Impacts of different monoculture types on stream benthic macroinvertebrate and fish communities

Abstract

Agribusiness is one of the main economic activities in Brazil, which caused the removal of much of its natural vegetation for the expansion of monoculture areas. Once aquatic environments have a direct relationship with the surrounding terrestrial environment, it is essential to understand the monocultures’ impact on adjacent streams and, especially, how aquatic communities react to these impacts. Our aim was to verify the effects of different monoculture types on stream benthic macroinvertebrate and fish communities’ structure. We compared the environmental characteristics and these communities’ structure in four streams located in native vegetation areas and four in each of three monoculture types (sugarcane, citrus, and eucalyptus), all belonging to the Paranapanema River basin, Southeastern Brazil. We found lower pH and dissolved oxygen and higher total phosphorus and fine substrate values in monoculture streams and these variables were also related to the lower abundance of macroinvertebrate groups more sensitive to environmental impacts. However, we did not find differences in fish communities or in their relationship with the different environmental characteristics observed. We also did not observe differences between the monoculture types in all comparisons made, which demonstrate that these plantations, although have different cultivation characteristics, cause similar negative impacts in the streams. Our study demonstrates the physical and chemical impacts of monoculture development on stream headwater communities. Regulatory measures such as increased riparian vegetation and contour farming and terracing may be critical to protect and restore headwater streams from monoculture impacts.