Rapid long-distance multispecies transport of shorefish larvae to the oceanic tropical eastern Pacific, revealed by DNA barcodes and otolith aging of larvae captured over the Galapagos Rift

Intensive sampling at a site over the Galapagos Rift hydrothermal vents in the tropical eastern Pacific Ocean yielded 1338 shorefish larvae. At least 77 species in 29 families of shorefishes were identified using mitochondrial DNA barcoding and morphology. The species were not characteristic of the Galapagos or Cocos Island faunas, but included continental marine, brackish, and freshwater species not recorded on the offshore islands. Larvae of 3 species of freshwater amphidromous Sicydium gobies were present, including an undescribed species from the Rio Pichende in Panama. Also captured were larvae of 5 continental brackish and estuarine gobioid species and about 20 other species from soft-bottom, continental shelf habitats not found on the islands, some ranging south only to Panama or Colombia. Among reef fishes, the barcodes of 3 species did not match the Galapagos Islands population: the scorpionfish Scorpaenodes species matched the continental nominal species, and the razorfish Xyrichtys species and chameleon wrasse (Halichoeres dispilus) matched populations from Panama, about 1000 km to the northeast. The range of sizes and ages of some species were especially wide, indicating a continuing inflow of continental shorefish larvae. The youngest larvae were 23 days old, and the youngest Panama-sourced larvae were 6 weeks old, indicating straight-line offshore transport of at least 15–20 km/d.