Eddy-wind interactions stimulate extraordinary mid-ocean plankton bloomsOne-sentence summary: Mid-ocean eddies, together with wind-forced motions, cause episodic bursts of nutrient supply to the upper ocean, changes in plankton community structure, and export of organic material to the deep sea. Understanding the controls on primary production in the upper ocean is of fundamental importance for two main reasons. First, primary productivity sets a firstorder constraint on the energy available to sustain oceanic ecosystems. Second, fixation and subsequent sinking of organic particles removes carbon from the surface ocean (the so-called "biological pump"), which plays a key role in partitioning of carbon dioxide between the ocean and atmosphere. Geochemical estimates of new production (1) surpass the apparent rate of nutrient supply by vertical mixing by a factor of two or more in subtropical oceans (2-6), which constitute some of the largest biomes on earth. Two possible mechanisms to supply the "missing" nutrient locally include nitrogen fixation by cyanobacteria (7-10), and intermittent upwelling by mesoscale eddies and submesoscale processes (11-21).

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.

This review provides an assessment of sediment trap accuracy issues by gathering data to address trap hydrodynamics, the problem of zooplankton "swimmers," and the solubilization of material after collection. For each topic, the problem is identified, its magnitude and causes reviewed using selected examples, and an update on methods to correct for the potential bias or minimize the problem using new technologies is presented. To minimize hydrodynamic biases due to flow over the trap mouth, the use of neutrally buoyant sediment traps is encouraged. The influence of swimmers is best minimized using traps that limit zooplankton access to the sample collection chamber. New data on the impact of different swimmer removal protocols at the US time-series sites HOT and BATS are compared and shown to be important. Recent data on solubilization are compiled and assessed suggesting selective losses from sinking particles to the trap supernatant after collection, which may alter both fluxes and ratios of elements in long term and typically deeper trap deployments. Different methods are needed to assess shallow and short-term trap solubilization effects, but thus far new incubation experiments suggest these impacts to be small for most elements. A discussion of trap calibration methods reviews independent assessments of flux, including elemental budgets, particle abundance and flux modeling, and emphasizes the utility of U-Th radionuclide calibration methods.

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