Historical Ecology and Invasion Biology: Long-Term Distribution Changes of Introduced Freshwater Species

Abstract

We used historical written accounts from Spain to describe the long-term dynamics in the distributions of tench (Tinca tinca), common carp (Cyprinus carpio), and white-clawed crayfish (Austropotamobius italicus) from the sixteenth century to the present. The results show the widespread, human-mediated expansion of the three species and support their introduced status, which has been controversial for tench and crayfish. The temporal patterns of spread of the three species differ dramatically. Although tench and crayfish expanded rapidly, carp spread mainly during the twentieth century, probably because of hydrologic alterations to Spanish streams. This prolonged time lag in the expansion of an introduced species calls for precaution when judging species invasiveness. Austropotamobius italicus is the focus of several conservation actions in Spain, a strategy that should be questioned in the view of the crayfish's probable introduced status. This work provides an example of how historical ecology analyses may have implications for present-day environmental management.