Physiological and ecological responses of Arctic phytoplankton to changing ocean conditions

The Arctic Ocean is changing rapidly, with less sea ice and warmer temperatures than in the past. Tiny microscopic algae called phytoplankton form the foundation of Arctic marine food webs. Their responses to these changes will influence the future of the Arctic Ocean, from marine nutrient cycling and carbon uptake to the productivity of ecosystems and fisheries. This project will study a unique collection of living Arctic phytoplankton gathered during a recent polar expedition to identify the species it contains and determine how they respond to environmental stress and competition from species moving northward from warmer waters. The project will create the largest publicly available collection of living Arctic phytoplankton in the U.S., develop K-12 educational materials about the Arctic, and provide interdisciplinary training for engineering students in biology to enhance the STEM workforce. Declining sea ice, warmer surface waters, and shifting seasonal light availability are changing the physical environment of the Arctic Ocean. At the same time, the Arctic’s extreme variation in photoperiod remains unchanged, creating environmental conditions unlike those found elsewhere. This project will test whether Arctic phytoplankton are more robust to changing environmental conditions than expected because of their specialized adaptations to cold temperatures and extreme light variation, or whether competition with sub-Arctic taxa will ultimately constrain their ability to persist. The investigators will first characterize the species composition and biogeographic distribution of previously collected Arctic phytoplankton, using molecular methods and metabarcoding, while contributing cultures to a national repository. They will then quantify responses of representative Arctic species to temperature, light, photoperiod, and combinations of these factors through controlled laboratory experiments measuring growth and physiology. These data will be used to develop mechanistic models that predict species responses to multiple environmental drivers. Predictions will be evaluated against observed species distributions in the Arctic. Finally, the investigators will study whether sub-Arctic taxa might outcompete Arctic species, despite their potentially unique adaptations. Together, these activities will improve understanding of how Arctic marine ecosystems respond to changing ocean conditions, strengthening the scientific foundation for managing living marine resources and anticipating future changes in the Arctic. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.