Browsing by Author "*, Njiru Murithi James2"

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  • Publication
    Publication
    Spatial and temporal distribution and diversity of zooplankton along a salinity gradient between the Lake Naivasha and the Lake Oloiden | The Eldoret National Polytechnic
    (Eldoret National Polytechnic, 2023-07-07) Guto Kerubo Carolyne1; *, Njiru Murithi James2; , Getabu Albert1; , Gichana Moraa Zipporah; GK Carolyne
    There has been an increase in the water level in the Lake Naivasha (fresh water) which led toits merging with Lake Oloiden (saline). This was due to the increase in rainfall: associatedwith climate change. This may have an impact on the zooplankton community (biodiversity)due to the salinity gradient that resulted. A study was conducted to investigate the spatial andtemporal distribution and diversity of zooplankton along a salinity gradient between the LakeNaivasha and the Lake Oloiden. The salinity was measured insitu using a YSIMultiparameter meter and zooplankton were sampled twice by towing a zooplankton net witha flow meter for 10 minutes (monthly, per site for one year). The zooplankton were identifiedand analyzed under a compound microscope (×100). The species diversity, evenness andspecies richness index were computed. The salinity was higher in Oloiden ST1 and ST2 ascompared to the rest of the sites while the correlation showed a slight positive associationbetween salinity and zooplankton numbers. A total of 17 species were identified and theybelonged to the following families: Branchionidae, Lecanidae, Trichocercidae, Sisidae,Daphnidae and Cyclopoidae. The density (Ind/l) was highest for daphnidae, cyclopoidae andsisidae; however, Lake Oloiden had a lower density as compared to the rest of the sites. Thediversity index was low; H’= 0.87 for Oloiden ST2 and H’=0.64 for Crescent. Speciesrichness (d) was highest (2.84) for Oloiden ST2 and lowest in Crescent (1.24). Speciesevenness was highest in Crescent (0.83) and lowest in Oseria (0.71). The diversity index,evenness and Margalef’s index was higher in Lake Oloiden as compared to Lake Naivasha.The salinity gradient had an impact on the distribution and diversity of zooplankton; speciesdiversity, evenness and species richness increased with increase in salinity.
  • Publication
    Publication
    Spatial and temporal variation in water quality between the Lakes Naivasha and Oloiden in the Kenyan Rift Valley.
    (The Eldoret National Polytechnic, 2023-07-06) Guto Kerubo Carolyne1; *, Njiru Murithi James2; , Getabu Albert1; , Gichana Moraa Zipporah1
    Lakes Naivasha and Oloiden merged due to the rise in the water level in the former. A studywas conducted for one year in an endeavor to investigate spatial temporal variation of selectphysical and chemical parameters between the Lakes Naivasha and Oloiden. The waterquality was sampled monthly in each site in Lake Oloiden and Lake Naivasha by measuringsome water quality variables insitu and collection of water samples for laboratory analysis.The water depth and the secchi depth were measured in each site while some physicalchemical parameters were measured insitu using a YSI Multiparameter probe. Nutrients(phosphates and nitrates), total suspended solids, chlorophyll-a analysis was done in thelaboratory using the standard methods. The lakes depth and the secchi depth have increasedin both lakes. The phosphates varied site-wise and chlorophyll-a concentration has decreasedpost water level rise. Lake Oloiden’s temperature, pH, conductivity and salinity were higheras compared to the Lake Naivasha’s. The principal component analysis showed 4 principalcomponents (PCA-1 to PCA-4) which accounted for 94.7% of the variation. PCA-1 andPCA-2 biplots suggested: a link between chlorophyll-a to orthophosphates, nitrates,phosphates (Oloiden ST1 and ST2). Oseria and Korongo sites were closely associated withthe secchi depth, lake depth, pH and salinity. 4 distinct clusters were noted: Crescent,Malewa, midsection (Midlake, Korongo, Oseria) and Lake Oloiden (Oloiden ST1 and ST2).The increase in the water level and the merging of saline and fresh water ecosystem led to thecreation of a salinity gradient; an area where abiotic and biotic processes are non-linear.There was spatial temporal variation in water quality among the sites. Analysis of variance inwater quality in the Lake Naivasha and Lake Oloiden provided an insight about water qualitystatus: associations between water quality variables and sites may aid in effectivemanagement decisions