Department of Natural Resources
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Item Macroinvertebrate metrics and lipid profiles as potential indicators of land use influence in a high altitude tropical highland stream (Sagana River Basin, Kenya)(Elsevier, 2024) Odhiambo, Charles O.; Ngugi, Charles C.; Sharma, Rekha R.; Oyoo-Okoth, ElijahLand use practices near river ecotones result in numerous inputs of terrestrial materials into the river ecosystem. While macroinvertebrates population metrics is widely used in monitoring water quality changes, including those induced by humans, the use of lipid profiles in these organisms to monitor influence of land use practices is rather ignored. The aim of this study was to determine lipid profile in macroinvertebrates as potential indicator of human influence in Sagana River Basin, a high altitude tropical highland stream in Kenya. Sites were selected based on differences in land use activities delineated: forest with minimal land use activities, while cropland and saw milling areas had varying degrees of land use activities, with urban areas designated as sites with most human impacts. The macroinvertebrate metrics such as occurrence, abundance, diversity, percentage of oligo chaetes and chironomids (%OC), as well as the Ephemeroptera, Plecoptera and Trichoptera (%EPT) index differed relative to land use changes. Variation in the Fatty Acids (FAs), alcohols and sterols in benthic mac roinvertebrates was related to the land use activities along the stream. Evidently, streams traversing the urban areas had higher concentrations of Phospholipid fatty acids (PLFA), while streams traversing croplands had the highest neutral lipid fatty acids (NLFA). The dominance of monounsaturated FAs (MUFAs) in forest, shortchain FAs (SCFAs) and polyunsaturated FAs (PUFAs) in croplands and longchain FAs (LCFAs) near urban areas clear indicate different sources of these materials, mainly from terrestrial sources. Individual fatty acids, alcohols and sterols profiles discerned difference in land use changes. The concentrations of SCFAs, MUFAs, LCFAs, TeoH, 27Δ5.22, 28Δ5,24, 28Δ5,22, 29Δ5,22 and 29Δ5,22 in the benthic macroinvertebrates samples were positively associated with OC%, EPT, total abundance and eH’. Meanwhile the concentration of phytol, AqOH, 27Δ5 and SCOH were associated with Simpson index. The current findings support the combination of macroinvertebrates species composition, abundance, diversity and lipids profiles to detect land use activities at the riverine scale. While implementing catchment-based river management and conservation activities should incorporate lipid analysis as a management tool. There is need for continuous monitoring of long term trends in land use activities on the changes in lipid content of the macroinvertebratesItem Fishing power of conventionally harvested wetland baitworms compared to black soldier fly larvae as alternative baits in tropical artisanal hook fishery(2018) Kihia, C. M.; Gitonga, L. M.; Tembo, J. E.; Kanyeki, E.; Munguti, J.; Muli, B.Extensive and intensive, harvesting of earthworms and polychaetes from wetland substrate, for artisanal hook fishery, affect structural and functional integrity of these critical habitats. Cultured Black Soldier Fly larvae (BSF, Hermitia illucens), are suggested as sustainable alternatives. This study compares bait and landed fish properties of wild earthworm (Eisinia sp) and polychaete (Marphysa mossambica), with cultured BSF larvae as bait, in hook fishery. Participating fishers, were supplied with known quantity of bait, and the duration and quantity of fish obtained, monitored. Hook casting, attractiveness and killing power, as well as fish quality and quantity, were computed and compared among sites and bait. Results reveal significant (P<0.05) differences in bait and landed fish properties. Lower bait casting (8.8%), but higher attractiveness (0.96) and killing power (55%), were obtained using polychaete in marine habitats, than either earthworms or BSF. Similarly, higher fish landings s (0.59 kg.hr-1), were obtained using polychaete, than comparable BSF or earthworm (<0.1 kg. hr-1. We surmise that wild baitworms, are easier to handle, attract and land more fish, leading to higher variety and abundant landed fish, than cultured BSF larvae. Lower performance of BSF is attributed to; poor response of target fish to imprinted physical and chemical attributes of the bait. This may imply that fishers, have limited justification for substituting cultured BSF, with conventional wild baitworm in artisanal fishery. Further elucidation of drivers to bait choice and performance coupled with improvement in cultured bait quality might, provide sustainable solutions.Item Spawning interactions between hatchery-reared and wild naturalized rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) in high-altitude tropical