Fungi in Porites lutea: association with healthy and diseased corals

Abstract

Healthy and diseased scleractinian corals have been reported to harbour fungi. However, the species of fungi occurring in them and their prevalence in terms of biomass have not been determined and their role in coral diseases is not clear. We have found fungi to occur regularly in healthy, partially dead, bleached and pink-line syndrome (PLS)-affected scleractinian coral, Porites lutea, in the reefs of Lakshadweep Islands in the Arabian Sea. Mostly terrestrial species of fungi were isolated in culture from these corals. Hyaline and dark, non-sporulating fungi were the most dominant forms. Fungal hyphae extended up to 3 cm within the corals. Immunofluorescence detection using polyclonal immunological probes for a dark, initially non-sporulating isolate (isolate # 98-N28) and for a hyaline, non-sporulating fungus (isolate # 98-N18) revealed high frequencies of these in PLS-affected, dead and healthy colonies of P. lutea. Total fungal biomass accounted for 0.04 to 0.05% of the weight of corals in bleached corals and was higher than in PLS-affected and healthy colonies. Scanning electron microscopy revealed the presence of fungi within the carbonate skeleton and around polyps. Fungi appear to be a regular component of healthy, partially dead and diseased coral skeleton.KEY WORDS: Scleractinian coral · Porites lutea · Bleaching · Pink-line syndrome · Fungi · Immunofluorescence probe · Lakshadweep Islands · Arabian sea · India Resale or republication not permitted without written consent of the publisherDis Aquat Org 47: [219][220][221][222][223][224][225][226][227][228] 2001 MATERIALS AND METHODS Study area. Diseases of corals were surveyed in the lagoon and intertidal zones of Kavaratti Island of the Lakshadweep archipelago off the south-west coast of India. The Lakshadweep archipelago comprises 36 islands with 12 atolls and lies between 10-12°N and 71°40'-74°E in the Arabian Sea ( Fig. 1) and forms the northern part of the Laccadive-Chagos Ridge. Samples of Porites lutea were collected in the lagoon at a depth of 3 to 5 m and samples of P. compressa were collected from the intertidal zone of reef flat in Kavaratti Island. Bleached and PLS-affected corals were collected in October and November 1998 and April 1999.Frequency of fungi isolated from corals. Small pieces from the surface of healthy-looking colonies of Porites lutea and those showing PLS were chiselled and collected in sterile plastic bags under water. The samples were taken in ice and processed within 2 h of collection. The coral samples were broken further into smaller pieces inside the same plastic bags, thereby avoiding exposure of the broken surface to air to avoid contamination by aerial opportunistic fungi. The broken pieces ranging in size from 3 to 5 mm 3 were directly plated on 1:5 diluted corn meal agar medium (HI-MEDIA, Mumbai, India) prepared with halfstrength sea water and fortified with streptomycin (0.5 g l -1 medium) and penicillin (100 000 U l -1 medium) to inhibit bacterial growth. The presence of aerial fungi in the experi...

Disease and immunity in Caribbean and Indo-Pacific zooxanthellate corals

“…3D) affect 16 Caribbean (Table 2) and 24 Indo-Pacific (Table 3) scleractinian species, 1 Caribbean hydrozoan, and at least 5 species of Caribbean gorgonians (Table 2; Squires 1965, Cheney 1975, Morse et al 1977, Bak 1983, Goldberg et al 1984, Loya et al 1984, Peters et al 1986, Hunter & Peters 1993, Le Champion-Alsumard et al 1995, Grygier & Cairns 1996, Coles & Seapy 1998, Green & Bruckner 2000, Yamashiro et al 2000, Ravindran et al 2001, Dube et al 2002. Acroporids appear to be the most susceptible to neoplasia (Peters et al 1986, Coles & Seapy 1998, and this may be due to the rapid growth rates of this genus (Peters et al 1986).…”

“…With the exception of microorganism-induced nodule or gall formation (Cheng & Wong 1974, Morse et al 1977, Goldberg et al 1984, Le Champion-Alsumard et al 1995, Grygier & Cairns 1996, Aeby 1998, Ravindran et al 2001, Dube et al 2002, the etiology of coral skeletal anomalies is unknown (Peters et al 1986, Coles & Seapy 1998, Yamashiro et al 2000. Parasitic and commensal organisms have been ruled out as potential causal agents of the skeletal anomalies described by Peters et al (1986) in the Florida Keys and by Yamashiro et al (2000) in Japan.…”

“…Porites compressa and P. lobata in Kaneohe Bay, Oahu, Hawaii develop grossly visible pink nodules in response to the encystment of the digenetic trematode Podocotyloides stenometra within the tentacles of the coral polyps ( Ravindran et al 2001, E. C. Peters pers. comm.).…”

Study on the effects of near-future ocean acidification on marine yeasts: a microcosm approach

“…Yeasts play an important role in the breakdown of plant and refractory material and the cycling of nutrients (Meyers and Ahearn 1974;Kutty and Philip 2008) and are frequently found on decaying algae (van Uden and Castelo Branco 1963;Seshadri and Sieburth 1971;Patel 1975). Additionally, yeasts occur associated with marine animals, for example, fish, shrimps, mussels, corals, and seabirds (van Uden and Castelo Branco 1963;Kawakita and van Uden 1965;Ravindran et al 2001;Burgaud et al 2010;Yang et al 2011). Notably, pathogenic yeast species can also cause infections in animal hosts such as marine mammals and copepods (Seki and Fulton 1969;Higgins 2000).…”

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

“…Ravindran et al (2001) studied fungi in both healthy and diseased corals ( P. lutea and Porites compressa ) from the Lakshadweep Islands in the Indian Ocean. These fungi grew inside the skeleton and around the coral polyps and ultimately penetrated the coral tissues.…”