Primary production seasonal cycles

In spite of these caveats, studies of enzyme activities in sediments show some recurring features. Seasonal cycles in primary productivity in temperate... 

Smith WO, Marra J, Hiscock MR, Barber RT (2000) The seasonal cycle of phytoplankton biomass and primary productivity in the Ross Sea, Antarctica. Deep-Sea Res Part II 47 3119-3140... 

Smith EM (1998) Coherence of microbial respiration rate and cell-specific bacterial activity in a coastal planktonic community. Aquat Microb Ecol 16 27-35 Smith WO Jr, Nelson DM, DiTullio GR, Leventer AR (1996) Temporal and spatial patterns in the Ross Sea phytoplankton biomass, elemental composition, productivity and growth rates. J Geophys Res 101 18455-18466 Smith WO Jr, Marra J, Hiscock MR, Barber RT (2000) The seasonal cycle of phytoplankton biomass and primary productivity in the Ross sea, Antarctica. Deep-Sea Res II 47 3119-3140... 

In chapter 14, John Melack and Bruce Forsberg provide a quantitative assessment of the role of floodplain lakes in regional cycles of C, N, and P. Floodplain lakes were found to be important centers of organic carbon production and delivery to the river system. The combined primary production of macrophytes, forests, periphyton, and plankton associated with floodplain lakes is estimated at 117 Tg C yri, of which only 24% is remineralized in the lakes. As a result, an estimated 90 Tg C yr are delivered to the river system by continual and seasonal exchanges. This input alone amounts to... 

Jenkins, W. J., and Goldman, J. C. (1985). Seasonal oxygen cycling and primary production in the... 

In a study of sediment trap samples collected at a depth of 3,200 m in the Sargasso Sea, Bacon et al. (1985) found that the fluxes of several radionuclides exhibited a seasonal cycle in phase with the total mass flux of particles. Mass flux, in turn, was found to be closely coupled to the seasonal cycle of primary production in surface waters of this region (Deuser et al., 1981). Seasonally varying fluxes of radionuclides produced in the deep sea (e.g., Th, Pa, and °Pb) are inconsistent with the view that these nuclides are removed by scavenging to small particles which constitute the bulk of particle mass in the deep sea and which are inferred to sink at an average rate of several hundred meters per year (Section 6.09.3). A seasonal cycle in the flux of these nuclides implies that scavenging in the deep sea responds rapidly to changes in the export of particles from surface waters. 

An especially important gap in the present knowledge of processes changing the characteristics of water masses within the Southern Ocean centers on the effect of the seasonal cycle, the formation and dissolution of pack ice and its associated biological processes. One aim must be to explain the paradox of the mismatch of dissolved nutrient concentration and the primary production in the pelagic ecosystems (9). One important hypothesis that needs further testing is the possibility of Fe limitation of nutrient uptake (10). 

Fig. 1 Seasonal cycles of productivity and global average rates of primary production. Reprinted from Koblentz-Mishke et a/. (1970), with permission from Scientific Exploration of the South Pacific, Courtesy of the National Academy of Sciences, Washington, DC.

These seasonal cycles of productivity are shown schematically in Fig. 1, along with a map of current estimates of primary production rates. In the north Pacific zooplankton population growth supresses the spring bloom. 

On a localized basis, human activity can affect the carbon cycle indirectly by increasing the supply of mineral nutrients to aquatic environments. A large nutrient supply supports high levels of primary productivity by phytoplankton (algae and cyanobacteria), a process described as eutrophication. Under natural conditions, eutrophication is usually seasonal outside the tropics, being related to the stratification of the water column and the succession of phytoplankton (see Section 3.2.4). When nutrients are exhausted in the upper... 

Ice is a key attribute linked to cycles of primary productivity on continental shelves. Marginal ice zones (MIZ) are some of the most dynamic areas in the world s oceans with large seasonal and inter-annual fluctuations in ice cover and ice transport. These are unique habitats with specific communities dependent upon the physicochemical structure of the ice (Thomas Dieckmann, 2002). 

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