Environment & Ecology : Ecology And Functions Of An Ecosystem
UPSC CSE Prelims 2025
Statement 2 is correct. Marine phytoplankton and photosynthetic bacteria are significant contributors to global oxygen production, accounting for approximately 50% of the world's oxygen. Organisms such as Prochlorococcus, a type of marine cyanobacterium, are particularly important, contributing a substantial portion of this total.
Statement 1 is incorrect. While tropical rainforests are vital for oxygen production, oceans collectively produce more oxygen than rainforests. Marine organisms, including phytoplankton, algae, and photosynthetic bacteria, are the primary producers of atmospheric oxygen, contributing a greater share to the global oxygen budget.
Statement 3 is incorrect. Well-oxygenated surface water contains significantly less dissolved oxygen compared to atmospheric air. For instance, typical dissolved oxygen levels in well-oxygenated surface water are around 8 mg O₂/L, whereas atmospheric air contains approximately 210 mg O₂/L. Therefore, surface water does not contain several folds higher oxygen; rather, it contains substantially less.