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Figure 1. The use of green turtles and dugongs as habitat indicators. (A) A green turtle (Chelonia mydas) (B) A dugong (Dugong dugon). Both species feed on seagrasses and so the location of their foraging sites may indicate seagrass habitat. (C) Green turtles can be satellite tracked from their nesting beaches to their, sometimes, very discrete foraging grounds. Here the tracks of 8 green turtles that had nested on Diego Garcia, in the Chagos Archipelago, are shown. Red stars show the end point of each track, i.e., the location of each turtle’s foraging grounds. (D) Modern satellite tracking can provide very high accuracy locations (e.g., Fastloc-GPS) (black dots) allowing space use on foraging grounds to be accurately assessed. In this case the foraging home-range is shown for one of the turtles tracked in (C). Red, orange, blue colors show the 50, 90, and 95% kernel home-range estimates. On-site validation of the foraging habitats used by (E) dugongs and (F) green turtles in the Indo-Pacific has confirmed the hitherto unknown location of extensive seagrass beds. (E) An aerial photo of 50+ foraging dugongs. Black arrows indicate three of the dugongs. (F) An aerial photo (from a drone survey) of 20+ foraging green turtles. Black arrows indicate three of the green turtles. Note the grazed area (white) around each green turtle. Photo in (A) courtesy of RD and BS Kirkby in (B) courtesy of EH Meesters, (C,D) from Hays et al. (2014), (E) courtesy of Susan Sobtzick and (F) courtesy of MC.

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