Phytoplankton biomass

NH4+ is recycled rapidly and repeatedly between living biomass (phytoplankton, the zooplankton that graze on them, protozoans, bacteria and archaea) and the inorganic nutrient form, which is released from heterotrophic metabohsm and grazing. Nitrate, on the other hand, is new N because it is virtually absent from the euphotic zone most of the time and must be transported into the system by physical means—mixing or upweUing from deep waters or faUing in rain — in order for phytoplankton to use it. The rate of supply can be equated with the steady... 

Prey biomass = Phytoplankton biomass/10 DOCUMENT In kg wet weight. 

Temperature also affects production rates but, through its influence on the thermal expansion of water, it also induces changes in the depth of vertical mixing and resistance to wind-stirring processes. Reactions to temperature of other components of the food chain are also important in the regulation of phytoplankton biomass by consumers. Different phytoplankton species, with important morphological differences, are differentiated selectively by the interplay of these factors. " ... 

In this way, the near-linear chlorophyll-phosphorus relationship in lakes depends upon the outcome of a large number of interactive processes occurring in each one of the component systems in the model. One of the most intriguing aspects of those components is that the chlorophyll models do not need to take account of the species composition of the phytoplankton in which chlorophyll is a constituent. The development of blooms of potentially toxic cyanobacteria is associated with eutrophication and phosphorus concentration, yet it is not apparent that the yield of cyanobacterial biomass requires any more mass-specific contribution from phosphorus. The explanation for this paradox is not well understood, but it is extremely important to understand that it is a matter of dynamics. The bloom-forming cyanobacteria are among the slowest-growing and most light-sensitive members of the phytoplankton. ... 

Recently, the ocean-basin distribution of marine biomass and productivity has been estimated by satellite remote sensing. Ocean color at different wavelengths is determined and used to estimate near-surface phytoplankton chlorophyll concentration. Production is then estimated from chlorophyll using either in situ calibration relationships or from empirical functional algorithms (e.g., Platt and Sathyendranth, 1988 Field et al., 1998). Such studies reveal a tremendous amount of temporal and spatial variability in ocean biological production. 

To understand the distribution and pathways of organic material in the ocean the key question is "What happens to that 99% of the phytoplankton biomass that is remineralized between photosynthesis and burial "... 

Oceanic surface waters are efficiently stripped of nutrients by phytoplankton. If phytoplankton biomass was not reconverted into simple dissolved nutrients, the entire marine water column would be depleted in nutrients and growth would stop. But as we saw from the carbon balance presented earlier, more than 90% of the primary productivity is released back to the water column as a reverse RKR equation. This reverse reaction is called remineralization and is due to respiration. An important point is that while production via photosynthesis can only occur in surface waters, the remineralization by heterotrophic organisms can occur over the entire water column and in the underlying sediments. 

The oceanic biota reservoir (4) is also within the surface layers. Although organisms reside at all depths within the ocean, the overwhelming majority reside within the photic zone where phytoplankton dominate. The oceanic biota reservoir only contains roughly 1 /30 as much P as the land biota reservoir. This is primarily because oceanic biomass is composed of relatively short-lived organisms, while land biomass is dominated by massive long-lived forests. 

Jassby AD (2008) Phytoplankton in the upper San Erancisco Estuary recent biomass trends, their causes, and their trophic significance. San Erancisco Estuary Watershed Sci 6(1) Article 2. http //repositories.cdlib.org/jmie/sfews... 

Peech Cherewyk 2002 Tsui and Wang 2004). Phytoplankton have a constrained trophic position are not consumed by fish, wildlife, or humans, and are indirectly relevant to the pnbhc or the policy commnnity. They wonld respond veiy rapidly — within minntes or honrs — to changes in MeHg concentrations in water. Phytoplankton obtain MeHg directly from water (Mason et al. 1996), and algal density can inlinence concentrations of MeHg in phytoplankton via biomass dilntion (Pickhardt et al. 2002). 

Phytoplankton Biomass and Communities Longitudinal and Interannual Variations... 

Sabater et al. [3] performed chemical and planktonic analyses at 31—43 sampling sites scattered along the main course of the Ebro (Fig. 1). Twenty-five sites covered from the upper reach down to the Ebro Reservoir to the reservoirs of Flix, Mequi-nenza and Ribaroja, while the other six were downstream up to 30 km from the river mouth. Samples were collected in June and October 2005 and 2006. Other surveys were completed in 2008 and 2009. Physical, chemical, and biological analyses were performed at all sites and were later related to the phytoplankton biomass. 

Reynolds CS, Descy JP (1996) The production, biomass and structure of phytoplankton in large rivers. Arch fur Hydrobiol Suppl 113 161-187... 

Phytoplankton, mixed populations 21 pg Pb/L for 4 days Reduced biomass 3... 

G.C. Cadee and J. Hegeman, Phytoplankton in the Marsdiep at the end of the 20th century 30 years monitoring biomass, primary production, and Phaeocistis blooms. J. Sea Res. 48 (2002) 97-110. 

L. Lampert, B. Queguiner, T. Labasque, A. Pichon and N. Lebreton, Spatial variability of phytoplankton composition and biomass on the eastern continental shelf of the Bay of Biscay (north-east Atlantic Ocean). Evidence for a bloom of Emiliana huxleyi (Prymnesiophyceae) in spring 1998. Coni. Shelf Res. 22 (2002) 1225-1247. 

Finally, it is noteworthy that not all marine organisms are classifiable as POM. Viruses, small bacteria, and archaea can pass through 0.2-p,m filter pores and, thus, are technically part of the DOM. Although these organisms are small (0.2 to 20 x 10 gC/cell for viruses and bacteria, respectively), their high numbers (10 to lO and 10 to 10 cells/L, respectively) cause their collective biomass in seawater to be similar to that of phytoplankton and zooplankton (<2mm) (Table 23.2). The biomass of the archaea and the macrozooplankton (>2 mm) are currently unknown. Nonetheless, these two groups play very important biogeochemical roles as described later. 

The most abundant compound class found in phytoplankton and bacteria are the proteins. As shown in Table 23.3, proteins make up about half of their dry weight. In comparison to eukaryotic phytoplankton, bacteria are enriched in RNA and DNA. Because proteins and nucleic acids are relatively enriched in nitrogen as compared to carbohydrates and lipids (Table 23.4), bacterial biomass is enriched in nitrogen relative to eukaryotic phytoplankton. 

The entire phytoplankton biomass of the global oceans is consumed every 2 days to 2 weeks. Thus, the standing stock tells us little about how much organic... 

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