A preliminary assessment of the invasiveness of the Indo-Pacific sponge Chalinula nematifera on coral communities from the tropical Eastern Pacific

Abstract

This is the first report of a sponge that overgrows live corals in the tropical Eastern Pacific ocean. Chalinula nematifera, native from the Indo-Pacific region, is an invasive sponge recorded for the first time in 2003 on coral communities from the Isla Isabel National Park (Mexican Pacific Ocean). Later, in 2006, it was found also on coral reefs from the Cabo Pulmo National Park; 217 nautical miles far away. It has been suggested that C. nematifera was introduced as fouling on ship hulls that have arrived at Isla Isabel from the Indo-Pacific. In this paper we examined the habitat specificity and the distribution and abundance through time of C. nematifera. While there were no significant variations in abundance through time, this species showed a very high specificity for living on live corals of the genus Pocillopora (94% vs. 6% on rocks). One of the environmental parameters that may explain this specificity for ramified corals is the low light intensity inside the coral colony, which was 96% lower than outside it. Coral reefs are currently struggling with a multitude of impacts that have weakened their resilience and pushed them away from equilibrium. As a result, more attention on ecology of corals is necessary. Although the abundance of C. nematifera seems to be stable, long-term monitoring programs (including studies of growth rates and recruitment) are needed to determine if this species could represent a threat to the Mexican coral ecosystem in the future.