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Picoplankton carbon flux in Chesapeake Bay

1991; Inter-Research; Volume: 78; Linguagem: Inglês

10.3354/meps078011

1616-1599

TC Malone, HW Ducklow, E.R. Peele, SE Pike,

Ocean Acidification Effects and Responses

Although it is increasingly clear that picoplankton play a major role in the oceanic carbon cycle, relatively little is known concerning the significance of picoplankton in coastal systems subject to significant evironmental variance on tidal to interannual scales.Here w e report on seasonal and interannual patterns of variability in the productivity and biomass of phototrophic and heterotrophic picoplankton (P-and H-PICO, respectively) and on the flow of carbon from phytoplankton to H-PICO.Annual cycles in the biomass and productivity of both picoplankton trophic levels exhibit winter-spring minima and summer maxima but do not appear to be directly coupled in terms of carbon flow from P-to H-PICO.H-PICO exceeds P-PICO durlng sprlng when picoplankton productivity is 1 0 ~1 , and P-PICO exceeds H-PICO during summer when productivity is high.P-PICO productlvity and biomass increase rapidly each year to an early summer peak (20",, of total phytoplankton productlvity on average) immediately following the collapse of the spring diatom bloom.In contrast, H-PICO productivity and the abundance of bacterioplankton (the predominant group of H-PICO) increase slowly to a late summer peak (equivalent to 16 % of phytoplankton productivity on average).Recently released phytoplankton exudates are a major source of dissolved organic carbon with H-PICO taking u p an average of 54 % during spring and 8 3 ?hduring summer Variations in H-PICO are closely coupled to the release of DOC, most of which is produced by phytoplankton > 2 pm.New nutrient input to the Bay appears to be coupled to H-PICO productivity \rla increases in the productlvlty and DOC release of phytoplankton > 2 pm in slze.