Thermal sensitivity of pelagic primary producers changes with nutrient supply  . Phosphorus limitation lowers the temperature optimum for growth of phytoplankton, making these organisms more prone to heat stress . This trend may hold for open-ocean phytoplankton, which are often iron- limited  . Such temperature-nutrient interactions might be especially relevant during summer MHWs , when primary producers are often nutrient-limited and near their thermal limits. Increasingly frequent and intense MHWs along with projected decreases in nutrient availability  may push some primary producers beyond tolerance thresholds. Temperature- nutrient interactions can also alter the photosynthesis-to-respiration ratio in phytoplankton . Overall, rising metabolic rates due to warming will be restricted to primary producers in high- nutrient regions  . For zooxanthellae-containing corals, nutrient supply from upwelling or from runoff can increase coral susceptibility to bleaching during warm-season MHWs .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report