streams, Kenya(Wiley, 2022-07) Njue, Justus N.; Ngugi, Charles C.; Mucai, Muchiri; Opiyo, Mary A.Rainbow trout (Oncorhynchus mykiss) is among the most widely translocated fish species in the world. The current study evaluated the spawning interactions between naturalized and wild rainbow trout from two high-altitude second-order streams, in Kenya. Data on total length, weight, condition factor, fecundity, fertilization, egg diameter and fry survival were collected on spawning rainbow trout between March and December 2021. Length–weight relationship showed parabolic equations as W = 0.0144L2.900, W = 0.0069L3.0285 and W = 0.00027L3.175 for wild fish stock, hatcheryreared and wild × hatchery-reared rainbow trout, respectively. Total fecundity differed significantly among the hatchery-reared, wild fish and the cross of the two (p < 0.05). The fertilization rate showed significant differences (p < 0.05), with no discernable difference observed between the hatchery-reared and crossed (wild × hatchery-reared). There was a positive correlation among the total fecundity to female egg weight, female body weight, fertilization rate and eyed egg survival in all the populations. Relative fecundity was significantly different among the three groups of fish (p < 0.05), but the differences between the hatchery and the crossed (wild × hatchery-reared) fish showed no significant differences. We recommend the use of crossed (wild × hatchery-reared) populations for fry production for use in aqua-culture as they presented the highest fecundity and gave the best outcome of fry with high survival.Item Anthropogenic activities affect forest structure and arthropod abundance in a Kenyan biodiversity hotspot(2023-07) Kung'u, Gladys Nyakeru; Cousseau, Laurence; Githiru, Mwangi; Habel, Jan ChristianLand-use change remains the main threat to tropical forests and their dependent fauna and flora, and degradation of existing forest remnants will further accelerate species loss. Forest degradation may result directly from human forest use or through spatial effects of land-use change. Understanding the drivers of forest degradation and its effects on biodiversity is pivotal for formulating impactful forest management and monitoring protocols, but such knowledge is lacking for many biodiversity hotspots, such as the Taita Hills in southeast Kenya. Here we first quantify effects of social factors (human activity and presence) at plot and landscape level, forest management (gazetted vs. non-gazetted) and spatial factors (fragment size and distance to forest edge) on the vegetation structure of indigenous Taita forest fragments. Next, we quantify effects of degraded vegetation structure on arthropod abundance and diversity. We show that human presence and activity at both the plot and landscape level explain variation in vegetation structure. We particularly provide evidence that despite a national ban on cutting of indigenous trees, poaching of pole-sized trees for subsistence use may be simplifying vegetation structure, with the strongest effects in edge-dominated, small forest fragments. Furthermore, we found support for a positive effect of vegetation structure on arthropod abundance, although the effect of daily maximum temperature and yearly variation was more pronounced. Maintenance of multi-layered forest vegetation in addition to reforestation maybe a key to conservation of the endangered and endemic fauna of the Taita Hills.Item Natural Radioactivity and radiological Hazard analysis of Construction stones from various queries in Machakos County Kenya. Radiation Protection Dosimetry.(2023-07) Muthama, MatsitsiThe radioactivity levels of rocks sampled from the quarries of Kyasioni, Mavoloni and Kathaana located in the lower Eastern County of Machakos in Kenya were determined. Forty-two samples were collected using stratified random sampling and analysed using NaI(TI) detector with a specially designed lead shield. The parametric values of activity concentration, absorbed dose, annual dose rate and hazard indices were estimated using activity-dose relations suggested in UNSCEAR and ICRP reports. The mean activity concentration for the entire work for 238U (226Ra), 232Th and 40K were 68.33 ± 3.11, 101.10 ± 1.83 and 1084.02 ± 30.28 Bq/kg, respectively. Kyasioni quarry presented the highest activity concentration of 74.75 ± 3.15, 118.48 ± 1.91 and 1120.35 ± 30.07 Bq/kg for 226Ra, 232Th and 40K, respectively. The average annual effective dose was estimated as 0.58 ± 0.01, 0.47 ± 0.01 and 0.52 ± 0.01 mSv/y for Kyasioni, Kathaana and Mavoloni quarries, respectively. Other radiological parameters estimated from the corresponding activities were within the recommended limits hence guaranteeing safety to the users.Item Globalization and Biodiversity Conservation Problems: Polycentric REDD+ Solutions(MDPI, 2019-02-19) Githiru, Mwangi; Njambuya, Josephine W.Noise barriers are