Meeting Abstract

37.4  Friday, Jan. 4  Among-site and between-species differences in monogenean parasite (Monopisthocotylea: Capsalidae) loads in two sympatric surgeonfishes (Acanthuridae) in the Virgin Islands NEMETH, D.*; SIKKEL, P.; MCCAMMON, A.; Univ. Virgin Islands, St. Thomas; Centre College, KY; Florida Atlantic Univ., Boca Raton dnemeth@uvi.edu

Monogenean trematode flatworms (Neobenedenia) are external fish parasites that can cause disease and mortality of infected individuals, especially in captivity. As poor water quality can lead to heavier parasite loads in captivity, we looked at whether wild host parasite loads varied among coral reef sites differing in proximity to shore and water flow. Monogeneans were quantified from the skin of two species of surgeonfishes collected at four sites in the U.S. and British Virgin Islands. Parasite loads of blue tang (Acanthurus coeruleus) varied significantly among sites (mean # parasites ranged from 0.1 to 7.7 per fish). Of the 90 ocean surgeonfish (A. bahianus) collected only 3% were infected with monogeneans compared with nearly 55% of the similar-sized blue tang from the same sites. Among infected fish, blue tang had a significantly higher parasite load compared to ocean surgeonfish. To determine if ocean surgeonfish are less susceptible to infection, both species were cleaned of parasites and translocated to a uniform aquarium where they were exposed to high densities of monogeneans. Significantly more blue tang became infected (100%, vs. 58% in ocean surgeonfish), with infected blue tang gaining significantly more parasites than ocean surgeon. Thus, we conclude that differences in parasite loads between the two surgeonfish in the wild reflect physiological differences that affect their susceptibility, rather than behavioral variation in microhabitat use or visits to cleaning stations. Variation in parasite loads among sites may indicate effects of habitat variation on fish health and fish population structure.