Outbreaks of disease in marine ecosystems are projected to increase in number and severity. Coral reefs are particularly vulnerable and critically important for maintaining associated biodiversity and providing goods and services to tropical coastal communities worldwide. Although millions of people depend on a multitude of coral reef associated species for essential proteins and micronutrients, there are no studies investigating the influence of coral disease outbreaks on pathogen loads in species residing in locations impacted by disease and the resultant ecosystem-wide impacts. In this study, we first used next-generation high-throughput amplicon sequencing of the 16S ribosomal RNA gene to assess differences in marine pathogen loads of juvenile reef fish that have newly recruited into reef corals with and without visual signs of disease lesions. Next, we conducted reef-scale field surveys to assess whether juvenile reef fish prefer habitats without visual signs of disease. Finally, extensive surveys along the Myeik Archipelago in Myanmar were conducted to examine whether reef sites with increased levels of coral disease impact site-attached fish abundance.
Results/Conclusions
Through the quantification of < 1.5 million high-quality bacterial taxonomic (OTU) reads, we find that juvenile coral reef fish have a 4-fold increase in tissue-associated bacterial pathogens when they recruit into corals with visual signs of disease compared to corals without disease. These results suggest that coral may act as a reservoir for pathogens that can be subsequently transmitted to site-attached fish communities, increasing disease levels in local fisheries species and threatening human health. Moreover, reef-scale surveys show that the same species of reef fish are twice as likely to be associated with coral that do not have visual signs of disease, suggesting active avoidance of sub-optimal habitat that can increase crowding that can lead to density-dependent competition and mortality. Finally, surveys of 14 sites spanning 80 km reveal significant decreases in site-attached coral reef fish as coral disease levels increase, demonstrating the role in which managing known local drivers of disease outbreaks on coral reefs may influence dependent fisheries at large-scales. Outcomes from this research will be used to globally forecast and predict locations where coral reefs and fisheries will be impacted by climate-associate disease outbreaks, enabling targeted management strategies that improve human livelihoods.