Environmental DNA (eDNA) reveals potential for interoceanic fish invasions across the Panama Canal

Abstract

Interoceanic canals can facilitate biological invasions as they connect the world's oceans and remove 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) metabarcoding and gillnetting) to survey fish communities in this unique waterway. Using COI (cytochrome oxidase subunit I) metabarcoding, we detected a total of 142 fish species, including evidence for the presence of sixteen Atlantic and eight Pacific marine fish in different freshwater sections of the Canal. Of these, nine are potentially new records. Molecular data did not capture all species caught with gillnets, but generally provided a more complete image of the known fish fauna as more small‐bodied fish species were detected. 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 fish invasions. The potential ecological and evolutionary consequences of this increase in marine fishes are not only restricted to the fish fauna in the Canal as they could also impact adjacent ecosystems in the Pacific and Atlantic Oceans.

Biological invasions alter the structure of a tropical freshwater food web

“…Future work should focus on quantifying the proportion of these species that becomes permanently established in the lake and how the structure and dynamics of the food web might continue to change over the coming decades. This will be particularly important given that the influx of marine and estuarine species into Lake Gatun appears to have accelerated in recent years, likely as a result of the recently completed expansion of the Panama Canal (Castellanos‐Galindo et al, 2020; Schreiber et al, 2023).…”

“…Finally, between the 1960s and 1990s, multiple non‐native freshwater fishes were intentionally introduced for aquaculture or fishing (Gonzalez, 1995), most notably the predatory Peacock bass ( Cichla monoculus ), which had dramatic and long‐lasting effects on the diversity and structure of the native fish community (Sharpe et al, 2017; Zaret & Paine, 1973). Although efforts have been made to document these invasions (Castellanos‐Galindo et al, 2020; Guiterrez et al, 1995; Schreiber et al, 2023; Sharpe et al, 2017) and to understand their impacts on community structure (Sharpe et al, 2017; Zaret & Paine, 1973), their consequences for the food web remain unexplored.…”

Ultra-sensitive detection of ecologically rare fish from eDNA samples based on the RPA-CRISPR/Cas12a technology

“…By capturing and analyzing DNA present in a range of terrestrial and aquatic environments, such as cave sediments, surface soils, and water from lakes, streams, and oceans, eDNA provides a non-invasive method for identifying and tracking the presence of species in the environment. 9 , 10 , 11 , 12 Currently, the most commonly used eDNA method involves extracting DNA from various environmental samples (such as air, water, and soil) and analyzing it using a targeted or passive approach. The targeted approach uses species-specific primers with quantitative PCR (qPCR), conventional PCR (PCR), and digital droplet (dd) PCR to detect the presence-absence and estimate the abundance of single species.…”