Nutrient enrichment can increase the severity of coral diseases

TLDR

Marine disease prevalence and severity have risen over the past two decades, threatening key species, likely due to human‑induced environmental changes that weaken host resistance or boost pathogen virulence. The study investigates whether nutrient enrichment heightens the severity of two Caribbean coral diseases—aspergillosis in *Gorgonia ventalina* and yellow band disease in *Montastraea annularis* and *M. franksii*.

Abstract

Abstract The prevalence and severity of marine diseases have increased over the last 20 years, significantly impacting a variety of foundation and keystone species. One explanation is that changes in the environment caused by human activities have impaired host resistance and/or have increased pathogen virulence. Here, we report evidence from field experiments that nutrient enrichment can significantly increase the severity of two important Caribbean coral epizootics: aspergillosis of the common gorgonian sea fan Gorgonia ventalina and yellow band disease of the reef‐building corals Montastraea annularis and M. franksii . Experimentally increasing nutrient concentrations by 2–5× nearly doubled host tissue loss caused by yellow band disease. In a separate experiment, nutrient enrichment significantly increased two measures of sea fan aspergillosis severity. Our results may help explain the conspicuous patchiness of coral disease severity, besides suggesting that minimizing nutrient pollution could be an important management tool for controlling coral epizootics.