Masters Theses:Department of Biological Scienceshttp://repository.embuni.ac.ke/handle/123456789/6322024-03-29T12:51:32Z2024-03-29T12:51:32ZCover Change and Vegetation Carbon Stocks of Mangrove Forests in Lamu County, KenyaMbatha, Anthony Mutuahttp://repository.embuni.ac.ke/handle/embuni/42832023-09-21T14:04:38Z2023-04-01T00:00:00ZCover Change and Vegetation Carbon Stocks of Mangrove Forests in Lamu County, Kenya
Mbatha, Anthony Mutua
Mangroves around the world are being threatened by a combination of natural and human factors. Losses of mangroves leads to reduced forest cover and enhanced carbon emission. This study assessed cover change, forest structure, natural regeneration, and carbon stocks of mangroves in Lamu County, Kenya. Landsat images were used to assess cover change from 1990 to 2019, and structural data were obtained in the field using the plot method. Using stratified random design, mangroves were sampled in 152 square plots of 400 m2 along belt transects established perpendicular to the waterline. Within each plot, all trees with stem diameters ≥ 2.5 cm were identified, counted and position marked, while those < 2.5 cm were counted and classified as juveniles. The following parameters were recorded: tree height (m), stem diameter (cm), and canopy cover (%); from which stem density (stems ha-1), basal area (m2 ha-1), volume (m3 ha-1), and biomass (t ha-1) were enumerated. Six mangrove species were encountered during this study. Based on importance value index, the dominant mangrove species in Lamu were Rhizophora mucronata (Lam.) and Ceriops tagal (perr.) C.B. Rob., that accounted for more than 70% of the mangrove formations. Mean standing density of the mangroves was estimated at 2,339±241 stems ha-1 (range:1,607-3,092 stems ha-1), with a basal area of 24.26±3.18 m2 ha-1, and volume of 157.97±15.22 m3 ha-1. At least 42% of the forest was stocked with low-quality poles, indicating prolonged human pressure. However, natural regeneration rate of 7,342±450 juveniles ha-1 observed in the forest was considered adequate to support forest recovery following disturbance. The mean biomass was estimated at 354.98±49.81 Mg ha-1. This translates to vegetation carbon storage of 166.56±23.41 Mg C ha-1. Mangroves in Lamu were estimated at 35,678 ha, representing 62% of the country’s total. Approximately, 1,739 ha of mangroves were lost between 1990 and 2019, mainly due to anthropogenic activities, representing a decline of 60 ha yr-1. Total emission from loss and degradation of mangrove vegetation in Lamu was estimated at 41.64 Mg C ha-1; which translates to 9,169.13 Mg CO2e yr-1. Assuming an offset price of US$10/Mg CO2e, the estimated cost of avoided emissions in Lamu County is US$91,691.3 yr-1 plus other co-benefits such as fishery support and shoreline protection. Mainstreaming mangroves and associated blue carbon ecosystems into national development and climate change agendas could accelerate Kenya’s achievements to the Paris Agreement and other processes.
Thesis
2023-04-01T00:00:00ZMathematical Modelling and Simulation of Competition for Students’ Population Via Influence And Economic Factors With Holling Type Ii ResponseOdhiambo, Brian Otienohttp://repository.embuni.ac.ke/handle/embuni/42732023-09-21T12:36:51Z2023-08-01T00:00:00ZMathematical Modelling and Simulation of Competition for Students’ Population Via Influence And Economic Factors With Holling Type Ii Response
Odhiambo, Brian Otieno
The increase in Kenyan population attracted the establishment of more schools, both public schools and private schools. This was due to the need to cater for the increasing number of students being enrolled in schools. Moreover, the dynamics of students’ population both in public schools and private schools have created the changes in the schools’ population. This occurs through transfer from one category of school to the other, through completion of the learning period and through drop out due to unknown reasons. This subjected both the public schools and private schools to compete in order to maintain a good number of students under their custody. In this work, a modified Lotka-Volterra model of schools and non-enrolled entities population in the education system is studied. Private schools and non-enrolled entities play the role of a predator in public schools. Again, public schools and non-enrolled entities play the role of predators in private schools. This study uses integrated Holling type II functional response to analyze the model. Establishment of equilibrium points and their stability are determined using the Routh-Hurwitz criterion and eigenvalue method. Global stability has been done for the positive equilibrium point. Hopf bifurcation is also done around the positive equilibrium point. Data obtained from the Ministry of Education and the sources cited were used to estimate the model parameters. Finally, graphical illustration of various parameter is derived to show their effect on schools when they are varied. The study revealed that the increase in transfer rate from private to non-enrolled, transfer rate from public to non-enrolled and the non-enrolled entity predation on public schools greatly affects the schools’ population as they are the ones leading to predation in school. Therefore, proper strategies should be developed to focus on reducing the parameters that affects the schools’ population adversely to avoid leading schools’ population to extinct.
