Plant aquatic, effect

Compounds reported to have inhibitory effects on cyanobacteria have been isolated from a diverse range of organisms including terrestrial plants, aquatic plants, fungi, bacteria, actinomycetes, protozoa, and even from some species of green algae and cyanobacteria. The structural types... 

In aquatic plants adverse effects of mercury such as senescence, growth inhibition, decreased chlorophyll, protein and RNA content, inhibited catalase and protease activities, inhibited and abnormal mitotic activity, increased free amino acid content, discoloration of floating leaves, leaf and root necrosis, and death have been reported (Muramoto and Oki 1984, Mhatre and Cha-phekar 1985, Sarkar and Jana 1986). The level of mercury that results in toxic effects in aquatic plants varies greatly. Freshwater concentrations of between 50 and 3400 pg Hg " " or 0.8 to 6 pg methyl-mercury are toxic to plants, and for salt water 10 pg Hg " " for algae and 160 pg Hg " for seaweed are reported. No data are available on methylmercury in saltwater plants (EPA 1997). 

Receptors. The receptor can be a person, animal, plant, material, or ecosystem. The criteria and hazardous air pollutants were so designated because, at sufficient concentrations, they can cause adverse health effects to human receptors. Some of the criteria pollutants also cause damage to plant receptors. An Air QuaUty Criteria Document (12) exists for each criteria pollutant and these documents summarize the most current Hterature concerning the effects of criteria pollutants on human health, animals, vegetation, and materials. The receptors which have generated much concern regarding acid deposition are certain aquatic and forest ecosystems, and there is also some concern that acid deposition adversely affects some materials. 

W. Majewski and D. C. Miller, eds.. Predicting Effects of Power Plant Once-Through Cooling on Aquatic Systems, Technical Papers in Hydrology 20, United Nations Educational, Scientific and Cultural Organization (Unesco), Paris, 1979. 

A relatively small number of studies have reported on the effects of cumene on plants, fish, and other organisms. Studies of the effects of cumene on fresh and saltwater fish indicate the lowest reported toxic concentration (LC q) for fishes was 20 to 30 mg/L (18). The solubiUty of cumene is about 50 mg/L (19). Among invertebrates, the lowest reported concentration that was toxic to test organisms was 0.012 mg/L after 18 hours (20). The only available data on the effect of cumene on aquatic plants indicate that the photosynthesis of several species was inhibited at concentrations from 9 to 21 mg/L (19). 

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... 

Heavy metals on or in vegetation and water have been and continue to be toxic to animals and fish. Arsenic and lead from smelters, molybdenum from steel plants, and mercury from chlorine-caustic plants are major offenders. Poisoning of aquatic life by mercury is relatively new, whereas the toxic effects of the other metals have been largely eliminated by proper control of industrial emissions. Gaseous (and particulate) fluorides have caused injury and damage to a wide variety of animals—domestic and wild—as well as to fish. Accidental effects resulting from insecticides and nerve gas have been reported. 

Contains information on the toxic effects of5,600 chemicals on more than 2,800 aquatic species of animals and plants, excluding birds, aquatic mammals, and bacteria. Has now been incorporated into ECOTOX Data System. Hours 8 00 a.m. to 4 30p.m. CST, Monday - Friday. 

The ECOTOXicology database is a source for locating single chemical toxicity data for aquatic life, terrestrial plants and wildlife. ECOTOX integrates three toxicology effects databases AQUIRE (aquatic life), PHYTOTOX (terrestrial plants), and TERRETOX (terrestrial wildlife). These databases were created by the U.S. EPA, Office of Research and Development (ORD), and the National Health and Environmental Effects Research Laborator) (NHEERL), Mid-Continent Ecology Division... 

For organisms, the acidification of lakes may cause stealthy and almost imperceptible effects. At first, only very small changes can be detected, but as the waters become increasingly acidic, more and more species are eliminated. A pH of greater than 6 in a lake is required to ensure that most of the aquatic organisms will thrive. As a pH of less than 5 is reached, only a small number of very hardy plant and animal species survive. Figure 1 illustrates this progressive decline. 

Terrestrial ecosystems (plants and animals) under water scarcity suffer from water stress, and aquatic ecosystems of intermittency in water flow. Water scarcity has implications on hydrologic resources and systems coimectivity, as well as negative side-effects on biodiversity, water quality, and river ecosystem functioning. Finally, water scarcity has also direct impacts on citizens and economic sectors that use and depend on water, such as agriculture, tourism, industry, energy and transport. 

These high levels were sporadic and transitory. However, some of them were high enough to have caused phytotoxicity, and more work needs to be done to establish whether herbicides are having adverse effects upon populations of aquatic plants in areas highlighted in this study. It should also be borne in mind that there may have been additive or synergistic effects caused by the combinations of herbicides found in these samples. For example, urea herbicides such as diuron and chlortoluron act upon photosynthesis by a common mechanism, so it seems likely that any effects upon aquatic plants will be additive. Similarly, simazine and atrazine share a common mechanism of action. 

Significant levels of herbicides have also been detected in rivers, although these are usually transitory. Heavy rainfall can move herbicides from agricultural land to nearby ditches and streams due to runoff, and in soils that are high in clay, percolation of water occurs through deep fissures with consequent movement into neighboring water courses. Such events under extreme weather conditions are likely to have contributed to the pulses of herbicide contamination observed in some rivers. Questions have been asked about possible effects of such episodic pollution on populations of aquatic plants. 

Physico-chemical properties Effects on aquatic animals and plants... 

Considerable interest has been expressed in the industrial use of stabilised hypothatous acids (water reacted with chlorine, bromine or iodine). This innovation imitates the stabilisation of oxidised bromide that occurs in natural systems.51 These occur as mechanisms of control on the surface of some aquatic plants in the mammalian immune defences.52 Certain marine algae produce hypobromous acid using bromoperoidases53 which is not only an effective mechanism but exhibits good specific toxicity. 

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