Water, essential for all living organisms, in

Water, is an essential natural resource for life. Globally, water exists in various forms (gas, liquid, solid) and in various places (water bodies)– there can be a clear distinction drawn between marine and freshwater ecosystems (Azizullah et al., 2011; Liu and Lipták, 2000).  These ecosystems cover about three quarters of the earth, and provide various ecosystem services. Marine systems, are by far the most expansive water source– this however, does not make is a drinkable resource. Despite being part of the ¾ coverage, freshwater makes up only 3% of that. Moreover, only about 0.01% is available for human use (Azizullah et al., 2011; Vörösmarty,C.J. et al., 2010). Therefore, the freshwater ecosystems around the world are the most valuable and should be managed in a long-term scheme.  So its recognized that freshwater is a valuable, but globally scarce natural resource with clean and safe freshwater being essential for all living organisms, in addition to playing a critical role in ecological, economic and community processes (Dudgeon et al., 2006; Maas and Bettis, 2013; Taylor et al., 2005). Due to the availability of safe freshwater resources being fundamentally linked to water quality,  there is a need to assess the health/ quality of aquatic water systems (E. Bellinger and Sigee, 2010).

One such surface freshwater system is a wetland, often described as being an interface between a terrestrial and aquatic ecosystem– such as; swamps, marshes and bogs (Hu et al., 2017; Sims et al., 2013). There seems to a general agreement of the importance of wetlands, this is not only due to them being globally threatened but how they act as a “biodiversity reservoir” (Hu et al., 2017; Schuijt, 2002; Sims et al., 2013). This concept was described by Sims et al (2013), whereby a wetland was said to have the ability to foster a number of different flora and fauna that in turn will differ with the varying hydrology in wetlands. The aforementioned varying hydrology–quality and volume, is a notable feature that ultimately governs the composition of the wetlands. This is important to understand, as these changes are usually due to natural and human activities that may impact the health of the system. 

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Water management strategies for freshwater systems has been orientated to support the needs of the main benefactors of the system. One of the biggest part of this, is assessing the water quality of the system. The 1950s are considered the early days of modern water quality monitoring, as the researchers made use of specific indicators such as chemical and physical variables (Chapman, 1996).  The physico-chemical measurements– total dissolved solids, conductivity and redox potential, is able to provide a sort of classification of the water body as a comparison to ones of a similar nature (Ambasht, 2014; Chapman, 1996). The amount of oxygen there is in a water body is important, as it firstly, is essential for all biological life forms and as it majorly impacts the solubility of metals. The measurement of total dissolved solids presents determines the mineral content within a system. The mineral content is an essential feature of the water quality as it results from the balance between dissolution and precipitation (Chapman, 1996). To measure these, there needed to be guidelines and standard techniques. The 50s saw the testing of water quality by chemical techniques, which became the norm.  This process concerned the testing of inorganic nutrients, acidity, salinity, organic and inorganic pollutants to determine the levels of metals, nutrients and pesticides etc. in the water by laboratory analyses (chromatographic and spectroscopic methods). It was later used in combination with the testing of the physical characteristics–temperature, pH, dissolved oxygen, electric conductivity etc. (Allan et al., 2006; E. Bellinger and Sigee, 2010).

Bioindicators

There has been growing interest in the use of biological indicators, due to them being extremely valuable in the assessment of water quality. Kolenati (1848) and Cohn (1853) were the first to note that biota that occurred in organically polluted systems were different from those in non-polluted systems (quoted by (E. Bellinger and Sigee, 2010; Mateo et al., 2015). This is due to the biological matter having an integrated response their environment, thus being able to indicate if there are fluctuations in water quality (Onyema, 2016; Reid et al., 1995). Therefore, stressed systems can often reflect a change in the number of individuals within a taxon, reduction in taxon richness and a predominance of taxa that are pollutant tolerant (Cranston et al., 1996). The fluctuations in water quality could possibly be missed if one is only using intermittent physico-chemical analysis. If one wished to preserve the diverse biological communities and maintain the health of the system, then it would be beneficial to monitor the aquatic communities rather than just measuring the physio-chemical variables (Mateo et al., 2015; Sims et al., 2013).

Measurements gained from bioindicators provide detailed information about the biota and species richness in the water system. Knowing this, there are two basic requirements, besides being located within the site, that must be met before a biological indicator is chosen. Firstly, it must be sensitive to changes– in both the biotic and abiotic environment and secondly, their response must be causal and predictable in order for researches to reliable information (Li et al., 2010; Reid et al., 1995).  It has been mentioned that the biological measurements provide detailed information concerning the biota and the species richness, but above that, the biological assessment includes an assortment of indices that help describe the structure of the biological community and its abundance (Sims et al., 2013). The individual’s tolerance and sensitivity levels are taken into consideration in the creation of the various indices.

