Peer Reviewed Journal Articles (Inter.) (FT)
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- ItemSustainable process to co‑synthesize nano carbon dots, nano hydroxyapatite and nano β‑dicalcium diphosphate from the fish scale(Springer, 2021-05-13)The conventional protocols for the extraction of biological hydroxyapatite employ the prior removal of organic material using severe chemical treatment, which quite often limit the purity and crystalline properties of synthesized hydroxyapatite. The present study describes a process to co-synthesize four high value nano products from scale of Labeo rohita, viz. nano carbon dots, nano hydroxyapatite, nano β-dicalcium diphosphate and nano carbon dot—hydroxyapatite composite. In the process, the organic matter in fish scale is converted to nano carbon dots by a hydrothermal process using acetic acid (1:1) and the mineral residue precipitated was converted to hydroxyapatite, following a sintering protocol. The acetic acid not only functioned as a medium to release the mineral—organic linkage but also acted as a base to hydrolyze the collagenous proteins linked with calcium phosphate in the fish scales. The hydrolyzed collagenous protein was in turn transformed into fluorescent nano carbon dots. β-Dicalcium diphosphate was seen attached over carbon dots, which was separated by crystallization followed by high temperature sintering. Hydroxyapatite: carbon dot composite was synthesized through a hydrothermal method. The spectral and morphological studies of the composite showed strong interaction between carbon dot and hydroxyapatite. All the synthesized materials were characterized using ultraviolet visible spectroscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, atomic force microscope, transmission electron microscope and electrochemical impedance techniques. The study proposes a sustainable method for the complete utilization of fish scale by converting into high value nano products
- ItemAssessment and refinement of CDOM retrieval methods for coastal waters in the South Eastern Arabian Sea(Springer, 2025-11-13)CDOM, an important ocean colour product, accounts for 90% of non-water UV absorption in the upper ocean. CDOM absorption triggers photochemical reactions resulting in the release of greenhouse gases and alters microbial bioavailability of organic matter. The three different approaches for retrieving adg(λ) from satellite data were validated using aCDOM(λ) generated from OC-CCIderived remote sensing reflectance (Rrs) and in situ measured aCDOM(λ). The multiple linear regression(MLR) model performed better than the two exponential decay models in quantifying CDOM in the UV region. The better performance of Rrs-based algorithms indicated that absorption-based algorithms need considerable improvement when compared to algorithms based on the combined absorption by detrital matter and CDOM (adg(λ)). As a result, the absorption-based algorithm was modified as the ASCDOM algorithm, which demonstrated improved retrieval at 275, 355, 38 and 412 nm for aCDOM(λ). The ASCDOM algorithm’s strong statistical performance highlights its accuracy in retrieving satellite products for water quality evaluations and ocean colour monitoring.
- ItemReproductive potential and stock status of the anadromous shad, Tenualosa ilisha (Hamilton, 1822): Implications for managing its declining fisheries in northern Bay of Bengal bordering India(Elsevier, 2021-03-20)The anadromous shad, Tenualosa ilisha is a fish of high economic importance in countries flanking the Bay of Bengal (BoB). Its fishery in the northern BoB bordering India and the associated Bhagirathi– Hooghly river system has been declining. Scientific explanations on the existing fishery management recommendations, especially the length at first maturity (Lm50), minimum legal size (MLS), minimum mesh size for fishing nets and stock status were limited, raising serious concerns on the sustainability of its fisheries. Through the examination of its reproductive cycle, using histological maturity identifiers, the Lm50 of males and females were redefined at 265 mm TL/ 1.0 year age and 305 mm TL/ 1.2 year age, respectively. The size-based fecundity, sex ratio and abundance revealed that females of 281–360 mm TL/ 1.0–1.6 year of age have maximum reproductive potential. In the catch, 45%– 65% of males and females were below Lm50. The temporal progression of mean length in the catch (MLC) and female length at maturity showed declining trend. Application of length-based indicators (LBI) and stock assessment models showed the fishery in near full exploitation, less optimal and undergoing multi-generation, indiscriminate, size-selective overfishing. The spawning stock biomass (SSB) has declined to 26.8% of the virgin SSB, while the yearly spawning potential ratio (SPR) ranged from 0.04 to 0.29, which is lower than the SPR threshold (0.3) suggested for sustaining a fishery. The species is both growth and recruitment overfished. Though the mean annual catch is marginally lower than the estimated maximum sustainable yield (MSY) of 32,953 t, any increase in fishing effort would further impact the SSB. Based on the results, a MLS of 360 mm TL, minimum mesh size of 110 mm for fishing gear and a precautionary annual catch limit of 30,000 t suggested for management, and the potential impact of implementing these on fishers’ catches discussed.
- ItemSeasonal Changes of the Major Fouling Organisms in Cochin Harbour(Ocean Research, 1998)Biofouling census in Cochin Harbour, the rank correlation coefficients between the members of the fouling community and their dependence on environmental perturbations are reported. The affinity/ coexistance between major taxa of foulers is examined by cluster analysis through coefficient of correlation . Maximum correlation is observed between polyzoans and tube-dwelling worms. Modiolus sp.. barnacles and oysters ranked next in their order of coexistence-. The higher fouling biomass observed is attributed to the profusion of species. their fastcr growth and attainment of sexual maturity at an early date in the tropics.
- ItemMicroplastics in the edible and inedible tissues of pelagic fishes sold for human consumption in Kerala, India(Elsevier, 2020)Microplastics in commercially important seafood species is an emerging area of food safety 9 concern. While there have been reports of plastic particles in the gastrointestinal tract of 10 several species, presence of microplastics in edible fish tissues has not yet been reported from 11 India. This study examined the presence of microplastics in the edible (muscle and skin) and 12 inedible (gill and viscera) tissues of nine commercially important pelagic fish species from 13 Kerala, India. A total of 163 particles consisting mainly of fragments (58%) were isolated. 14 Out of 270 fishes analysed (n = 30 per species), 41.1% of the fishes had microplastics in their nedible tissues while only 7% of fishes had microplastics in their edible tissues. The quantity of microplastics in inedible tissue was significantly larger in filter feeders than, that in visual 17 predators (p< 0.05). The average abundance of microplastics in edible tissues was 0.07 ± 0.26 items/fish (i.e., 0.005 ± 0.02 items/g) and was 0.53 ± 0.77 items/fish (i.e., 0.054 ± 0.098 items/g) in inedible tissues. The results suggest the possibility of human intake of microplastics by the consumption of pelagic fishes from this region, albeit in small quantities.