Because of the strong monsoon winds, the western Indian Ocean has one of the highest concentrations of phytoplankton blooms among tropical oceans in summer. Monsoonal wind forcing causes strong coastal and open ocean upwelling, which delivers nutrients into upper zones with enough light for photosynthesis and phytoplankton formation.
These phytoplankton blooms benefit the marine ecosystem by serving as the foundation of the marine food chain and, eventually, larger fish species. The Indian Ocean has the second-highest proportion of the most economically valuable tuna catch. Its fish are very important to the neighboring countries for both internal consumption and export. Russian, Japanese, South Korean, and Taiwanese fishing boats also fish in the Indian Ocean, primarily for shrimp and tuna. According to research, rising ocean temperatures are wreaking havoc on the marine ecosystem.
According to a study on phytoplankton changes in the Indian Ocean, marine plankton in the Indian Ocean has declined by up to 20% over the last six decades. Tuna harvest rates have similarly plummeted 50-90% over the last half-century, owing primarily to growing commercial fishing, with ocean warming adding further stress to the fish species.
The most prolific ecosystems in the Indian Ocean include coral reefs, seagrass beds, and mangrove forests. Coastal areas yield 20 tons of fish every square kilometer. However, these places are also becoming more urbanized, with populations typically topping several thousand people per square kilometer, and fishing practices becoming more successful and often damaging beyond sustainable levels, as sea surface temperature rises and coral bleaching spreads.