Download The Floating Islands of Lake Dupuis

The Floating Islands of Lake Dupuis
The floating islands of Lake Dupuis are a special case. They play an important ecological role. As mentioned above, a part of the bank
was flooded when the water level of Lake Masson raised. The vegetation had not been removed prior to the flooding. By the end of the
50’s, all bays had been cleaned with the exception to the one in front of the hotel l’Estérel, where only trees had been cut. Eventually, the
decomposition gasses elevated the bottom of the lake thus creating the floating islands.
We can still count three floating islands in Lake Dupuis. The biggest one is a peat bog. The main species found are shrubs from the
heath family. There are also some beautiful carnivorous plant colonies. In addition, a typical peat bog orchid, the rose pogonia (Pogonia
ophioglossoides), has been seen. The other two smaller islands are characterized as a wet meadow. The species found are mainly
herbaceous plants. Another carnivorous species was spotted, the horned bladderwort (Utricularia cornuta), a species confined to humid
and mostly bare shores. When sampling the vegetation, bullfrogs and some bird species where observed on the islands.
In 1992, a project was submitted to the Bureau d'audiences publiques (BAPE) in order to remove the floating islands and to dredge the
bottom of the bay. The main objective behind this project was “… to restore a more environmental aspect, increase the public security
and ensure the housing market value”. The project was rejected by the BAPE, because it was not justified on an environmental point of
view and would not have brought any economic benefits. An important impact would have emerged from recreating the sediment
suspension which would have re-released contaminants and phosphorus in the water. These works could have led to water
contamination (contaminants) and might have amplified the lake eutrophication problem (phosphorus).
It is important to mention that the presence of the floating islands is not a consequence of the lake eutrophication as mentioned by the
promoter of that time, but a result of all the modifications made around Lake Dupuis since the start of the century.
Source: Groupe Hémisphère – Études des Lacs d’Estérel [Study of Estérel lakes]