Trophic pyramid

Eutrophic water. A water basin with a very high content of nutrients and increased biological productivity (75gCm 2yr 1 750 gCm 2yr ). Some elements of the trophic pyramid are suppressed for lack of oxygen. 

To increase the reliability of assessing the role of the World Ocean in the global carbon cycle, a more detailed description is needed of the production processes in ocean ecosystems. Along with the physical and chemical processes of transformation and motion of carbon in the ocean medium, the biological processes play an important role. In particular, phytoplankton, just like the nutrient elements, assimilates dissolved C02 from saltwater. As a result, an organic substance is formed that partially goes to the nutrient chains of the trophic pyramid of a given basin of the World Ocean and partially descends to bottom sediments. The totality of all the... 

Let us suppose the food bonds between trophic levels are adequately described by the Ivlev model (i.e., the consumption of various kinds of food by the /th trophic level is proportional to the efficiency of their biomasses). Taking into account the diagram of food bonds developed by Kondratyev et al. (2003b) and the structure of the trophic pyramid of a typical ocean ecosystem, we can consider each trophic level in detail. 

Figure 6.3. Block diagram of energy flows (calm-3 da-1) in the trophic pyramid of the Arctic Basin ecosystem. This is realized as block MEF. The boxes with elements denote the generalized trophic levels of the Arctic ecosystem. All of the elements are described by means of averaged parameters for the biological community of the northern seas. It is supposed that this trophic pyramid takes place in each of the Arctic Basin seas. The trophic relations between the elements of the model are described on the basis of the energy principle (Nitu et al., 2000b). Biomasses, rates of production and exchange (respiration), and food rations are expressed in energy units. Total nitrogen serves as a nutrient salts prototype in the model.

Let us consider the following components of the Okhotsk Sea ecosystem mentioned in Table 6.21. The trophic pyramid X = vy, where xtj is a binary value equal to 1 or 0 under the existence or absence of a nutritive correlation between the z th and y th components, respectively. Let us define the biocomplexity as a function ... 

Table 6.21. Trophic pyramid of the Okhotsk Sea ecosystem considered in calculations of the biocomplexity indicator. 

This section introduced a methodology to move from a verbal description of biocomplexity to its numerical representation. In future studies it will be necessary to take into consideration bottom relief, climate trends, ice field dynamics, detailed components of the trophic pyramid, bottom sediments, and the structure of currents. Also, it will be necessary to add to Formula (6.31) elements describing anthropogenic impacts on the ecosystem considered in a socio-economic sense. 

The bioaccumulation of pollutants in the tissues of organisms at different levels of the trophic pyramid... 

Let us consider now the food chain. Chemicals which accumulate in one organism at one trophic level in the food chain (a prey) owing to tissue binding are further concentrated at the subsequent trophic level. The highest tissue will occur at the top of the trophic pyramid. This holds especially true for human beings who are indeed at the top of different food chains. The mechanism of bioaccumulation can be best understood by a simple ecosystem model (Spain, 1982). Figure 5 shows the time course of concentration of a non-metabolized pesticide at each trophic level following the constant influx of a pesticide into the environmental compartments. 

FIGURE 2-18 Pyramids of biomass (g/m2) in three ecosystems. Typically, the biomass of a given trophic level is less than the biomass of lower trophic levels, giving rise to a pyramid when box sizes are drawn proportional to biomass. This is the consequence of decreasing energy availability at successively higher trophic levels [data are from Odum (1971)]. 

FIGURE 5.5.5 The food pyramid, ako called trophic levels. Energy is transferred from the bottom to the top with an efficiency between levels of about 10%. (From Fried, G.H. and Hademenos, G.J., Theory and Problems of Biology, Schaum s Outlines, McGraw-Hill, New York, 1999. With permission.)... 

Figure 6.4 Energy Flow Through the Filter Bed Ecosystem. Bacteria and fungi present in the zoogleal film assimilate nutrients from the settled sewage and constitute the first tropic level. Bacteria and fungi are eaten by the second trophic level mainly protozoans. Rotifers and nematode predators constitute the third trophic level. At the summit of the food pyramid are worms and insect larvae. The bed represents a complex and highly integrated ecosystem in which the bed community is responsible for complete oxidation of the organic content of the sewage.

---