Fungi and Their Role in Corals and Coral Reef Ecosystems

Abstract

Fungi in coral reefs exist as endoliths, endobionts, saprotrophs and as pathogens. Although algal and fungal endoliths in corals were described way back in 1973, their role in microboring, carbonate alteration, discoloration, density banding, symbiotic or parasitic association was postulated almost 25 years later. Fungi, as pathogens in corals, have become a much discussed topic in the last 10 years. It is either due to the availability of better tools for investigations or greater awareness among the research communities. Fungi which are exclusive as endoliths (endemic) in corals or ubiquitous forms seem to play a role in coral reef system. Fungi associated with sponges and their role in production or induction of secondary metabolites in their host is of primary interest to various pharmaceutical industries and funding agencies. Fungal enzymes in degradation of coral mucus, and plant detritus hold great promise in biotechnological applications. Unravelling fungal diversity in corals and associated reef organisms using culture and culture-independent approaches is a subject gaining attention from research community world over.

Fungal association with sessile marine invertebrates

“…Endolithic fungi have been shown to elicit a defensive response in corals, and have thus been suggested to elicit a parasitic, rather than saprophytic (or mutualistic) nature of association (Le Campion-Alsumard et al, 1995; Bentis et al, 2000; Golubic et al, 2005; Raghukumar and Ravindran, 2012). Perhaps the most striking example for potential parasitism has been the study of Aspergillus sydowii , a common terrestrial fungus suggested to cause an epidemic in the sea fan Gorgonia ventalina that can also confer symptoms to G. flabellum (Geiser et al, 1998; Kim and Harvell, 2004).…”

The roles of endolithic fungi in bioerosion and disease in marine ecosystems. I. General concepts

“…The heterotrophic microbial endoliths include a few documented parasitic species in the Ascomycota (true fungi) and Labyrinthulomycota (Stramenopilia) (Kohlmeyer 1969; Raghukumar and Lande 1988; Porter and Lingle 1992; Golubec et al 2005; Raghukumar and Ravindran 2012) and these aggressive species may attack and feed on the photosynthetic endoliths. The heterotrophic endoliths are thought to release proteolytic enzymes which facilitate the breakdown of proteins left over from the process of formation of the shells by the animals.…”

“…Although fungi undoubtedly play many important ecological roles in coral ecosystems, they have been largely ignored in the past (Bentis et al 2000). Our current and very limited knowledge of the roles of fungi in corals and coral reef ecosystems has been reviewed in detail by Raghukumar and Ravindran (2012). Corals, lichens and mycorrhizae are all symbiotic relationships involving fungi.…”

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

“…Many species of fungi are known to bore into solid rock, sand grains and shells and can cause disease in many animal and plant tissues in marine ecosystems (Rosenberg and Ben-Haim 2002; Golubic et al 2005; Pitt and Hocking 2009; Raghukumar and Ravindran 2012; Burge et al 2013). In this review, we discuss what is known about the different ecotypes of Ascomycota (true fungi) with emphasis on anamorphic stages of Aspergillus sydowii and other species, which bore into skeletons of corals or shells of molluscs and infect the soft tissues of these animals causing diseases in marine ecosystems.…”