COS 192-6 - Spatial patterns of pink lesions on the massive coral Porites spp. during 2 outbreaks in Moorea, French Polynesia suggest a link to anthropogenic stress
PhD Candidate University of California - Los Angeles, United States
Background/Question/Methods
Infection outbreaks can alter the structure and functioning of ecosystems, and evidence suggests outbreaks may be increasing in marine systems. Thus, understanding spatial patterns of infection and associated factors that may promote outbreaks is increasingly important in the Anthropocene. Coral in the genus Porites respond to infection by forming raised pink polyps. In July of 2016 and 2021, we observed an outbreak of pink lesions (PL) on coral on the north shore of Moorea, French Polynesia. We quantified spatial patterns in prevalence and dispersion on fringing and back reefs and within two bays with developed watersheds, hypothesizing prevalence (% infected per site) and dispersion (pattern on individual colonies) would be highest within the impacted bays. We also quantified dispersion at a high prevalence site using Morisita’s index.
Results/Conclusions
At low and medium prevalence sites in 2016, 15-20% of colonies had PL compared to 11% in 2021, while high prevalence sites exceeded 90% infected in both years. Overall, aggregation decreased with prevalence, with the low prevalence site highly clustered and the high prevalence site randomly dispersed. Thus, it is unlikely for a colony to be heavily infected unless surrounded by infected colonies. At one impacted site, prevalence was higher in 2021 than in 2016, which could infer that human development has worsened conditions in that area or outbreak cycles along the northern shore can be site dependent. Overall, our results imply PLs in Porites of Moorea are associated with anthropogenic stressors from developed watersheds, which contrasts with patterns found in other reef systems where infection tends to be higher with clearer water. Understanding the cause of these contrasting results may further our understanding of the drivers of this coral infection’s dispersion, density, and its host susceptibility.
