Trophic relations

Iken K (1996) Trophic relations between macroalgae and herbivores in Potter Cove (King George Island, Antarctica). Rep Polar Res 201 1-206... 

Kikuchi, T., 1979. 3apane e contributions on consumer ecology in eelgrass (Zostera marina L.) beds, with special reference to trophic relations and resources in inshore fisheries. Aquaculture, 9 195-160. 

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.

Current prokaryotes have between 480 and 8000 genes, of which core components define their trophic relations to their environments. Mycoplasma geiiitalium, a metabolically minimal organism because it depends on the organically richest... 

This observation remains valid, as does the view (Parsons LeBrasseur, 1970 Sheldon etal., 1977) that the main variable in determining what eats what is the relative size of predator and prey. However, there have been major changes in the understanding of trophic relations since the 1970s. 

Carbon turnover in terrestrial ecosystems is mostly linked to biochemical reactions of three types of organisms. Primary biomass is produced by autotrophic organisms, mainly plants. Their biomass is transformed into new but chemically similar secondary biomass of consumers. These are connected by trophic relations in food chains and carbon recycling systems. Nonliving biomass is again mineralized by decomposers to carbon dioxide, water, and minerals. The basic biochemical pathways such as glycolysis, the pentose-phosphate cycle (Calvin cycle), and the Krebs cycle are for all organisms nearly identical. Only a few main biochemical pathways produce metabolites for biomass production, in particular cell walls. 

Mark-Kurik, E. (1995) Trophic relations of Devonian fishes . Geobios, Memoire special, 19, 121-3. 

Bioconcentration, Bio accumulation and Biomagnification. These aspects are determined by the physicochemical properties of a chemical, an organism s ability to excrete the chemical, the organism s lipid content and its trophic level. Bioconcentration relates to the difference between the environmental concentration and that of the body tissues. A high bioconcentration factor (BCF) predisposes to bioaccnmulation. The upper limit of bioaccnmulation is determined by lipid levels in the organism s tissues. Whether the resultant body burden causes biomagnification in the food chain depends upon the metabolic capabilities of the exposed organism. 

The first case is based on a hypothetical stream receiving a metal-poUuted source (for instance the outlet of a metal factory). In this case, metal concentration is expected to be driven by dilution, being higher under low-flow than under base-flow conditions and minimum during floods. Metal accumulation is expected to be maximum under low-flow conditions and proportional to the duration of this water scarcity situation. Chronic exposure will lead to community adaptation, which is often related to changes in species composition. Metals will therefore be bioaccumulated in fluvial biofihns and transferred to higher trophic levels in the fluvial food web. 

Discrimination factors on different trophic levels in relation to the trace element content... 

Amino acid synthesis in heterotrophs primarily relies on dietary protein rather than on lipids or carbohydrates (Schwarcz, 2000), and thus the isotopic composition of the resulting new collagen is related more to dietary protein rather than to bulk diet. Trophic... 

Cizdziel JV, Hinners TA, Pollard JE, Heithmar EM, Cross CL. 2002. Mercury concentrations in fish from Lake Mead, USA, related to fish size, condition, trophic level, location, and consumption risk. Arch Environ Contam Toxicol 43 309-317. 

In addition to their role in chemical defense, DMSP-lyase products may also function as chemical cue in more complex trophic cascades. In the natural environment DMS-production is related to zooplankton herbivory [60] and can thus act as an indicator for the availability of food for planktivorous birds. Indeed, some Antarctic Procellariiform seabirds can detect DMS (22) and are highly attracted to the cue, as was shown with DMS-scented oil slicks on the ocean surface [61]. The odors released during zooplankton grazing (DMS) as well as those of zooplankton itself (e.g., trimethylamine and pyrazines) are attractive to birds [62], thus assisting vertebrate search behavior. 

According to results from clinical trials, the agonistic effects of tamoxifen detected in animals were also observed in the human uterus as it produces a trophic effect and an increase in the incidence of endometrial pathology, which is related to endometrial thickening (> 4 mm). Its use seems to be associated with an increase in endometrial cancer, which is related to the length of treatment and the accumulated dose of tamoxifen. Nevertheless, these tumors do not seem to be more aggressive or to have a worse prognosis than those found in women who do not follow this treatment or who receive hormone therapy. 

The health of the population is closely related to the environmental situation in industrial areas. Heavy metals were the priority contaminators in large industrial centers of Ukraine for a long period of time [1]. They penetrated into the environment inside industrial wastes, and then circulate in trophic chains and reside in tissues of plants, animals, and humans. Our previous analyses showed that soil Zn deficiencies... 

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