Poriferan abundance is negatively associated with coral health in the mesoamerican reef

The Mesoamerican Reef is the second largest coral reef in the world and has experienced a 50% loss of coral coverage in recent decades. Due to the high biodiversity of marine life that depend on the Mesoamerican Reef, identifying drivers of coral loss is crucial. This study was designed to assess the relationship between the presence of yellow band disease (YBD) and white plague type-II (WPII) on stony corals with environmental (water depth) and biological stressors (abundance of sponges in close proximity) in the reef surrounding the Bay Islands, Honduras. Both radial and parallel transect survey techniques were used to quantify the abundance of seven sponge species within a one-meter radius of Orbicella species and Montastraea cavernsoa. The strongest predictor of coral health was the abundance of Callyspongia plicifera, followed by Svenzea zeai, in close proximity to diseased coral. A weak, but positive, correlation between poriferan abundance and the presence of disease lesions on coral was observed. However, no significant relationship of disease prevalence with water depth was observed. Additionally, no differences in the prevalence of disease lesions between four species of native stony corals were observed. These findings suggest coral species are equally susceptible to bacterial pathogens, but that close association with poriferans may increase the transmission and persistence of harmful bacteria in coral reef ecosystems.