Biometrical Study Of Brine Shrimp (Artemia franciscana) With Special Emphasis On Hatching Efficiency And Hatching Percentage In Tropical Condition At Bangladesh

The present study was carried out to investigate the hatching efficiency and hatching percentage of untreated and decapsulated cysts of Artemia franciscana at three salinities; 30 ppt, 35 ppt and 40 ppt. This study revealed that the hatching efficiency and hatching percentage were higher in case of decapsulated cysts. First hatching of nauplius from cysts were observed after 14 hours and 13 hours of incubation for untreated and decapsulated cysts, respectively. The values of hatching efficiency and hatching percentage were also higher at 35 ppt in untreated and decapsulated cysts. At 35 ppt, the hatching efficiency after 48 hours of incubation was 1.42× 105 for decapsulated cysts and the value for untreated cysts was 8.96× 104 nauplii per gram cysts. After 96 hours of incubation, the hatching percentage for decapsulated cysts were 75%, 89% and 90% at 30 ppt, 35 ppt and 40 ppt, respectively; and the values were 55%, 62.5% and 60% for untreated cysts at respected salinities, 30 ppt, 35 ppt and 40 ppt. The mean diameter for untreated and chorionic cysts were 242.2±1.90 µm and 213.5±3.167 µm respectively, with a chorionic thickness of 14.35 µm. This study would help the hatchery managers to understand the efficiency of larval live feed, since adequate data are lacking on the hatching performances of Artemia cysts in Bangladesh

A rapid survey of herpetofaunal diversity in Nijhum Dwip National Park, Bangladesh

The ecological effects of habitat use by herpetofaunal species vary widely and recognizing relative habitat value will help to improve conservation theory and practice in a particular landscape. To understand how different habitat uses influence diversity in riparian landscapes, we studied reptile and amphibian assemblages across major habitats (agricultural land, forest, human habitation, and waterbodies) in Nijhum Dwip National Park, Bangladesh. A total of 35 herpetofaunal species were found; among them, 17 were directly observed and 18 were reported from a questionnaire survey. Among the observed species, the Asian Common Toad Duttaphrynus melanostictus was the most commonly seen (relative abundance 0.32). We found that forest habitat contained a greater diversity of herpetofauna than other habitats followed by agricultural land, human habitation, and waterbodies. We also found 8 habitat specialist species and 9 generalist species in this study. Our results show that different habitats support different species assemblages in Nijhum Dwip National Park, signifying the importance of diversified habitats for the herpetofaunal population. Understanding this importance is crucial for identifying matrix environments that can complement the forest habitats of sensitive as well as specialist herpetofaunal species

Surveillance of Vibrio spp. in Penaeus monodon Collected from Shrimp Pond of Satkhira, Bangladesh

Vibrio is the most common genera associated with crustaceans and often causing significant economic losses. Many Vibrio species are pathogenic to human and have been implicated in food borne diseases. The present study was conducted to identify Vibrio spp. from the tiger shrimp (Penaeus monodon) of shrimp pond at Satkhira, Bangladesh. A total number of 33 Vibrio species isolates were identified from 20 shrimp samples through a series of morphological, physiological and biochemical tests. The work reports the prevalence of Vibrio spp. in the pond environments and the existence of three Vibrio species such as V. alginolyticus, V. parahaemolyticus and V. harveyi were identified. In the study of antibiogram, all isolates were shown 100% sensitive to streptomycin, ciprofloxacin and chloramphenicol. Maximum 41% isolates were shown resistant to co-trimethaxozole whereas 30% and 24% resistant to azithromycin and novobiocin respectively

Three dispersal routes out of Africa: A puzzling biogeographical history in freshwater planarians

Aim Freshwater planarians may have a wide geographical range despite their assumed low vagility. Found across four continents, Dugesia may have either an ancient origin on a large palaeo landmass, followed by colonisation in different regions before continental fragmentation, or a more recent origin and subsequent transoceanic dispersal. We seek to resolve between these two hypotheses. Location Africa, Eurasia and Australasia. Taxon Genus Dugesia (Platyhelminthes: Tricladida: Dugesiidae). Methods We used data from the sequencing of six gene fragments and comprehensive taxonomic sampling of Dugesia from across its distribution range to reconstruct the phylogeny of this genus using maximum likelihood and bayesian inference methods. We conducted two phylogenetic dating analyses using Platyhelminthes fossils and palaeogeological events. Basing on the time-calibrated molecular phylogenetic framework we evaluated the contribution of vicariance and dispersal to the biogeographical evolution of Dugesia. By reconstructing the ancestral areas and present-day potential distribution using BioGeoBEARS and niche modelling, we elucidated the biogeographical history of the genus. Results The present-day distribution of Dugesia is a result of different vicariance and dispersal events. However, we also found evidence of transoceanic dispersal. Consistent with previous hypotheses, Dugesia dates to the Upper Jurassic in the Afro-Malagasy Gondwana region. We unveiled a novel biogeographical scenario for the genus, involving multiple events of colonisation in Eurasia from continental Africa via at least three dispersal routes. Main conclusions Dugesia is an ancient genus having reached its present distribution through a complex history of dispersal and vicariant events following its origin in southern Gondwana. Despite the low vagility of Dugesia, we found evidence of their overseas dispersal

Genome of Tenualosa ilisha from the river Padma, Bangladesh

Abstract Objective Hilsa shad (Tenualosa ilisha), is a popular fish of Bangladesh belonging to the Clupeidae family. An anadromous species, like the salmon and many other migratory fish, it is a unique species that lives in the sea and travels to freshwater rivers for spawning. During its entire life, Tenualosa ilisha migrates both from sea to freshwater and vice versa. Data description The genome of Tenualosa ilisha collected from the river Padma of Rajshahi, Bangladesh has been sequenced and its de novo hybrid assembly and structural annotations are being reported here. Illumina and PacBio sequencing platforms were used for high depth sequencing and the draft genome assembly was found to be 816 MB with N50 size of 188 kb. MAKER gene annotation tool predicted 31,254 gene models. Benchmarking Universal Single-Copy Orthologs refer 95% completeness of the assembled genome