MIT Study Finds Polar Phytoplankton Shifting to More Carbohydrates and Less Protein Amid Climate Change

Phytoplankton, microscopic algae that form the foundation of the marine food web, are undergoing compositional changes in response to warming ocean conditions, according to a study by researchers at the Massachusetts Institute of Technology (MIT). The study, led by Shlomit Sharoni and Mick Follows, combines a predictive model with 40 years of observational data from polar seas.

It indicates that rising sea surface temperatures and melting polar ice are prompting these organisms to allocate more carbon toward carbohydrates and lipids, while reducing protein production.

Phytoplankton perform photosynthesis near the ocean's surface, absorbing sunlight and nutrients like nitrogen to generate energy. They serve as the primary food source for zooplankton, krill, jellyfish, and larger marine animals, ultimately supporting fisheries and human consumption of seafood.

In polar regions, where light levels are lower and nutrients are abundant, the algae historically prioritize protein synthesis to capture available light efficiently.

The MIT research, published in the journal Nature Climate Change, documents a measured decline in protein content among polar phytoplankton. This empirical evidence aligns with the model's predictions, showing that under warmer conditions, the algae adapt by favoring carbohydrate production.

Such changes provide more calories per unit but lower essential nutrients, potentially affecting the health and reproduction of organisms higher in the food chain.

In contrast, the model predicts that subtropical phytoplankton, in brighter and nutrient-scarce environments, may increase protein production and decrease carbohydrates as temperatures rise. This projected shift has not yet been observed in field data.

The study highlights how environmental factors influence carbon allocation in phytoplankton, with polar species currently showing reduced protein output based on long-term monitoring.

These alterations at the base of the food chain could have cascading effects on marine ecosystems, including fish stocks and apex predators like whales, which rely on nutrient-rich prey. The research does not model specific impacts on higher trophic levels but notes the potential for widespread changes across latitudes.

Affected communities, such as coastal fisheries dependent on stable marine productivity, may face challenges as ocean warming continues.

Ongoing monitoring and further studies are needed to track these trends and assess ecosystem-wide consequences. The findings underscore the sensitivity of polar marine environments to climate change, where ice melt and temperature increases are accelerating. International efforts to mitigate global warming could influence the pace of these phytoplankton adaptations.