Diet & Nutrition of Sea Turtles for Research in Foraging Ecology
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Sea Turtles 911


Flushing turtle stomach contents out for diet analysis Scientists capture and restrain a sea turtle for dietary research by using a gastric lavage technique, which flushes stomach contents out for data collection.

Research in the feeding ecology of sea turtles can encompass very invasive methods. For example, on page 3, the Diet Study of the Materials and Methods section of this research publication describes a procedure in which scientists induce vomiting in sea turtles to collect stomach contents for dietary analysis. In brief, "turtles were placed on their back, and the mouth was opened using a pry bar until a veterinary mouth gag was inserted to keep it open. A tube lubricated with vegetable oil was inserted in the oesophagus and clean seawater was pumped at low and constant pressure"(Carrion-Cortez et al., 2010). It is apparent that conducting research on the foraging ecology and diet of sea turtles can cause discomfort to the turtle and hazards to the researcher, especially when utilizing the esophageal Gastric Lavage Technique as standardized in the Marine Turtle Research Manual for Diet Sampling and Diet Component Analysis.

Although research is vital to the conservation of sea turtles, animal welfare is even more important to the mission of Sea Turtles 911. Thus, volunteers for Sea Turtles 911 should NOT capture, restrain, and use this invasive method on turtles, as many institutions do. Volunteers are always advised to use minimally-invasive methods to collect data on sea turtles without disturbing them.

Microscope view of algae Microscopic view of Gracilaria salicornia, an invasive algae consumed by sea turtles.

For dietary and foraging studies, volunteers will observe and film sea turtles feeding. After the turtle moves away from their targeted food item, volunteers will collect leftover food scraps to identify and analyze samples. Field microscopes will be used to identify the species of food samples being consumed and a smartphone adapter, which attaches to the microscope's viewfinder, will be used to record photographic data of the food samples. By collecting data of the food items consumed by sea turtles at basking beaches, we will have a better understanding of the foraging ecology of basking sea turtles. Through this study, we aim to determine whether the foraging ecology and diet of sea turtles have any effect on the frequency and location of their basking behavior.

Foraging green sea turtle diet
Research Publications on the Foraging Ecology and Diet of Green Sea Turtles in Hawaii:

  1. Arthur (2008) A Comparison of Immature Green Turtles (Chelonia mydas) Diets among Seven Sites in the Main Hawaiian Islands.

  2. Bahr (2018) Observations of a rapid decline in invasive macroalgal cover linked to green turtle grazing in a Hawaiian marine reserve.

  3. Balazs (2017) Ocean pathways and residential foraging locations for satellite tracked green turtles breeding at French Frigate Shoals in the Hawaiian Islands.

  4. Esteban (2020) A global review of green turtle diet: sea surface temperature as a potential driver of omnivory levels.

  5. McDermid (2007) Nutritional Composition of Marine Plants in the Diet of the Green Sea Turtle (Chelonia mydas) in the Hawaiian Islands.

  6. McDermid (2015) Nonnative Seashore Paspalum vaginatum Consumed by Hawaiian Green Sea Turtles: Evidence for Nutritional Benefits.

  7. McDermid (2020) Identification of Gastrointestinal Microbiota in Hawaiian Green Turtles.

  8. Russell (2000) Identification Manual for Dietary Vegetation of the Hawaiian Green Turtle (Chelonia mydas).

  9. Russell (2009) Dietary Shifts by Green Turtles (Chelonia mydas) in the Kaneohe Bay Region of the Hawaiian Islands: A 28-Year Study.

  10. Russell (2015) Increased use of non-native algae species in the diet of the Green Turtle (Chelonia mydas) in a primary pasture ecosystem in Hawaii.

  11. Van Houtan (2014) Eutrophication and the dietary promotion of sea turtle tumors.

  12. Work (2014) The story of invasive algae, arginine, and turtle tumors does not make sense.