The Lac Rose geosite (NE Dakar, Senegal): Stakes of the preservation of an exceptional geopatrimony threatened of disappearance

摘要

This study is part of a wide multidisciplinary research program initiated in Senegal for the promotion of geodiversity and is the continuation of previous works carried out in the Dind??f??lo Community Nature Reserve. It aims to strengthen the Senegalese states??? proposal for Lac Rose to acquire the status of UNESCO World Heritage Site, Biosphere Reserve and Ramsar site. To evaluate the geosite, we tried to take into account the concerns of the quantitative site evaluation method according to Brilha (2016). The Lac Rose is located about 30 km NE of Dakar and is characterized by its salty waters containing the green halophilic alga Dunaliella salina, which is responsible for its pink coloration. Its bottom is a thin saline crust on top of a mud rich in foraminifera, ostracods and diatoms, which study has enabled to reconstruct its history. Around the Lac Rose, several ecosystems have been described (ponds, dunes, lakeshore fringe), whose conservation depends on the conservation of the lake that faces threats due to lack of water and salt supply along with the backfilling of the depression. Our proposal is based on four among ten criteria proposed by UNESCO for the World Heritage Convention implementation: criterion 8 verified by the historical reconstruction of the lake; criterion 5 justified by the extraction of salt, shells and dune sand; criterion 7 justified by the pink coloration of the lake waters and criterion 9 justified by the development of Dunaliella salina. Ultimately, this work will pave the way for implementing of UNESCO World Heritage Site and will support the State of Senegal in its program to set up a geopark in the Dakar region.