Laboratory models for the study of coral pathologies

Abstract

Worldwide, the scleractinian corals that characterize contemporary coral reef communities are exhibiting a variety of pathological conditions. These conditions range from diseases linked with specific pathogens to the syndrome known as bleaching. The latter phenomenon involves the loss or reduction of the symbiotic zooxanthellae on which the corals depend. Bleaching appears to be a generalized stress syndrome, but in some cases it may be due to pathogenic infections. A full understanding of coral pathologies requires the development of laboratory models. We have developed two complementary protocols that will facilitate the study of coral pathologies at a number of levels. The first method involves the induction of bleaching by exposing the coral to an acute period of reduced temperature. The second protocol allows the dissociation of coral polyps into a number of cell types that can be maintained long-term in primary culture. Among these are multicellular endothelial isolates (MEI) that contain zooxanthellae and show a high rate of motility. The bleaching protocol will enable investigators to study the processes by which corals recover from bleaching, and it will offer a standard that can be compared to other conditions that lead to bleaching. The cell culture technique will enable the study of mechanisms underlying pathological conditions at the cellular level, and permit studies of how pathological conditions disrupt the relationship between corals and their zooxanthellae.