The West Antarctic Peninsula (WAP) provides an ideal natural laboratory to observe how climate change will alter biophysical interactions in the upper ocean. Namely, the coastal WAP exhibits some of the most rapid warming on Earth, headlined by accelerated melting of glaciers and profound disturbance of seasonal sea ice cycles. These changes are in turn associated with distinct, cascading perturbations throughout the food web from algae to penguins. Using two decades of time series data collected by the Palmer Long Term Ecological Research (LTER) program, we assessed if there were any trended changes in the photobiology and growth of phytoplankton communities associated with interdecadal change in the WAP. Our findings reveal a distinct, ecosystem-wide shift in algal photobiology, with a significant increase in the proportion of accessory pigments over 25 years. Most notably, we quantified a near doubling of photoprotective carotenoids in the algal community since 1995, coincident with a shoaling of surface ocean mixed layer depths and a boost in algal biomass and productivity. Our time series shows a persistent shallowing of the upper mixed layer that is accompanied by widespread photoacclimation of the resident phytoplankton communities towards a more high-light adapted state. This implies a beneficial shift in the prevailing biophysical conditions of the region, likely with far-reaching implications for the ecosystem’s biogeochemical function, and supports other studies that suggest light limitation as a primary driver of primary productivity in this region.

Primary Presenter: Quintin Diou-Cass, Rutgers University (qpd1@marine.rutgers.edu)

Authors:

Quintin Diou-Cass, Rutgers University, Center for Ocean Observing Leadership (RUCOOL), Department of Marine and Coastal Sciences  (qpd1@marine.rutgers.edu)

Nicole Waite, Rutgers University, Center for Ocean Observing Leadership (RUCOOL), Department of Marine and Coastal Sciences  (waite@marine.rutgers.edu)

Oscar Schofield, Rutgers University, Center for Ocean Observing Leadership (RUCOOL), Department of Marine and Coastal Sciences  (oscar@marine.rutgers.edu)