Omnivorous Turtles More Likely To Consume Marine Debris

Omnivorous green turtles seem to have a harder time than carnivorous loggerhead turtles at distinguishing artificial marine debris from food.

AsianScientist (Jun. 28, 2016) – By attaching video cameras to sea turtles, a University of Tokyo joint international research group has discovered that omnivorous green turtles were more likely to consume artificial marine debris than carnivorous loggerhead turtles. The study was published in Scientific Reports.

Previous analyses of stomach contents have showed that the amount of debris ingestion was different between loggerhead turtles (Caretta caretta) and green turtles (Chelonia mydas). However, the reason for this inter-specific difference was not known because the process of the debris ingestion is difficult to observe under natural conditions.

The international research group, led by Professor Katsufumi Sato of the University of Tokyo Atmosphere and Ocean Research Institute, compared responsive behavior to artificial debris between these species under natural conditions. They deployed animal-borne video cameras on the backs of sea turtles from 2007 to 2015, obtaining a total of 60 hours of video data from ten loggerhead turtles and 52 hours from six green turtles.

According to their findings, the encounter-ingestion ratio of carnivorous loggerhead turtles was 17 percent, whereas the ratio for omnivorous green turtles was 62 percent. These results suggest that for green turtles, drifting artificial debris was hard to distinguish from common dietary elements such as jellyfish.

From the video footage, green turtles were found to have confused drifting debris near the water surface with their normal dietary intake. Credit: Takuya Fukuoka
From the video footage, green turtles were found to have confused drifting debris near the water surface with their normal dietary intake. Credit: Takuya Fukuoka

“Ingestion of artificial marine debris by sea turtles is considered as a significant threat to their health and can lead to death,” said Sato.

“However, it should be noted that ingestion of marine debris does not necessarily have immediate lethal effect, as it appears that sea turtles frequently ingested natural debris such as bird feathers, stones and leaves, and a lot of natural and artificial debris are able to pass and excrete them.”

Sato noted that further research is required to understand the threat of debris ingestion on the health of sea turtles.


The article can be found at: Fukuoka et al. (2016) The Feeding Habit of Sea Turtles Influence Their Reaction to Artificial Marine Debris.

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Source: University of Tokyo; Photo: Shutterstock.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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