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Indicator species has immensely essential in ecology and evolutionary as a result of their morphology and ability to indicate freshwater aquatic environments. Macro-invertebrates qualify as indicator species, because they have exceptional adaptive qualities. Macro-invertebrates have adapted survival tactics, which enable them to survive even in extreme conditions or damaged climates. Several studies have been conducted to examine the reason why macro-invertebrates are a good indicator species in freshwater aquatic environments. This is because their adaptive techniques they develop in every new environment put their qualities in question. However, it is likely that adaption of Macro-invertebrates can inhibit them as indicator species to indicate pollutants and freshwater conditions. In general, indicators species are used in assessing pollution of aquatic environments. This is achieved through measuring the number of species surviving in aquatic environments to understand how pollutants have affected aqua life. According to Connolly, macro-invertebrates have been studied from a wide evolutionary perspective with an aim of understanding their survival tactics in their habitats (Crossland & Pearson 2004),. For instance, some factors making a good indicator species is whether they reproduce quickly, have low mobility, and have a recognized range of tolerances. As conditions in an environment get worse, some macro-invertebrates perish while others mange to live longer. Adaptations leading to high survival of most macro-invertebrates also indicate the condition of the particular aquatic environment.
Rivers, lakes, streams, and ponds hold not more than 1/1000% of water in the planet Earth. However, these water bodies serve critical operations for either human life or the environment. Freshwater aquatic environments provide habitat for many animal, plant species, and sustain ecological systems. They support daily human activities such as providing recreation, hydropower, industrial use, livestock, wastewater treatment, irrigation, and drinking water among other uses. Additionally, fresh waters affect the condition and extent of other water sources such as coastal systems, wetlands, and ground water. The condition of freshwater aquatic environments reflects arrange of features in evolution and adaptations. Attributes such as the clarity and temperature are among physical characteristics. Chemical characteristics comprise attributes such as chemical contaminants, nutrients, salinity. The chemical attributes can possibly affect the quality of water as well as interfering with the aquatic food web (EEB 390 14). The biological characteristics in question are pathogens and diseases. Biological features refer to the condition of plant and animal populations including the condition of their habitat. Apart from the environment affecting, these features are capable of affecting human health especially through recreational activities, cleaning and drinking contaminated water (Fernando & Cheng 76).
Macro-invertebrates are found in all types of water, starting from the smallest fresh water streams to the largest fresh water lakes. In fact, these species are also found in the water accumulating in pitcher plants. Macro-invertebrates form an integral section of aquatic ecosystems. They adapt new living strategies and survive in these habitats. They recycle decaying animal and plant material back to their food web. These species are vital food for waterfowl and fish. After emerging from the water, the adults become essential food for mammals, reptiles, and insectivorous birds. Many biting insects such as midges and mosquitoes begin their life cycles in streams, rivers, ponds, and lakes (Hughes & Larsen 345).
Despite the fact that macro-invertebrates are an important Indicator Species of Freshwater Aquatic Environments, there are still huge gaps in our knowledge regarding of the Bornean/Sabah fauna. Several researches have been conducted, but further studies to record additional species refine their distribution patterns and increase knowledge in their adaptation and evolution. Some species such as Trichoptera, Odonata are only known to exist in certain habitat. This requires extensive research to document their occurrence in fresh water environments. There are other species only known to exist from Borneo. This requires extensive research to understand their adaption and evolution and the reason why they only exist in that state, in case they really do not exist somewhere else (Reynoldson B. et al. 47).
Adaptive features in macro-invertebrates
Aquatic macro-invertebrates have a diverse assortment of behavioral and structural respiratory adaptations. This suggests that, different taxa vary in their oxygen requirements as well as tolerance to hypoxia. Respiration differs in different macro-invertebrates. For instance, some aquatic insects respire through diffusion using cuticles while others require spiracular gills or tracheal for respiration. In other groups, adults such as adult elmid beetles respire using a plastron. This is an air bubble that functions like a physical gill to allow oxygen diffusion into the tracheal system. Other aquatic insects use pigments to respire. For example, Notonectidae and Chironomidae have hemoglobin. These differences reflect in reactions to changes in Dissolved Oxygen Concentrations (DO). Oxygen conformers are species with internal Oxygen Concentrations reflecting the external environment like in Ephemera vulgate and mayflies Baetis sp. On the other hand, oxygen regulators are species with internal Oxygen Concentrations independent of their external environment such as Leptophlebia marginata and Cloeon dipterum. These physical factors interact with the biophysical adaptive characteristics to determine the response and distribution of species.
Factors influencing fresh water environments and macro-invertebrates
Point source pollution
This includes pollutants discharged directly to the water surface. Industrial operations and sewage contaminants including treated sewage products contain some material whith chemical pollutants, which affect the water and ultimately the macro-invertebrates in the water.
