Li, J., A. J. Miller, D. J. Amaya, Q. Wang, P. Li, Y. Gu and P. Bai, 2025:
Vertical structure of chlorophyll-a during Marine Heatwaves in the California Current Ecosystem.
Communications Earth & Environment, in press.
Abstract. In the past decades, the California Current Ecosystem has experienced
intense marine heatwaves, which have induced significant disruptions to local phytoplankton communities.
Here, using 30-year cruise observations, we identify a previously undocumented vertical structure
in chlorophyll-a concentration response to marine heatwaves, characterized by reductions in the
surface layer coupled with increases in the subsurface. By integrating observations and coupled
physical-biogeochemical model products, we demonstrate that declines of surface chlorophyll-a are
primarily attributed to suppressed nutrient upwelled to the upper ocean. Although surface irradiance
increased modestly (+3.5%), light availability in the subsurface layer improved substantially (+21.7%)
due to reduced phytoplankton shading at the surface. Concurrent with enhanced lateral nutrient
transport, phytoplankton growth at depth was promoted during heatwave events. This study highlights
the pivotal role of subsurface phytoplankton dynamics in shaping the vertical chlorophyll-a
concentration structure and its variability under extreme events.
Preprint (pdf)