Black Spot Syndrome (BSS): Investigating parasite suppressing or enhancing Acanthurus sp behavior on Turks and Caicos reefs

Ewa Krzyszczyk, School for Field Studies, Center for Marine Resource Studies, South Caicos, Turks and Caicos Islands and Madelyn Hair, Center for Marine Resource Studies, The School for Field Studies, South Caicos, Turks and Caicos Islands; Department of Biology, University of Richmond, Richmond, VA

Background/Question/Methods
Parasites are abundant in marine habitats yet are rarely included in food web publications. Parasites can play a role in altering their host’s behavior to enhance their transmission. A parasite of interest that is increasing in the Caribbean causes Black Spot Syndrome (BSS). Although BSS is present in many fish, it is especially prevalent in the Ocean Surgeonfish, Acantharus sp., an important herbivore on coral reefs. This study explores whether the parasite causing BSS manipulates trophic transmission by suppressing or enhancing Acantarus behavior at three reefs around South Caicos, Turks and Caicos Islands. Ten-minute focal follows were conducted on 218 fish at three reef sites over 22 days in April and November 2019. Reef sites were chosen due to their proximity to Pandion haliaetus nests (final host of parasite) and prevalence of BSS. Studied subjects were divided into their respective stages of infection: non-infected (0 spots, N=44), stage 1 (1-4 spots, N=69), stage 2 (5-10 spots, N=56) and stage 3 (11+ spots, N=49). Activity budgets (foraging, traveling, resting, and hiding), instantaneous behavior events (being cleaned and chased, chasing, defecating, and rubbing), and bite rate (as bites per minute) on rock, sand, or coral were analyzed.
Results/Conclusions
Results showed that at two of the reefs (Admiral’s Aquarium and Shark Alley) non-infected fish were found to forage significantly more than infected fish with no differences found for resting, hiding, or traveling. The third reef (HDL), site nearest to a P. haliaetus nest, indicated no difference in any activity with infection status. Nor was there any difference in activity budget between stage of infection at any reef site. However, there were significant differences between stage of infection and foraging rates (bites per minute), season dependent. Specifically, non-infected fish had higher foraging rates than stage 1 and stage 3 fish and stage 2 fish foraged more than stage 1 and stage 3 fish. These preliminary results indicate parasite-induced suppressing and enhancing changes in Acantarus foraging behavior, suppressing foraging rates at the beginning of infection (stage 1) and enhancing in later stages of infection (stage 2). The possibility of reduced foraging rates at stage 3 could be due to debilitated locomotion. Many spots on stage 3 fish were on the caudal and dorsal fin and their reaction speeds to potential threats were reduced. Altered locomotion is a common effect of parasitism and future research will explore this potential predation-enhancing behavior further.