T he annual cycle of greening and degreening of plants is probably the most obvious sign of life on Earth. It is caused by the biosynthesis of ∼10 tons of chlorophylls (Chls) in spring and their degradation in fall. The biochemistry of Chl breakdown to linear tetrapyrroles has been worked out in land plants (1), but little was known about the process in marine organisms, which contribute a comp...

were prepared from two enteric bacterial species, Escherichia coli and Enterococcus faecalis. Counts of CFU of NSB and RSB and total numbers of RSB and FLB were monitored over time, both in the presence and in the absence of natural microbiota. In the presence of natural microbiota, no differences were observed between CFU counts of NSB and RSB, but RSB total numbers were 1 to 4 orders of magni...

industrial activities lead to an increase in heavy metal burden in rivers. sediment and algae (spirogyra sp.) samples were collected from the shoor river to investigate their heavy metal concentrations. dry and ashed samples of algae and sediment were digested using concentrated nitric acid. heavy metals (as, fe, zn and cr) concentration measured using an icp-oes instrument (perkinelmer, usa). ...

Regarding the effects of UV-B radiation on aquatic ecosystems, recent scientific and public interest has focused on marine primary producers and on the aquatic web, which has resulted in a multitude of studies indicating mostly detrimental effects of UV-B radiation on aquatic organisms. The interest has expanded to include ecologically significant groups and major biomass producers using mesoco...

Background: Evaluation of herbicide pollution in aquatic environments needs the great concern and the most important echo-pollutant effects of herbicides are related to their effects on non target aquatic organisms. Native fish can serve as a proper bio-indicator for evaluation  of pollution on aquatic ecosystems. OBJECTIVES: To find environmentally friendly herbicides, in this study the acute ...

Community respiration (R) rates are scaled as the two-thirds power of the gross primary production (P) rates of aquatic ecosystems, indicating that the role of aquatic biota as carbon dioxide sources or sinks depends on its productivity. Unproductive aquatic ecosystems support a disproportionately higher respiration rate than that of productive aquatic ecosystems, tend to be heterotrophic (R > ...

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