Skeletal tumor formations in the massive coral Pavona clavus

Abstract

Skeletal tumor formations in the massive coral Pavona clavus were investigated for 3 yr on the northern Pacific coast of Costa Rica in a reef composed almost exclusively of this species. A field survey of tumor incidence showed that more than half of the population presented this phenomenon and that frequencies increased with depth. Up to 37 tumors per colony were recorded, and the largest tumor size was 37.5 m 2 , covering the whole colony surface area. Tumors and healthy skeletons and tissues were studied by scanning and transmission electron microscopy, histology, in situ alizarin marking for growth rates, and x-ray radiographs of skeletal slabs. Macroscopic and microscopic analyses of skeletons revealed the presence of 3 types of tumors (Types I to III). No cytological changes or intracellular infection by parasitic agents were recorded. The only cellular change observed was the reduced numbers of zooxanthellae in tumorigenic tissues. Tumors begin their growth as a single polyp and develop for scores of years without any sign of cellular necroses. Tumors grew faster than healthy parts; however, their skeletal density was lower, with a higher Mg content making it less resistant to bioerosion. Two yr of in situ isogeneic and allogeneic contacts between healthy and tumor fragments revealed no infection or transfer of the tumor to the healthy tissue, even following isogeneic fusion combinations of healthy versus tumor fragments. We suggest that the terminology often used to characterize tumors in hard corals ('tumor', 'neoplasm', 'hyperplasia') does not reflect the pathogenesis and etiology of this phenomenon. The terms 'skeletal tumor' or 'calicoblastic epithelioma' seem more fitting for this de novo genesis.

Skeletal structure and progression of growth anomalies in Porites australiensis in Okinawa, Japan

“…However, if no free space is available, GAs would likely overgrow healthy partners. Gateño et al (2003) observed healthy tissues overgrown by GA tissues in Porites clavus. Peters et al (1986) and Work et al (2008) reported that progressive growth of GAs in Acropora spp.…”

“…Higher growth rates of GAs compared to healthy tissues have been reported for Acropora formosa (Cheney 1975), A. palmata (Peters et al 1986), Platygyra pini, P. sinensis (Loya et al 1984), and Pavona clavus (Gateño et al 2003). GAs probably overgrow adjacent healthy regions using energy supplied from the adjacent tissue.…”

“…Several researchers have investigated whether GAs are transmissible (Peters et al 1986, Gateño et al 2003, Kaczmarsky & Richardson 2007. Most studies have not detected positive transmissions, although transmissions of GAs by direct contact and waterborne substances were reported in Porites colonies (Kaczmarsky & Richardson 2007).…”

“…Recently, GAs have been reported to occur worldwide (Yamashiro et al 2000, Gateño et al 2003, Kaczmarsky 2006, Work et al 2008, McClanahan et al 2009, Stimson 2010.…”

Coral disease dynamics in the central Philippines

“…PUWS is characterized by discrete, bleached, round foci, 3 to 5 mm in diameter, that may result in ulcerations that coalesce and cause tissue loss and colony mortality (Raymundo et al 2003). Other Indo-Pacific diseases not previously observed in the Philippines include, but are not limited to, Porites pink-line syndrome (Ravindran & Raghukumar 2002) and coral tumors (Coles & Seapy 1998, Hunter 1999, Yamashiro et al 2000, Gateño et al 2003. Coral reef bleaching in the Philippines has caused acute losses of coral cover (Raymundo & Maypa 2002, Wilkinson 2002.…”