The study was conducted by Thomamo B. Benjamin, Kelemogile Mmolawa, Gaolathe Tsheboeng, Marks Ditlhogo, and Francis O. Arimoro, who sampled three fixed stations along the river between February and May 2026. The stations were deliberately chosen to represent a gradient of urban influence: an upstream reach near the A1 Highway with relatively low-density development, a midstream reach cutting through the most densely built-up part of the city, and a downstream reach near the Tlokweng Road corridor that integrates the cumulative drainage of the entire urban catchment. Because the Segoditshane flows through residential, commercial, institutional, and industrial zones, it functions as the city’s principal stormwater conduit, collecting runoff, wastewater influence, and diffuse pollutants along its roughly 14-kilometer corridor through the metropolitan area.

The physicochemical results reveal a river under measurable strain. Dissolved oxygen fell from a mean of 7.59 milligrams per liter at the upstream station to roughly 4.8 to 5.0 milligrams per liter at the midstream and downstream sites, a decline of about 36 percent that the authors link to rising organic loading. Electrical conductivity climbed from around 734 to 742 microsiemens per centimeter upstream and midstream to 952 microsiemens per centimeter downstream, an increase of nearly 30 percent that reflects the accumulation of dissolved salts, nutrients, metals, and other urban-derived ions. Biochemical oxygen demand rose from 3.28 milligrams per liter upstream to 8.75 midstream, chemical oxygen demand more than doubled from 18.5 to 45 milligrams per liter, and total dissolved solids increased from 455 to 590 milligrams per liter downstream. Nitrate concentrations also rose steadily along the continuum, while phosphate peaked at the midstream station.

These chemical shifts tracked a semi-quantitative urban pressure assessment developed by the team. The upstream site scored 3 on a ten-point pressure scale, with roughly 25 percent impervious surface cover, a surrounding population density of about 1,500 people per square kilometer, and only one or two major stormwater outfalls. The midstream site, embedded in the densest urban fabric, scored 8, with approximately 70 percent impervious cover, 4,500 people per square kilometer, and five to seven outfalls. The downstream site scored highest at 9, combining about 60 percent impervious cover, seven to ten stormwater outfalls, high wastewater influence, and full integration of upstream drainage. The close agreement between these pressure scores and the measured water chemistry suggests that catchment development and drainage connectivity are central to the environmental degradation documented in the river.

Against this backdrop, the biological story is striking. Over four monthly sampling campaigns, the team collected 1,238 macroinvertebrate individuals representing 16 families from five insect orders, identified to family level using South African Scoring System Version 5 taxonomic keys. Abundance collapsed along the urban gradient, from 718 individuals upstream to 436 midstream and just 84 downstream. The upstream station was dominated by pollution-tolerant Diptera, particularly non-biting midges of the family Chironomidae with 250 individuals and mosquitoes of the family Culicidae with 156, alongside moderate numbers of predatory water bugs and damselflies. The midstream station supported a more balanced assemblage including mayflies of the family Baetidae, dragonflies and damselflies, and several families found nowhere else in the study, such as Gomphidae, Micronectidae, Scirtidae, and Gyrinidae. The downstream reach held only six families, with Baetidae, Chironomidae, Libellulidae, and a handful of others accounting for nearly all individuals.

Diversity metrics added an important nuance to this pattern. Although the upstream station recorded the highest raw abundance, its Shannon diversity of 1.844 was the lowest of the three sites, a consequence of dominance by a few opportunistic taxa. The midstream station, by contrast, posted the highest values for nearly every metric: 11 families, a Margalef richness index of 1.645, Shannon diversity of 2.265, Simpson diversity of 0.886, and Pielou’s evenness of 0.945. This midstream diversity maximum is one of the study’s most notable findings, suggesting a non-linear response along the river continuum. Rather than a simple slide from good to bad conditions, the pattern points to intermediate disturbance dynamics, in which moderate environmental stress and greater habitat heterogeneity at the midstream reach widen the range of niches available, allowing sensitive and tolerant taxa to coexist while competitive exclusion is dampened.

A modified application of the South African Scoring System reinforced this interpretation. The midstream station achieved a SASS score of 58, twelve scoring taxa, and an average score per taxon of 4.83, corresponding to a condition of Good under the SASS5 framework. The upstream station scored 35 with an ASPT of 3.89, rated Fair, while the downstream station fell to a score of 23 and an ASPT of 3.83, rated Fair to Poor. The authors caution that because their pooled multi-habitat sampling differed from the standardized SASS5 kick-sampling protocol, these indices should be read as comparative indicators of relative condition rather than formal ecological status classifications. Even so, the convergence of abundance, richness, diversity, and biotic index data on the same spatial pattern lends weight to the overall conclusion.

