Mapping global lake aquatic vegetation dynamics using 10-m resolution satellite observations.

Area of Science:

• Environmental Science
• Remote Sensing
• Ecology

Background:

• Aquatic vegetation is vital for lake health, supporting biodiversity and water quality.
• Spatiotemporal monitoring of aquatic vegetation is essential for lake ecosystem management.
• A comprehensive global assessment of aquatic vegetation distribution has been lacking.

Purpose of the Study:

• To develop an automated algorithm for mapping global aquatic vegetation distribution using satellite imagery.
• To provide the first-ever global assessment of lacustrine aquatic vegetation dynamics.
• To analyze trends and influencing factors of aquatic vegetation changes worldwide.

Main Methods:

• Developed an automated identification algorithm for Sentinel-2 Multispectral Instrument (MSI) data with 94.4% accuracy.
• Mapped aquatic vegetation distribution across 1.4 million lakes globally using 14.8 million satellite images (2019-2022).
• Analyzed historical data to assess changes in aquatic vegetation in 170 lakes from the early 1980s to 2022.

Main Results:

• Aquatic vegetation was identified in 81,116 lakes across six continents, with a cumulative maximum area of 16,111.8 km².
• Global median aquatic vegetation occurrence was 3.0%, with higher percentages in South America (7.4%) and Africa (4.1%).
• 72.4% of analyzed lakes showed a decline in aquatic vegetation from the early 1980s to 2022, particularly in Asia and Africa.

Conclusions:

• This study provides the first global map of aquatic vegetation distribution and dynamics.
• Significant declines in aquatic vegetation highlight urgent conservation needs.
• Lake physical characteristics and surrounding environments are key factors influencing vegetation distribution, alongside blooms and temperature.