Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Parameters
• Instruments
• Deployments
• Project Information
• Program Information
• Funding

Mesozooplankton community grazing, expressed as ug pigment m^-2 h^-1, for 5 size classes (2-0.5, 0.5-1, 1-2, 2-5, and >5 mm) and total. Samples were collected during ring net tows on the MV1008 cruise in the Costa Rica Dome (CRD) region of the Eastern Tropical Pacific Ocean.

Mesozooplankton net collections
Mesozooplankton sampling was conducted using a standard 1-m2 ring net with 202-um Nitex mesh, towed obliquely for 20 min at a ship speed of 1-2 kts. A General Oceanics flowmeter was attached across the net mouth to record volume filtered, and a Vemco depth meter was fastened to the net frame to record tow depth and duration. The target depth of tows was 150m. Once on deck, the net was washed down with seawater and the contents of the cod end placed in a bucket with carbonated water to prevent gut evacuation. Separate splits (each of typically 1/8th of the sample) were used for biomass and gut-fluorescence determinations, with the latter done first to minimize pigment degradation. Each of these subsample splits was wet sieved into five size classes of 0.2-0.5, 0.5-1, 1-2, 2-5, and >5 mm.

Gut pigment and grazing estimates
Each size-fractioned sample for gut pigment analysis was concentrated onto a 47-mm 202-um Nitex filter and immediately frozen in liquid nitrogen for processing on shipboard or in the lab. The filters were subsampled for the three smallest size classes, by placing the frozen filters centered under a plastic template and sectioning into 8 pie-shaped fractions with a thin knife blade. Analyses were carried out in duplicate. The replicate 1/8th samples were ground in 90% acetone using a sonicator to extract pigments, and the homogenate was centrifuged to remove particulates. For the 2-5 mm size class, typically the whole sample was processed, although if very dense a smaller subsample was taken. The >5 mm size class was always processed in its entirety. Concentrations of chlorophyll a (Chl a) and phaeopigments (Phaeo) were then measured using a Turner 10AU fluorometer.

For each size-fraction analyzed, the investigators computed the depth-integrated grazing rate (GR) using phaeopigments only to obtain conservative rates. The GR was calculated in the euphotic zone as:

GR = [ (pig * D) / (vol * f) ] * K

where GR is the grazing rate (ug m-2 h-1), pig is the measured pigment value (ug, based on phaeopigments), f is fraction of sample analyzed, D is depth of tow (m), vol is the volume of water filtered (m3), and K is the gut evacuation rate constant. For K, the investigators used the rate constant of 2.1 h-1 derived from shipboard gut evacuation experiments at 140°W during the JGOFS EqPac program, which had similar temperatures as those encountered in the CRD.

BCO-DMO transposed size_class columns into rows.

Research was aimed at improved understanding of plankton dynamics, carbon and nutrient fluxes, and potential trace element limitation in the Costa Rica Dome region of the eastern tropical Pacific. The specific science objectives of the 2010 R/V Melville cruise (MV1008) were:
1) to assess grazing and trace metal/nutrient controls on primary production and phytoplankton standing stocks;
2) to quantify carbon and elemental fluxes and export rates from the euphotic zone; and
3) to measure microbial population, processes, stable isotope abundances associated with the OMZ and nitrite maxima.

Additional information about MV1008 can be found in the cruise report (PDF).

NOTE: The original proposal and award abstract are not relevant. The project was originally funded by NSF as experimental tests of phytoplankton controls in the Arabian Sea. Piracy concerns in the region led to the cancellation of the research cruise in 2009, and a Change of Scope request was approved to focus the project on related issues in the Costa Rica Dome (CRD).

Though this project is not formally affiliated with any large program, it aligns with IMBER's emphasis on community ecology and biogeochemistry, and the OCB focus on carbon-based measurements of production, grazing and export processes.

The BCO-DMO database includes data from IMBER endorsed projects lead by US funded investigators. There is no dedicated US IMBER project or data management office. Those functions are provided by US-OCB and BCO-DMO respectively.

The information in this program description pertains to the Internationally coordinated IMBER research program. The projects contributing data to the BCO-DMO database are those funded by US NSF only. The full IMBER data catalog is hosted at the Global Change Master Directory (GCMD). 

IMBER Data Portal: The IMBER project has chosen to create a metadata portal hosted by the NASA's Global Change Master Directory (GCMD). The GCMD IMBER data catalog provides an overview of all IMBER endorsed and related projects and links to datasets, and can be found at URL http://gcmd.nasa.gov/portals/imber/.

IMBER research will seek to identify the mechanisms by which marine life influences marine biogeochemical cycles, and how these, in turn, influence marine ecosystems. Central to the IMBER goal is the development of a predictive understanding of how marine biogeochemical cycles and ecosystems respond to complex forcings, such as large-scale climatic variations, changing physical dynamics, carbon cycle chemistry and nutrient fluxes, and the impacts of marine harvesting. Changes in marine biogeochemical cycles and ecosystems due to global change will also have consequences for the broader Earth System. An even greater challenge will be drawing together the natural and social science communities to study some of the key impacts and feedbacks between the marine and human systems.

To address the IMBER goal, four scientific themes, each including several issues, have been identified for the IMBER project: Theme 1 - Interactions between Biogeochemical Cycles and Marine Food Webs; Theme 2 - Sensitivity to Global Change: How will key marine biogeochemical cycles, ecosystems and their interactions, respond to global change?; Theme 3 - Feedback to the Earth System: What are the roles of the ocean biogeochemistry and ecosystems in regulating climate?; and Theme 4 - Responses of Society: What are the relationships between marine biogeochemical cycles, ecosystems, and the human system?

The Ocean Carbon and Biogeochemistry (OCB) program focuses on the ocean's role as a component of the global Earth system, bringing together research in geochemistry, ocean physics, and ecology that inform on and advance our understanding of ocean biogeochemistry. The overall program goals are to promote, plan, and coordinate collaborative, multidisciplinary research opportunities within the U.S. research community and with international partners. Important OCB-related activities currently include: the Ocean Carbon and Climate Change (OCCC) and the North American Carbon Program (NACP); U.S. contributions to IMBER, SOLAS, CARBOOCEAN; and numerous U.S. single-investigator and medium-size research projects funded by U.S. federal agencies including NASA, NOAA, and NSF.

The scientific mission of OCB is to study the evolving role of the ocean in the global carbon cycle, in the face of environmental variability and change through studies of marine biogeochemical cycles and associated ecosystems.

The overarching OCB science themes include improved understanding and prediction of: 1) oceanic uptake and release of atmospheric CO2 and other greenhouse gases and 2) environmental sensitivities of biogeochemical cycles, marine ecosystems, and interactions between the two.

The OCB Research Priorities (updated January 2012) include: ocean acidification; terrestrial/coastal carbon fluxes and exchanges; climate sensitivities of and change in ecosystem structure and associated impacts on biogeochemical cycles; mesopelagic ecological and biogeochemical interactions; benthic-pelagic feedbacks on biogeochemical cycles; ocean carbon uptake and storage; and expanding low-oxygen conditions in the coastal and open oceans.