Scientists with the nonprofit research and advocacy organization Conservation International recently braved intense river rapids in Suriname’s rainforest, locating 60 animals that may be undocumented species, including six frogs and eleven fish.

Spokesman Trond Larsen said the Arlington, Virginia-based group cataloged wildlife and studied freshwater resources, during a three-week trek in southeast Suriname, near its border with Brazil. The team’s expedition moved through the upper Palumeu River watershed, which includes one of the world’s most remote and unexplored rainforests.

The possibly new species include a brown tree frog dubbed “cocoa frog,” and a type of poison dart frog which locals incorporate when hunting. The group has worked for years in Suriname, in the sparsely-populated area. Larsen commented, “Given the rate at which so many populations of frogs are declining and disappearing around the world, it’s pretty exciting to be discovering new species.”

The team gathered data on 1,378 species of plants, mammals, birds, insects, amphibians and fish. Thirty indigenous guides helped the scientists navigate boats bogged down by supplies through raging rivers, and guided them through the forest.

Among the species cataloged were a new type of tetra fish, a strangely pigmented catfish, and nine other types of new-looking fish. A reddish dung beetle less than an inch long, the second smallest in South America, was also found.

Suriname makes great strides to protect its rainforest, and put aside 10 percent of the country’s area to establish the Central Suriname Nature Reserve in 1998. Still, thousands of mostly Brazilian miners also work in the region, employing the dangerous practice of using mercury to separate gold from ore. The mercury in turn contaminates the watershed.

Regardless, the researchers found mostly clean water in the area they’d studied, though some of the mercury levels were too high for the samples to be safe to drink. With no active mining operations upstream in the vicinity, Larsen thinks that the rise is due to the mining activities occurring in neighboring countries.

Images via Conservation International.