Metabolism ecosystem

In addition to reproductive effects, fish exposed to endocrine disrupters may have a decreased response to stress or decreased growth and metabolism which can affect their ability to survive, or to defend themselves against predators. All of these factors can affect the ability of the species to survive and to reproduce itself in sufficient numbers to maintain the stocks on which our commercial and sport fisheries are based. Not all fish species will be equally susceptible to the effects of endocrine disrupters. Selective sensitivity to such effects, especially those affecting reproduction, may well lead to major changes in the flora and fauna of some of our major aquatic ecosystems as the balance between fish, mammals, invertebrates and plants, and between predators and prey, is destabilised... 

A general conclusion from the review of the distribution of plutonium between different compartments of the ecosystem was that the enrichment of plutonium from water to food was fairly well compensated for by man s metabolic discrimination against plutonium. Therefore, under the conditions described above, it may be concluded that plutonium from a nuclear waste repository in deep granite bedrock is not likely to reach man in concentrations exceeding permissible levels. However, considering the uncertainties in the input equilibrium constants, the site-specific Kd-values and the very approximate transport equation, the effects of the decay products, etc. — as well as the crude assumptions in the above example — extensive research efforts are needed before the safety of a nuclear waste repository can be scientifically proven. 

Numerous studies have shown that increased levels of UV affect photosynthetic activity (10-23), growth rate (24), nitrogen metabolism (25), and locomotion (26) of phytoplankton. Additionally, increases in UV-B are likely to alter community diversity as well as phytoplankton species composition. Thus, by weakening the base of the food web and altering trophodynamic relationships, UV-induced changes could potentially have far-reaching effects on the entire ecosystem. 

Artigas J, Romani AM, Gaudes A, et al (2009) Benthic structure and metabolism in a Mediterranean stream from biological communities to the whole stream ecosystem function. Fresh. Biol. 54 DOI 10.1111/j.l365-2427.2008.02140.x... 

In Europe the situation is radically different. Isotopic variations at the bottom end of the food web, brought about by differences in plant metabolism (C3, versus C4 and CAM), and origin of the fixed COj, (causing a systematic discrepancy between terrestrial and marine ecosystems) are generally absent. This leads to relatively small variations in ratios at the beginning of... 

Finally, an outline of how the same approach to modeling can be applied to questions of nitrogen metabolism and to food chains in ecosystems is presented. We would argue that the value of such an approach lies at least as much in helping to better define issues, and in suggesting new, testable hypotheses, than in providing explanations which may rest on oversimplified assumptions. 

Varanasi, U., Stein, J.E., and Reichert, W.L. et al. (1992). Chlorinated and aromatic hydrocarbons in bottom sediments, fish and marine mammals in US coastal waters laboratory and field studies of metabolism and accumulation. In C.H. Walker and D.R. Livingstone (Eds.) Persistent Pollutants in Marine Ecosystems, Oxford, U.K. Pergamon Press, 83-118. 

MCBAIN A J, MACFARLANE G T (2001) Modulation of genotoxic enzyme activities by non-digestible oligosaccharide metabolism in in-vitro human gut bacterial ecosystems. J Med Microbiol. 50 833-42. 

Organisms in natural ecosystems may not be actively dividing but may, nonetheless, be metabolically active. This may be particularly important for ultramicro marine bacteria in their natural habitat. 

Results from experiments on biodegradation in which readily degraded substrates such as glucose are added have probably restricted relevance to natural ecosystems in which such substrates exist in negligible concentration. However, readily degraded substrates in addition to those less readily degradable undoubtedly occur in biological-waste-treatment systems. In these circumstances, at least three broadly different metabolic situations may exist ... 

In natural ecosystems, microbial growth and metabolism may be limited by the concentrations of inorganic nutrients such as nitrogen, phosphorus, or even iron. Systematic investigation of these... 

Mackie Rl, BA White, MP Bryant (1991) Lipid metabolism in anaerobic ecosystems. Crit Rev Microbiol 17 449-479. 

These studies have revealed a number of cardinal aspects of microbial ecology (a) the complexity of bacterial ecosystems, (b) the number of organisms of hitherto undetermined taxonomy, (c) the existence of organisms that have not been cultivated, and (d) the difficulty of assigning metabolic roles to many of the genomic sequences that have been revealed. Some examples are given to... 

Jackson TA. 1998. Mercury in aquatic ecosystems. In Langston WJ, Bebiarmo MJ, editors. Metal metabolism in aquatic environments. London, UK Chapman Hall, p. 77-158. 

G. A. Gilbert, C. P. Vance, and D. L. Allan. Regulation of white lupin root metabolism by phosphorus availability. Phosphorus in Plant Biology Regulatory Roles in Molecular. Cellular, Organismlc, and Ecosystem Processes (J. P. Lynch and J. Deikman. eds,), American Society of Plant Physiologists, 1998, p. 157. 

Estimates of the diversity of DNA-based soil organisms so far have not been able to answer the questions concerning the functions of soil ecosystem, although, they can serve as an efficient tool for explaining DNA diversity in situ. The presence of a certain microbial gene does not assure that the metabolic process, for which the gene is responsibile, is carried out. The challenge for molecular techniques is to provide quantitative measures for microbial cells and activities rather than Just qualitative measures. To this purpose, DNA-based techniques... 

Chemical manipulation of phenolic allelochemical production in plants has two potential values 1) for study of the role of phenolic allelochemicals in plant interactions with other organisms and 2) to alter such interactions for agricultural purposes. The first of these uses has already been accomplished on a limited scale (21, 22, 50, 51, 84, 86), however, there is no published evidence of the latter. This does not mean that herbicide and growth regulator-influences on plant secondary metabolism do not affect agricultural ecosystems by changing allelochemic compositions of plants. It is likely that this is the case, but it... 

PEST. This code ( 3) was developed within the framework of Rensselaer Polytechnic Institute s CLEAN (Comprehensive Lake Ecosystem Analyzer) model. It includes highly elaborated algorithms for biological phenomena, as described in this volume (44). For example, biotransformation is represented via second-order equations in bacterial population density (Equation 5) in the other codes described in this section PEST adds to this effects of pH and dissolved oxygen on bacterial activity, plus equations for metabolism in higher organisms. PEST allows for up to 16 compartments (plants, animals, etc.), but does not include any spatially resolved computations or transport processes other than volatilization. 

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