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...

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.

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Coral reefs are degraded by the synergistic action of climate and anthropogenic stressors. Coral cover in the Palk Bay reef at the northern Indian Ocean largely declined in the past decade due to frequent bleaching events, tsunami and increased fishing activities. In this study, we carried out a comparative assessment to assess the differences in the recovery and resilience of three spatially distant reefs viz. Vedhalai, Mandapam and Pamban along Palk Bay affected by moderate, severe and low fishing pressure respectively. The assessment was based on the juvenile coral recruitment pattern and its survivability combined with availability of hard substratum, live coral cover and herbivore reef fish stock. The Vedhalai reef has the highest coral cover (14.6 ± 6.3%), and ≥90% of the live corals in Vedhalai and Mandapam were affected by turf algal overgrowth. The density of herbivore reef fish was low in Vedhalai and Mandapam reefs compared to the Pamban reef with relatively few grazing species. The juvenile coral diversity and density were high in the Pamban reef and low in Vedhalai and Mandapam reefs despite high hard substratum cover. In total, 22 species of juvenile corals of 10 genera were recorded in Palk Bay. Comparison of the species diversity of juvenile corals with adult ones suggested that the Pamban reef is connected with other distant reefs whereas Vedhalai and Mandapam reefs were self-seeded. There was no statistically significant difference in the survivability of juvenile corals between the study sites, and in total, ≥90% of the juvenile corals survived the high sedimentation stress triggered by the northeast monsoon and bleaching stress that occurred recurrently. Our results indicated that the human activities indirectly affected the juvenile coral recruitment by degrading the live coral cover and contributed to the spatial variation in the recovery and resilience of the Palk Bay reef. Low species diversity of the juvenile corals will increase the vulnerability of the Palk Bay reef to species-specific endemic threats.

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Phosphatase Producing Bacteria (PPB) and Inorganic Phosphate Solubilizing Bacteria (IPSB) are important to reef nutrition. These microbes and phosphate concentration play a significant role in the productivity of coral reef ecosystems. A study was conducted in Gulf of Mannar coral reef ecosystem to understand the diversity of these groups of bacteria and their competence in mineralizing the phosphate. The PPB isolates were identified under six genera i.e. Bacillus, Pseudomonas, Micrococcus, Vibrio, Arthrobacter and Brevibacterium. Likewise, the IPSB isolates were also identified that belong to six genera i.e. Bacillus, Arthrobacter, Pseudomonas, Flavobacterium, Flavomonas and Micrococcus. Among the PPB and IPSB strains, Bacillus represented more number of species than others. PPB exhibited maximum activity between pH 8 and 9 and the lowest was at pH 6. Among the phosphatase producers Bacillus cereus (546) showed maximum activity (0.333 mmol/l P) at pH 8. In general, the phosphatase activity in most of the Bacillus species varied with reference to different pH. The species Bacillus megaterium (573) showed highest phosphate solubilizing activity (0.906 mmol/l P) by producing 2-ketogluconic acid. The production of organic acids and phosphatase enzymes by these bacterial groups are responsible for the conversion of insoluble inorganic and organic phosphates into soluble forms which are available for the reef organisms.

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