Discovery of the Sea Grass Halophila decipiens (Hydrocharitaceae) in the Diet of the Hawaiian Green Turtle, Chelonia mydas

Abstract

The herbivorous Hawaiian green turtle (Chelonia mydas L.) has expanded its forage to include a newly reported sea grass species, Halophila decipiens Ostenfeld, that is closely related to the previously documented food item, Halophila hawaiiana Doty & Stone. Halophila decipiens was first reported in Hawai'i in the literature in 2001, but our investigations have found it in reef specimens preserved from 1979 and in more recent samples from green turtle forestomachs. Its presence as a dietary item indicates that green turtles probably began utilizing this species after 1998. The status of H. decipiens as an indigenous species to Hawai'i, its effects on turtle pastures, and the adjustment of feeding behavior of C. mydas to the presence of a species abundant and available as a food source are discussed.