Researchers from the Sustainable Amazon Network looked at the status of fauna species in 83 separate streams in parts of the still heavily forested eastern Brazilian Amazon that are undergoing rapid agricultural intensification. These small forest streams often make up more than 80% of all the water courses in a given part of the Amazon, the largest source of freshwater on the planet.

The study highlighted the strong influence of human disturbances taking place at some distance away from the study sites, often outside officially protected areas, and thus outside the remit of mainstream conservation plans and legislation.

“When we think about Amazon biodiversity we tend to think of colourful birds, mammals, insects and amphibians. But the small streams in and around the Amazon are also incredibly biodiverse,” says lead author Dr Cecília Gontijo Leal, a researcher at the Emílio Goeldi Museum in Brazil.

“In just one 150 metres stretch of one stream we found more fish species than are found in whole countries like Sweden or Denmark. Some of them were new to science, and others were found in only a few individual streams. Many of these species could be at risk because of changes upstream that are beyond the reach of current conservation efforts.”

Amazonian fish are important for the world

The team’s findings demonstrate the importance of considering private property, as many of the streams originate outside protected parks and reserves. The most important environmental legislation in Brazil for regulating activities on private properties, the Brazilian Forest Code, mainly deals with the vegetation along watercourses, but not forest further away or the range of other activities in the catchment that could impact on the health of stream fauna.

“The health of small Amazonian streams depends on the health of the catchments they are part of,” says co-author Dr Toby Gardner, a Senior Research Fellow at the Stockholm Environment Institute, and one of the co-authors of the study.

“Forests far away from the margins are also important, as well as other factors that are overlooked in the legislation, such as dirt roads and agriculture intensification upstream.”

The study also points to a need to reconsider how another aspect of the Forest Code is implemented. The team’s findings underscore the importance of keeping compliance efforts in the same river basin, even if that means compensation activities outside the farm property.

“Our results highlight the complex challenges of conservation in tropical forest streams,” adds co-author Dr Paulo Pompeu, professor at the Federal University of Lavras in Brazil. “Protecting this biodiversity matters, not just for the Amazon but also for the world. Almost 10% of the planet’s vertebrates are freshwater Amazonian fish.”

Read the journal article published in the Journal of Applied Ecology »