Nonpoint source pollution
This reflects excess sediments; contaminants and nutrients in runoff from suburban and urban areas, for example, storm water and agricultural activities. Other recreational activities such as marinas, boating, and acid mining drainage are sources of nonpoint pollution. Nonpoint source pollution is also impacted by land cover and land utilization. Nonpoint sources are more variable as compared to point sources.
This includes heavy metals, acidic aerosols, and other airborne pollutants, which might be deposited openly on water. It may also include contaminants, which might wash into fresh water bodies after being deposited on land.
These are non-indigenous animal and plant species, which can harm the human health, the economy or the environment. Invasive species crowd out resident species and change the chemical and physical condition of water bodies. This affects and forces them to adapt appropriately and those species, which cannot adapt perish (Reynoldson et al. 5)
Rainfall influences the amount and timing of erosion and runoff. On the other hand, other elements of weather and climate change influence mixing, heating, and cooling in water bodies. This affects the movement of pollutants and the cycling of nutrients. Ultimately, this affects aquatic organisms in the water body. Mineral composition and sediments of bedrock helps in determining whether a water body will be vulnerable to acidification.
The degree and amount of water flow influences the condition of fresh waters and the aquatic organism living in it. Flow patterns in streams influence sediment and contaminant loads, while water bodies’ shape changing such as creating artificial ponds and removing deep pools influence water temperature.
Water Flow and Level
The flow rate and level of water also affect the quality of water and the organisms surviving there. Some animals and plants communities are sensitive to flow rate and level. Other organisms adapt to particular seasonal variations in flow. Stressors affecting water levels and water flow ultimately affects the condition of the freshwater habitat, for instance, dams limit the migration of some fish species.
Classification of Freshwater Benthic Macro-invertebrates
Gastropoda (snails and slugs)
Malacostraca (isopods, crayfish, scuds)
Mollusca (All molluscs)
Annelida (All segmented worms)
Arthropoda ( insects, crustaceans spiders)
(Three pairs of limbs, three body parts)
Bivalvia (clams/ mussels)
Oligochaeta (water earthworms)
Hemiptera (true bugs)
Lepidoptera (moths/ butterflies)
Megaloptera (dobsonflies, alderflies, fish flies)
Diptera (double-winged flies)
Unionoida (Stream mussels)
Veneroida (clam asian)
Invertebrates as Displayers
Using freshwater benthic macro-invertebrates like indicators the watercourse to be examined is methodologically sampled. As macro-invertebrates are consolidated, the taxa are conserved and recognized back in the laboratory. The moment taxa are recognized species richness like total figure of taxa and other measures or metrics are dogged and utilized as displayers of water eminence. These metrics comprise of the following:
• Configuration metric = (% of every taxon)
• Trophic metric = functional nourishing groups (% Filterers)
• Habit measure = behavior features (% Clingers)
• Tolerance measure = Tolerance stages (% intolerant taxa).
Functional nourishing groups offer a better comprehension of food web linkages. Categories include omnivore, predator, collector, shredder, piercer, and scraper/grazer. A predator concerns all macro-invertebrate, which feeds on the rest of invertebrates such as dragonflies. An omnivore concerns a generalist feeder, which is capable to feed both living and dead organic matter such as crayfish. Collectors devour fine portions of organic matter such as the leaf fragments and other material on the watercourse bottom. This group may be further separated into filtering collectors and suspension feeders such as clams, or even gathering collectors like caddisfly larvae. The grazer/scraper category comprises of invertebrates, which feed on devolved algae situated on inundated underwater surfaces like snails. Shredders eat abrasive organic matter like leaves that are sowbugs (EEB 390 14).
Lastly, the piercers nourish by penetrating the tissues of supplementary organisms. These are inclusive of the real bugs of the command hemiptera. Feeding trophic or measures dynamics include functional feeding groups that offer information on the equilibrium of feeding plans in the benthic accumulation. Examples include the feeding alignment of scrapers, gatherers, shredders, predators, and filterers. Trophic dynamics that are food types are included and comprised the relative profusion of herbivores, omnivores, deprivers, and carnivores. Without relatively steady food subtleties, an inequality in functional feeding group results in reflecting strained conditions. Specialized feeders like scrapers, shredders and piercers are the further sensitive creatures. They are believed to be well signified in healthy watercourse. Generalists like filterers and collectors have a wider range of satisfactory food materials than experts. Therefore, there are more adaptable to pollution, which might change availability of a particular food. Nonetheless, filter feeders are believed to be sensitive in sluggish curving streams.