As the monitoring practice evolved, it has become more sophisticated as it now included the use of water chemistry, particulate material and aquatic biota (Chapman, 1996). There has been growing interest in the use of biological indicators, due to them being extremely valuable in the assessment of water quality. Kolenati (1848) and Cohn (1853) were the first to note that biota that occurred in organically polluted systems were different from those in non-polluted systems (quoted by (E. Bellinger and Sigee, 2010; Mateo et al., 2015). This is due to the biological matter having an integrated response their environment, thus being able to indicate if there are fluctuations in water quality (Onyema, 2016; Reid et al., 1995). Therefore, stressed systems can often reflect a change in the number of individuals within a taxon, reduction in taxon richness and a predominance of taxa that are pollutant tolerant (Cranston et al., 1996). The fluctuations in water quality could possibly be missed if one is only using intermittent physico-chemical analysis. If one wished to preserve the diverse biological communities and maintain the health of the system, then it would be beneficial to monitor the aquatic communities rather than just measuring the physio-chemical variables (Mateo et al., 2015; Sims et al., 2013).

Measurements gained from bioindicators provide detailed information about the biota and species richness in the water system. Knowing this, there are two basic requirements that must be met before a biological indicator is chosen. Firstly, it must be sensitive to changes– in both the biotic and abiotic environment and secondly, their response must be causal and predictable in order for researches to reliable information (Ambasht, 2014; Li et al., 2010; Reid et al., 1995). Ambasht (2014), also stated that whatever species that is chosen as the bioindicator should be widespread in its distribution along the water body. It has been mentioned that the biological measurements provide detailed information concerning the biota and the species richness, but above that, the biological assessment includes an assortment of indices that help describe the structure of the biological community and its abundance (Sims et al., 2013). The individual’s tolerance and sensitivity levels are taken into consideration in the creation of the various indices (Ambasht, 2014; Cox, 1975).

This physio-chemical analysis might be an important indicator of environmental change; however, it only represents the short-term conditions of when it was spot sampled. Moreover, the analyses process is expensive and it doesn’t provide any measure on its influence on biological communities (Allan et al., 2006; Lavoie et al., 2004; Patil et al., 2012).

Chapman (1997), argued that “the selection of variables for any water quality assessment programme depends upon the objectives of the programme. Appropriate selection of variables will help the objectives to be met, efficiently and in the most cost effect “. This concept rings true as to why there has been a shift to assessments that are based more on the biological side. Firstly, bioindicators, unlike just measuring the physico-chemical factors, provides information past just the shot-sample state. Meaning, that the bioindicators has the ability to convey information on the past state, in addition to the current state. This concept was argued by Ambasht (2014), who stated that chemicals found in water bodies are able to undergo “large flacuations in a relatively short time”, therefore, its quite inefficent to measure the water chemistry (Oberholster et al., 2008). The cost effectiveness of using bioindicators also outweighs the information gained from chemical analyses. Moreover, due to bioindicators having an integrated relationship to the system, they are able to provide a better view. Therefore, when looking at a system (once a bioindicator has been chosen) the presence or absence of that particular species is used as an indicator of the ecological status of the system (E. Bellinger and Sigee, 2010).

Algae

In both the freshwater and marine systems, algal groups are the important primary producers. The term algae not only encompass macroalgae, but also microalgae divisions. In lakes and rivers, the generated biomass of the microalgal groups account for the foundation of the various food chains.  (E. G. Bellinger and Sigee, 2010).

 

Because of their ubiquity and species richness, algae are key biological indicators that can be used in testing the ecological condition and biological integrity of waterbodies (wetlands) (E. Bellinger and Sigee, 2010). It can determine environmental factors– such as, light, pH, salinity, oxygen levels, water current velocity, etc. Diatoms are one taxonomic algal group, which have been favoured as a bioindicator (Czerwik-Marcinkowska and Zietarski, 2011). This is due to their sensitivity to the environmental factors such as temperature, pH, and varying light conditions, that is linked to their species composition and abundance (Cranston et al., 1996). Their silica frustule allows these bioindicators to not only provide information on the current health of the system, but also they act as quantitative indicators of past water quality (Czerwik-Marcinkowska and Zietarski, 2011; Damery et al., 2009).

Phytoplankton communities are sensitive to alterations in their habitats, and thereby, phytoplankton total biomass and many phytoplankton species are utilized as indicators of aquatic habitat qualifications. Phytoplankton/algal communities give more evidences concerning alterations in water quality than nutrient or chlorophyll-a concentration. Water quality is a whole of physical, chemical, and biological properties of the water (Gökçe, 2016)

 

When using phytoplankton communities as a whole,

It is important to consider that the phytoplankton community changes quickly as a response to changes in water quality. The first reaction on such changes in the water environment is a quantitative change of the phytoplankton community. The amount of algae increases or decreases depending on the type of impacts on the water mass, which is followed by qualitative changes of the phytoplankton community. New species colonize in the lakes and some of the original species may decrease in importance based on local extinction in some cases (Gökçe, 2016)