One species can hide another.
A phrase that is well known to bathers when they walk through seagrass beds made up of aquatic plants rather than algae!
The aquatic plants that tickle bathers' feet are usually vascular plants such as pondweeds, which are completely harmless. They are attached to the bottom of the lake by their rhizomes and have stems that can exceed 3 metres, leaves that are clearly visible in the water and flowers in the form of small greenish multiflorous spikes that emerge above the surface. In autumn, these plants disappear, leaving behind a rhizome, rich in reserve substances, from which the following year's vegetation will grow.
Conversely, the brownish or greenish vegetation visible on boat hulls and on stones at the water's edge that become very slippery are colonies formed by small (microscopic) algae. Algae are aquatic plants without stems or flowers. These microscopic, unicellular algae make up the phytoplankton that form the basis of the food chain.
Lake Geneva also contains other aquatic plants such as characea. Attached to the seabed, they rarely exceed 60 centimetres. They have almost disappeared from Lake Geneva because they are very sensitive to eutrophication (high input of nutrients such as phosphorus).
This vegetation, which forms grass beds, is ideal for aquatic fauna, providing a habitat or food base.
Grab your masks and explore the seagrass beds of Lake Geneva to find out more about aquatic plants!
For further information: CIPEL
