Population Characteristics of Selected Small Pelagic Fish Species along the Tanzanian Coast

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 commersonii, and Spratelloides gracilis landed at Kilwa Kivinje, Kipumbwi and Shangani along the Tanzanian coast. These landing sites were chosen because of their locations and importance in the small pelagic fishery. Sampling was done monthly from October 2018 to June 2020. The catch composition was site specific such that  E. heteroloba dominated at Kilwa Kivinje and Shangani, while E. punctifer dominated at the Kipumbwi site. Further analysis shows allometric coefficient to be greater than 3 for A. sirm and E. punctifer, indicating positive allometric growth, while for S. commersonii and S. gracilis, the allometric coefficient was less than 3, indicating negative allometric growth. Our findings showed that length at first maturity (L50) differed, implying that these species start spawning at different sizes, an essential biological reference for sustainable small pelagic fish exploitation. We recommend seasonal closure of the fishery to maintain reproductive seasons since many species are multiple spawners. Keywords: Population; Small pelagic; Maturity; Tanzani

Antimicrobial and Cytotoxicity Activity of Clausena anisata, Acokanthera shemperii and Olea europaea Growing in Tanzania

This research article published by the European Journal of Medicinal Plants,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 Mandela African Institution of Science and Technology, Arusha, Tanzania, from April 2014 to June 2014. Methodology: 96-well micro dilution method was used in antimicrobial assay. Extracts were loaded in the wells of the first row, followed by serial dilution and 50 μl of the bacterial suspensions (0.5 MacFarland standard turbidity) were added in each well. The first concentration which showed no bacterial growth was considered as minimum inhibition concentration. Method developed by Meyer et al 1982 was adopted in cytotoxicity activities. Results: All extracts indicated antibacterial activity on at least three to five of the tested seven bacteria and two fungi species with MIC value ranging 0.7812 - 12.5 mg/mL. The highest activity was demonstrated by Olea europaea leaf methanolic, Acokanthera shemperii stem bark and Clausena anisata twigs ethyl acetate extracts with MIC value of 0.7812 mg/mL against Pseudomonas aeruginosa while the same MIC value was exhibited by Olea europaea stem bark methanol against Proteus mirabilis. However the Olea europaea root methanolic extract inhibited the growth of Pseudomonas aeruginosa and Salmonella kisarawe with MIC value of 0.7812 mg/mL. Olea europaea leaf methanolic and stem bark methanolic which demonstrated high antimicrobial activity were non toxic against brine shrimp larvae with LC50 value of 369.8272 and 226.1566 µg/mL, while Clausena anisata twigs ethyl acetate, Acokanthera shemperii stem bark ethyl acetate and Olea europaea root methanolic extracts were toxic with LC50 value of 6.21276, 67.4179 and 92.3089 µg/mL respectively. Conclusion: This study has unveiled antimicrobial and cytotoxicity properties of Clausena anisata, Acokanthera shemperii and Olea europaea

Variation in Symbiodinium ITS2 Sequence Assemblages among Coral Colonies

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 the environmental tolerance of the symbiosis. Surprisingly, the question of how Symbiodinium diversity partitions within a species across spatial scales of meters to kilometers has received little attention, but is important to understanding the intrinsic biological scope of a given coral population and adaptations to the local environment. Here we address this gap by describing the Symbiodinium ITS2 sequence assemblages recovered from colonies of the reef building coral Montipora capitata sampled across Kāne'ohe Bay, Hawai'i. A total of 52 corals were sampled in a nested design of Coral Colony(Site(Region)) reflecting spatial scales of meters to kilometers. A diversity of Symbiodinium ITS2 sequences was recovered with the majority of variance partitioning at the level of the Coral Colony. To confirm this result, the Symbiodinium ITS2 sequence diversity in six M. capitata colonies were analyzed in much greater depth with 35 to 55 clones per colony. The ITS2 sequences and quantitative composition recovered from these colonies varied significantly, indicating that each coral hosted a different assemblage of Symbiodinium. The diversity of Symbiodinium ITS2 sequence assemblages retrieved from individual colonies of M. capitata here highlights the problems inherent in interpreting multi-copy and intra-genomically variable molecular markers, and serves as a context for discussing the utility and biological relevance of assigning species names based on Symbiodinium ITS2 genotyping

Growth performance of five different strains of Nile tilapia (Oreochromis niloticus) introduced to Tanzania reared in fresh and brackish waters

