Giant otter | adibarocas

Giant otters live in South America's neotropical freshwater ecosystems. They are top carnivores, feeding on fish of various sizes. The species is listed as Endangered by the IUCN. Giant otters are sensitive to the degradation of Amazon freshwater environments, mostly as a result of human activity.

Our project focuses on freshwater ecosystems of Peru's Madre de Dios province, threatened by by artisanal gold mining. Widely practiced in Amazon lakes and rivers, this extractive activity impacts riparian and aquatic environments by driving the release of mercury, the production of engine noise and bank habitat deforestation. We study giant otter populations in mined areas and also in the adjacent Manu National Park. Both are areas of high conservation value because they are biodiversity hotspots.

Our work includes behavioral observations and monitoring of several giant otter groups. In a recent publication, we examined how giant otters respond to distinct types of human activity. We found that, when ecotourism is responsible and strictly regulated, giant otters may become habituated to the presence of humans and show reduced defensive behavior. However, in areas with extractive activities, such as commercial fishing and gold mining, giant otter tend to avoid humans and keep their distance.

We also catch and sample fish, on which giant depend for feeding, to understand their abundance and mercury levels in oxbow lakes. In a recent paper, we found that fish abundance and biomass are considerably lower outside protected areas. The main fish species found in protected oxbow lakes were carnivorous piranhas, whereas in lakes exposed to mining and fishing, fish who feed on detritus were the most frequent. Analyses of mercury levels in these fish suggest that especially larger, carnivorous fish in lakes with increased bank deforestation can accumulate high amounts of this toxic substance, with implications for the health of local otters and local communities.

Our long-term presence in both Manu National Park and unprotected oxbow lakes outside it enables us to gain insights on the specific processes by which gold mining drives habitat deterioration. An example is our assessment of water quality, which indicates that levels of dissolved oxygen and transparency are lower in lakes with human activity. We also used a drone to assess the giant otter's aquatic and terrestrial habitats. The resulting paper suggests that giant otters prefer well-drained bank areas with dense forest canopy cover, and open water and fallen logs in the water. Our ongoing analyses are aimed at examining the influences of environmental factors and human activity on giant otter abundance, survival and reproductive success.

Giant otters are top predators in the oxbow lakes and rivers they inhabit. However, whether their presence and abundance have impacts on the biodiversity and productivity of these sensitive ecosystems is not clear. We are currently sampling zooplankton communities and maesuring water quality and chlorophyll levels in oxbow lakes to understand the relative influences of extractive activities such as gold mining and top carnivores. The results should have implications for local human communities in the Madre de Dios region and the ecosystem services they depend on.

The giant otter project also works with local communities in the Madre de Dios gold mining corridor to understand their perceptions towards giant otters and Amazon freshwater ecosystems. Since 2018, we have an educational presence in these places. Our community team works in local schools and conducts environmental education workshops. Our goal is to promote a better understanding of local freshwater ecosystems and the best ways conserve them.

Our recent publication examines how gold mining and the state of the aquatic environment are perceived by local people, and how likely they are to contribute in conservation initiatives. Opinions and perceptions are mixed, but it appears that local gold miners are concerned for the state of rivers and animals and are willing to paarticipate in actions that promote change and make their activities more sustainable.

Between 2021 and 2023, our community team started a recycling project, in participation with the municipality of Laberinto, involving several primary schools in the area. In addition, team members conduct workshops, in which students learn about the aquatic ecosystems surrounding them and use art to draw the animals and plants they are familiar with.

This project is led by the San Diego Zoo Wildlife Alliance, in collaboration with the WildCRU unit from the University of Oxford.