Dense vegetation covers the entire body of water, sometimes reaching all the way to the surface.
Certain species clearly dominate the environment:
- Myriophyllum (from Brazil): Light green plant with very fine foliage, rapidly forming dense carpets that can reach the surface.
- Heterophyllous: Invasive species with robust stems, capable of rapidly colonizing a body of water and forming dense meadows.
- Elodea: Fast-growing submerged plant, recognizable by its flexible stems and strong propagation capacity.
- Hornwort: Unrooted plant developing directly in water, creating thick vegetation masses when it proliferates.
- Spiked water-milfoil: A rooted plant identifiable by its erect stems whose spikes emerge above the water in the summer.
Result: Navigation is blocked (propellers caught), fishing is impossible (lines snagged), and swimming areas are closed. Often, the water between the poles remains crystal clear. This is a misleading sign that the problem isn’t due to water quality, but to the light reaching the bottom.