To connect community structure with environmental conditions, the researchers employed Canonical Correspondence Analysis, a multivariate ordination technique that relates species distributions to measured gradients. Based on twelve station-by-month observations, the analysis showed that the first two canonical axes together explained 97.82 percent of the constrained family-environment variation, with Axis 1 accounting for 65.72 percent and Axis 2 for 32.10 percent, both statistically significant under Monte Carlo permutation tests. Axis 1 loaded most strongly on ammonia, pH, dissolved oxygen, depth, and phosphate, while Axis 2 was associated with electrical conductivity, flow velocity, depth, nitrate, and phosphate. Because several environmental variables were strongly correlated with one another, the authors interpret the ordination as an exploratory description of interacting gradients rather than a test of independent drivers. Upstream assemblages aligned with higher pH and oxygen, midstream communities with flow, depth, and nutrients, and downstream assemblages with elevated conductivity and nitrate.

The findings fit squarely within the theory of environmental filtering, which holds that local abiotic conditions act as a sieve, favoring species whose traits allow survival under prevailing conditions while excluding those that cannot cope. In the Segoditshane River, the filters include oxygen depletion, nutrient enrichment, rising salinity indicated by conductivity, altered flow and depth, and habitat simplification driven by impervious surfaces and channel modification. Tolerant families such as Chironomidae and Culicidae thrived where organic enrichment and standing water created favorable breeding conditions, while moderately sensitive predators like Gomphidae and Aeshnidae were largely confined to the midstream reach, and the relatively sensitive Baetidae and Simuliidae persisted mainly where localized hydraulic refugia offered patches of suitable habitat. Importantly, the authors warn that the higher proportional contribution of sensitive taxa downstream should not be mistaken for recovery; it more likely reflects the loss of other groups from an already depauperate community.

The study carries practical weight for a rapidly urbanizing semi-arid region where conventional chemical monitoring alone can underestimate cumulative ecological degradation. Because macroinvertebrates integrate environmental stress over weeks and months, they provide a biological memory that instantaneous water samples lack. The authors argue that their results establish a baseline for biomonitoring in the Segoditshane River and support integrated catchment management spanning water-quality protection, stormwater management, habitat restoration, and long-term ecological monitoring. They also outline future priorities, including year-round monitoring across the full hydrological cycle, greater spatial replication, habitat-specific sampling, trait-based and species-level approaches, and the incorporation of environmental DNA metabarcoding to sharpen taxonomic resolution. As Gaborone continues to grow, the Segoditshane’s insect communities may prove to be among the most honest witnesses to the city’s environmental trajectory.

Subject of Research: Urban pollution signatures and environmental filtering of benthic macroinvertebrates along abiotic gradients in a semi-arid river in Botswana

Article Title: Urban pollution signatures and environmental filtering of benthic macroinvertebrates along abiotic gradients in a semi-arid river in botswana

Article References: Benjamin, T. B., Mmolawa, K., Tsheboeng, G., Ditlhogo, M., & Arimoro, F. O. (2026). Urban pollution signatures and environmental filtering of benthic macroinvertebrates along abiotic gradients in a semi-arid river in botswana. Environmental Challenges, 25, Article 101661. https://doi.org/10.1016/j.envc.2026.101661

Image Credits: AI Generated

DOI: 10.1016/j.envc.2026.101661

Keywords: benthic macroinvertebrates, environmental filtering, urban pollution, semi-arid river, water quality, biomonitoring, SASS5, dissolved oxygen, electrical conductivity, Botswana, Gaborone, canonical correspondence analysis

The research, led by Tiro Theodore Monamo together with Mpho Keetile and Gobopamang Letamo of the Department of Statistics, Demography and Population Studies at the University of Botswana, used in-depth, semi-structured interviews with 18 older adults aged 65 and above who live with various forms of disability. Participants were recruited through health service networks in the Serowe/Palapye District, a setting that combines urban infrastructure with deeply rural and underserved communities. The team analysed the transcripts thematically with ATLAS.ti software, anchoring the analysis in Smith’s Interpretative Phenomenological Analysis, a method designed to capture the depth of individual lived experience while still identifying patterns shared across narratives.

