The Major Concerns in Environmental Conservation - Essay Example

The Use and Applicability of Bio-Indicator Organisms in the Environmental Assessment of Freshwater and MarineSystems Introduction In freshwater and marine environments, the use of bio-indicators in the assessment of the health of water has become a common phenomenon. This assessment is important due to the fact that life in such ecosystems has been endangered by increased pollution. Sources of pollution in aquatic environments include wastes from industries, sewages and chemicals resulting from farming activities. Therefore, the assessment of the health of aquatic environments is essential in order to determine the quality of water and whether that water can support life. According to Durranti, a bio- indicator is defined as a plant or animal species whose presence or absence gives information on the state of a given environment (Chu, Chanb and Chow 2005). The Use and Applicability of Various Bio-Indicator Organisms in the Environmental Assessment of Freshwater and Marine Systems There exist several bio-indicators that have been applied to measure the health status of freshwater and marine environments. To begin with, Chin argues that by identifying the kind of animal species present in a given water body, biologists are able to analyze the quality of water in that water body (Chin 2006). For instance, the presence of many carnivore fish species might suggest a higher quality of water compared to a water body dominated primarily by omnivores. A healthy water body supports life for many micro-organisms that are predated upon by the carnivore fish. For many years, fish have been used to indicate the quality of water bodies. This has been accomplished through determining the kind of fish that live in a given water body, measuring alterations in fish species composition and species proportion (Jackson 2001). Changes in fish length and tropic level can as well be used in determining the health of aquatic environment. Fish are the most appropriate bio-indicators due to the fact that they live in water throughout their life, live for many years, differ in the way they exhibit tolerance to pollutants and are easy to collect and identify. The comet assay in Tilapia rendalli was used in monitoring the level of water pollution in Lake Igapo, near the Londrina metropolitan region in Brazil (Csuros and Csuros 2002.). From the experiment, it was established that samples from the lake had a high number of comets and mainly in second and third classes. Thus the results suggested that Lake Igapo is an aquatic environment that was characterized by a high level of genotoxicity and other pollutants. In Izmir Bay of Mediterranean (in Western Turkey), fish are used to determine the level of water pollution in the sea (Gonenc 1999). Izmir is an industrial and commercial centre. The presence of metals such as lead and zinc in freshwater and marine environments can be indirectly measured using inorganic acids, such as sulphuric acid and hydrochloric acid (Turner and Tessier1995). These acids are applied on intestinal specimens of different fish species. If the above metals are present, the acids react with the specimens to form oxides. Bonnan notes that some aquatic pollutants might remain active for many years and through several generations. Examples include mutagenic and carcinogenic compounds (Farris, J. et al 1993). Genotoxicity biomarkers can be applied in sentry organisms to enhance the identification and assessment of mutagenic hazards and their sources. One of the most suitable methods of identifying the response of organisms to such contaminants is by use of micronucleus (MN) test. This can be used as an index of the total genetic damage of cells during the lifespan of an organism. Fish and bivalves have been the main target for such experiments. Gill and haemocyte cells are the commonly used tissues. Due to rising carbon dioxide concentration s in the 21 century, the acidity of sea water has increased as well. Consequently, global temperatures have been driven up, including those of sea waters. As a result, sea levels have risen by several centimeters due to thermal expansion and retreating ice sheets (Wexler, Gilbert, Hakkinen, and Mohapatra 2009.). Seabirds can be used as indicators of such aquatic environmental changes (Giesy, Newsted, Lam and Wu 2008). They can be used to measure the ecosystem’s responses to global warming since their breeding success in land is a bit easier to monitor than the tropic changes in water. For instance, when the sea temperatures are high, the reproduction of copepod species of Pribilof Islands declines. This results in reduction of the offspring of the species. Most aquatic invertebrates also referred to as benthic macro-invertebrates, live at the bottom of water bodies. Benthic macro-invertebrates, such as, polychaetes can be used to determine the quality of water in marine environments since their response to pollutants is fairy well. Polychaetes live in water for the greater part of their life and mostly stay in regions where their survival chances are high (Hart and Fuller 1974). They exhibit high level of tolerance to stressors in marine environments. They can thrive well in conditions of low oxygen and sewage pollution. T hey also have a long life span. Moreover, they have limited mobility. All these adaptations enable them to avoid pollutants and other stressors. Earthworms can be used as bio-indicators for mercury pollution. Mercury from mining and industrial activities finds its way into water bodies. The most preferred species of earthworm for this kind of assessment is the Eisenia foetida (CCM Information Corporation. 1971). Research has shown that E. foetida species have the ability to accumulate mercury in their tissues. The higher the accumulation of mercury in their tissues, the higher the presence of mercury in a given water body and vice versa. The presence of mercury inside the tissues of earthworms can be tested using organic acids such as tannic acid (Shaw1984). Moluscs can also be used as bio-indicators of the health of water in aquatic environments. Freshwater mollusks are sensitive to water quality due to the permeability of their skins and also due to their need of sufficient supply of oxygen (Tribo 2008). Acidification of water has led to extinction of some species ofmollusks. Examples of freshwater and marine mollusks that have been reported to go to extinction include Nancibella quintalia and Carelia kalalauensis (Boersema, and Reijnders 2007). Richter suggests that Crabs, juvenile fish, herons and diving ducks can be used as indicators of the quality of water in shallow water habitats. These include habitats such as wetlands and marshy areas. These organisms are useful here since they are sensitive to excess nutrients and turbid conditions. Shellfish reefs, adult fish and waterfowl are useful in aquatic reefs. They can be used as indicators for water quality since they are sensitive to turbid conditions, sedimentation