| Aerial photographs and in situ data of the Glenan archipelago permit the establishment of a cartography of its Zostera marina seagrass beds. Due to the exceptionally clear water, it was possible to distinguish submerged structures, such as rocks, sand dunes, maerl beds and seagrass meadows on the photographs. The distribution of Zostera meadows was incorporated into a geographical information database through scanning, and then compared with historical data. Ten aerial photographic surveys, made over a sixty-year period from 1932 to 1992 were available. The earliest of these surveys showed the seagrass beds to be in goad condition. Low cover in 1952 suggests that the Zostera meadows within the studied area were subject to severe destructions, presumably... |
