Tolerance of Brazilian brain coral Mussismilia braziliensis to sediment and organic matter inputs

Abstract

In Brazil, where reefs occur in markedly turbid environments, the relationship between sedimentation/organic matter and corals is poorly known. Thus, the ex situ effects of sediment with and without organic matter over the ΔF/Fm and physical state of Mussismilia braziliensis were analyzed. The ΔF/Fm and coral physical state, evaluated through the susceptibility index to sedimentation (SI), were measured in seven colonies exposed to sedimentation (0–450mgcm−2day−1) free of organic matter after 45days of exposure, and in 12 colonies exposed to sedimentation (0–500mgcm−2day−1) with organic matter content (10%), in which case ΔF/Fm was measured after 72h and SI after 120h. In both cases there were effects of increasing sedimentation on the SI with no effect on ΔF/Fm. Despite the tolerance to high sedimentation rates shown by this coral, we noted that the presence of organic matter might reduce its tolerance to sedimentation stress.