Diversity of Macro Invertebrates of the River Rwizi in Western Uganda: A Citizen Science-BioBlitz Approach

This study elucidates the pivotal role of citizen science-BioBlitz methodologies for rapid assessment of the macro-invertebrate taxa within the threatened River Rwizi of South-western Uganda. Utilizing a comprehensive mixed-methods approach, the investigation focused on six distinct river segments to demonstrate the efficacy of participatory citizen science-BioBlitz approaches conducted by experts, students and community volunteers. BioBlitz events included rigorous macro-invertebrate sampling at each of the selected sites along River Rwizi on nine occasions, incorporating collaborative taxonomic identification procedures involving experts, students, and the local community. Analyzing pollution concerns, diversity metrics, and community narratives yielded insights into river health and socio-ecological dynamics. A total of 43 macro-invertebrate families across 17 orders were documented with class Insecta dominating. Participants in BioBlitz events expressed predominantly positive sentiments, emphasizing satisfaction, education, and heightened awareness, besides negative sentiments rooted in historical mistrust. Intriguingly, the study unveiled an unforeseen trend in macro-invertebrate taxa richness, rising from upstream to urban sprawl and diminishing at peri-urban downstream sites. The study underscores the potential of citizen science-BioBlitz methodologies in advancing community science education and unraveling the intricate dynamics of threatened river ecosystems. The insights offered are invaluable for policymakers and conservationists seeking effective strategies to address challenges in the River Rwizi and comparable ecosystems. .

The Physico-Chemical Quality of Effluents of Selected Sewage Treatment Plants Draining into River Rwizi, Mbarara Municipality, Uganda

As population increases in urban areas, the domestic and industrial activities increase resulting in an increase in the volumes of wastewater and anthropogenic pollution, hence posing a threat to public health and environment. This study assessed the physical chemical quality of two main sewage plant effluents discharging into River Rwizi. Effluent water samples were analyzed for dissolved oxygen, colour, turbidity, total suspended solid, total iron, phosphates, alkalinity, magnesium, calcium carbonate, temperature, pH, ammonium, electrical conductivity, chloride and nitrates. Parameters were analyzed following standard methods of APHA (1985). The values obtained were compared with EPA (2001), NWSC (2015) and NEMA (1999) standards for waste water. Results showed that the mean values most of the parameters tested were higher than the recommended EPA, NWSC and NEMA standards. The mean colour was 1627.67°C and 1414.33°C in Kakoba and Taso sewage effluents respectively compared to EPA (20-150), NWSC (500) and NEMA (300) standards (p > 0.05). The mean alkalinity was 1390.17 mg/l and 1308.33 mg/l for Kakoba and Taso respectively compared with EPA (400) and NWSC (800) standards. DO had a mean concentration of 68.27 mg/l and 63.03 mg/l in Taso and Kakoba respectively compared to EPA and NEMA standard of 5 mg/l. Mg was 243.29 mg/l and 246.49 mg/l in Kakoba and Taso sewage effluents respectively compared to NEMA standard for waste water of 100 mg/l (p > 0.05). The mean pH was 8.26 and 8.16 in Taso and Kakoba sewage effluents respectively compared to NWSC and NEMA standard of 6.0 - 8.0. Phosphate mean concentration levels were 32.2 mg/l and 27.11 mg/l for Taso and Kakoba respectively compared to standards of EPA (0.5 - 0.7 mg/l) and NEMA (10 mg/l). NO3 was 10 mg/l and 5.83 mg/l in Kakoba and Taso sewage effluents respectively compared to NWSC maximum permissible limit of 5 mg/l. The mean NH4 concentration was 385.33 mg/l (Kakoba) and 50.0 mg/l (Taso) compared to the EPA guideline range (0.2 - 4 mg/l). Chloride (Cl) had a mean of 833.33 mg/l in Kakoba compared to EPA (250 mg/l), NWSC and NEMA (500 mg/l) standards. Therefore the study recommends for effective treatment of waste effluents from Kakoba and Taso sewage treatment plants before recycling in order to avoid pollution of river Rwizi.

The Physico-Chemical Quality of Streams and Channels Draining into River Rwizi, South Western Uganda

There is an increased human population along the catchment area of river Rwizi who are engaged in various activities with potential to contaminate river Rwizi especially along the streams. Studies have been done to examine the physico-chemical quality of the mainstream river Rwizi in Mbarara Municipality. However, the comprehensive source of contamination may be beyond the municipality and yet the streams have not been investigated to substantiate their contribution on quality degradation of the river and this formed the basis of the study. This study determined the physico-chemical parameters of streams draining into river Rwizi. Raw water was purposively selected from streams in the upstream, midstream and downstream sections of the river. Water samples were analyzed for 15 physico-chemical parameters including dissolved oxygen (DO), colour, turbidity, total suspended solid (TSS), total iron (Fe), phosphates (PO3-4), alkalinity, magnesium (Mg), calcium carbonate (CaCO3), temperature, pH, ammonium (NH+4), electrical conductivity (EC), chloride (Cl) and nitrates (NO3). The water samples were analyzed following the standard methods of American Public Health Association and standard operating manual (1985). The obtained values were also compared with the international Environmental Protection Agency (EPA, 2001) guidelines for water quality and the National Environment Management Authority (NEMA, 1999) standards for waste water. The results showed that most of the streams in the downstream generally recorded the highest levels (p i.e. bus park stream (temperature, 27.6°C;colour, 431.17 TCU;TSS, 99.33 mg/l;alkalinity, 468.33 mg/l;Mg, 121.89 mg/l;CaCO3, 588.67 mg/l;Cl, 333.33 mg/l), Kikutu stream (turbidity, 123.58 NTU;EC, 698 μs/cm;DO, 55.73 mg/l;PO3-4, 12.85 mg/l), Kakyeka upper (pH, 10.52;NH+4, 46.67 mg/l), Rwentondo (Fe, 3.44 mg/l) and Kakyeka GBK (NO3, 10.83 mg/l). Most of the parameters downstream were higher than the EPA guideline (temperature, 25°C;colour, 20 - 150 TCUs;TSS, 50 mg/l;alkalinity, 400 mg/l;Cl, 250 mg/l;DO, 5 mg/l;PO3-4, 0.5 - 0.7 mg/l;pH, 5.5 - 9.0;NH+4, 0.2 - 4 mg/l;Fe, 0.2 - 2.0 mg/l) and NEMA standards (colour, 300 TCUs;Mg, 100mg/l;DO, 5mg/l;PO3-4, 10 mg/l;pH, 6.0 - 8.0). On the other hand, the streams in the upstream registered the lowest values of the parameters i.e. Kibimba (temperature, 17.28°C;EC, 31 μs/cm;PO3-4, 0.24 mg/l), Kasharara (colour, 15.17 TCU;TSS, 2.5 mg/l;pH, 6.23;alkalinity, 19.67 mg/l;DO, 9.99 mg/l;Mg, 4.41 mg/l;CaCO3, 23.17 mg/l) and Karungu (turbidity, 7.02 mg/l;Fe, 0.12 mg/l). Calcium carbonate hardness of the waters ranged from soft to excessively hard across the stream. The variations of the parameters detected in the streams in the downstream could reach adverse conditions if no intensive measures are taken to regulate the different anthropogenic activities within the catchment of river Rwizi.