In the context of ecosystem productivity, marine upwelling zones are important as they increase the marine productivity by bringing the 1) Decomposer microorganisms to the surface 2) Nutrients to the surface. 3) bottom-dwelling organisms to the surface. Which of the statements given above is/are correct?

Upwelling is the rise of cold, nutrient-rich deep water into the sunlit surface layer. It happens when offshore winds push surface water away from the coast (Ekman transport), as off Peru, northwest Africa and the Somali-Arabian coast during the summer monsoon. Deep water carries nitrates and phosphates from the decomposition of sinking organic matter, but phytoplankton cannot use them without light. Once they reach the surface, phytoplankton bloom and the food chain above them expands. So only statement 2 is correct, which makes the answer B.

Core concept: primary productivity in the photic zone is limited by nutrient supply, and upwelling is the physical process that removes that limit. This connects to fisheries and to the monsoon-linked upwelling along the Indian coasts, a useful Mains link to coastal livelihoods.

• Statement 1 is wrong: decomposers are mainly bacteria and fungi concentrated in sediments and deeper waters. Upwelling is not a mechanism for bringing them up to boost productivity.
• Statement 3 is wrong: upwelling moves water masses, not bottom-dwelling organisms as a defining process. Benthic communities largely stay on the seabed.

Trap: choosing A because statement 1 sounds ecologically plausible. The question asks what upwelling actually supplies to raise productivity, and the direct answer is nutrients.