and excessive nutrients (Richter 2003). The marine amphibod, Rhepoxynius abronius, can be used in determining the effects of sediment contaminations. This can be done through performing sediment toxicity tests. However, the application of toxicity tests is problematic due to the fact that natural factors, such as, salinity, ammonia and grain size may mystify findings through increasing the laboratory sediments that are sometimes considered nontoxic. This might interfere with the findings. Most ocean waters, especially those of the Indian Ocean, are subjected to pollutants from industrial and sewage wastes. This results in contamination of water and loss of the biodiversity. When certain animals in such ecosystems are exposed to xenobiotics, their metabolic functions are disturbed. This results in damage of their genetic material, activation of their antioxidant systems and detoxifying enzymes (Pott and Turpin 1998). Such changes can be used as potential biomarkers in measuring the stresses such animals undergo. Oysters, clams and Mytelid oysters are examples of animals that can be used in such experiments (Combiatta 1998). Aquatic plants (Macrophytes) can be used to assess the quality of water in both fresh-water and marine environments. As Arbor suggests, macrophytes are found in or near water bodies where they can be emergent, sub-emergent or in form of floating vegetation. Macrophytes provide substrate for aquatic invertebrates and cover for various species of fish. They as well provide food and oxygen for aquatic organisms (Barinova, Petrov, and Nevo 2006). The absence of macrophytes may suggest poor quality of water due to salinization, turbidity and presence of herbicides. On the other hand, overabundance of macrophytes which is as a result of high nutrient levels may interfere with fishing and recreational activities. Macrophytes are useful indicators of the quality of any water body due to the fact that they respond to light, nutrients, metals, herbicides and salt. Moreover, aquatic plants can be easily sampled and may not require detailed laboratory analysis (Lichtfouse, Schwarzbauer and Robert 2005). Mangroves thrive well in salt-water and acidic environments and hence can also be used to indicate the healthy of a water body. Examples of subclasses of Mangroves in Australian waterways are common in wave-dominated estuaries and on tidal creeks (Dokulil 2003). Mangroves are also sensitive to pollution. For instance, floating industrial oils lead to suffocation of most species of mangroves (Offwell Woodland & Wildlife Trust 2010). This pollution also leads to genetic alteration of various mangrove species, hence change in composition and fitness. Although considered as irreplaceable tools for experimentation, aquatic plants can also be indirectly used as bio-monitors in investigating the health of freshwater and marine environments. This can be done through measuring their photosynthetic activity, detoxification enzymes, heat shock proteins and secondary metabolites among other factors under conditions of various stressors (Hammond 1993). The stressors may include thermal energy, light, herbicides or organic contaminants. The metabolism of aquatic plants will keep on changing due to varying conditions of stressors. A good example of an aquatic plant for this kind of experimentation is the phytobenthos. This is an autotrophic species that inhibits the phytobenthos zone and is sensitive to changes in the concentration of nutrients, toxic contaminants, light climate, mechanical stress and other human induced disturbances. Algae can be used as bio-indicators in determining the level of metal concentration and general toxicity of aquatic environments. Algae have been successfully used in assessment of streams, larger rivers, lakes and wetlands all over the world (Belpaire and Goemans 2003). This can be reflected through the presence and absence of both tolerant and non-tolerant algae. Moreover, the quality of a water body can be assessed through evaluation of the quality of algae species diversity. For instance, the phytoplankton species can be used in determining and monitoring the level of acidity in lakes and oceans. This can be done through the usage of sediment cores of algae (diatom and chrysophyte) abundance and distribution. The acidity of lake and ocean waters affects the distribution of these two classes of phytoplankton and hence can be used in predicting the acidity of a water body based on cell counts. Periphytons can also be used in measuring the state of water bodies. Nixon defines Periphytons as some kind of benthic algae that are normally found attached to rock and higher plant surfaces (Nixon 2009). They are the sensitive indicators of environmental changes that occur in lotic waters. When subjected t chemicals and other intoxicants, periphytons wither and die. Therefore, their absence on the surfaces of larger plants and rocks in freshwater and marine suggests toxicity (Scott, Medioli and Schaefer 2001). Other typical marine indicators include zooplanktons, phytoplankton and benthos. Zooplanktons are sensitive to conditions of low oxygen, excess nutrients and toxic pollutants. They are therefore vital for the future generation of fishers in helping them in the assessment of the health of water since they serve as food for animals in the higher tropic levels ( Marques, Salas, Patricio and Teixeira 2009). Benthoses get affected under conditions of high carbon dioxide, excess nutrients and excessive toxic pollutants (Wrona and Cash 1996). Phytoplanktons are sensitive to excess nutrients, especially phosphorous and nitrogen (Penta 2009). Leatherland notes that swimming in and drinking water from a water body dominated by pathogenic microorganisms might be dangerous to the human health. Pathogenic microorganisms are disease causing agents that get their way into the water bodies from the intestines of infected animals and humans. These kinds of organisms are too small to be seen by a naked eye. The concentration of pathogenic microorganisms in a water body can be measured through the frequency of the outbreak and distribution of pathogenic diseases in a given human population. For example, in a research carried out between 1987 and 1996, about 16% of waterborne-disease outbreaks in the United States were attributed to the bacterial pathogen pseudomonas aeruginosa (Leatherland 2009). Conclusion One of the major concerns in environmental conservation is assessing the level of pollutants available. The healthy of a given environment can be determined using physical, chemical and biological indicators. Biological quality is important in describing the health state of ecosystems. Therefore the application of bio-indicators in assessing the quality of any environment is inevitable. Due to their ability to integrate biotic and abiotic environmental components, living organisms are the most suitable bio-indicators of the quality of fresh and marine waters. 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