Of turtles and trees: Nutritional analysis of tree heliotrope (Heliotropium foertherianum) leaves consumed by green turtles (Chelonia mydas) in Hawai?i

摘要

Fallen, senescent leaves of tree heliotrope (Heliotropium foertherianum), a ubiquitous shoreline tree from the Indian Ocean, tropical Asia, Australia, and the western and central Pacific, are a novel food item for green turtles (Chelonia mydas) in Hawai?i. Leaves were collected in two seasons and analyzed for proximate nutrients, including dry matter, ash, crude fat, crude protein, carbon:nitrogen (C:N) ratio, gross energy, as well as dietary fibers (ADF and NDF), lignin, and total phenol content. The senescent leaves showed a high C:N ratio, and measurable phenolic compounds, but were low in protein (x = 5.5%) and fat (x = 2.2%) based on dry weight. Gross energy averaged 4500 Kcal/kg ash-free dry weight; therefore, H. foertherianum could provide more calories than other marine food sources for Hawaiian green turtles. Green turtles elsewhere within the broad geographic range of tree heliotrope’s distribution may also consume senescent leaves that fall into coastal waters.