Ocean ecosystems

Ocean disposal Disp>ersal Acids, bases Contact with ocean ecosystem... 

Tortell, P. D., M. T. Maldonado, and N. M. Price. 1996. The role of heterotrophic bacteria in iron-limited ocean ecosystems. Nature 383 330—332. 

Interannual oscillations in C02 concentration in the atmosphere correspond to changes in the use of fossil fuels. The intra-annual variability of atmospheric C02 correlates to a greater extern with the dynamics of land ecosystems and to a lesser extent with the dynamics of ocean ecosystems. 

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... 

The ocean covers 71% of the planet s surface and is the source of a substantial amount of foodstuffs consumed by humans (around 1 % of total food consumption), the remaining 99% of food is obtained from cultivated land. At the same time, the total amount of organic matter produced in the ocean is approximately equal to that produced by land vegetation. By rough estimates, the total biomass of nekton constitutes 5.3 1091. The catch of fish and other species from the World Ocean is estimated at 70 106 t/yr, which constitutes 20% of the protein consumed by humans. The catch of traditional species is close to the limit for their sustainability ( 90 106 t/yr-100 106 t/yr). However, it is not a limit to the industrial ability of ocean ecosystems in general, since the supplies of krill and other biological objects are still used little. 

This disproportion between the role of land and ocean ecosystems in food production is explained, primarily, by the fact that agriculture has been intensively developed, whereas in the seas and oceans development has been poor by comparison. Possible ways of increasing ocean bioproductivity have not been considered beyond catching animals at the end of the trophic chains of natural communities of the World Ocean (i.e., fish and whales). Each successive trophic level gains about 0.1% of the share of energy accumulated at a previous level. On land, two levels of organisms (vegetation and herbivores) are used, but in the ocean and in the seas there are up to five levels. The direct use of non-fish species will make it possible to sharply increase the amount of protein obtained from the ocean. 

Variability of the patchy topology and vertical structure is connected with seasonal cycles and has been well studied experimentally in many climatic zones of the World Ocean. The typical qualitative and quantitative indicators of this variability have been found. The combined distributions of abiotic, hydrological, and biotic components of the ocean ecosystems have been studied. Vetrov and Roman-kevich (2004) analyzed conditions for the carbon cycle formation in the Barents, White, Kara, East-Siberian, and Chukchi Seas, considering the relationships between... 

The complexity and mutual dependence of all the processes in the ocean substantially hinder discovery of the laws of formation of phytoplankton spots and establishing correlations between the various factors that regulate trophic relationship intensity in ocean ecosystems. For instance, many studies revealed a close relationship between primary production and phytoplankton amount. At the same time, this relationship breaks down depending on the combination of synoptic situation and insolation. It turns out that the extent of this breakdown depends much on the combination of groups of phytoplankton (Legendre and Legendre, 1998). 

An efficient way of studying the vertical structure of ocean ecosystems is to numerically model them based on measurements of their characteristics (Kuck et al., 2000). To derive the model, it is necessary to know the structure of the trophic relationships in ecosystems, specific features of hydrological conditions, and information about other characteristics of the environment. Experience in such modeling has pointed up a possibility for efficient prediction of the dynamics of World Ocean communities. Examples of such models include a 3-D model of the ecosystem of the Peruvian current (Krapivin, 1996), of the Okhotsk Sea (Aota et al., 1993), and others. In all these models the main task was parameterizing a unit for the vertical structure of the ecosystem. 

Each element of ocean ecosystem A can be described by a number of parameters, and the connection between elements can be presented as that between the respective parameters. Then, on the whole, ecosystem A can be described by N time-dependent parameters x (t) = xj(t),j = 1,..., IV. The structure A(t) and behavior A(t) of ecosystem A, which can be observed in more or less detail, are functions of these parameters. Therefore, the ecosystem itself A(t) = A(t), A(t), as a combination of structure and behavior, is a function of these parameters ... 

According to the principles mentioned above, the derivation of a numerical model of ocean ecosystem A requires either a detailed description of its states or derivation of an adequate complex of numerical models of energy exchange between the trophic levels taking place in A, as well as the interactions of biotic, abiotic, and hydrophysical factors. Of course, in this case an availability of a certain set of hypotheses is assumed concerning the character of the balanced relationship in ecosystem A. 

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. 

Zooplankton are an important trophic element in the ocean ecosystem presented at an integral level Z which implies the presence of a large number of sub-levels with untersecting trophic bonds. Zooplankton feed on phytoplankton and bacterio-plankton, and are themselves food for nekton r and detritophages D. 

Figure 3.12. Longitude-averaged rates of atmospheric C02 assimilation by both land and ocean ecosystems with two scenarios of anthropogenic emissions of carbon 6.26GtC/yr (dashed curve, 2000) and 10.6GtC/yr (solid curve, predicted for 2020). Notation Ha = A//32 I Uh I IIa Hi Hi "<) (GtC yr-1).

Natural terrestrial ecosystems - 19(1 TgN/yr Nature oceanic ecosystems - 30 TgN/yr leguminous crops - 40 TgNA r Combustion - 20 TgN/yr Chemical fertilizer - 20 TgN/yr... 

The dissipation of moving kinetic energy, geothermic flow on the ocean bed, heat effects of chemical processes in the ocean ecosystem, and freezing and melting of the ice are not considered to be global determinants of water temperature fields. Therefore, the SSMAE does not consider these effects. 

Arrigo KR, Worthen DL, Robinson DH (2003) A coupled ocean-ecosystem model of the Ross Sea. Part 2 iron regulation of phytoplankton taxonomic variability and primary production. J Geophys Res 108(C7) 3231. DOI 10.1029/2001J C000856... 

Phaeocystis sp. (Prymnesiophyceae). II. Pigment Composition. J Phycol 34 496-503 Wells ML (1999), Manipulating iron availability in nearshore waters. Limnol Oceanogr 44 1002-1008 Wells ML, Price NM, Bruland KW (1994) Iron limitation and the cyanobacterium Synechococcus in equatorial Pacific waters. Limnol Oceanogr 39 1481-1486 Worthen DL, Arrigo KR (2003) A coupled ocean-ecosystem model of the Ross Sea. Part 1 Interannual variability of primary production and phytoplankton community structure. In DiTullio GR, Dunbar RB (eds) Biogeochemistry of the Ross Sea. Antarct Res Ser 78 93-105... 

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