Chlorophyll response and High Productivity Zone contraction in northern Perú during the 2017 Coastal El Niño

Mogollón R.; Espinoza-Morriberón D.; Velasquez O.; Yabar G.; Villena M.; Tam J. · Progress in Oceanography (2026) · DOI: 10.1016/j.pocean.2026.103679

Resumen

The 2017 Marine Heatwave event was characterized by significant positive sea surface temperature anomalies driven by weakened and reversed wind patterns, from mid-January to mid-April. The wind reversal during the Coastal El Niño favored downwelling processes, limiting the upward transport of nutrient-rich waters and causing a rapid collapse in surface phytoplankton biomass. Additionally, reduced latent heat flux and increased shortwave radiation further exacerbated surface warming. From February to March 2017, chlorophyll-a concentrations showed strong negative anomalies (more than −3 mg m−3), with the High Productive Zone (HPZ) contracting significantly, from 300 km offshore in January to nearly 25 km from the coast during this two-months period, while the total HPZ area decreased by up to 130,000 km2 in March, demonstrating a sharp decline in surface chlorophyll-a concentration. However, as physical drivers tend to return to typical seasonal values by April, upwelling resumed, positive chlorophyll-a anomalies emerged indicating a relatively rapid recovery of phytoplankton biomass, and the HPZ re-expanded toward climatological levels. These findings emphasize the sensitivity of the northern Peruvian marine ecosystem to short-term climate variability. Given the increasing frequency of these climatic events, understanding the physical drivers of ecosystem changes is critical for predicting future impacts and informing adaptive management strategies.

Instituciones: Universidad Ricardo Palma; Universidad Tecnológica del Perú