Nutrient loading alters the performance of key nutrient exchange mutualisms

Area of Science:

• Ecology
• Environmental Science
• Symbiosis Research

Background:

• Mutualisms between phototrophs (e.g., plants, algae) and heterotrophs (e.g., fungi, corals) are crucial for ecosystem function, biodiversity, and food security.
• Nutrient loading can disrupt the balance of these symbiotic relationships by altering the costs and benefits for each partner.

Purpose of the Study:

• To investigate how nutrient enrichment affects the performance of mutualistic interactions between phototrophs and heterotrophs in both terrestrial and marine ecosystems.
• To identify factors mediating the impact of nutrient enrichment on these mutualisms.

Main Methods:

• Utilized meta-analyses to synthesize data from various studies on nutrient exchange mutualisms.
• Analyzed the decoupling of mutualism performance under nutrient enrichment scenarios.

Main Results:

• Demonstrated a widespread decoupling in mutualism performance across diverse environments, where phototrophs benefited from nutrient enrichment at the expense of their heterotrophic partners.
• Found that heterotroph identity, their reliance on phototroph-derived carbon, and the type of nutrient enrichment (nitrogen vs. phosphorus) significantly influenced the outcomes for different mutualisms.

Conclusions:

• Nutrient-driven decoupling of mutualisms can alter community structure and ecosystem processes.
• The disruption of nutrient exchange mutualisms due to global nitrogen and phosphorus cycle alterations poses a significant emerging threat to ecosystems and food production.