Bolbometopon Muricatum

Galaxea, Journal of Coral Reef Studies 23: 7-8（2021）

Photogallery

On the use of the bumphead parrotfish Bolbometopon( muricatum) as a mobile shelter by a bluefin trevally Caranx( melampygus) in an oceanic reef system in the Philippines

Kent Elson S. SORGON1, Victor S. TICZON1, Badi R. SAMANIEGO1, 2, Marion Michael A. BACABAC1, and Jesus Gabriel C. FETIL1

1 Aquatic Zoology Research Laboratory, Animal Biology Division, Institute of Biological Sciences, College of Arts and Sciences, University of the Philippines Los Baños, College, Laguna, Philippines 4031 2 School of Environmental Science and Management, University of the Philippines Los Baños, College, Laguna

* Corresponding author: K. E. S. Sorgon E-mail: [email protected], [email protected]

Communicated by Andrew Baird (Ecology Editor)

Keywords Carangidae, parrotfish, sheltering behavior, Apo Reef Natural Park

The bluefin trevally Caranx melampygus Cuvier, 1833 is an obligate piscivore common in Indo-Pacific and East Pacific reefs and has been known to act as both a transient (i.e., transitory) roving and an ambush predator (Sancho 2000; Sancho et al. 2000). On 26 September 2020, a Caranx melampygus with a total length (TL) of ~45 cm was seen sheltering in a ~100 cm TL bumphead parrotfishBolbometopon muricatum (Valenciennes, 1840) in a reef crest (~8 m deep) in Apo Reef Natural Park, an oceanic reef system ~30 km off Sablayan, Occidental Mindoro, Philippines. The parrotfish was spotted by the first author when he observed the caudal fin of the trevally behind the anal fin of the parrotfish (Fig. 1A). The trevally swam extremely close to the parrotfish, the latter not showing any aggressive behavior towards the former (Fig. 1B). The trevally maintained the same swimming speed as the parrotfish (Supporting Information 1) and adopted a darker coloration (“pigmented phase”) usually

Fig. 1 A) Left lateral view of Bolbometopon muricatum with the caudal fin ofCaranx melampygus (white arrow) seen behind the parrotfish’s anal fin. B) Posterior view of the sheltering association showing the proximity of the trevally to the parrotfish. C) Right lateral view of the association showingC. melampygus in pigmented phase. Photos: K. Sorgon. 8 Sorgon et al.: Bluefin trevally sheltering in a large parrotfish seen in ambush attacks (Sancho 2000) (Fig. 1C). The parrotfish did not forage during the duration of the association. The second author recorded the same association and behavior during a repeat survey of the area in December 2020. Trevallies are known to utilize various prey capture strategies (e.g., Baird 1993; Sancho 2000; Sancho et al. 2000) with the Atlantic yellow jack Carangoides bartholomaei (Cuvier, 1833) being the only other carangid known to shadow in non-foraging megafauna (i.e., sea turtles) (Mendonça et al. 2011). Because the sheltering C. melampygus did not feed during the interaction, the precise nature of this behavior remains unknown. Nuclear-follower associations are common in coral reef fishes, and the observed sheltering behavior may be related to shadowing, a foraging strategy employed by follower species such as trevallies when feeding (e.g., Baird 1993). The “pigmented phase” exhibited by the trevally may suggest camouflaging when using mobile shelters to ambush unsuspecting prey. This observation advances our understanding of foraging strategies of Indo-Pacific trevallies by presenting a potential mechanism to counter pelagic mesopredator recognition by benthic fish species.

Acknowledgements The authors would like to thank the Department of Environment and Natural Resources – Apo Reef Natural Park Protected Area Management Office (DENR-ARNP PAMO) for logistical support during the surveys. Robert Beringuela and Efraim Pagador of DENR-ARNP PAMO provided on-site assistance during data collection. Funding support was granted by the Department of Science of Technology – Philippine Council for Agricultural, Aquatic, and Natural Resources Research and Development (DOST-PCAARRD) through the Spatiotemporal Monitoring and Rehabilitation Technology for Coral Reefs (SMaRT-Corals) project. We thank the Topic Editor and one anonymous reviewer for their comments that have greatly improved the study.

Compliances The study is observational and does not require any local and/or national animal use permits.

References Baird TA (1993) A new heterospecific foraging association between the puddingwife wrasse, Halichoeres radiatus, and the bar jack, Caranx ruber: evaluation of the foraging consequences. Environ Biol Fishes 38: 393-397 Mendonça P, Grossman A, Sabino J, Haimovici M (2011) Under sea turtles: yellow jacks, Carangoides bartholomaei, use swimming turtles as shelter in the tropical south-western Atlantic. Mar Biodivers Rec 4(e72): 1-3 Sancho G (2000) Predatory behaviors of Caranx melampygus (Carangidae) feeding on spawning reef fishes: a novel ambushing strategy. Bull Mar Sci 66: 487-496 Sancho G, Petersen CW, Lobel PS (2000) Predator-prey relations at a spawning aggregation site of coral reef fishes. Mar Ecol Prog Ser 203: 275-288

＊ESM Supplementary Information 1. can be downloaded from the J-STAGE website: https://doi.org/10.3755/galaxea.23.1_7