Aspergillus sydowii and Other Potential Fungal Pathogens in Gorgonian Octocorals of the Ecuadorian Pacific

Abstract

Emerging fungal diseases are threatening ecosystems and have increased in recent decades. In corals, the prevalence and consequences of these infections have also increased in frequency and severity. Coral reefs are affected by an emerging fungal disease named aspergillosis, caused by Aspergillus sydowii. This disease and its pathogen have been reported along the Caribbean and Pacific coasts of Colombia. Despite this, an important number of coral reefs worldwide have not been investigated for the presence of this pathogen. In this work, we carried out the surveillance of the main coral reef of the Ecuadorian Pacific with a focus on the two most abundant and cosmopolitan species of this ecosystem, Leptogorgia sp. and Leptogorgia obscura. We collected 59 isolates and obtained the corresponding sequences of the Internal Transcribed Spacers (ITS) of the ribosomal DNA. These were phylogenetically analyzed using MrBayes, which indicated the presence of two isolates of the coral reef pathogen A. sydowii, as well as 16 additional species that are potentially pathogenic to corals. Although the analyzed gorgonian specimens appeared healthy, the presence of these pathogens, especially of A. sydowii, alert us to the potential risk to the health and future survival of the Pacific Ecuadorian coral ecosystem under the current scenario of increasing threats and stressors to coral reefs, such as habitat alterations by humans and global climate change.

The roles of endolithic fungi in bioerosion and disease in marine ecosystems. II. Potential facultatively parasitic anamorphic ascomycetes can cause disease in corals and molluscs

“…They reported the incidence of aspergillosis, an emerging fungal disease caused by A. sydowii in gorgonian corals ( G. ventalina and G. flaballum ) in the Caribbean. Soler-Hurtado et al (2016) also reported this disease in gorgonian corals ( Leptogorgia obscura and L. sp.)…”

“…However, Toledo-Hernández et al (2008) stated that they doubted that A. sydowii is the only fungus that can cause aspergillosis in G. ventalina because it is not always present in diseased corals. Soler-Hurtado et al (2016) found A. sydowii and other potential fungal pathogens in gorgonian octocorals of Ecuador (see below). Since A. sydowii can be present in healthy corals, perhaps environmental factors are involved as well.…”

“…Fruiting bodies have not been observed for many species in the ocean, which makes identification more difficult. The prevalence and consequences of infection caused by Ascomycota and other fungi have increased in frequency and severity in recent decades (Soler-Hurtado et al 2016). Many species of Ascomycota produce toxins, which are directly harmful to many animals including humans.…”

“…Soler-Hurtado et al (2016) isolated 17 fungal species, including A. sydowii (7% of isolates) from healthy corals in Columbia. However, the samples were taken from a depth of 10–15 m, where low oxygen availability would limit fungal growth.…”

“…The prevalence and consequences of these infections have increased in frequency and severity in recent decades (Soler-Hurtado et al 2016). …”