Biotic Invasions in a Mediterranean Lagoon

Many non-indigenous species have been found during recent decades in the Lagoon of Venice; many of these species are rapidly becoming both widespread and abundant. Reported here is the invasion of an accidentally introduced bryozoan Tricellaria inopinata, which dominated the Lagoon's fouling community within seven years of its initial detection. Recent declines in its population as well as those of indigenous bryozoans illustrate the importance of placing invasions in the context of the hydrological, chemical and biotic changes that occur in the Lagoon environment. This revised version was published online in July 2006 with corrections to the Cover Date.