Heat Waves Alter Macrophyte-Derived Detrital Nutrients Release under Future Climate Warming Scenarios

Area of Science:

• Ecology
• Climate Change Science
• Aquatic Ecosystems

Background:

• Global temperatures and extreme heat events are rising.
• Understanding heat wave impacts on freshwater ecosystems is crucial for management.
• Little is known about heat wave effects on macrophyte detritus decomposition.

Purpose of the Study:

• To investigate the impact of warming and heat waves on macrophyte detritus decomposition.
• To compare the effects of continuous warming versus fluctuating heat waves on decomposition processes.
• To assess the release of carbon, nitrogen, and phosphorus during decomposition under different warming scenarios.

Main Methods:

• A mesocosm experiment was conducted.
• Macrophyte detritus decomposition was studied under two warming treatments: a fixed increment (+4 °C) and a fluctuating heat wave simulation (0–6 °C above ambient).
• Dry mass loss and nutrient (C, N, P) release were measured.

Main Results:

• Both warming and heat waves significantly increased detritus dry mass loss and carbon release.
• No significant difference in dry mass loss or carbon release was observed between the fixed warming and heat wave treatments.
• Significantly different amounts of nitrogen and phosphorus were released between the two warming treatments, indicating asymmetric nutrient release patterns.

Conclusions:

• Moderate warming accelerates macrophyte detritus decomposition and nutrient release primarily based on energy input.
• Heat waves cause asymmetric alterations in nitrogen and phosphorus release dynamics from detritus.
• Future climate change may alter nutrient ratios (N/P) in aquatic systems, impacting ecosystem structure and function, particularly plankton communities.