Browsing by Author "Nehemia, A."

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Benthic macroinvertebrate assemblages in mangroves and open intertidal areas on the Dar es Salaam coast, Tanzania
(NISC (Pty) Ltd and Taylor & Francis, 2015) Rumisha, C.; Shukuru, H.; Lyimo, J.; Maganira, Justine Daudi; Nehemia, A.
The assemblages of benthic macroinvertebrates in mangroves and open intertidal areas of the Dar es Salaam coast, Tanzania, was investigated in 2013–2014, revealing 56 species. Higher density, species richness and diversity were recorded in open intertidal areas, compared to nearby mangrove forests. Non-metric multidimensional scaling indicated differences in assemblages between mangrove and open intertidal samples. These differences were confirmed by analysis of similarity. SIMPER identified an average dissimilarity of 97.24% between mangroves and open intertidal samples, most of which were due to the malacostracan Uca annulipes and the gastropod Cerithidea decollata. PRIMER RELATE indicated significant correlation between macroinvertebrate assemblages and the measured physico-chemical parameters salinity, pH, redox potential and sediment particle size, whereas BIOENV and the Monte Carlo permutation test indicated that redox potential, sediment particle size and pH contributed significantly to variation in species composition. Mangroves were dominated by the gastropod C. decollata, and by the malacostracans Neosarmatium africanum and U. annulipes, and open intertidal areas by the bivalves Dosinia hepatica and Eumarcia paupercula. Due to the rich biodiversity in open intertidal ecosystems, it is recommended that conservation efforts along the Tanzanian coast should focus here.
Genetic diversity and structure of opsaridium microlepis along lake Nyasa, Tanzania
(Tanzania Journal of Agricultural Sciences, 2023) Nehemia, A.; Mwakalesi, A. J.
Opsaridium microlepis is a fish species that serves as a source of revenue and protein to most people living near Lake Nyasa. However, the population of this species has witnessed a worrisome decline, leading the International Union for Conservation of Nature (IUCN) to classify it as a threatened fish species. The current work used partial mitochondrial cytochrome oxidase subunit I (COI) sequences to investigate the genetic diversity, effective population size, and structure of O. microlepis along the Lake Nyasa areas of Tanzania. The findings indicated that Kafyofyo had the highest nucleotide diversity (π = 0.20%) and haplotype diversity (h = 0.78), while Katumba had the lowest nucleotide diversity (π = 0.08%). The lowest haplotype diversity (h = 0.50) was recorded at Katumba and Mbambabay. The molecular analysis indicated significant differences across the subpopulations investigated (Overall PhiST (ΦST) = 0.093, P < 0.05). The mean Sum of Square deviation (SSD), Harpending's raggedness index (HRI), Tajima's D (D), and Fu's Fs (Fs) were 0.014, 0.157, 0.108, and -0.88680 respectively and neither the mismatch distribution nor the neutrality test findings were significantly different from zero. The mismatch distribution supports the idea of sudden population expansion. Consequently, the effective population size estimates are large for sampling sites with higher genetic diversity. Thus, the current study's findings can serve as a foundation for long-term strategic plans to conserve and manage populations of O. microlepis in areas with low genetic diversity and effective population size.