First documentation of encrusting specimen of Cliona delitrix on Curaçao: a cause for concern?

The coral excavating sponge Cliona delitrix is one of the most aggressive and conspicuous excavating sponges on Caribbean reefs. While C. delitrix is very prominent displaying its typical encrusting growth form (β-stage) on the Caribbean island of Bonaire, it is rather elusive and only exhibits a papillated habitus (α-stage) on the neighboring island of Curaçao. Here I document the first two encrusting specimen of C. delitrix on Curaçao and discuss potential explanations for island-specific differences in its habitus and occurrence. An increase of encrusting specimen could have profound consequences for Curaçaoan reefs and should thus be monitored closely.