When viewed from space, the shoals, seagrass beds, and mudflats of Mauritania’s Banc d'Arguin National Park often blend with sand and sea in beautiful ways.
So it was on December 28, 2019, when the Operational Land Imager (OLI) on Landsat 8 captured this natural-color image of the park’s shallow coastal waters. The mostly barren dunes on the shore drew a contrast with the maze of coastal mudflats (dark brown) and shallow seagrass beds (green) that grow beneath a few meters of water. Deeper channels (dark blue) meander and flow among the sea grass and sandy shoals.
While signs of life are rare on this mostly arid land, the upwelling of cool, nutrient-rich water offshore causes the park’s coastal areas to burst with marine life. Whales, dolphins, and seals all make appearances. Thriving finfish and shellfish populations attract migratory birds to breeding sites here. Expansive tidal mudflats support upwards of 2 million shorebirds, making Banc d'Arguin one of the largest meeting places for Palaearctic birds in the world. Several endangered marine mammals occasionally turn up, notably monk seals and humpback dolphins.
But Landsat does more than deliver an occasional pretty picture. Scientists have analyzed 20 years of satellite observations and found that the park’s extensive seagrass beds have remained remarkably healthy and resilient, despite weathering occasional damage from storms and dust that temporarily killed grasses in certain areas.
NASA Earth Observatory image by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. Caption by Adam Voiland.