Macro-Invertebrates Community Case Study

In this study, macro-invertebrates community was used to establish the pollution tolerance index of four wastewater stabilization ponds at University of Eldoret in Kenya. The stabilization ponds have not been expanded since the inception of the university despite the ever rising population of students and staff. As such this study was set to evaluate the efficiency of the wastewater stabilization ponds in wastewater restoration by the use of bioindicators. Since chemical analysis is expensive and hazardous to human health, index of benthic integrity that uses macro-invertebrates communities was used in the study. Macro-invertebrates were sampled from one identified site of each of the four wastewater stabilization ponds monthly for a period
Bioindicators are developed for ecosystem health assessment, for human effects and interventions, human health assessment, and for evaluating sustainability (Burger, 2006). Bioindicators are recommended for water quality assessment as they are less costly and environmentally friendly biomonitoring tool (Aura et al., 2010). Biomonitoring of ecosystems require the use of bioindicators that are biologically and methodologically user friendly, and can effectively be used to provide early warnings (Burger, 2006). Focus is now being directed towards aquatic organisms, which are used as ecological indicators (bioindicators) of water quality (Wenn, 2008). Among the most commonly used bioindicators for assessing water quality status include macro-invertebrate communities. Macro-invertebrates are commonly used to monitor the health status of different watersheds (Holt, 2010). Unlike chemical analysis that gives snapshot status, macro-invertebrates provide cumulative effects of long term status of watersheds (Andem et al., 2015). Macro-invertebrates populations have families with differential responses to pollution and thus their relative abundance is used to infer the nature, load and severity of polution (Wenn, 2008). Macro-invertebrates possess hallmark traits making them ideal biological monitoring tool for assessment of aquatic ecosystems’ integrity (Carignan, 2002 and Holt
(IBI) are of different versions developed for different regions and for varying ecosystems. Benthic-index (B-IBI) and pollution tolerance index (PTI) are the most commonly used indices in assessment of aquatic ecosystems. (B-IBI) is used in assessment of samples from deep regions of streams and rivers (Kerans and Karr, 1994), while PTI is used in sampling from riffles and other shallow areas to detect moderate to severe stream quality degradation (Mark et al., 1997). PTI is useful in developing an information data base and the concept of developing tolerance ranges of organisms (Mark et al., 1997). The PTI groups macro-invertebrates into three categories on the basis of pollution; sensitive, moderately sensitive, and tolerant groups (Mark et al., 1997). These groups are assigned numerical values depending on their pollution tolerance values. For wastewater, a PTI value greater than 23 is considered as excellent condition, a PTI of 17-22 indicates that the water quality is good; a PTI between 11 and16 indicates fair water quality while water with PTI below 10 is considered as poor quality. Currently the United States Environmental Protection Agency uses PTI to determine quality of water using macro-invertebrates (Idroos and Manage 2012). Macro-invertebrates that are used to calculate the PTI include aquatic worms,