Department of Natural Resourceshttps://karuspace.karu.ac.ke/handle/20.500.12092/19492024-03-28T05:02:53Z2024-03-28T05:02:53ZMacroinvertebrate metrics and lipid profiles as potential indicators of land use influence in a high altitude tropical highland stream (Sagana River Basin, Kenya)Odhiambo, Charles O.Ngugi, Charles C.Sharma, Rekha R.Oyoo-Okoth, Elijahhttps://karuspace.karu.ac.ke/handle/20.500.12092/30552024-03-13T00:00:14Z2024-01-01T00:00:00ZMacroinvertebrate metrics and lipid profiles as potential indicators of land use influence in a high altitude tropical highland stream (Sagana River Basin, Kenya)
Odhiambo, Charles O.; Ngugi, Charles C.; Sharma, Rekha R.; Oyoo-Okoth, Elijah
Land 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 macroinvertebrates
Research article on Macroinvertebrate metrics and lipid profiles
2024-01-01T00:00:00ZFishing power of conventionally harvested wetland baitworms compared to black soldier fly larvae as alternative baits in tropical artisanal hook fisheryKihia, C. M.Gitonga, L. M.Tembo, J. E.Kanyeki, E.Munguti, J.Muli, B.https://karuspace.karu.ac.ke/handle/20.500.12092/30512024-02-21T00:00:16Z2018-01-01T00:00:00ZFishing power of conventionally harvested wetland baitworms compared to black soldier fly larvae as alternative baits in tropical artisanal hook fishery
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.
Reserch article on fishing power of conventionally harvested wetland
baitworms compared to black soldier fly larvae
2018-01-01T00:00:00ZSpawning interactions between hatchery-reared and wild naturalized rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) in high-altitude tropical streams, KenyaNjue, Justus N.Ngugi, Charles C.Mucai, MuchiriOpiyo, Mary A.https://karuspace.karu.ac.ke/handle/20.500.12092/30002023-11-28T00:00:20Z2022-07-01T00:00:00ZSpawning interactions between hatchery-reared and wild naturalized rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) in high-altitude tropical streams, Kenya
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.
Spawning interactions between hatchery-reared and wild naturalized rainbow trout (Oncorhynchus mykiss, Walbaum,
1792)
2022-07-01T00:00:00ZAnthropogenic activities affect forest structure and arthropod abundance in a Kenyan biodiversity hotspotKung'u, Gladys NyakeruCousseau, LaurenceGithiru, MwangiHabel, Jan Christianhttps://karuspace.karu.ac.ke/handle/20.500.12092/29842023-11-21T00:00:36Z2023-07-01T00:00:00ZAnthropogenic activities affect forest structure and arthropod abundance in a Kenyan biodiversity hotspot
Kung'u, Gladys Nyakeru; Cousseau, Laurence; Githiru, Mwangi; Habel, Jan Christian
Land-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.
Anthropogenic activities affect forest structure and arthropod abundance
2023-07-01T00:00:00Z