Scraping and grazing herbivorous/detritivorous fish display opposite feeding behaviours under different protection regulations

ABSTRACT

Herbivorous and detritivorous fish display complex feeding behaviour, and research into how feeding behaviour changes with environmental and social variables is lacking. Such knowledge is imperative to infer how herbivory/detritivory will differ, in light of shifting resources and communities and specifically whether reefs can recover from disturbance. Fish abundance, feeding rate, body size, diet and schooling feeding of three major functional groups (scrapers, grazers and browsers) were examined across reef types under different fishing regulations. Scrapers and grazers (parrotfishes and surgeonfishes) were more abundant and displayed the highest feeding rates on reef flats. Scrapers mainly resided inside the restricted zone, while more grazers were found in the general use zone, where macroalgal abundance was highest. Browsers (rabbitfishes) were seldom observed and patchily gathered on the reef flat and reef slope in both zones. Thus, fishing protection did not appear to benefit grazers and browsers, whereas more scrapers gathered on shallow reef flats in the protection zone. Scraper and grazer feeding rates increased from an individual to a pair and increased with body size, these factors led to variations in feeding behaviours across reef types and protection regulations. Protection appears to benefit scrapers and variations in feeding rates were largely related to school size. Lastly, grazer density was associated more with macroalgal coverage than protection status. The opposite feeding behaviours of scrapers and grazers indicates not only protection status, but fishing restrictions and size limit regulations are needed to maintain coral reef fisheries and functional diversity on coral reefs in Taiwan.

KEYWORDS:

• Bottom-up and top-down regulation
• functional groups
• no-take marine protected areas
• marine reserves
• schooling behaviour

Acknowledgements

We are grateful for the field and laboratory assistance provided by YuFung Zeng and other researchers, especially Dr Shaolun Liu for the algal identification. We also thank Derek Ho for statistical analysis advice. The raw data of this study are based on the collective assignments of Teng-Teng Tan, Yu-Yuan Hsieh and Jia-Hsuan Chen, Department of Life Science, Tunghai University.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethics approval and consent to participate

All data in this study were collected through in situ observations and collections from fish markets and fishers, no fish were killed by any of the authors during this study. In situ fish observations and fish market sampling did not require animal ethics permits by the animal ethics committee of Tunghai University (Approved by Taichung City, Animal Protection and Health Inspection Office, No. 10500081571).

Consent for publication

Not applicable

Availability of data and materials

The datasets supporting the results of this article are available in the figshare repository, https://doi.org/10.6084/m9.figshare.12362726.v2

Additional information

Funding

This work was supported by the Kenting National Park Headquarters, Taiwan under Grant number 488-103-02 and the Ministry of Science and Technology, Taiwan under Grant number 103-2313-B-029-004.