Leonard J Chauka

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Verified

Leonard verified their affiliation via an institutional email.

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• PhD
• Senior Lecturer at University of Dar es Salaam

The growth parameters of Lethrinus harak were studied in Zanzibar water from 308 samples collected between June 2019 to May 2020 at Unguja Ukuu and Mkokotoni landing sites. The annulus count indicated that the majority of fishes captured were of three and four years old and very few were five, six, and seven years of age with a mean length of 17.69...

The Spotted sardinella Amblygaster sirm are small pelagic fish that are important protein source to coastal communities in the Indo-West Pacific. In this study, a cytochrome c oxidase subunit 1 (COI) gene of A. sirm from Tanzania was amplified to assess the species' genetic structure and demographic history. All individuals collected were identifie...

Although small pelagic fishing in Tanzania is rising, lack of information on population structure has been a significant concern in its management. This study aimed to determine the species composition, length-weight relationship and length at first maturity of Amblygaster sirm, Encrasicholina heteroloba, Encrasicholina punctifer, Stolephorus comme...

Five introduced strains of Nile tilapia ( Oreochromis niloticus ) were tested for growth performance both in fresh- and brackish-water (2 salinity units) environments for 56 days. The BIG NIN, GIFT, Chitralada, “Ruvu Farm” and Silver YY strains with initial mean average weight (± standard error) of 96.4 ± 6.90 g, 104.1 ± 7.19 g, 137.2 ± 7.21 g, 53....

Coral reefs are amongst the most vulnerable ecosystems to climate change. This study was conducted to evaluate the fluxes in the adaptations of reef-building corals to climate change. In order to explore this, chlorophyll a fluorescence, Symbiodinium abundance and types were monitored in nursery-reared corals for two years in three species that dif...

Tilapia hatcheries in Tanzania rely heavily on importing germplasm. Nevertheless, the genetic structure of the imported stocks is poorly understood. In the current study, the level of genetic diversity and differentiation of eight populations of Nile tilapia (Oreochromis niloticus) strains imported in Tanzania was investigated. Four of the studied...

Underpinning the success of coral reefs in nutrient poor marine environments is mutualism established between corals and members of the phylum Symbiodiniaceae. In recent decades, reef-building corals have been affected by multiple stressors including bleaching, which results largely from elevated sea surface temperature and exposure to excessive so...

Coral reefs are among the most vulnerable ecosystems to current trends of climate change. Most of the reef systems along the coast of Tanzania have remained severely damaged following the 1997/1998 El-Niño that caused a massive coral bleaching, resulting into a wide spread of coral death. It is important therefore to find out/establish whether reef...

Pollution, turbidity and coral bleaching history, as well as coral diversity, vary along the Tanzanian coastline. Prior to this study, it was not known whether exposure to such environmental variation might have influenced the diversity and distribution of Symbiodinium along this coastline. Such information can provide insight into whether Tanzania...

Aims: To evaluate antimicrobial and cytotoxicity activities of Clausena anisata, Acokanthera shemperii and Olea europaea against seven Gram negative bacteria and fungal species. Study Design: Bioassay of antimicrobial assay was done using 96-well micro-dilution method. Place and Duration of Study: School of Life Science and Bioengineering, Nelson...

Using high-resolution genetic markers on samples gathered from across their wide distributional range, we endeavoured to delimit species diversity in reef-building Pocillopora corals. They are common, ecologically important, and widespread throughout the Indo-Pacific, but their phenotypic plasticity in response to environmental conditions and their...

With the current increase in frequencies of coral bleaching events, knowledge on genetic diversity of symbiotic algae in the genus Symbiodinium harbored by reef building corals is important in understanding how coral reefs will respond to global climate change. This study was conducted since very little is known about genetic diversity of Symbiodin...

Establishment of symbiosis with thermal tolerant Symbiodinium type is widely believed to be amongst the functional adaptation mechanism employed by reef-building corals (RBCs) to bleaching. In this study, Symbiodinium types found in 66 most common RBC species have been studied together with photo-physiology of the selected corals and their respecti...

Symbiodinium ITS2 secondary structures. (DOC)

Endosymbiotic dinoflagellates in the genus Symbiodinium are fundamentally important to the biology of scleractinian corals, as well as to a variety of other marine organisms. The genus Symbiodinium is genetically and functionally diverse and the taxonomic nature of the union between Symbiodinium and corals is implicated as a key trait determining t...

Many scleractinian corals must acquire their endosymbiotic dinoflagellates (genus Symbiodinium) anew each generation from environmental pools, and exchange between endosymbiotic and environmental pools of Symbiodinium (reef waters and sediments) has been proposed as a mechanism for optimizing coral physiology in the face of environmental change. Ou...