Food sources and trophic structure of fishes and benthic macroinvertebrates in a tropical seagrass meadow revealed by stable isotope analysis

ABSTRACT

Stable carbon and nitrogen isotope analysis was used to examine the food sources and trophic structure of 17 fish species and six groups of benthic macroinvertebrates in a seagrass meadow in North Sulawesi, Indonesia. The seagrass, their associated epiphytes, sediment organic matter (SOM) and particulate organic matter (POM) were identified to be the food sources, with δ¹³C values ranging from −19.49 (POM) to −9.66‰ (seagrass). The δ¹³C of the 23 fauna taxa were between −18.57 (Arothron manilensis) and −11.62‰ (Protoreaster sp.). For five of the six groups of benthic macroinvertebrates, seagrass and their epiphytes contributed more than 69.4%. For 14 of the 17 fish species, seagrass and their epiphytes are the main contributors. For 15 of the 17 fishes, the trophic levels inferred from SIA are lower than those from the previously reported diet composition analysis. These findings show that seagrass and their epiphytes are consumed by most of the fish and benthic macroinvertebrates, and are important for a large portion of the food web in seagrass meadows in the Coral Triangle area.

RESPONSIBLE EDITOR:

• Margot Hessing-Lewis

KEYWORDS:

• Food source
• North Sulawesi
• seagrass meadow
• stable isotope analysis

Acknowledgements

We thank all anonymous reviewers for their comments which greatly improved this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The present study was supported by grants from the China-Indonesia Maritime Cooperation Fund project, ‘China-Indonesia Bitung Ecological Station Establishment’, and the National Natural Science Foundation of China (no. 31101902). The Natural Science Foundation of Fujian Province of China (no. 2012J05074, 2014J01127), the China Scholarship Council (no. 201309660067) and the Scientific Research Foundation of the Third Institute of Oceanography, SOA (no. 2015024) also contributed to this work.