Transport of Marine Life between Oceans through the Panama Canal

Abstract

THE water in most of the Panama Canal is fresh with no measurable salinity (Fig. 1). Because of this, the intermingling of Atlantic and Pacific marine fauna, after the projected United States sea level canal is completed, is a subject of speculation and interest¹. The towing of an assortment of marine animals through the canal with a limited in-transit mortality as a result of the low salinity suggests that there is a continued gene flow among fouling animals on either side of the canal. This experiment does not suggest that the freshwater of the Panama Canal is not a barrier to most intertidal non-sessile organisms in their normal mode of transport by larvae or adult movements. For these animals it is probably a most effective barrier and quite unlike the situation at Suez where migrations are commonly recorded². But for typical fouling organisms, such as barnacles and the like, a conservative estimate of the marine fouling transported between each ocean by normal ship traffic is 252,000 kg/yr.