the most widespread solution to mitigate noise produced by the continuous growth of vehicular traffic, thus reducing the large number of people exposed to it and avoiding unpleasant effects on health. However, conventional noise barriers present the well-known issues related to the diffraction at the edges which reduces the net insertion loss, to the reflection of sound energy in the opposite direction, and to the complaints of citizens due to the reduction of field of view, natural light, and air flow. In order to avoid these shortcomings and maximize noise abatement, recent research has moved toward the development of sonic crystals as noise barriers. A previous review found in the literature was focused on the theoretical aspects of the propagation of sound through crystals. The present work on the other hand reviews the latest studies concerning the practical application of sonic crystal as noise barriers, especially for road traffic noise mitigation. The paper explores and compares the latest developments reported in the scientific literature, focused on integrating Bragg’s law properties with other mitigation effects such as hollow scatterers, wooden or recycled materials, or porous coating. These solutions could increase the insertion loss and frequency band gap, while inserting the noise mitigation action in a green and circular economy. The pros and cons of sonic crystal barriers will also be discussed, with the aim of finding the best solution that is actually viable, as well as stimulating future research on the aspects requiring improvement.Item 290IMPACTS OF COMMUNITY ACTIVITIES ON ENVIRONMENTAL RESOURCES: THE POTENTIAL FOR DEVELOPING PAYMENT SCHEMES FOR ENVIRONMENTAL SERVICES(VDM Dr Muller Gmbh and co, 2011-01) Kiptum, Andrew; Kipkoech, Anderson; Omondi, Humhprey; Adano, Wario R.; Osano, Odipo; iryahwaho, Byamukama B; Agasha, AnnahNatural resources have continued to be degraded largely because of lack of well-defined property rights, population pressure, high levels of poverty and the lack of proper understanding of deleterious impacts of human activities on forest and watershed resources depletion. The social cost of exploiting the resources is larger than the private benefits and individuals have incentives to excessively extract natural resources at an expense of conservation. This study considers the socio-economic aspect, farm size and activities, water availability, the distance of the agricultural activities to the edge of the forest and riverbank and agricultural management practices employed by the population in Mt. Elgon District of Western Kenya. A proxy price was obtained using hypothetical structured question on willingness to pay and willingness to accept. The sample of 236 households was used to obtain data. Field surveys, structured questionnaires, interviews with key informants, and review of secondary sources were the main tools used for data collection. Statistical package for social science (SPSS) and Excel was the main software for data analysis. The results reveal average household of 8 persons, with most households living below poverty threshold (one dollar per person per day) and on average farm size holdings of 3.105 acres per household. The results also show that most farms are within the edge of the forest and riverbank at a distance ranging about 8 km and 1 km, respectively. More than 50% of the sample population do not practice water and soil management, resulting in reduced physical properties of the water such as volume of water, turbidity, taste and smell to undesired state. The contingent value of ecosystem pricing from willingness to pay (WTP) and willingness to accept (WTA) exercise yield mean prices of the responses Ksh. 728.82 and Ksh. 6,631.44, respectively. In conclusion, the household activities of the community in Mt Elgon landscape encourage resource depletion. Therefore, adoption of sustainable agriculture and ecosystem management that consider conservation of natural resource in order to have desired qualities of the ecosystem products and to reduce the costs to the population living downstream and around are recommended. There is need to educate the local population living around the forest and watershed areas to practice sound farming practices.Item The Biological Assessment and Rehabilitation of the World’s Rivers: An Overview(Water, 2021-01-31) Feio, Maria João; Hughes, Robert M.; Callisto, Marcos; Nichols, Susan J.; Odume, Oghenekaro N.; Quintella, Bernardo R.; Kuemmerlen, Mathias; Aguiar, Francisca C.; Almeida, Salomé F.P.; EguíaLis, Perla Alonso; Arimoro, Francis O.; Dyer, Fiona J.; Harding, Jon S.; Jang, Sukhwan; Kaufmann, Philip R.; Lee, Samhee; Li, Jianhua; Macedo, Diego R.; Mendes, Ana; Mercado-Silva, Norman; Monk, Wendy; Nakamura, Keigo; Ndiritu, George G.; Ogden, Ralph; Peat, Michael; Reynoldson, Trefor B.; Rios-Touma, Blanca; Segurado, Pedro; Yates, Adam G.The