Nearly 400 new species have been discovered in the Amazon rainforest, and they're at risk.

Researchers found 381 new species during a two-year study in the Amazon region conducted between 2014 and 2015, according to a report from the World Wildlife Fund and the Mamiraua Institute for Sustainable Development released on Wednesday in Sao Paulo, Brazil.

Researchers were reportedly discovering a new species every two days on average and found 216 previously unknown plants, 93 fish, 32 amphibians, 20 mammals, 19 reptiles and one bird. The discoveries were found across all of the nine South American countries that are touched by the rainforest.

Earth is home to an estimated total of 8.7 million species, and experts suggest more than 80 percent of them have not been identified. The Amazon, in turn, is the world's largest tropical rainforest and houses the world's largest collection of living species of plants and animals.

Researchers' most recent discoveries were plentiful, but they said the plants and animals could be lost almost as quickly as they were found. All of the discovered species, after all, were found in areas at risk from human activity.

"Given the accelerated level of habitat change, many species may become extinct even before science has the opportunity to discover them, identify and study them," according to the report.

The report – the third in a series that has found some 2,000 new species discovered over the last 17 years – comes amid a growing environmental dispute over mining and natural conservation in Brazil.

For their part, the report's authors pledged to continue research in the region, saying, for the sake of monitoring and preserving biodiversity "the work cannot stop."