Routine analyses of srDNAs with Dpn II and with Taq I revealed a zooxanthella in our surveys (see below) that was different from Symbiodinium A, B, and C (Fig.
Symbiodinium E was the predominant zooxanthella from all three Montastraea species: it occurred in 35 of 43 corals and was the only zooxanthella detected in 18 of these.
6), which was the only taxon of zooxanthella observed between 6.
1992; Rowan and Knowlton, 1995) regarded as one species of coral hosting one species of zooxanthella.
We propose that the Symbiodinium E we observed r epresents a taxon of zooxanthella that occurs in certain habitats not because it performs best in those habitats, but because it tolerates them, whereas Symbiodinium A, B, and C do not.
Anecdotal observations are consistent with our interpretation of Symbiodinium E as a stress-tolerant zooxanthella.
Nevertheless, RFLP data indicate that genotype C2 represents a taxon of zooxanthella, Symbiodinium C2, that is distinct from the Symbiodinium C that occurs commonly in M.
annularis (Results) suggests that our experimental treatment enabled this zooxanthella to exploit a host sp ecies with which it does not commonly associate.
annularis at Rio Carti associate predominantly with Symbiodinium E--an opportunistic taxon of zooxanthella (above) that may also be stress-resistant (Toller et al.