biological assessment of rivers i.e., their assessment through use of aquatic assemblages, integrates the effects of multiple-stressors on these systems over time and is essential to evaluate ecosystem condition and establish recovery measures. It has been undertaken in many countries since the 1990s, but not globally. And where national or multi-national monitoring networks have gathered large amounts of data, the poor water body classifications have not necessarily resulted in the rehabilitation of rivers. Thus, here we aimed to identify major gaps in the biological assessment and rehabilitation of rivers worldwide by focusing on the best examples in Asia, Europe, Oceania, and North, Central, and South America. Our study showed that it is not possible so far to draw a world map of the ecological quality of rivers. Biological assessment of rivers and streams is only implemented officially nation-wide and regularly in the European Union, Japan, Republic of Korea, South Africa, and the USA. In Australia, Canada, China, New Zealand, and Singapore it has been implemented officially at the state/province level (in some cases using common protocols) or in major catchments or even only once at the national level to define reference conditions (Australia). In other cases, biological monitoring is driven by a specific problem, impact assessments, water licenses, or the need to rehabilitate a river or a river section (as in Brazil, South Korea, China, Canada, Japan, Australia). In some countries monitoring programs have only been explored by research teams mostly at the catchment or local level (e.g., Brazil, Mexico, Chile, China, India, Malaysia, Thailand, Vietnam) or implemented by citizen science groups (e.g., Southern Africa, Gambia, East Africa, Australia, Brazil, Canada). The existing large-extent assessments show a striking loss of biodiversity in the last 2–3 decades in Japanese and New Zealand rivers (e.g., 42% and 70% of fish species threatened or endangered, respectively). A poor condition (below Good condition) exists in 25% of South Korean rivers, half of the European water bodies, and 44% of USA rivers, while in Australia 30% of the reaches sampled were significantly impaired in 2006. Regarding river rehabilitation, the greatest implementation has occurred in North America, Australia, Northern Europe, Japan, Singapore, and the Republic of Korea. Most rehabilitation measures have been related to improving water quality and river connectivity for fish or the improvement of riparian vegetation. The limited extent of most rehabilitation measures (i.e., not considering the entire catchment) often constrains the improvement of biological condition. Yet, many rehabilitation projects also lack pre-and/or post-monitoring of ecological condition, which prevents assessing the success and shortcomings of the recovery measures. Economic constraints are the most cited limitation for implementing monitoring programs and rehabilitation actions, followed by technical limitations, limited knowledge of the fauna and flora and their life-history traits (especially in Africa, South America and Mexico), and poor awareness by decision-makers. On the other hand, citizen involvement is recognized as key to the success and sustainability of rehabilitation projects. Thus, establishing rehabilitation needs, defining clear goals, tracking progress towards achieving them, and involving local populations and stakeholders are key recommendations for rehabilitation projects (Table 1). Large-extent and long-term monitoring programs are also essential to provide a realistic overview of the condition of rivers worldwide. Soon, the use of DNA biological samples and eDNA to investigate aquatic diversity could contribute to reducing costs and thus increase monitoring efforts and a more complete assessment of biodiversity. Finally, we propose developing transcontinental teams to elaborate and improve technical guidelines for implementing biological monitoring programs and river rehabilitation and establishing common Water 2021, 13, 371 3 of 45 financial and technical frameworks for managing international catchments. We also recommend providing such expert teams through the United Nations Environment Program to aid the extension of biomonitoring, bioassessment, and river rehabilitation knowledge globally.Item Naïve plant communities and individuals may initially suffer in the face of reintroduced megafauna: An experimental exploration of rewilding from an African savanna rangeland(PLOS ONE, 2021-04-06) Young, Truman P.; Kimuyu, Duncan M.; Odadi, Wilfred O.; M.Wells, Harry B.; Wolf, Amelia A.Excluding large native mammals is an inverse test of rewilding. A 25-year exclosure experiment in an African savanna rangeland offers insight into the potentials and pitfalls of the rewilding endeavor as they relate to the native plant community. A broad theme that has emerged