recently. This recognition comes as direct observations in the field show unexpected trends. In the Sargasso Sea, for example, shallow carbon export has increased in the last decade but the corresponding shift in phytoplankton community composition during this time has not been towards larger cells like diatoms. Instead, the abundance of the picoplanktonic cyanobacterium, Synechococccus, has increased significantly. The trophic pathways that link the increased abundance of Synechococcus to carbon export have not been characterized. These observations helped to frame the overarching research question, "How do plankton size, community composition and trophic interactions modify carbon export from the euphotic zone". Since small phytoplankton are responsible for the majority of primary production in oligotrophic subtropical gyres, the trophic interactions that include them must be characterized in order to achieve a mechanistic understanding of the function of the biological pump in the oligotrophic regions of the ocean.

This requires a complete characterization of the major organisms and their rates of production and consumption. Accordingly, the research objectives are: 1) to characterize (qualitatively and quantitatively) trophic interactions between major plankton groups in the euphotic zone and rates of, and contributors to, carbon export and 2) to develop a constrained food web model, based on these data, that will allow us to better understand current and predict near-future patterns in export production in the Sargasso Sea.

The investigators will use a combination of field-based process studies and food web modeling to quantify rates of carbon exchange between key components of the ecosystem at the Bermuda Atlantic Time-series Study (BATS) site. Measurements will include a novel DNA-based approach to characterizing and quantifying planktonic contributors to carbon export. The well-documented seasonal variability at BATS and the occurrence of mesoscale eddies will be used as a natural laboratory in which to study ecosystems of different structure. This study is unique in that it aims to characterize multiple food web interactions and carbon export simultaneously and over similar time and space scales. A key strength of the proposed research is also the tight connection and feedback between the data collection and modeling components.

Characterizing the complex interactions between the biological community and export production is critical for predicting changes in phytoplankton species dominance, trophic relationships and export production that might occur under scenarios of climate-related changes in ocean circulation and mixing. The results from this research may also contribute to understanding of the biological mechanisms that drive current regional to basin scale variability in carbon export in oligotrophic gyres.


DatasetLatest Version DateCurrent State
Protist rates from epifluorescence counts; cyanobacteria rates from flow cytometry; bulk rates from extracted chlorophyll-a from R/V Atlantic Explorer cruises AE1102, AE1118, AE1206, AE1219 in the Sargasso Sea, BATS, 2011-20122015-01-16Final no updates expected
Abundance and biomass of protists from epifluorescence counts and bulk biomass from extracted chl-a from samples from R/V Atlantic Explorer cruises AE1102, AE1118, AE1206, AE1219 in the Sargasso Sea, Bermuda Atlantic Time-Series Station in 2011-122015-01-13Final no updates expected
Jellyfish Database Initiative: Global records on gelatinous zooplankton for the past 200 years, collected from global sources and literature (Trophic BATS project)2014-08-28Final with updates expected
Abundance and biomass of ciliates from inverted microscope counts from samples taken on R/V Atlantic Explorer cruises AE1102, AE1118, AE1206, AE1219 in the Sargasso Sea, Bermuda Atlantic Time-Series Station in 2011-2012 (Trophic BATS project)2013-08-22Final no updates expected
Pigment concentrations (HPLC) from R/V Atlantic Explorer cruises AE1102, AE1118, AE1206, AE1219 in the Sargasso Sea, Bermuda Atlantic Time-Series Station (BATS) from 2011-2012 (Trophic BATS project)2013-06-14Final no updates expected
ChemTax based chl-a of algal groups from R/V Atlantic Explorer cruises AE1102, AE1118, AE1206, AE1219 in the Sargasso Sea, Bermuda Atlantic Time-Series Station (BATS) from 2011-2012 (Trophic BATS project)2013-06-14Final no updates expected
Size-fractioned primary production rates from samples collected on R/V Atlantic Explorer cruises AE1102, AE1118, AE1206, AE1219 in the Sargasso Sea Bermuda Atlantic Time-Series Station in 2011-2012 (Trophic BATS project)2013-06-14Final no updates expected
Biogeochemical and biological data from Niskin bottle samples from R/V Atlantic Explorer cruises AE1102, AE1118, AE1206, AE1219 in the Sargasso Sea, Bermuda Atlantic Time-Series Station from 2011-2012 (Trophic BATS project)2013-05-21Final no updates expected
Sediment trap flux collected from R/V Atlantic Explorer cruises AE1102, AE1118, AE1206, AE1219 in the Sargasso Sea, Bermuda Atlantic Time-Series Station from 2011-2012 (Trophic BATS project)2013-05-01Final no updates expected

People

Lead Principal Investigator: Tammi Richardson
University of South Carolina

Co-Principal Investigator: Robert Condon
Dauphin Island Sea Lab (DISL)

Co-Principal Investigator: Susanne Neuer
Arizona State University (ASU)


Programs

Ocean Carbon and Biogeochemistry [OCB]