Session 48: From cellular scales to phytoplankton biogeography in the ocean

03.07.2025 17:30

The session with Suzana Gonçalves Leles will be organized by Ralf Steuer.

Presentation summary

Warming and nutrient limitation are major stressors that affect primary production in the ocean, with cascading impacts on the food web. Yet, we lack a mechanistic understanding of how phytoplankton manage the combined stress of heat-damage and nutrient-limitation and the implications of these responses for phytoplankton biogeography.

By combining theory, proteome allocation modeling, and climate projections, we identified two potential competing strategies for multi-stressor growth: (1) increase growth temperature optima through higher nutrient uptake efficiency and smaller cells, or (2) invest in heat-mitigation mechanisms achieving higher thermal tolerance at the cost of growth and larger cells.

By simulating the optimal metabolic strategies of different phytoplankton functional types across a latitudinal gradient, we found that cyanobacteria are more vulnerable in warmer tropical regions due to greater heat sensitivity and lower storage capacity, indicating a potential ecological niche for larger phytoplankton, such as diatoms, in a warming ocean.

Our findings challenge the current understanding that the smallest phytoplankton should prevail across the global ocean as the climate warms.

See also: Suzana Leles, Naomi M. Levine, (2023) Mechanistic constraints on the trade-off between photosynthesis and respiration in response to warming. Sci. Adv. 9, eadh8043. DOI:10.1126/sciadv.adh8043

 

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