Dynamics of environmental variables during the incidence of algal bloom in the coastal waters of Gujarat along the northeastern Arabian Sea

• Published in: Environmental monitoring and assessment Vol. 195; no. 10; p. 1238
• Main Authors: Vase, Vinaya Kumar, Raman, Mini, Sahay, Arvind, R., Shikha, K., Rajan, K.R., Sreenath, Dash, Gyanaranjan, J., Jayasankar, Rohit, Prathibha, R., Ratheesh Kumar
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.10.2023; Springer Nature B.V
• Subjects: Algae; Algal blooms; Anaerobic microorganisms; Atmospheric Protection/Air Quality Control/Air Pollution; Biodegradation; Biogeochemistry; Biology; Chlorophyll; Chlorophyll a; Climate change; Coastal waters; Coasts; Colour; Correlation; Dissolved oxygen; Earth and Environmental Science; Ecology; Ecotoxicology; Environment; Environmental Management; Environmental monitoring; Fisheries; Fishery resources; Food chains; Locations (working); Marine biology; Marine fish; Marine fisheries; Mathematical analysis; Microorganisms; Monitoring/Environmental Analysis; Nitrates; Nutrient dynamics; Nutrients; Ocean color; Oceanography; Oceans; Organic matter; Oxygen; Phosphates; Plankton; Remote sensing; Salinity; Trichomes; Variability; Variables; Northeastern Arabian Sea, NEAS; Nutrients; Multivariate analysis; Chl
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-023-11827-0

The dynamics of physico-chemical, nutrient, and chlorophyll- a variables were studied in the bloom and non-bloom locations along the off-Gujarat coastal waters to understand the variability in biogeochemistry using multivariate analytical tests. The dissolved oxygen was significantly lower in the bloom stations (3.89 ± 0.44 mgL −1 ) than in the non-bloom stations (5.50 ± 0.70 mg L −1 ), due to the biological degradation of organic matter in addition to anaerobic microbial respiration. Nutrients (PO 4 and NO 3 ) and Chl- a concentrations were recorded higher in the bloom locations at 0.83 ± 0.21 µmol L −1 , 4.47 ± 0.69 µmol L −1 , 4.14 ± 1.49 mg m −3 , respectively. PO 4 and NO 3 have shown a significantly higher positive correlation of r  = 0.73 and r  = 0.69 with Chl- a for bloom data than the non-bloom data. The percentage variance contributed by PC1 and PC2 for both bloom and non-bloom locations were estimated at 52.33%. The variable PO 4 explains the highest 24.19% variability in PC1, followed by Chl- a (19.89%). The PO 4 triggers the bloom formation and also correlates to the higher concentrations of Chl- a in the bloom locations. The bloom concentration ranges from 9553 to 12,235 trichomes L −1 . The bloom intensity has shown a significant positive correlation with Chl- a ( r  = 0.77), NO 3 ( r  = 0.56), and PO 4 ( r  = 0.30), but a negative correlation was noticed with DO ( r  =  − 0.63) and pH ( r  =  − 0.49). The study also initiates a way forward research investigation on ocean-color technologies to identify and monitor blooms and climate change–driven factors for bloom formation. The occurrence of bloom and its influence on fishery resources and other marine biotas will open many research windows in marine fisheries, oceanography, remote sensing, marine biology, and trophodynamics.