Two broader theoretical lenses shaped the interpretation. The social model of disability reframes disability not simply as a bodily limitation but as the product of barriers erected by society, from inaccessible buildings to discriminatory attitudes. A life-course perspective, meanwhile, allowed the researchers to trace how personal, social and structural factors accumulate and interact over decades, shaping how a person arrives at old age and how they experience disability within it. Together, these frameworks pushed the study beyond a catalogue of impairments toward an account of how disability is made, endured and negotiated across a lifetime.

What emerged from the interviews is a picture of compounding disadvantage. Participants described declining health and memory loss, but they placed equal or greater weight on social exclusion, inadequate access to healthcare and economic marginalisation. For many, the loss of income-earning capacity in old age collided with the costs of transport, medication and daily necessities, while distance to clinics and the quality of services added further friction. Social isolation compounded these pressures: reduced mobility and shifting family structures left some older adults cut off from the community networks that had once sustained them. The findings suggest that disability in later life cannot be understood as a purely medical phenomenon; it is woven into systems of care, economy and belonging.

Yet the study refuses a narrative of pure deprivation. Alongside the hardships, participants reported genuinely positive dimensions of ageing, including emotional growth, spiritual acceptance and pride in the contributions they had made across their lives. Many framed their later years through faith and a sense of completion rather than solely through loss. This duality, the authors argue, is essential for anyone hoping to design policy for this population: interventions that treat older adults with disabilities only as recipients of need miss the agency, purpose and meaning that participants themselves identified as central to their lives.

That agency took concrete, culturally grounded forms. Coping strategies reported by participants included engaging in light physical activity, making traditional dietary adjustments, and turning to prayer as a source of strength and structure. Equally important were efforts to remain socially and culturally relevant, finding alternative roles and ways of contributing when physical limitations closed off previous ones. Participants drew on indigenous knowledge to self-manage health conditions, and many articulated a deep sense of purpose that persisted despite disability. These are not trivial details; they represent resources, familial, cultural and personal, that any serious policy framework would need to strengthen rather than bypass.

The study’s conclusions point squarely at structural reform. The authors argue that addressing the needs of older adults with disabilities in Botswana requires policy changes that strengthen community-based care, improve physical and service accessibility, and integrate both ageing and disability into national development plans. At present, they note, existing policies often overlook the complex realities faced by this population, particularly in rural and underserved communities where the intersection of age and disability is most acute. The researchers call for rights-based, contextually grounded approaches to healthy ageing, an orientation that treats older adults with disabilities as rights-holders with agency rather than as passive beneficiaries of charity.

The significance of the work extends beyond Botswana’s borders. Sub-Saharan Africa is ageing faster than many public health systems are prepared for, and research on the intersection of ageing and disability in the region remains thin. By documenting lived experience with methodological rigour, the study contributes to a growing body of literature that can inform regional policy, from the design of community care programmes to the inclusion of disability considerations in healthy-ageing strategies. It also demonstrates the value of phenomenological methods in demographic and population health research, where large surveys often flatten the textures of experience that determine whether policies actually work on the ground.

The research was conducted with extensive ethical safeguards. It received clearance from the University of Botswana Institutional Review Board and regulatory approval from the Ministry of Local Government and Traditional Affairs, with additional approval from the Serowe District Health Management Team and Palapye Primary Hospital management. Written informed consent was obtained from all participants, who were informed of their right to withdraw at any stage, and all quotations were anonymised to protect identities. The study received no external funding, and the authors declare no competing interests. The article is published open access under a Creative Commons licence, making the full findings available to researchers, policymakers and communities across the region.

For Botswana, the message of the study is ultimately one of both warning and opportunity. The warning is that systemic, cultural and economic barriers, not just functional decline, shape disability in later life, and that ignoring them will deepen inequality as the population ages. The opportunity lies in the resilience the researchers documented: older adults are already managing their health, sustaining their communities and finding meaning despite constrained circumstances. Policy that builds on those existing strengths, while dismantling the barriers that exhaust them, could transform what it means to grow old with a disability in Botswana, and offer a model for the wider region.

Subject of Research: Lived experiences of ageing and disability among older adults in Botswana

Article Title: Lived experiences of ageing and disability among older adults in Botswana

Article References: Monamo, T. T., Keetile, M., & Letamo, G. (2026). Lived experiences of ageing and disability among older adults in Botswana. Discover Social Science and Health. https://doi.org/10.1007/s44155-026-00478-4

Image Credits: AI Generated

DOI: 10.1007/s44155-026-00478-4

Keywords: ageing, disability, Botswana, older adults, lived experiences, qualitative research, interpretative phenomenological analysis, social model of disability, life-course perspective, sub-Saharan Africa, healthy ageing, community-based care