eDNA Metabarcoding Reveals Spatial Patterns of Marine Communities Along the Beagle Channel (Tierra del Fuego, Argentina)

The Beagle Channel, located south of Tierra del Fuego (~54° S), is South America’s southernmost intracoastal ecosystem. Here, we applied environmental DNA metabarcoding using a partial sequence of the 12sRNA mitochondrial gene to evaluate the seasonal and spatial dynamics of marine vertebrate communities along the longitudinal gradient of the Beagle Channel. Water samples were collected across seasons and sites spanning the central and eastern sectors of the channel. Vertebrate DNA was amplified and analyzed against a custom reference database enriched with locally generated sequences. A total of 43 vertebrate taxa were detected, including 25 fish, 13 mammals, and 5 seabirds. Vertebrate assemblages were spatially structured along the longitudinal gradient of the Beagle Channel, with the central sector characterized by higher relative abundances of Fuegian sprat (Sprattus fuegensis), Southern elephant seal (Mirounga leonina), South American fur seal (Arctocephalus australis), and domestic species, whereas the eastern sector showed higher relative abundances of fish species including silversides (Odontesthes spp.), Magellanic rockcod (Paranotothenia magellanica), and striped rockcod (Trematomus hansoni), as well as mammals including southern sea lion (Otaria flavescens), North American beaver (Castor canadensis), and native grass mice (Abrothrix spp.). This spatial differentiation was associated with contrasting environmental conditions. No significant seasonal effect was detected. This study provides the first environmental DNA-based baseline of marine vertebrates on the Beagle Channel and validates this approach for ecosystem-scale biodiversity monitoring in subantarctic coastal environments.