An introduction about Genotoxicology Methods as Tools for Monitoring Aquatic Ecosystem: Present status and Future perspectives
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Aquatic ecosystems that have become degraded under stress show similarities both in the signs of pathology and in the mechanisms that promote degradation. A review of the transformations in several aquatic systems, including the Laurentian Great Lakes (Canada/US), the Baltic Sea (Finland) and Lake Chapala (Mexico) reveals signs of ‘ecosystem distress’, including alterations in primary and secondary productivity, nutrient cycling, species diversity and biotic composition. A shift from a predominantly vertical to horizontal nutrient spiraling characterizes all three aquatic ecosystems, as does a reduction in the abundance of the larger (high-valued) fish stocks. Once the health of robust systems begins to decline, mechanisms are called into play that tend to perpetuate the ecosystem breakdown. The process may be difficult to reverse, even when sources of initial stress are removed.
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Nitrogen is a critical nutrient linked to degradation of freshwater and marine ecosystems. The nitrogen inputs to terrestrial ecosys- tems and subsequent loadings to aquatic ecosystems have been doubled and changed the nitrogen cycle as population and hu- man activities increased over the past century. One of the consequences of human alter- nation of the nitrogen cycle is the eutrophication of marine and freshwater ecosystems. We tested if climate variability can change nitrogen loading from terrestrial to aquatic ecosystems. We used stream nitrogen concen- trations from 2,125 sites and climate data from 301 stations from 30 eco-regions across British Columbia, Canada, to test our ob- jective and to compare it with anthropogenic loading of nitrogen in the same regions. We show that elevated air temperature and associated precipitation resulted in increase in nitrogen loading from terrestrial to aquatic ecosystems. Furthermore, inorganic ni- trogen (IN) loading increased more rapidly than organic nitrogen (ON) with increasing air temperature. Each oC increment annu- al air temperature caused a 24% increase in nitrogen loading to aquatic ecosystems and a 22% increase in ratio of IN: ON concen- trations in stream water. We also show that the coastal mountains ecosystems seem to be more vulnerable to temperature induced nitrogen loss than the interior ecosystems. We suggest that cli- mate warming and elevated loading of nitrogen from terrestrial to aquatic ecosystems will have major implications for the quality of water in freshwater and coastal marine ecosystems.
Terrestrial ecosystem
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Nitrogen Cycle
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Abiotic factors are very important in the aquatic ecosystems because they create the frame in which the organisms develop. In order to evaluate the seasonal variation of the abiotic and biotic factors, three different aquatic ecosystems were investigated: a natural ecosystem, a transformed ecosystem and an artificial ecosystem. The physical, chemical and bacteriological parameters of water, A Chlorophyll, as well as the aquatic invertebrates from surface and benthic zone were determined. A comparative analyze of the seasonal dynamics in the three lakes shows us that the artificial ecosystem is the less stabile of all. The biodiversity of aquatic ecosystems is maximal in the natural ecosystem, followed by far by the transformed and artificial ecosystems
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Parasites may mediate ecosystem functioning through a number of direct and indirect mechanisms, but the importance of parasitism at the ecosystem scale is poorly understood. Measuring the density of free-living and parasitic consumers in units that are directly comparable provides a first step toward understanding the importance of parasitism to ecosystem processes. I sampled 2 streams in the New Jersey Pine Barrens seasonally for 1 y to measure the biomass density of all major consumer groups, including macroparasites infecting fish and macroinvertebrates. Parasites made up a small percentage of consumer biomass in Pine Barrens streams, representing just 0.00643 to 0.00733% of total consumer biomass annually. These low values contrast with higher estimates from other aquatic ecosystems, where parasite biomass exceeds that of some free-living consumers. The mean biomass densities of all consumer groups differed significantly between the 2 streams, perhaps because of stream characteristics, such as productivity or pH. Comparison of parasite biomass density in these 2 streams with that in 3 other types of aquatic ecosystems reveals substantial variation both within and among ecosystem types. Methodological differences among published studies complicate comparisons of parasite biomass across ecosystems. I reviewed the methods used in previous studies on parasite biomass and argue for a consistent and transparent method for future research. Comparing the biomass of free-living and parasitic consumers is a first step toward understanding the ecosystem-level importance of parasitism, but more work is needed to understand the specific mechanisms by which parasites influence ecosystem processes and the magnitude of parasite effects.
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Organic carbon accumulation in the sediments of inland aquatic and coastal ecosystems is an important process in the global carbon budget that is subject to intense human modification. To date, research has focused on quantifying accumulation rates in individual or groups of aquatic ecosystems to quantify the aquatic carbon sinks. However, there hasn't been a synthesis of rates across aquatic ecosystem to address the variability in rates within and among ecosystems types. Doing so would identify gaps in our understanding of accumulation rates and potentially reveal carbon sinks vulnerable to change. We synthesized accumulation rates from the literature, compiling 464 rate measurements from 103 studies of carbon accumulated in the modern period (ca. 200 years). Accumulation rates from the literature spanned four orders of magnitude varying substantially within and among ecosystem categories, with mean estimates for ecosystem categories ranging from 15.6 to 73.2 g C m-2 y-1 within ecosystem categories. With the exception of lakes, mean accumulation rates were poorly constrained due to high variability and paucity of data. Despite the high uncertainty, the estimates of modern accumulation rate compiled here are an important step for constructing carbon budgets and predicting future change.
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Carbon fibers
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Mesocosm
Marine ecosystem
Terrestrial ecosystem
Freshwater ecosystem
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Abstract Aquatic ecosystems that have become degraded under stress show similarities both in the signs of pathology and in the mechanisms that promote degradation. A review of the transformations in several aquatic systems, including the Laurentian Great Lakes (Canada/US), the Baltic Sea (Finland) and Lake Chapala (Mexico) reveals signs of ‘ecosystem distress’, including alterations in primary and secondary productivity, nutrient cycling, species diversity and biotic composition. A shift from a predominantly vertical to horizontal nutrient spiraling characterizes all three aquatic ecosystems, as does a reduction in the abundance of the larger (high-valued) fish stocks. Once the health of robust systems begins to decline, mechanisms are called into play that tend to perpetuate the ecosystem breakdown. The process may be difficult to reverse, even when sources of initial stress are removed.
Marine ecosystem
Nutrient cycle
Lake ecosystem
Freshwater ecosystem
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