Biological water quality assessment in the degraded Mutara rangelands, northeastern Rwanda

Abstract

Rwanda is a heavily overpopulated country that also suffers from overstocking with livestock, especially following the return of war refuges after the civil war (1991–1995). At present, approximately 20% of the human population in Nyagatare District in northeastern Rwanda has no access to clean drinking water and sanitation. We used a biotic index based on the presence of selected families of aquatic macroinvertebrates, derived from the “Tanzania River Scoring System” (TARISS), to assess water quality at N = 55 sites in the Mutara grasslands in Nyagatare District. Poor water quality became evident across most sampling sites both in the Muvumba (mean ± SE TARISS score 5.25 ± 0.10) and Karangazi Rivers (4.79 ± 0.12). Using a general linear model, we asked whether direct effects of land use forms and input of anthropogenic wastewater have an impact on water quality. Our results found no immediate effects of both forms of disturbance/pollution, probably because overall water quality was already poor. Our study is intended to serve as a starting point for continuous monitoring of water quality in the Mutara rangelands in NE Rwanda. The method applied here is cost-efficient, requires only basic equipment, and training local students to apply this technique can provide a solid basis for its implementation in future surveys related to public health. Electronic supplementary material The online version of this article (10.1007/s10661-019-7226-5) contains supplementary material, which is available to authorized users.

Serological Evidence of Exposure to Peste des Petits Ruminants in Small Ruminants in Rwanda

“…The presence of livestock and wildlife and trade movements across countries, could have contributed to the introduction of PPR in north and west parts of Rwanda. Last but not least, Rwanda has experienced large movements of returning citizens from neighboring countries in 1994 and from Tanzania in 2007 as well as Burundian refugees in 2015 (46)(47)(48). These movements of people and their livestock could have contributed to the introduction of PPR in various regions of Rwanda.…”

Water pollution affects fish community structure and alters evolutionary trajectories of invasive guppies (Poecilia reticulata)

“…This led to a sharp increase in human population density (483.1 individuals/km 2 ; NISR, 2014) and severe overstocking with cattle (64.9 individuals/km 2 ; Wronski et al, 2017). Further details on the history, ecology and hydrography of our study area can be found in Dusabe et al (2019). ], and presence/absence of macrophytes.…”

“…Our present study tested the generality of this pattern, but this time focusing on a paleotropical stream ecosystem in the upper Nile drainage (Swain, 2011). Streams in the heavily overpopulated and overstocked Mutara rangelands in northeastern Rwanda receive pollution chiefly from domestic wastewater and cattle dung (Dusabe et al, 2019). At the same time, the human population of Nyagatare district is critically dependent on clean surface water as a source of drinking water (Ministry of Infrastructure, 2010).…”

“…We asked whether species compositions of teleost fishes in the studied stream ecosystem change in dependence of diffuse sources of pollution, making use of previously published data on water pollution levels collected at the same time as the data presented here (Dusabe et al, 2019). This part of the study was motivated by the idea that assessing fish communities could represent another cost-efficient, bioindicator-based approach for the assessment of water quality, augmenting the previously described macrozoobenthos-based approach (Dusabe et al, 2019). Given previous work, we predicted a higher likelihood of occurrence (considering presence/absence data, prediction 1a) and higher local abundances/densities of invasive guppies (count data) with increasing pollution levels (prediction 1b).…”

Rapid Bioassessment Protocols Using Aquatic Macroinvertebrates in Africa–Considerations for Regional Adaptation of Existing Biotic Indices

“…It has also been adapted for non-wadeable, deltaic aquatic biotopes in the Okavango Delta in Botswana: Okavango Assessment System (OKASS; Dallas, 2009). TARISS has been used in Ugandan and Rwandan rivers to assess water quality (Dusabe et al, 2019;Tumusiime et al, 2019), although identifications of macroinvertebrates were done on preserved samples in the laboratory and not in the field, and in the case of Dusabe et al (2019), the TARISS sampling protocol was not followed as biotopes were combined.…”