UC research concludes Acacia invasion affects aquatic communities in streams

Research led by the University of Coimbra (UC) has concluded that the invasion of riparian forests by Acacia species has an impact on the aquatic communities in streams. Details of the study are published in the journal Freshwater Biology.

According to the latest report of the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES), the invasion of non-native species is a serious threat to biodiversity and ecosystem integrity. The silver wattle (Acacia dealbata), a tree native to Australia, is one of the main invasive species in central Portugal, particularly in the Mondego river basin, where it already occupies significant areas.

Verónica Ferreira, a researcher at the Centre for Marine and Environmental Sciences of the Faculty of Sciences and Technology of the University of Coimbra (FCTUC), says: "This study shows that the invasion of native riparian forests by non-native species can severely disrupt stream ecosystems," and emphasises the importance of considering ecosystem interdependence when assessing the impact of invasive species on native riparian forests.

Ferreira warns that “changes in the diversity of aquatic species in streams within invaded forests are concerning. Less diverse communities may struggle to cope with environmental changes, such as those associated with climate change, and may be less effective in performing essential ecosystem functions, such as nutrient recycling."

Verónica Ferreira believes that: "the best option is to protect the riparian zones in the upper reaches of the river basins, which are generally better preserved. This may involve limiting human access and continuous monitoring to eliminate the presence of isolated mimosa seedlings".

This study was carried out as part of the project ‘EXSTREAM - Effects of EXotic tree species on STREAM communities and processes: the case of invasion of native forests by Acacia spp.’ funded by the Fundação para a Ciência e a Tecnologia (FCT) and coordinated by Verónica Ferreira, in collaboration with Professor and researcher Albano Figueiredo from the Centre of Studies on Geography and Spatial Planning (CEGOT) of the Faculty of Arts and Humanities of the University of Coimbra (FLUC).

The paper “Effects of Acacia invasion on water quality, litterfall, aquatic decomposers, and leaf litter decomposition in streams” is available here.