Observations at a green sea turtle, Chelonia mydas, cleaning station identify three cleaning fish symbionts

Abstract

A cleaning station used by juvenile green sea turtles, Chelonia mydas, was found in Brewers Bay, St Thomas, US Virgin Islands. Video observations identified three fish species previously undocumented to participate in this symbiotic relationship. From May 7th to August 12, 2020, a total of 27 h of video recordings of this cleaning station were made during various times throughout the daylight hours resulting in the capture of 612 min of cleaning behavior which consisted of 108 separate cleaning events. At least six green turtles were observed using the cleaning station, but the exact number of turtles could not be confirmed as individual turtles could not always be recognized. Large fish, such as barracudas and jacks, were also observed using the same cleaning station. Turtles were observed using the cleaning station for self-cleaning and cleaning by fish. Juvenile French angelfish, Pomacanthus paru, juvenile Queen angelfish, Holacanthus ciliaris, and small schools of slippery dick wrasses, Halichoeres bivittatus, were observed cleaning green turtles. The angelfish cleaned mainly the head, carapace, and plastron, while the wrasses cleaned mostly the soft parts of the turtle, which suggests some nitch partitioning. The most extended observed cleaning session was 69 min. However, short sessions were more common, with an average duration of 6.2 min and a median duration of 3.0 min. Self-cleaning was performed by rubbing on nearby rocks and a polypropylene rope suspended above the cleaning station. The shared use of a cleaning station and its cleaner fish by multiple turtles likely reduces the epizootic load on the turtles but may increase the transmission of diseases such as fibropapillomatosis. No statistical difference in the duration of cleaning was detected between turtles with and without apparent tumors during the limited observations of this study. Additional research is needed, but these findings may help determine the role of these cleaner fish in the ecology of marine ecosystems and the health of green sea turtles in the Caribbean.