Temperature fluctuations in a warmer environment: impacts on microbial plankton

Area of Science:

• Microbial Ecology
• Aquatic Ecosystems
• Climate Change Biology

Background:

• Warming significantly impacts microbial food web structure and function.
• Previous experimental studies often used constant temperature conditions, overlooking temperature fluctuations.
• Jensen's inequality highlights that organism performance under constant conditions differs from performance under variable conditions.

Purpose of the Study:

• To review evidence on how warming effects on microbial plankton are modified by temperature fluctuations.
• To synthesize findings on the impacts of variable temperatures on plankton abundance, diversity, and metabolism.
• To identify knowledge gaps and suggest future research directions.

Main Methods:

• Literature review of experimental studies on warming and temperature fluctuations in microbial plankton.
• Analysis of how fluctuating temperatures alter responses to warming in terms of phytoplankton evenness, photosynthesis, and growth.
• Examination of effects on cyanobacterial biomass, recruitment, and cellular nutrient quotas.

Main Results:

• Fluctuating temperatures can intensify warming-induced reductions in phytoplankton evenness and gross photosynthesis.
• Variable temperatures may synergistically increase phytoplankton growth.
• Fluctuations can reduce warming's positive effect on cyanobacterial biomass and reverse effects on nutrient quotas.
• Some studies found no significant alteration of warming effects by temperature fluctuations.

Conclusions:

• Temperature fluctuations play a critical role in mediating warming effects on microbial plankton.
• Current research is limited to specific species and ecosystems, with short-term responses.
• Future research must explore diverse ecosystems, trophic levels, and longer temporal scales, including evolutionary adaptation.