How El Niño Alters Marine Life in the Pacific

• Official onset of El Niño in June 2026 is driving warmer-than-normal sea surface temperatures and disrupting oceanic circulation in the equatorial Pacific.
• Data from NASA’s PACE satellite shows a significant decline in chlorophyll-a concentrations, a key indicator of phytoplankton abundance, compared to neutral conditions in 2025.
• The reduction in phytoplankton is triggering ripple effects throughout the marine food web, leading to fishery closures and ecological distress in coastal regions like Peru.

Mechanisms of Phytoplankton Decline

• El Niño weakens equatorial trade winds, allowing the ocean's warm surface layer to extend deeper.
• This process suppresses the upwelling of cool, nutrient-rich water that is essential for fueling phytoplankton growth.
• Scientists expect these regional declines to intensify as the current El Niño event continues to strengthen.

Ecological and Economic Consequences

• The scarcity of phytoplankton reduces food supplies for zooplankton, fish, seabirds, and marine mammals.
• Peru’s Ministry of Production has repeatedly suspended anchovy fishing to protect the local industry as populations decline.
• Observed wildlife behavior, such as pelicans venturing into urban ports for food, highlights the severity of the habitat disruption.

Advancements in Satellite Monitoring

• The PACE mission, launched in February 2024, is providing the first global, near-daily hyperspectral measurements of an entire El Niño event.
• Researchers are utilizing this data to monitor the response of specific phytoplankton communities and to study broader climate impacts on atmospheric aerosols and land-based vegetation.