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Saturating relationship between phytoplankton growth rate and nutrient concentration explained by macromolecular
Jongsun Kim1,2, Gabrielle Armin2, Keisuke Inomura2
1School of Earth, Environmental, and Marine Sciences, University of Texas Rio Grande Valley, Brownsville, TX, USA.
Current Research in Microbial Sciences
|December 15, 2022
Summary
Phytoplankton growth rate saturates with nitrate due to internal cellular processes. Increased allocation to essential molecules like proteins limits growth, even with abundant nutrients, revealing internal cellular control.
Area of Science:
- Marine biology
- Oceanography
- Biogeochemistry
Background:
- Phytoplankton are crucial for global photosynthesis and biogeochemical cycles.
- Phytoplankton growth rate is a key indicator of productivity and competitiveness.
- The saturating relationship between phytoplankton growth and nutrient concentration is well-documented but mechanistically unclear.
Purpose of the Study:
- To elucidate the mechanisms behind the saturating relationship between phytoplankton growth rate and nitrate concentration.
- To provide a macromolecular interpretation of phytoplankton growth-nutrient dynamics.
- To investigate the role of intracellular macromolecular allocation in nutrient-limited growth.
Main Methods:
- Utilized a mechanistic model incorporating phytoplankton metadata.
- Analyzed the relationship between nitrate concentration, intracellular nitrogen requirements, and growth rate.
- Examined macromolecular allocation to biosynthetic and photosynthetic components.
Main Results:
- At low nitrate, growth rate increases non-linearly with nitrate due to rising nitrogen demand for biosynthesis and photosynthesis.
- At high nitrate, growth rate saturates due to limitations in carbon assimilation and maximal allocation to cellular components.
- Model-generated growth rate-nitrate relationships align with empirical data across diverse phytoplankton taxa.
Conclusions:
- Intracellular macromolecular allocation provides a mechanistic explanation for the observed phytoplankton growth-nutrient saturation.
- Phytoplankton growth is primarily controlled by internal cellular processes and resource allocation strategies.
- Understanding cellular allocation is key to predicting phytoplankton productivity in changing oceanic nutrient conditions.
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