Signals of selection in the mitogenome provide insights into adaptation mechanisms in heterogeneous habitats in a widely distributed pelagic fish – Nature Scientific Reports (2020)
Indian oil sardine (Sardinella longiceps) is a widely distributed pelagic species in the Indian Ocean exhibiting wide fluctuations in landings. We investigated the molecular mechanisms of adaptation of Indian oil sardine to wide environmental clines to understand the potential for resilience in this species in the present scenario of climate change. Signals of diversifying selection indicating adaptive capacity were observed in key functional regions involved in oxidative phosphorylation pathway of the mitochondrial genome. These changes were more prevalent in South Eastern Arabian Sea (SEAS), which is one of the most dynamic seas due to fluctuations in productivity, temperature and dissolved oxygen. Northern Arabian Sea (NAS) populations also exhibited selective mutations albeit at a lower level than South East Arabian sea populations and these mutations were rare in Bay of Bengal (BoB) Populations. The present study provided evidence for the presence of locally adapted populations in the Indian oil sardines. The study also provided insights into the excellent adaptive capacity and resilience of this species to climatic fluctuations and the mechanisms by which pelagic species thrive in the changing oceans. The most resilient populations were observed in the SEAS which encompasses the Malabar upwelling zone, a historically productive region for the Indian oil sardine. The locally adapted populations with specific mutations can be monitored over space and time to understand climate change impacts and to devise management measures. Management measures can be implemented at a zonal level considering that SEAS populations are the most diverse followed by NAS and BoB populations.
This study is the outcome of a fruitful collaboration between ICAR-Central Marine Fisheries Research Institute (CMFRI) and CSIR-National Institute of Oceanography (NIO).
The rich diversity of marine macroalgae and their associated bacterial flora represent a potential reservoir of bioactive compounds with valuable biotechnological and pharmaceutical use. Heterotrophic bacteria associated with the intertidal macroalgae were isolated and evaluated for their pharmacological properties using various in vitro models. Among 148 cultivable isolates, more than 50% were dominated by ?-Proteobacteria and Firmicutes, wherein 53 of them showed consistent antibacterial activity against a broad spectrum of clinically significant pathogens. The bacteria were characterized by extensive microbiological, molecular and chemical identification tools. The heterotrophs Bacillus amyloliquefaciens MTCC 12716 and Shewanella algae MTCC 12715 isolated from a red marine macroalga Hypnea valentiae exhibited potential anti-infective properties against multidrug-resistant pathogens, such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecalis (minimum inhibitory concentration of 6.25–12.5 µg/mL). The organic extract of B. amyloliquefaciens displayed significantly greater antioxidative properties (IC90?<?1 mg/mL) and the activities showed considerable positive correlation (r2?>?0.8, P?<?0.05) with the inhibitory activities against angiotensin converting enzyme-I, pro-inflammatory cyclooxygenases and 5-lipoxygenase, dipeptidyl peptidase-4 and hydroxymethylglutaryl coenzyme A reductase, which were associated with hypertension, inflammation, diabetes, and hypercholesterolemia, respectively. The applications of nuclear magnetic resonance-based fingerprinting to analyze the characteristic signals in the solvent extracts and to correlate them with the pharmaceutical properties were underlined. The heterotrophic bacterium B. amyloliquefaciens MTCC 12716 might, therefore, serve as a potential therapeutic candidate to develop products with wide pharmaceutical applications.
The study was aimed to investigate the relationship between various morphometric measurements and meristic counts and to establish the length-weight relationships (LWRs) and length-length relationships (LLRs) of flat needlefish Ablennes hians (Valenciennes, 1846) that were collected from longline fisheries in the south-eastern Arabian Sea between October 2015 and August 2017. Twenty-two morphometric measurements and four meristic counts of 173 specimens were examined for biometric analysis, and 350 specimens (45-122 cm TL, 90-2585 g TW) were analyzed for studying LWRs. Morphometric variables showed a significant correlation between the variables with the highest observed correlation between SL, FL and TL (r > 0.99). The descriptive statistics for all the meristic counts were found within the range provided by the earlier authors. A differential relative growth was observed across morphometric characters. Strong positive allometry was recorded for pectoral fin length, the height of dorsal and anal fin and pre-ventral length, whereas pronounced negative allometry was evident in case of morphometric variables from the head region. The LWRs showed similar growth pattern for male (b = 3.447) and female (b = 3.299) individuals. Therefore, the LWR was expressed for pooled data as W = 0.000321L3.312 (R2 = 0.929, p < 0.001).
A single specimen of longspine grouper was collected at a depth of 30–40 m by a single day trawler from the waters of Gujarat. The species is considered as ‘least concern’ by IUCN. The fish was examined for key morphometric and meristic characters such as body length and depth, head length, fin lengths, spine and rays counts, lateral line scale count, gill rakers count, shape and distribution pattern of spots on the body. The present study reports the first record of the species from north-west coast of India describing its extension of geographical distribution and addition of one more species to the biodiversity of Gujarat.
Pomfrets (Genus Pampus) are commercially important fish in the Indo-Pacific region. The systematics of this genus is complicated because of morphological similarities between species. The silver pomfret from Indian waters has long been considered to be Pampus argenteus. Morphological and molecular examination of specimens from the Arabian Sea and Bay of Bengal regions suggested the silver pomfret from the region represents two species that are distinct both from each other and from P. argenteus from the South China Sea. Based on detailed morphological, meristic and molecular examinations, the most common species from the Indian Ocean was found to correspond with the descriptions of Stromateus candidus (Cuvier), which is resurrected from the synonymy of P. argenteus and redescribed here as Pampus candidus (new combination). The second species, which has restricted distribution in Indian waters needs further studies to arrive at taxonomic conclusions and is hence not described in the current study. Lectotypes are also designated for Pampus candidus.
Vulnerability assessment frameworks are used in many countries to provide a primary assessment status of marine fish stocks and their susceptibility to change in response to external factors. With increasing evidence that the marine fisheries of India are likely to face major impacts of changing climate along with other natural and anthropogenic factors, a study was carried out to determine the relative vulnerability of 68 species of finfish and shellfish along the Indian coast. Species selection was based on their abundance and importance in the fishery across 4 zones in the country (northeast, northwest, southeast and southwest) and on biological characteristics like growth, reproduction and predator–prey interactions. Vulnerability assessment was based on the relation between exposure, sensitivity and adaptability attributes, expressed as V = (E + S) ? A. The exposure attributes selected were environmental parameters that have a direct impact on the fish stocks. Sensitivity attributes were biological characteristics that are indicative of the ability or inability of the species to respond to external pressures. Adaptive capacity attributes were biological and ecological traits that could help the species to adapt to a fluctuating or changing environment. About 69% of the species studied are highly vulnerable along the Indian coast, with their susceptibility being higher along the east coast. Fishing pressure contributes significantly to stock fluctuations and reproductive output. Species with restricted geographic distribution are especially vulnerable to climate change. The outcome of this study will serve as an effective tool in prioritizing mitigation and fishery management strategies on a regional basis in the country.