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Steinberg, DK, Landry MR.  2017.  Zooplankton and the ocean carbon cycle. Annual Review of Marine Sciences, Vol 9. 9:413-444., Palo Alto: Annual Reviews   10.1146/annurev-marine-010814-015924   Abstract

Marine zooplankton comprise a phylogenetically and functionally diverse assemblage of protistan and metazoan consumers that occupy multiple trophic levels in pelagic food webs. Within this complex network, carbon flows via alternative zooplankton pathways drive temporal and spatial variability in production-grazing coupling, nutrient cycling, export, and transfer efficiency to higher trophic levels. We explore current knowledge of the processing of zooplankton food ingestion by absorption, egestion, respiration, excretion, and growth (production) processes. On a global scale, carbon fluxes are reasonably constrained by the grazing impact of microzooplankton and the respiratory requirements of mesozooplankton but are sensitive to uncertainties in trophic structure. The relative importance, combined magnitude, and efficiency of export mechanisms (mucous feeding webs, fecal pellets, molts, carcasses, and vertical migrations) likewise reflect regional variability in community structure. Climate change is expected to broadly alter carbon cycling by zooplankton and to have direct impacts on key species.

Landry, MR, Peterson WK, Lorenzen CJ.  1995.  Zooplankton grazing, phytoplankton growth, and export flux: Inferences from chlorophyll tracer methods. ICES Journal of Marine Science. 52:337-345.   10.1016/1054-3139(95)80049-2   AbstractWebsite

Chlorophyll tracer methods were used on six cruises in the Southern California Eight to assess mesozooplankton grazing rates (gut fluorescence), fecal pellet export from the euphotic zone (pigment flux to sediment traps), the partitioning of grazing impact between micro- and mesozooplankton (pigment budget), and phytoplankton growth. Mesozooplankton grazing estimates ranged from 16 to 44% of phytoplankton growth rates during the six cruises, with the mean seasonal average for the spring cruises about double (39%) that from the autumn cruises (20%). Only 23 to 32% of the measured mesozooplankton grazing on phytoplankton was lost rapidly enough from the euphotic zone to be recovered as phaeopigment flux into sediment traps. Since most (68 to 77%) of the grazing activity of mesozooplankton, as inferred from the gut pigment method, does not settle rapidly out of the euphotic zone, it is functionally equivalent (i.e. remineralized within the euphotic zone) to that of microzooplankton as defined by the pigment budget method. The gut fluorescence estimates of mesozooplankton grazing were about equal generally to the sum of micro- and mesozooplankton grazing as inferred from the pigment budget model. Moreover, estimates of phytoplankton growth from the pigment budget were consistently low by a factor of 3 and 4 compared with rates inferred from C-14 estimates of production and an assumed C:Chl ratio of 50. Previous studies in systems dominated by large pellet-producing metazooplankton and/or direct cell sinking of phytoplankton have demonstrated that the combined pigment budget estimates of phytoplankton losses were consistent with independent estimates of phytoplankton growth. The lack of such agreement in the present study suggests that the approach may not account adequately for the grazing of protistan microzooplankton.

Hoover, RS, Hoover D, Miller M, Landry MR, DeCarlo EH, Mackenzie FT.  2006.  Zooplankton response to storm runoff in a tropical estuary: bottom-up and top-down controls. Marine Ecology-Progress Series. 318:187-201.   10.3354/meps318187   AbstractWebsite

Zooplankton successional patterns and response times were characterized in a tropical estuary following a major storm-runoff event to evaluate the effects of a nutrient perturbation on community composition and dynamics. Intensive water-column monitoring in southern Kaneohe Bay, Hawaii, showed that dissolved macronutrients - NO3- + NO2-, SRP (soluble reactive phosphorus) and Si(OH)(4) - increased significantly immediately following the initial runoff event. Bottom-up effects were evident in both phytoplankton and zooplankton communities. An initial phytoplankton bloom was dominated by small cells and lasted only a few days, while post-bloom pigment concentrations showed a more gradual increase in total chlorophyll a and a shift to a diatom-dominated community. The initial bloom had an unexpectedly large influence on zooplankton growth and reproduction on extremely short time scales. Appendicularians exhibited the most dramatic response, with biomass increasing 6-fold in 1 d, and abundances reaching values only rarely observed in these waters. Response covaried with organism size, with larger components of the community, especially calanoid copepods and gelatinous zooplankton, increasing as new resources became available. Post-bloom changes in zooplankton and phytoplankton community structure also suggest significant top-down controls on phytoplankton and zooplankton community biomass and structure, with increased predation on appendicularians and copepods resulting in partial release of grazing pressure on small and large cells, respectively. Nutrient-rich runoff can have significant and surprisingly rapid impacts on zooplankton population dynamics in tropical coastal waters via direct, pulsed, food influences on the growth and reproduction of omnivorous organisms and the indirect stimulation of secondary consumers.