Dataset: Mesozooplankton Production Estimates
Deployment: USJGOFS_SMP

As part of the JGOFS Synthesis and Modeling Initiative, we propose to conduct a number of tasks which will synthesize JGOFS mesozooplankton research. A major objective of the JGOFS Synthesis efforts will be to determine how food web structure influences carbon cycling within the euphotic zone and the sinking carbon flux. Mesozooplankton grazing (consumption of phytoplankton and protozoa), sloppy feeding (DOM release), fecal pellet production and downward carbon transport due to diel vertical migrators (part of carbon export) are essential elements of this analysis. Although this proposal focuses on mesozooplankton, we emphasize that our efforts will be collaborative with other JGOFS synthesis efforts. We will participate with other groups who are synthesizing and modeling biological control of biogeochemical fluxes.

Using the JGOFS datasets from the Sargasso Sea (ZOOSWAT), North Atlantic (NABE), Equatorial Pacific (EqPac), Arabian Sea (ASPS) and Southern Ocean (AESOPS, when available), as well as other appropriate data (i.e. from VERTEX and SUPER) we will examine the predictive relationships between mesozooplankton biomass, grazing and fecal pellet production with phytoplankton biomass (by size), protozoa biomass, total primary production (by size), new production and export flux. We will write a synthesis paper which describes these relationships, with the overall goal of elucidating the role of mesozooplankton in carbon cycling and export in the ocean. Our results will provide essential parameters for realistic models of carbon cycling in the euphotic zone.

The ZOOSWAT program at the time series station off Bermuda (BATS) conducted a complete inventory of the stocks and grazing rates of all major heterotrophs (flagellates, ciliates, copepods, salps), stocks and production of phytoplankton and bacteria, and estimates of export flux. We will synthesize this data by using our empirically derived rate parameters to construct a carbon model of food web interactions in the euphotic zone. The model forecasts of plankton biomass and carbon export will be compared to the data collected as part of the ongoing BATS program to test how these carbon exchange rates (consumption by different heterotrophs, export flux from the euphotic zone) vary under different environmental conditions.

We will examine the role of mesozooplankton in DOC production by synthesizing our data on DOC production via slopping feeding in the Equatorial Pacific and Arabian Sea with other published results. We hope to derive predictive relationships between DOC production, mesozooplankton biomass and feeding which can be used to estimate the amount of DOC produced by mesozooplankton in the JGOFS process studies. These estimates are needed for euphotic zone carbon models.

We will examine the role of diel vertical migration of mesozooplankton in the downward transport of carbon and nitrogen form the euphotic zone to the deep waters (the active flux). In this synthesis, we will employ the data sets from NABE, ZOOSWAT, EqPac and the ASPS, and others if available. In our estimates of the active flux, we will consider both metabolism and losses associated with mortality of the migrators. This latter component of the active flux has previously been neglected. We intend to establish predictive relationships between the active flux and relevant properties such as total and new production, among others. We will also examine with the above data sets, the role of mesozooplankton predation as the closure term in simple models of nutrients-herbivores. With a variety of published models of production, we will also estimate production rates of these oceanic zooplankton and the degree to which they may be food-limited. We will use estimates of mesozooplankton production and growth efficiencies to constrain our measurements of phytoplankton and microzooplankton ingestion rates.