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, 53.2 +/- 6.98 g and 95.3 +/- 7.11 g, respectively were used. Individuals were tagged and pooled in hapas (12 mx8.5 mx2 m each), aligned into different ponds (20 mx20 m each). Stocking density of 5 fish/m(2) and 350 g/kg crude protein diet were used. Overall, the average weight gain for GIFT strain was 7.5%, 32%, 45% and 86.5% higher than BIG NIN, Chitralada, "Ruvu Farm" and Silver YY strains, respectively, across both environments. All strains performed significantly better (p<0.05) when reared in brackish-water than their respective counterparts in freshwater, except for the BIG NIN strain. The morphometric correlations for all strains in both environments ranged from moderate (0.50) to strong positive (0.92). The GIFT strain demonstrated superior growth and genotype by environment interaction was weak and not important to be prioritized in breeding programs

A genetic view of Indo-Pacific Pocillopora

Sample list including locations, ORF and ITS2 designations, microsatellite allelic data, and structure input file

Blind to morphology: genetics identifies several widespread ecologically common species and few endemics among Indo-Pacific cauliflower corals (Pocillopora, Scleractinia)

Aim: 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 nearly featureless microskeletal structures confound taxonomic assignments and limit an understanding of their ecology and evolution.Location: Indo-Pacific, Red Sea, Arabian/Persian Gulf.Methods: Sequence analysis of nuclear ribosomal (internal transcribed spacer 2, ITS2) and mitochondrial (open reading frame) loci were combined with population genetic data (seven microsatellite loci) for Pocillopora samples collected throughout the Indo-Pacific, Red Sea and Arabian Gulf, in order to assess the evolutionary divergence, reproductive isolation, frequency of hybridization and geographical distributions of the genus.Results: Between five and eight genetically distinct lineages comparable to species were identified with minimal or no hybridization between them. Colony morphology was generally incongruent with genetics across the full range of sampling, and the total number of species is apparently consistent with lower estimates from competing morphologically based hypotheses (about seven or eight taxa). The most commonly occurring genetic lineages were widely distributed and exhibited high dispersal and gene flow, factors that have probably minimized allopatric speciation. Uniquely among scleractinian genera, this genus contains a monophyletic group of broadcast spawners that evolved recently from an ancestral brooder.Main conclusions: The delineation of species diversity guided by genetics fundamentally advances our understanding of Pocillopora geographical distributions, ecology and evolution. Because traditional diagnostic features of colony and branch morphology are proving to be of limited utility, the identification of Pocillopora species for future ecological and experimental work should rely on genetic characters that will improve research and aid in conservation strategies for these and other reef-building corals, including the detection of real and mistaken endemic populations

Blind to morphology: genetics identifies several widespread ecologically common species and few endemics among Indo-Pacific cauliflower corals (Pocillopora, Scleractinia)

ABSTRACT Aim 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 nearly featureless microskeletal structures confound taxonomic assignments and limit an understanding of their ecology and evolution. Location Indo-Pacific, Red Sea, Arabian/Persian Gulf. Methods Sequence analysis of nuclear ribosomal (internal transcribed spacer 2, ITS2) and mitochondrial (open reading frame) loci were combined with population genetic data (seven microsatellite loci) for Pocillopora samples collected throughout the Indo-Pacific, Red Sea and Arabian Gulf, in order to assess the evolutionary divergence, reproductive isolation, frequency of hybridization and geographical distributions of the genus. Results Between five and eight genetically distinct lineages comparable to species were identified with minimal or no hybridization between them. Colony morphology was generally incongruent with genetics across the full range of sampling, and the total number of species is apparently consistent with lower estimates from competing morphologically based hypotheses (about seven or eight taxa). The most commonly occurring genetic lineages were widely distributed and exhibited high dispersal and gene flow, factors that have probably minimized allopatric speciation. Uniquely among scleractinian genera, this genus contains a monophyletic group of broadcast spawners that evolved recently from an ancestral brooder. Main conclusions The delineation of species diversity guided by genetics fundamentally advances our understanding of Pocillopora geographical distributions, ecology and evolution. Because traditional diagnostic features of colony and branch morphology are proving to be of limited utility, the identification of Pocillopora species for future ecological and experimental work should rely on genetic characters that will improve research and aid in conservation strategies for these and other reef-building corals, including the detection of real and mistaken endemic populations