ORIGINAL PAPER A preliminary assessment of the invasiveness of the Indo-Pacific sponge Chalinula nematifera on coral communities from the tropical Eastern Pacific Enrique A ´ vila Æ Jose ´ Luı ´s Carballo Received: 17 December 2007 / Accepted: 12 February 2008 / Published online: 27 February 2008 Ó Springer Science+Business Media B.V. 2008 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 monitor- ing programs (including studies of growth rates and recruitment) are needed to determine if this species could represent a threat to the Mexican coral ecosys- tem in the future. Keywords Abundance Á Chalinula nematifera Á Distribution Á Eastern Pacific Á Invasive sponge Á Pocilloporid corals Introduction Non-indigenous species introduced to a new envi- ronment often compete with native species for resources, as well as carry a variety of parasites and pathogens potentially exacerbating impacts (Eldredge and Smith 2001; Altman and Whitlatch 2007). Most estuarine and marine species introductions have been associated with shipping (Tokioka 1953; Monniot et al. 1985; Nishikawa 1991; Carlton and Geller 1993; Cohen and Carlton 1995; Lambert and Lambert 1998; Ruiz et al. 2000). Through this dispersal mechanism, many species are transported from harbour to harbour in ballast water and fouling of the ship hulls (Carlton and Geller 1993). The better-known invasive marine invertebrates are mol- luscs (Carlton et al. 1990), ascidians (Lambert and Lambert 1998), bryozoans (Levin et al. 2002), poly- chaetes (Luppi and Bas 2002) and crabs (Cohen and Carlton 1995), which have caused disruptions to the E. A ´ vila (&) Á J. L. Carballo Laboratorio de Ecologı ´a del Bentos, Instituto de Ciencias del Mar y Limnologı ´a, Universidad Nacional Auto ´noma de Me ´xico, Estacio ´n Mazatla ´n, Avenida Joel Montes Camarena S/N, Apartado Postal 811, Mazatlan 82000, Mexico e-mail: kike@ola.icmyl.unam.mx 123 Biol Invasions (2009) 11:257–264 DOI 10.1007/s10530-008-9230-5