2018 Pufferfish Corallivory on the Massive Coral Porites lobata in the Galápagos Islands

Guy Harvey Oceanographic Center Facility

Arothron meleagris is an obligate corallivorous pufferfish that scrapes tissue off the coral skeleton with its parrot-like beak. It is a common member of coral communities in the Galápagos Islands where it predominantly feeds on zooxanthellate scleractinian corals. Since the predatory sea star Acanthaster plancii is absent from the Archipelago, A. meleagris may be the most significant coral predator in this region. It is hypothesized that this pufferfish preferentially feeds on elevated (ridged) regions of the coral colony as compared to smoother colony surfaces, allowing greater feeding efficiency. The purpose of this study was to determine if there is a relationship between frequency of Arothron meleagris bite marks and location (ridged vs. smooth) on massive Porites lobata colonies. Images of coral colonies that have A. meleagris bites were taken off of Darwin Island, Galápagos, Ecuador in 2012. These images were analyzed using CPCE in two ways, 1) bite frequency as it relates to overall colony morphology (ridged vs. smooth colonies) and 2) bite frequency as it relates to morphology within a colony (ridged vs. smooth areas of ridged colonies). The average bite frequencies between ridged and smooth colonies was analyzed and there was no significant difference (t-Test, p = 0.08). This may be due in part to the small sample size, and warrants further investigation in the future. Ridged colonies were then analyzed independently, comparing the bite frequencies of the ridged and smooth areas within the colony. This comparison did yield a significant result (t-Test, p = 0.01), suggesting that ridged areas are more frequently targeted by Arothron meleagris within ridged colonies. This may be due to ridged areas being more accessible, requiring less energy consumption to obtain necessary nutrients.