Thermal Dynamics of Marine Phytoplankton

Marine phytoplankton represent the foundation of oceanic food webs and drive roughly half of global primary production. Their growth, distribution and community composition are closely tied to thermal dynamics, encompassing both immediate physiological responses and longer-term evolutionary adaptations to changing temperatures. At the cellular level, temperature influences photosynthesis, respiration and nutrient uptake, shaping carbon fixation and elemental stoichiometry. Species vary in their thermal niches and temperature optima, leading to shifts in community structure as warming proceeds. Interactions between temperature and resource availability modulate metabolic rates, so that nutrient-limited regions may show dampened thermal sensitivity. Over generational timescales, phytoplankton can evolve altered thermal tolerance, with trade-offs in cold-water performance or nutrient acquisition. These processes have profound implications for biogeochemical cycling, climate feedbacks and marine ecosystem services, including fisheries yield and carbon sequestration.

Research from Nature Portfolio

Recent work has compared resurrected strains of a coastal diatom across a six-decade archive, revealing an upward shift of about 1 °C in its temperature optimum. Modern strains exhibit altered valve-to-girdle ratios and upregulated nitrate-metabolism genes under warmer conditions, suggesting that natural populations can evolve thermal tolerance at a realistic pace, albeit with reduced growth in cooler waters.

Empirically derived thermal-growth profiles for diatoms, dinoflagellates, cyanobacteria and coccolithophores have disclosed marked differences in temperature coefficients, growth maxima and thermal ranges. When applied to projected sea-surface temperatures for late-century scenarios, these taxon-specific traits predict divergent shifts in geographic distribution and productivity, indicating that blanket formulations of phytoplankton response may obscure important functional-type variability.

Thermal Dynamics of Marine Phytoplankton publication trend

The graph below shows the total number of articles in thermal dynamics of marine phytoplankton across all publications each year (not limited to Nature Index journals).

Technical terms

Thermal tolerance: The range of temperatures within which a phytoplankton species can maintain survival and growth.

Temperature optimum (Topt): The temperature at which growth rate or metabolic activity reaches its maximum for a given organism.

Acclimation: The reversible physiological adjustment of an individual organism to a change in environmental temperature.

Adaptation: Heritable changes across generations that enhance a population’s performance under specific thermal conditions.

Mesocosm: A controlled experimental enclosure that replicates natural environmental conditions to study ecological processes.

Metabolic rate: The speed at which phytoplankton convert substrates into energy and biomass, encompassing photosynthesis and respiration.

References

1. Temperature optima of a natural diatom population increases as global warming proceeds. Nature Climate Change (2024).
2. Marine phytoplankton functional types exhibit diverse responses to thermal change. Nature Communications (2021).
3. Cryptochrome PtCPF1 regulates high temperature acclimation of marine diatoms through coordination of iron and phosphorus uptake. The ISME Journal: Multidisciplinary Journal of Microbial Ecology (2024).
4. Warming increases the compositional and functional variability of a temperate protist community. The Science of The Total Environment (2024).
5. Comparative experimental evolution reveals species‐specific idiosyncrasies in marine phytoplankton adaptation to warming. Global Change Biology (2023).
6. Nutrient limitation suppresses the temperature dependence of phytoplankton metabolic rates. The ISME Journal: Multidisciplinary Journal of Microbial Ecology (2018).