Satellite observations from the Indian Space Research Organisation have detected a significant decline in marine productivity in parts of the tropical Pacific Ocean as an El Niño event develops.

The observations point to a fall in chlorophyll-a levels, an important indicator of microscopic marine life in the ocean. Phytoplankton and other microscopic organisms form the foundation of marine food chains, making changes in their abundance an important indicator of changes in ocean ecosystems.

Scientists have linked the decline to changes in ocean-surface wind patterns associated with El Niño. The climate phenomenon can alter wind circulation, ocean temperatures and the movement of nutrients in the upper layers of the sea.

Under normal conditions, ocean currents and winds help bring nutrient-rich water towards the surface in several parts of the Pacific. This process supports the growth of phytoplankton and contributes to marine productivity.

Changes associated with El Niño can weaken this nutrient supply, affecting the conditions required for marine organisms to thrive.

Satellite-based observations provide scientists with an opportunity to monitor these changes over large areas of the ocean. Chlorophyll measurements obtained from space can help researchers track variations in marine productivity and study their relationship with changing ocean conditions.

The latest observations highlight the value of Earth-observation satellites not only for land monitoring but also for studying the health of marine ecosystems.

Changes in ocean productivity can have wider implications because marine ecosystems support fisheries and play an important role in the global carbon cycle.

Continuous satellite monitoring can therefore help scientists understand how major climate patterns such as El Niño influence ocean ecosystems.

The findings also demonstrate the growing role of Indian space-based observations in monitoring environmental changes and improving understanding of large-scale climate processes.