Behavior and designations detail the precise functions of the organism such as the approach it searches for food or it moves. Habit designations comprise clingers, sprawlers, climbers, burrowers, divers, and swimmers. A clinger comprises of invertebrates that are able to remain stationery at the bottom substrates in moving waters. A hinker feeds in flooded aquatic undergrowth by climbing. A sprawler may be found devoted to both the substrates like rock surfaces or surface of submerged aquatic vegetation. Burrowers forage on fine organic materials whilst buried in residues of streams and lakes. Finally, divers and swimmers are established in the water pilaster. Swimmers can be able to control the speed and direction of their movements whilst they flow through the stream, as well as divers are capable to swim from the water surface to the base of the water. Habit methods note the means of existence between the benthic macro-invertebrates focused on the adaptations for upholding position and flowing about in the water environment. It has been noted that, in disturbed or polluted habitats the degree of insects containing fixed adaptations or retreats for attachment to water surfaces in moving water that is, clingers’ reduction.
Tolerance heights refers to organisms aptitude to tolerate numerous forms of strains like low liquefied oxygen levels, huge amounts of salinity or silt, or varying quantities of toxic chemicals. Tolerance levels may be resolute by observation of the incidence or dominance of particular taxa in certain water eminence conditions. The Intolerance/Tolerance measures are envisaged to be illustrative of comparative sensitivity to pollution or disturbance and can include figures of pollution intolerant taxa, tolerant or percent arrangement. In general, tolerance is non-specific to kinds of stressor (EEB 390 14).
Conclusions and Recommendations
By the use of indicators to directly examine environmental contaminants appears justified. Nonetheless, the current methods of directly examining contaminants might be more precise and cost efficient than this outdated use. Using displayers to assess populace habitat and trends suitability for the rest of species is unsuitable without confirmatory study, current rules, and mandates necessities this utilizes are scientifically difficult and have financial problems. The realization despite our examination that ecological displayers continues to be used due to the outdated firm established, current laws mandates their usage, and they are contemplated cost effective, at the minimum of term. Until alternative methods to environmental examination and wildlife nursing are established. It is advisable to establish the following recommendations to ensure safe use of ecological indicators more severe (Reynoldson et al. 143).
1. Clearly state examination goals, inclusive of criteria utilized criteria to establish when those objectives have been accomplished.
2. Use indicators when necessary and appropriate. The literature review indicates no clear guidelines to examine the moment an indicator is required. For “species management” that is, management of class instructed under political and socioeconomic criteria the usage of indicators is not most appropriate. Since, direct measurements of requisite species and resources the populations are required to assess management schedules. Likewise, in the case of “resource management” that is management of particular habitats or resources, direct measurement is typically feasible for instance, specific components and timber resources of wildlife environmental cost effective and averts the need for implication from the reply of an indicator. Generally, indicators must be utilized only when direct measurements are impossible. It is agreed that, “When everything else bobs, biologists may opt to the usage of displayers as means of getting some measurements of strains on a natural organization. This will normally result as a fall-back location when the potentials for studying the respected ecosystem mechanisms either indirectly or directly, are limited.”
3. Select indicator classes by criteria, which are explicitly and unambiguously defined, and in consensus with assessment objectives. In the cotemporary practice of expending indicators, assortment criteria are usually confounded. In order to avoid such problems, agencies must state the reason for selecting the criteria as well as their fundamental assumptions used in every assessment. Further, the uncompounded and rigorous processes utilized to select indicators must be stated. These stages would assist ensure that clarifications of results that do not surpass the limits of inference recognized by the assortment process.
4. To meet valuation goals, include all classes that fulfill stated assortment criteria. Relieving one indicator for the other or one principle for another like it is based on the quantities of evidence or because of subsidy, abates the precision and credibility of the investigation. Typically, all cliques of standards that, socioeconomic, ecological, and political are required to meet assessment objectives. Indicators from every criterion involve compromise in management plans to accommodate the necessities of the numerous indicators, and every extra indicator enhances to valuation costs. Such negotiations are preferable to strategies made under confused criteria, which may assume the collective requirements of a complete set of classes.
5. Know the ecology of the indicator in details. This might entail study to determine causes and effects of relationships. Due to assessments and the resulting recommendations depending on species particular data, all expectations about habitat, food necessities, and life history require to be confirmed. To enable this process, statistical and a conceptual model can be developed for every use of indicator species. The indicator can then be preserved as statistically estimator for instance, in a path reversion analysis, examining the precision and accuracy of the indicator’s capability to indicate.
6. Define and identify sources of prejudice in selecting, interpreting and monitoring indicator species. All technical and assessments decisions involves unavoidable worth judgments that, if treated officially, can be deliberated and the advantages of every determined.
7. Submit assessment methods, design of data collection, as well as statistical investigations to external review. Conclusions, recommendations and interpretations of management strategies can be reviewed at a particular interval and at accomplishment of monitoring. Contemporary, only small fractions of monitoring and assessment programs are studied. For instance, only 13 programs, which make 8%, were outwardly reviewed of 172 rare plant checking programs carried out by federal, private, and state organizations. Tolerant status quo catalogs, for example, carrying capacity, indicator species or diversity, with their associated limitations, might preclude other agencies from sufficiently assessing the biology integrity of ordinary systems and endorsing effective organization actions (Landres et al. 45).