Biomonitoring of Mucheke and Shagashe Rivers in Masvingo, Zimbabwe Using Macro-Invertebrates as Indicators of Water Quality

The traditional way of assessing water quality of water bodies is through measurement of biological, physical and chemical parameters. However, such assessments only reflect the concentration of pollutants at the time of sampling not periodic pollution events. The goal of the study was to evaluate the river health using the macro-invertebrates that are found within the Mucheke and Shagashe rivers of Masvingo City as water quality monitors. The South African Scoring System (SASS 5) was used to score using the sensitivity of macro-invertebrates to levels of pollution in the two river systems. The data collection process was carried in April 2017 at four sampling sites using the kick sampling method and results validated by testing the physical, chemical and biological characteristics of the water and comparing them with the macro-invertebrates score. Results showed that the mean sensitivity score of macro-invertebrates showed variations depending on the selected site. Sample sites B2 and A2 downstream of the two river systems show high levels pollution tolerant macro-invertebrates as compared to sites A1 and B1 that are on the upper course and have more of pollution sensitive macro-invertebrates. On validation, to a large extent the levels of pollution indicated by macro-invertebrates were found to be congruent to the levels of pollution indicated by the physical, chemical and biological parameters. The research concludes that the presence of specific types of macro-invertebrates can be used to assess the levels of pollution in Mucheke and Shagashe rivers of Masvingo City.

Assessment of the Ecological Status and Threats of Welala and Shesher Wetlands, Lake Tana Sub-Basin (Ethiopia)

The ecological status of the Welala and Shesher Wetlands, on the eastern side of Lake Tana, were studied during pre-rainy, main-rainy, post-rainy and dry seasons from May 2009 to January 2010. Species composition, diversity and abundance of macrophytes, benthic macro-invertebrates and birds were assessed and physico-chemical parameters were measured. Phosphate and silicate concentrations, conductivity, TDS and turbidity varied significantly (p 0.05) between the two wetlands. The values for dissolved oxygen and pH ranged between 4.8 - 7.8 mg/l and 6.7 - 7.6, respectively. The values for nitrate and phosphate ranged between 0.2 - 3.1 mg/l and 0.2 - 3.3 mg/l, respectively. A total of 274 benthic macro-invertebrate individuals belonging to 5 families were collected, 32, 699 individual birds belonging to 62 species were enumerated and 13 species of macrophytes were identified. The two wetlands are shrinking at an alarming rate, mainly because of unsustainable farming practices and a huge irrigation project on Ribb River which is at presently under construction. Farming practices include draining and pumping of water for irrigation and expansion of farmland at the cost of the wetlands. The construction of a dam in Ribb River prevents overflow from Ribb River into the wetlands and disrupts the connection with Lake Tana which is vital for the survival of these two wetlands. We conclude that the Welala and Shesher Wetlands are valuable wetlands which need urgently protection.

Effectiveness of Macroinvertebrate Species to Discern Pollution Levels in Aquatic Environment

The World is transforming more rapidly than ever before as a result of urbanization and industrialization. Such unrelenting destruction of nature has surpassed the capacity of mother Earth to support the aquatic ecosystem. Apart from freshwater macroinvertebrate species, there is no single measure of declining freshwater ecosystem that can capture either the short and long-term changes or the trend of overall freshwater ecosystem health. In that regard, the macroinvertebrates and physico-chemical variables were used as surrogates to determine levels of impairment within and between Pangani and Wami-Ruvu rivers’ basins in Tanzania. Spatial distribution of macroinvertebrate communities in the basins is significantly influenced by varying levels of environmental variables as a result of geomorphology and improper land uses. Principal Components Analysis (PCA) ordination showed two distinct patterns of biometrics that clearly discriminate reference sites from monitoring sites at each basin and consequently demonstrate the differences in water quality and physical habitat between the site categories. Similarly, distinctive macroinvertebrate species were observed and varied considerably among the site categories in the studied rivers as a function of tolerance levels. Impacted sites are characterized by either absence of any sensitive taxa or presence of few if any;greater dominance of only a few taxa that are tolerant to pollution. Therefore, the more diverse orders with a wider range of occurrences and tolerance to pollution (Ephemeroptera (E), Diptera (D), Odonata (O) and Trichoptera (T)) can be considered as potential bio-indicators in developing biomonitoring index for Tropical African Rivers as they showed a significant discriminating power that separated reference from monitoring sites.

Identification and Validation of Reference Sites in the Andhi Khola River,Nepal

Reference conditions having no or only minor anthropogenic disturbances, are a basic requirement for ecological studies in rivers. To study ecological impact of a dam, two sites were pre-classiifed as reference or least disturbed in the Andhi Khola River, Nepal, using Rapid Field Bioscreening （RFB） protocol. Biological （macroinvertebrates） and physico-chemical samples were collected in the month of January and February 2013. Multi-habitat sampling （MHS） was employed in sample collection of macro-invertebrates fauna. Validation of the pre-classiifed sites was done using several indices viz. Nepalese biotic score （NEPBIOS）, Biological monitoring working party （BMWP）, Hindu-Kush Himalayan biotic score （HKHBIOS）, Hilsenhoff （HILSENHOFF） ＆ National Sanitation Foundation Water Quality Index （NSFWQI）. The NEPBIOS, HKHBIOS, HILSENHOFF, RFB ＆ NSFWQI indices predicted the river quality at al two sites as good with quality class Ⅱ. Only BMWP/ASPT water quality index predicted the river quality at al two sites as Excelent with quality class Ⅰ. Hence preselected sites with quality of rank Ⅱ i.e. good qualities were validated as reference sites. The study demonstrated that the multi-metric approach is suitable for application in the monitoring and assessment of rivers where dams are built to produce hydropower.