Environmental DNA (eDNA) reveals potential for interoceanic fish
invasions across the Panama Canal
Interoceanic canals can facilitate biological invasions as they connect
the world’s oceans and dissolve dispersal barriers between bioregions.
As a consequence, multiple opportunities for biotic exchange arise and
the resulting establishment of migrant species often causes adverse
ecological and economic impacts. The Panama Canal is a key region for
biotic exchange as it connects the Pacific and Atlantic Oceans in
Central America. In this study, we used two complementary methods
(environmental DNA (eDNA) and gillnetting) to survey fish communities in
this unique waterway. Using COI (cytochrome oxidase subunit I)
metabarcoding, we detected a total of 142 taxa, including evidence for
the presence of sixteen Atlantic and eight Pacific marine fish inside
different sections of the Canal. Of these, ten are potentially new
records of marine taxa detected in the freshwater segment of the Canal.
Molecular data did not capture all species caught with gillnets, but
generally provided a more complete image of the fish fauna. Diversity
indices based on eDNA surveys revealed significant differences across
different sections of the Canal reflecting in part the prevailing
environmental conditions. The observed increase in the presence of
marine fish species in the Canal indicates a growing potential for
interoceanic exchange of fishes across the Isthmus. Monitoring using
eDNA is a rapid and efficient way to assess potential changes in the
fishes of this important waterway.