2023-08-01T00:00:00ZPutative Functions of Novel Antennae Chemosensory Gene Repertoire of Male Tsetse Fly, Glossina Morsitans MorsitansBwana, Billiah Kemuntohttp://repository.embuni.ac.ke/handle/embuni/42722023-09-21T12:22:04Z2022-11-01T00:00:00ZPutative Functions of Novel Antennae Chemosensory Gene Repertoire of Male Tsetse Fly, Glossina Morsitans Morsitans
Bwana, Billiah Kemunto
Tsetse fly is a primary vector of Human African Trypanosomiasis and Animal African
Trypanosomiasis. Tsetse fly exploits chemical cues from the environment to
distinguish a non- from suitable hosts. Genes in tsetse fly antennae code for proteins
and receptors that directly or indirectly mediate chemoreception. While
chemoreception-associated genes have been annotated, antennal genes in the Glossina.
m. morsitans genome with important functions have not been characterized. Antennaespecific
raw reads from adult flies exposed to four treatments, namely, fed, unfedexposed
to ε-nonalactone attractant, unfed-exposed to δ-nonalactone repellant and
unfed-exposed to paraffin diluent (control) were mapped onto G. m. morsitans geneset.
Reads that did not map were isolated and de novo assembled into transcripts.
Protein-coding gene regions associated with these transcripts were predicted,
annotated and curated as partial/complete genes. Annotated putative
orthologs/homologs for these genes in Drosophila melanogaster (Dm), Musca
domestica (Md) or Anopheles gambiae (Ag) genomes were identified. Finally,
differential expression of the novel or existing genes in relation to odor exposures
relative to no-odor control (unfed flies) were assessed and expression of existing genes
quantified through qPCR. Results showed that 45.21% of the sequenced reads did not
map to the gene set. These reads assembled into 72,428 unique transcripts that yielded
592 genes among which 202 were novel and 390 were improvements of existing genes
in the G. m. morsitans genome. Among the novel genes, 94 had orthologs in Dm, Md
or Ag and 88 had homologs in UniProt databases. These orthologs were putatively
associated with non-canonical olfactory roles, thus providing insight into their specific
roles in antennal physiological processes. A novel gene (GMOY014237.R1396) and
15 existing genes were differentially expressed in response to the attractant or
repellent. Differential expression through qPCR analysis unveiled three antennal
transcripts, i.e., the coat protein epsilon, cyclin-dependent kinase and odorant receptor
45, all three up-regulated in response to the attractant. Novel genes sequences were
adopted by VectorBase, updating the existing G. m. morsitans annotations. This study
identified 108 potentially tsetse fly-specific antennal genes. The novel antennal genes
could be used as baseline data in studies of other tsetse fly species, and with an
orientation towards attraction and or repellency in their control.
2022-11-01T00:00:00ZFood web structure of Nematode communities associated with rice in Mwea, KenyaMokuah, DorcasNyabokehttp://repository.embuni.ac.ke/handle/embuni/42682023-09-20T12:17:13Z2023-07-01T00:00:00ZFood web structure of Nematode communities associated with rice in Mwea, Kenya
Mokuah, DorcasNyaboke
In Kenya, rice is an important staple crop after wheat and maize and the rate of
consumption surpasses its production. Apart from consumption, rice is a cash crop for
smallholder farmers including those in Kirinyaga County. Despite its usefulness in
contributing to food security, rice production has remained low due to various
constraints. Among these are plant-parasitic nematodes (PPN) that account for up to
20% of yield losses. Other than the deleterious effect of PPN, rice agroecosystems
contain free living nematodes (FLN) that play important ecological roles such as
decomposition of organic matter and suppression of destructive PPN. However, through
various cropping practices, the diversity and structure of the nematode communities is
altered which affects crop productivity. This study examined the abundance and
additively partitioned diversity of nematode communitiesin rice in Mwea. Soil samples
were collected from 30 rice fields in Nyangati (15) and Tebere (15) in Mwea, Kirinyaga
county. Nematode extraction was done using the modified Baermann technique before
enumeration and identification to the genus level. To determine the differences in the
abundance of nematode genera, one-way analysis of variance (ANOVA) was used.
Spatial distribution of nematode communities in Nyangati and Tebere wasexamined
using Jaccard index-based non-metric multidimensional scaling.One-way ANOVA was
used to evaluate the differences in the indices and metabolic footprints in Nyangati and
Tebere. Gamma diversity was additively partitioned into α and β components in the R
package vegan.Turnover and nestedness components of beta diversity were computed
using the betapart package in R software. The relationship between soil properties and
nematode genera was evaluated using canonical correspondence analysis. There were 17
nematode genera in both regions with Aphelenchoides and Longidorus occurring in
greater proportions in Tebere.The population of Helicotylenchus was high in Nyangati
and Prodorylaimus occurred in high numbers in both regions.Aphelenchoides was
positively correlated to electrical conductivity while Helicotylenchus was negatively
correlated.The two regions could not be unequivocally ordered due to crossing of the
Renyi diversity profiles along the scale parameter.Genus richness partitioning, showed
that α and β components contributed 33.7% and 66.3% of the γ diversity,
respectively.Partitioning of beta diversity showed that nestedness contributed to the
overall nematode diversity observed in Nyangati and Tebere rice fields.Results obtained
from this study provide information that could aid in development and implementation
of effective and environmentally sound nematode management practices in rice.
2023-07-01T00:00:00Z