Seagrass repression by green turtles (Chelonia mydas) around Taiping Island in the south China sea: Experimental evidence and management insights

Chia-Hsuan Hsu; Chia-Yu Kuo; Yi Wei; Keryea Soong

doi:10.1016/j.marenvres.2024.106494

Seagrass repression by green turtles (Chelonia mydas) around Taiping Island in the south China sea: Experimental evidence and management insights

Mar Environ Res. 2024 Apr 7:198:106494. doi: 10.1016/j.marenvres.2024.106494. Online ahead of print.

Authors

Chia-Hsuan Hsu¹, Chia-Yu Kuo², Yi Wei³, Keryea Soong⁴

Affiliations

¹ Biodiversity Division, National Institute for Environmental Studies, Ibaraki, 305-8506, Japan.
² Planning and Research Division, National Museum of Marine Biology and Aquarium, Pingtung, 94450, Taiwan.
³ Taiwan International Cooperation and Development Fund, Taipei, 11157, Taiwan.
⁴ Department of Oceanography, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan. Electronic address: keryea@g-mail.nsysu.edu.tw.

PMID: 38733738
DOI: 10.1016/j.marenvres.2024.106494

Abstract

Seagrass meadows serve as critical marine habitats, offering numerous benefits to both humans and wildlife. Taiping Island, situated in the South China Sea, has been historically known for its abundant seagrass meadows. However, satellite imagery suggested there was a low density of seagrasses around Taiping Island. On the other hand, many green turtles (Chelonia mydas) were observed from the shore. To investigate this phenomenon, we conducted drone surveys of the shallow reefs and discovered a density of 902 ± 601 (mean ± SD) individual turtles per square kilometer during high tides. In addition, we conducted a cage experiment to test the hypothesis that large herbivores are impacting seagrass abundance negatively. The results indicated that the blade lengths of seagrasses in cages were significantly longer than those outside. It is likely that large herbivores such as green sea turtles are the key consumers of seagrass on the shallow reef flats of Taiping Island. Accordingly, further research and management should take into account that the increasing number of sea turtles may deplete the seagrasses and have an impact on the seagrass ecosystems.

Keywords: Chelonia mydas; Herbivores; Marine protected area; Seagrass; South China sea; Taiping island.