Resilience of Sentinel Diatom Species in Crude-Oil-Rich Marine Environment: A Simulation Study

Diatoms, a type of photosynthetic microalgae, play a crucial role in carbon fixation, accounting for approximately 40% of global carbon sequestration. They respond rapidly to environmental perturbations, making them critical indicators of dynamic marine ecosystems that are often impacted by crude oil contamination. This study aims to assess the resilience of diatom species under crude oil stress. We modelled six-member diatom consortia enriched from oil-contaminated regions of the Cambay basin, Gujarat, India. We exposed them to crude oil (500, 750, 1000 ppm), as well as nitrate (N) and phosphate (P) stress, over 30 days. Results indicated a decline in cell numbers and chlorophyll levels, accompanied by the rapid formation of lipid droplets (LDs). Chaetoceros gracilis, Surirella librile and Halamphora coffeaeformis showed robust resilience, surviving at 750 ppm, while no species thrived at 1000 ppm. Notably, LD formation emerged in S. librile, C. gracilis, H. coffeaeformis, and Navicula rostellata. Identifying them as tolerant and sensitive sentinel species could help earmark them as bioindicators for crude oil pollution and select species for ecological restoration in contaminated marine environments.