Distribution and Colonization of Limnoperna fortunei: Special Traits of an Odd Mussel

Abstract

The invasional success of Limnoperna fortunei was largely determined by the combination of two key components. One of them is rare biological traits of the species, generally unfavorable in freshwater bivalves: the possession of planktonic larvae and a sessile, byssate adult. The other component is man’s extensive modification of landscapes, in particular construction of reservoirs, large interbasin connections—canals and aqueducts and freshwater navigation. This combination was instrumental for the fast dispersal and success of a species that would otherwise have remained inconspicuous and restricted geographically. Environmental tolerance, while helpful, was probably of lesser importance. Possession of planktonic larvae results in a significant advantage for adults that manage to travel upstream, but is a major limitation for those that settle too close to the river outlet into the sea because their offspring are doomed due to expatriation into saline waters. Short rivers are therefore less vulnerable to colonization by self-sustaining populations, especially if there are no lakes or reservoirs along their path that can serve as refuge and seeding grounds for reproducing adults. In South America, interbasin spread has not occurred as fast as anticipated, but will most probably continue increasing.