As part of its Healthy Rivers programme, WWF Peru needed to survey six target aquatic species along the Marañón River in the northern Peruvian Amazon. The species included Amazon manatees, pink river dolphins and migratory catfish.

Traditional methods would have meant a separate survey for each species. With eDNA, all six could be surveyed together, along with the rest of the vertebrate fauna, saving both time and money. After just three sampling trips, WWF Peru had a comprehensive dataset covering 675 aquatic and non-aquatic species.

Sampling a vast landscape

The survey covered a vast stretch of the Marañón River, from the Andean slopes to the Brazilian border. Surveying even a few species across this distance with traditional techniques would have needed separate surveys, multiple trips and far more resources.

Sampling made simple

NatureMetrics trained two members of the local WWF Peru team in our aquatic eDNA sampling protocol, which is quick and simple for anyone to carry out in the field. Over three trips, the team collected samples at 40 points along the Marañón River.

The samples were analysed in our laboratories to survey all six target species at once, alongside the full vertebrate community. This gave WWF Peru far more data for the same investment of time and effort.

eDNA analysis detected 675 species, including 375 fish, 155 mammals and 65 birds.

Over half of the species detected were fish. This is expected, as fish shed lots of DNA and the Amazon has the highest diversity of freshwater fish in the world.

Among the mammals, 100 were non-aquatic species, including:

• Small mammals: many species of rodents and opossums
• Large ungulates: tapirs, deer and peccaries
• Top predators: jaguars and ocelots
• Other terrestrial species: giant anteaters and armadillos
• Arboreal species: almost all of the monkey species known in the area
• Bats: 25 species

An invaluable resource for measuring and protecting biodiversity

• One survey instead of many: A single, repeatable eDNA protocol replaced multiple specialist surveys, delivering landscape-scale data in a fraction of the time and cost.
• Comprehensive, auditable data: WWF Peru now has locational, occupancy and frequency data, plus diversity patterns, for 675 species across the river and surrounding forests.
• Endangered species detected: The survey recorded endangered species such as jaguars and giant river otters.
• Supporting local livelihoods: The data covers hundreds of fish species that are vital to local communities but almost impossible to survey any other way. That information supports conservation planning across the northern Peruvian Amazon.