from this research is that entire plant communities, as well as individual plants, adjust to the absence of herbivores in ways that can ill-prepare them for the return of these herbivores. Three lines of evidence suggest that these “naïve” individuals, populations, and communities are likely to initially suffer from herbivore rewilding. First, plots protected from wild herbivores for the past 25 years have developed rich diversity of woody plants that are absent from unfenced plots, and presumably would disappear upon rewilding. Second, individuals of the dominant tree in this system, Acacia drepanolobium, greatly reduce their defences in the absence of browsers, and the sudden arrival of these herbivores (in this case, through a temporary fence break), resulted in far greater elephant damage than for their conspecifics in adjacent plots that had been continually exposed to herbivory. Third, the removal of herbivores favoured the most palatable grass species, and a large number of rarer species, which presumably would be at risk from herbivore re-introduction. In summary, the native communities that we observe in defaunated landscapes may be very different from their pre-defaunation states, and we are likely to see some large changes to these plant communities upon rewilding with large herbivores, including potential reductions in plant diversity. Lastly, our experimental manipulation of cattle represents an additional test of the role of livestock in rewilding. Cattle are in many ways ecologically dissimilar to wildlife (in particular their greater densities), but in other ways they may serve as ecological surrogates for wildlife, which could buffer ecosystems from some of the ecological costs of rewilding. More fundamentally, African savannah ecosystems represent a challenge to traditional Western definitions of “wilderness” as ecosystems free of human impacts. We support the suggestion that as we “rewild” our biodiversity landscapes, we redefine “wildness” in the 21st Century to be inclusive of (low impact, and sometimes traditional) human practices that are compatible with the sustainability of native (and re-introduced) biodiversity.Item Naïve plant communities and individuals may initially suffer in the face of reintroduced megafauna: An experimental exploration of rewilding from an African savanna rangeland(PLOS ONE, 2021-04-06) Young, Truman P; Kimuyu, Duncan M.; Odadi, Wilfred O.; M.Wells, Harry B.; Wolf, Amelia A.Excluding large native mammals is an inverse test of rewilding. A 25-year exclosure experiment in an African savanna rangeland offers insight into the potentials and pitfalls of the rewilding endeavor as they relate to the native plant community. A broad theme that has emerged from this research is that entire plant communities, as well as individual plants, adjust to the absence of herbivores in ways that can ill-prepare them for the return of these herbivores. Three lines of evidence suggest that these “naïve” individuals, populations, and communities are likely to initially suffer from herbivore rewilding. First, plots protected from wild herbivores for the past 25 years have developed rich diversity of woody plants that are absent from unfenced plots, and presumably would disappear upon rewilding. Second, individuals of the dominant tree in this system, Acacia drepanolobium, greatly reduce their defences in the absence of browsers, and the sudden arrival of these herbivores (in this case, through a temporary fence break), resulted in far greater elephant damage than for their conspecifics in adjacent plots that had been continually exposed to herbivory. Third, the removal of herbivores favoured the most palatable grass species, and a large number of rarer species, which presumably would be at risk from herbivore re-introduction. In summary, the native communities that we observe in defaunated landscapes may be very different from their pre-defaunation states, and we are likely to see some large changes to these plant communities upon rewilding with large herbivores, including potential reductions in plant diversity. Lastly, our experimental manipulation of cattle represents an additional test of the role of livestock in rewilding. Cattle are in many ways ecologically dissimilar to wildlife (in particular their greater densities), but in other ways they may serve as ecological surrogates for wildlife, which could buffer ecosystems from some of the ecological costs of rewilding. More fundamentally, African savannah ecosystems represent a challenge to traditional Western definitions of “wilderness” as ecosystems free of human impacts. We support the suggestion that as we “rewild” our biodiversity landscapes, we redefine “wildness” in the 21st Century to be inclusive of (low impact, and sometimes traditional) human practices that are compatible with the sustainability of native (and re-introduced) biodiversity.