Figure 1

Reinfection process involving Cliona varians forma varians . Symbiodinium were released from recently collected sponges (step 1). The dark brown ring that can be seen in the cross-section of the sponge represents the pinacodermal region where Symbiodinium reside at high densities. The brown color comes from the symbiont populations. Aposymbiotic sponges grown in a light-tight aquarium were inoculated with Symbiodinium (step 2). These sponges were monitored for several days until signs of reinfection were noticeable at which point a sample was taken for subsequent molecular work (step 3).