Wide distributional range of marine sponges along the Pacific Ocean

Widespread geographic distribution of sponges should be rare, mainly because of the low dispersal capacity of their larvae and asexual products. Here we investigate the potential wide-scale distribution range in one marine sponge, Gelliodes wilsoni, that has been spread widely around the Pacific Rim by shipping. The species was originally described from the Philippines (western Pacific Ocean) by Wilson in 1925 as Gelliodes fibrosa. Recently, similar specimens have been collected from Guam (western Pacific Ocean), Hawaii, Palmyra Atoll (central Pacific Ocean), Acapulco Bay and Baja Peninsula (eastern Pacific Ocean). This species now appears to be widely distributed across the Pacific Ocean, and this distribution seems unlikely to have resulted from an extremely high dispersal capability; it is most likely the result of centuries of trans-Pacific shipping. We also propose the new name G. wilsoni for the species G. fibrosa originally described by Wilson because the same name was previously used by Dendy in 1905 to describe a species from Sri Lanka, which is morphologically different from the species described by Wilson. The case of G. wilsoni is not unique because several sponges (discussed here) have similar distribution patterns across the Pacific (at locations more than 10,000 km apart). This suggests an east–west connectivity and that widespread distribution in sponges is indeed possible, albeit the result of human activities. In an increasingly connected world our research highlights the importance of understanding connectivity across oceanic scales in order to predict where invasive species are likely to occur.