ASSESSMENT OF RIVER HEALTH IN MULANJE DISTRICT USING A BIOMONITORING APPROACH: A CASE STUDY OF LIKHUBULA, RUO, CHITAKALE AND CHANUNKHA.

Water quality assessment is the overall process of evaluating the physical, biological, and chemical characteristics of water. In developing countries like Malawi, water quality is largely monitored through water quality assessment comprising biological and physicochemical assessments, and to some extent water quality modeling. Biomonitoring is another water quality management approach that has not received much attention in Malawi. This current study investigated the utility of biomonitoring as a water quality management approach for selected rivers in the Mulanje district including Likhubula, Ruo, Chitakale, and Chanunkha.

This research was conducted in order to assess the river health condition of the Likhubula, Chitakale, Chanunnkha and Ruo river. The main environmental stressors that may affect the health conditions of these rivers include imacts from tea plantations where pesticides and fertilizers are used to increase cro yield. In addition to that there are isssues of deforestation in the Mulanje mountain and this study aimed at assessing whether the health condition of these rivers was affected by these factors.

The South African Scoring System (SASS) approach was used in this study. The approach involves sampling and identification of macroinvertebrates from each sampling site followed by the determination of the sensitivity scores of each species and group, and calculation of the Average Score per Taxa (ASPT). The ASPT was calculated as a biotic index and used to determine the ecosystem integrity and establish the ecological conditions of the rivers. The results showed that according the biotic index developed from the biomonitoring approach, the Likhubula, Chitakale and Chanunkha river were in a natural condition with the ASPT values of 7.6, 7.3 and 9. Ruo river on the other hand had an ASPT value of 6.6 which indicated that the river was in good condition with a few modifications

The ASTP values calculated correlated well with the basic physicochemical parameters measured for each site. These results have demonstrated the usefulness of biomonitoring for stream water quality assessments in the absence of physicochemical water quality assessments which are both time-consuming and resource intense. Further studies need to be conducted to assess the river health condition per section so that the overall condition of these rivers is known. In addition to that, there is a need for studies to characterize the dynamics of nutrient and pesticides loading which are hypothesized to cause the ecological conditions observed in this study.

The approach involves sampling and identification of macroinvertebrates from each sampling site followed by the determination of the sensitivity scores of each species and group, and calculation of the Average Score per Taxa (ASPT). The results showed that according the biotic index developed from the biomonitoring approach, the Likhubula, Chitakale and Chanunkha river were in a natural condition with the ASPT values of 7.6, 7.3 and 9. These results have demonstrated the usefulness of biomonitoring for stream water quality assessments in the absence of physicochemical water quality assessments which are both time-consuming and resource intense. Keywords: ASPT, Biomonitoring, Biotic Index, Macroinvertebrates, SASS, Water quality management

In southern region of Malawi there is a district known as Mulanje. According to NSO (2018), the area covers an area of 2,056 km2 and has a population of 684,107 with 325,115 males and 358,992 females. It is well known for its tea growing industry and Mulanje mountain which is one of the highest peaks in Southern Africa and it serves as an essential water catchment area surrounding lowlands and tea and pine plantation that have replaced much of the original vegetation. Mount Mulanje is a major catchment area and is a source of all rivers in Mulanje District which supplies clean drinking water to the people and the tea estates.

Traditional authority: Mulanje Mountain Forest Reserve

District: Mulanje

Coordinates: -15.93855, 35.634