Tissue regeneration in the coral Fungia granulosa: the effect of extrinsicand intrinsic factors

To understand how regeneration in corals may be affected by intrinsic and e xtrinsic factors, the process of repair of experimentally induced tissue le sions was investigated in the solitary scleractinian coral Fungia granulosa . Three lesion sizes were inflicted in situ on large, sexually mature indiv iduals (>5.5 cm diameter) and in small sexually immature (<5.0 cm) individu als. Repair was monitored using photography and computerized image analysis . This procedure was carried out in fall (September to November; post-repro ductive months), and repeated with a new set of corals in spring (March to May; gametogenic months). Reproductive effort was investigated histological ly 1 to 2 months following lesion infliction. In field experiments, there w as a significant difference in percent of tissue coverage 8 weeks after les ion infliction between spring and fall for all lesion sizes in large corals . During the fall, all lesion sizes in large corals were repaired within 8 weeks. Large lesions in small col als did not undergo repair regardless of season. During the spring, none of the corals underwent complete repair reg ardless of coral size, and many of the small corals died. In laboratory exp eriments, 83.3% of the corals kept at 25 <degrees>C and 16.7% of those kept at 21 degreesC underwent repair during the fall. None of the corals mainta ined at 21 degreesC and only 16.7% of those corals maintained at 25 degrees C underwent complete repair during spring. Though both fecundity and tissue regeneration were significantly reduced, gametogenesis continued in corals that had previously undergone experimental injury. These results indicate that in fungiid corals, regeneration is affected by intrinsic factors such as size and reproductive state as well as by environmental factors such as ambient water temperatures. Moreover, it is possible that, following injury , energetic resources are diverted from repair towards the maintenance of r eproductive effort.