Switching Harmful Algal Blooms to Submerged Macrophytes in Shallow Waters Using Geo-engineering Methods: Evidence...

Area of Science:

• Environmental Science
• Aquatic Ecology
• Eutrophication Management

Background:

• Human-induced eutrophication often leads to harmful algal blooms, hindering lake ecosystem health.
• Transitioning from algal to macrophyte dominance is crucial for lake restoration but rarely occurs naturally.
• Algal nutrients can potentially support macrophyte growth, but efficient transfer mechanisms are needed.

Purpose of the Study:

• To investigate a geo-engineering method for facilitating the transition from algal blooms to macrophyte dominance.
• To assess nutrient transfer from algae to macrophytes under different temperature conditions (8 and 25 °C).
• To evaluate the impact of flocculation and capping on algal bloom dynamics and macrophyte assimilation.

Main Methods:

• Application of a combined flocculation and capping geo-engineering treatment to eutrophic waters.
• Monitoring of algal bloom removal, decomposition, and nutrient incorporation into macrophyte biomass.
• Measurement of algal photosynthesis, respiration, chlorophyll-a concentrations, and 15N tracing for nutrient assimilation studies.

Main Results:

• The flocculation-capping treatment effectively removed Microcystis aeruginosa blooms and induced algal cell lysis.
• Algal photosynthesis and respiration rates were inhibited, with significantly reduced chlorophyll-a concentrations post-treatment.
• Potamogeton crispus assimilated 3.3% and 34.8% of algae-derived nitrogen at 8 and 25 °C, respectively.

Conclusions:

• The flocculation-capping method successfully facilitates the switch from algal to macrophyte dominance in eutrophic waters.
• This geo-engineering approach promotes nutrient cycling and aids in the restoration of aquatic ecosystems.
• The findings highlight the potential of targeted interventions for managing eutrophication and restoring lake health.