One Hundred Years of Suez Canal-A Century of Lessepsian Migration: Retrospect and Viewpoints

Abstract

Por, F. D. (Dept. of Zoology, Hebrew Univ., Jerusalem) 1971. One hundred years of Suez Canal–a century of Lessepsian migration: Retrospect and Viewpoints. Syst. Zool., 20:138–159. One hundred years has passed since one of the biggest biogeographical experiments started with the opening of the Suez Canal. The successful migration along the Canal of a great many Red Sea species into the Mediterranean is seen as a process to which most of these species were preadapted in the littoral environment of the Red Sea. The repeated transgressions of this sea into the basin of the Bitter Lakes and the existence—presently and in the past—of several slightly hypersaline lagoons along its shores, resulted in the creation of a special stock of species able to perform this migration. Progress through the Canal is either a step-by-step one, or a result of active swimming (or transport). Neither the role of planktonic spread by means of larvae and/or currents, nor the obstacles put by the salinity, should be overemphasized. The main factors in helping or hindering migration are considered to be the presence of suitable substrates and water transparencies in the Canal. The Levant Basin of the Mediterranean was also “preadapted” to receive the immigrants because of its high salinity and temperature and the resulting biological undersaturation with temperate fauna. Most probably this explains the one-way stream of the migrants into the Mediterranean. The distribution limits of the immigrants in the Mediterranean are most probably set by the increasing competitive capacities of the aboriginal species. The westward advance of the immigrants in the Mediterranean will probably become more pronounced after the damming of the Nile waters behind the newly erected Ass wan dam.