Phosphorus Cycling in Marine Ecosystems

Phosphorus is a vital macronutrient that underpins marine primary production, influencing global biogeochemical cycles and ecosystem health. In the ocean, phosphorus occurs primarily as dissolved inorganic phosphorus (DIP) and dissolved organic phosphorus (DOP). DIP, in the form of orthophosphate, is directly available to phytoplankton, but its scarcity in oligotrophic waters often compels microbial communities to exploit DOP through enzymatic hydrolysis. Key processes include remineralisation of sinking particles, microbial uptake, adsorption to particles and release via alkaline phosphatase and carbon–phosphorus lyase pathways. Spatial heterogeneity is controlled by factors such as freshwater inputs, atmospheric deposition, upwelling and anthropogenic nutrient loading. These variables drive nutrient ratios, shaping phytoplankton community structure and carbon export efficiency. Moreover, the coupling between phosphorus, nitrogen and trace-metal cycles determines the moderation of algal blooms and the efficacy of the biological carbon pump. Synthesis of recent findings emphasises the sensitivity of phosphorus dynamics to environmental change and highlights the role of microbial diversity, enzyme kinetics and human influences in regulating phosphorus availability and ecosystem productivity.

Research from Nature Portfolio

Recent studies have demonstrated that atmospheric deposition and riverine discharge jointly stimulate the utilisation of dissolved organic phosphorus in coastal seas by increasing nitrogen inputs that depress DIP availability and boost phosphatase activity, thereby rendering DOP a critical phosphorus source under nutrient-imbalanced conditions. Complementary work has revealed that the activity of alkaline phosphatases in the western North Atlantic can be limited by iron availability, indicating a biogeochemical linkage between iron supply and microbial phosphorus acquisition. These findings underscore the importance of trace-metal interactions and external nutrient drivers in modulating the efficiency of phosphorus cycling and consequent primary productivity in marine systems.

Phosphorus Cycling in Marine Ecosystems publication trend

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

Technical terms

Dissolved inorganic phosphorus (DIP): Orthophosphate ions readily assimilated by phytoplankton.

Dissolved organic phosphorus (DOP): Organic forms of phosphorus such as phosphoesters and phosphonates.

Alkaline phosphatase: Enzyme that hydrolyses phosphate esters to liberate orthophosphate under alkaline conditions.

Carbon–phosphorus lyase (C–P lyase): Enzyme complex that cleaves stable C–P bonds in phosphonates to release phosphorus.

Remineralisation: Conversion of organic phosphorus back to inorganic forms via microbial decomposition.

References

1. Atmospheric deposition and river runoff stimulate the utilization of dissolved organic phosphorus in coastal seas. Nature Communications (2024).
2. Iron limitation of microbial phosphorus acquisition in the tropical North Atlantic. Nature Communications (2017).
3. A dataset of global ocean alkaline phosphatase activity. Scientific Data (2023).
4. Multifunctionality of alkaline phosphatase in ecology and biotechnology. Current Opinion in Biotechnology (2024).
5. Phosphate‐limited ocean regions select for bacterial populations enriched in the carbon–phosphorus lyase pathway for phosphonate degradation. Environmental Microbiology (2019).