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Comparison of vegetation indices derived from a consumer-grade UAV and the Google Earth Engine platform for seasonal mangrove canopy assessment

Sun, 01 Jun 2025 00:00:00 GMT

Title: Comparison of vegetation indices derived from a consumer-grade UAV and the Google Earth Engine platform for seasonal mangrove canopy assessment Authors: Valderrama-Landerosa, L; Flores-de-Santiago, F; Rodríguez-Sobreyra, R; Flores-Verdugo, F Abstract: Mangrove forests, though classified as evergreen vegetation, exhibit substantial year-round litterfall, necessitating species-level phenological understanding for accurate remote sensing classification. This study compared monthly phenological variations across four mangrove classes viz., red (Rhizophora mangle), white (Laguncularia racemosa), and black mangrove (Avicennia germinans) in both shrub and fringe conditions, using consumer-grade UAV data and Sentinel-2 imagery from Google Earth Engine (GEE) over a 15-month period. Visible (RGB) data from UAV orthomosaics and Sentinel-2 were analysed using four RGB-vegetation indices, revealing similar temporal trends between platforms, though with consistently lower intensity values in UAV-derived data. Notably, the weakest correlations occurred in Rhizophora mangle and the shrub Avicennia germinans classes. These findings demonstrate UAVs´ potential for high-resolution phenological monitoring where spaceborne sensors lack sufficient resolution, while highlighting species-specific limitations for mangrove forest assessments. Page(s): 277-284

Occurrence of neoplastic lesion in spotted catfish (Arius maculatus Thunberg, 1792) from the estuarine environment, southeast coast of India

Sun, 01 Jun 2025 00:00:00 GMT

Title: Occurrence of neoplastic lesion in spotted catfish (Arius maculatus Thunberg, 1792) from the estuarine environment, southeast coast of India Authors: Koothan, V; Gopalakrishnan, A Abstract: Present study reports the neoplastic lesions in Arius maculatus (Spotted catfish), widely distributed species across the coastal waters of India, a phenomenon previously underreported for this species. A wild adult female Arius maculatus from the Vellar estuary, India, was found with a significant tumor. The gross morphology revealed a mass of fleshy, tumorous outgrowth located ventrally near the mandibular region, measuring approximately 2.5 cm × 2.6 cm × 2 cm, and presenting as an irregular, reddish-white. Comprehensive pathological examination, including histological analysis, revealed that the tumour exhibited aggregated eosinophils and anucleated inflammatory cells in areas of necrosis. Notably, no metastasis was detected, and no internal organs showed abnormalities. This report concludes that this is the first case documenting neoplastic lesions in Arius maculatus, histopathologically diagnosed as eosinophilic coagulative necrosis that may arise from tissue damage, contributing to the understanding of fish pathology and highlighting the need for further research to elucidate the environmental or genetic factors influencing tumour development in this species. Page(s): 285-292

Effect of offset hooks on catching efficiency and hooking positions of carangids, evidence from the Gulf of Mannar, India

Sun, 01 Jun 2025 00:00:00 GMT

Title: Effect of offset hooks on catching efficiency and hooking positions of carangids, evidence from the Gulf of Mannar, India Authors: Vasanth, K; Kalaiarasan, M; Madhavan, N; Venkata Sai, J; Gnanendra, V Abstract: The efficiency of different shapes of J hooks number 8 (non-offset straight hook, 10° offset kirbed hook, and 10° offset reversed hook) in Carangids longline fishing gears was studied in 15 fishing grounds in the Gulf of Mannar, India, from April to August 2022. For the comparative study, a total of 15 fishing trips were conducted for each experimental gear with a total effort of 6,750 hooks, resulting in a total catch of 176 fishes during the study. Amidst the hook shapes, the kirbed hook had the highest percentage composition of the carangids (43.75 %), followed by the reversed hook (30.68 %), and the straight hook (25.57 %). Furthermore, the overall hooking rate was higher for the kirbed hook than for the straight hook (5.1 % vs. 3 %). Considering the catch rate, the overall Catch Per Unit Effort (CPUE; individual/150 hooks) of the kirbed hook was higher (6.4 vs. 3.75) than that of the straight hook. The percentage of hooking position in the jaw was higher in the kirbed hook than that of the straight hook (55.84 % vs. 37.78 %) and was found to be lower in the gut system (14.29 % vs. 28.89 %). Among the three hook shapes tested, the overall performance of the 10° offset kirbed hook was found to be better than the other 10° offset reversed and non-offset J hook in terms of a catch efficiency, hooking rate, CPUE, and hooking position for carangids (< 0.05). Page(s): 293-299

New insights into the biochemical composition of estuarine diatom Halamphora sp. isolated from Munambam-Azheekode Estuary, Kerala, India

Sun, 01 Jun 2025 00:00:00 GMT

Title: New insights into the biochemical composition of estuarine diatom Halamphora sp. isolated from Munambam-Azheekode Estuary, Kerala, India Authors: S Lidiya, V; Aswathi, N; S Navaneeth, K; Adithya, V; Megha, S; G Sanilkumar, M Abstract: Halamphora sp., an amphoroid diatom, collected and isolated from the Munambam-Azheekode Estuary within the Vembanad-Kol, Ramsar site of India’s Kerala state. The biochemical composition of Halamphora sp. is depicted with special reference to salinity changes (10, 20, 30, and 40 psu) at two culture stages. The highest growth rate and maximum cell density occurred at 30 psu. Lower salinities promoted higher protein and carbohydrate content during the stationary phase, while lipid production was higher in the log phase at lower salinities. Notable amounts of short, medium, and long-chain fatty acids, with C20:5 and C22:6 being particularly prominent, along with increased levels of C18:3n3 Polyunsaturated Fatty Acids (PUFAs). The findings recommend that 30 psu provides optimal growth and nutritional composition for Halamphora sp. in various industrial applications, especially in the production of biodiesel and aquaculture feeds. Page(s): 300-304