New records of the centropagid Boeckella triarticulata (Copepoda: Calanoida) in Northern Italy: evidence of a successful invasion?

In the mid 1980's, the Australasian calanoid copepod Boeckella triarticulata was found in fish ponds of Northern Italy, representing the first record of this species for Europe. Its occurrence has not been reported for other Italian localities since 2005, when several specimens were found in the summer zooplankton of the Po River. It seems likely that B. triarticulata could be more widespread in the Po River valley than available distributional data suggest, considering both the scarcity of studies on the plankton of the main river channel and its adjacent water bodies as well as the high ecological plasticity of this centropagid species. The occurrence of this non-indigenous species in Italian waters may depend on the establishment of stable populations or on multiple reintroductions. Its threat as an invasive species is discussed on the basis of our preliminary results and from literature review.