Ecological analysis of macroinvertebrates in remediated ditches based on their functional traits

Sammanfattning

This study evaluated the effect of agricultural ditch rehabilitation using a two-stage design on water quality and the composition of functional traits in aquatic macroinvertebrate communities. Nineteen paired sites in southern and central Sweden were analysed, each with a remediated downstream section and an unremediated upstream section. No statistically significant differences were found in the physicochemical parameters analysed, although the remediated sections had lower maximum values and less dispersion for several pollutants. Likewise, traditional taxonomic indicators such as richness, total abundance and metrics based on Ephemeroptera, Plecoptera and Trichoptera (EPT) also showed no clear differences between conditions. However, functional analysis identified nine traits with a high contribution to functional dissimilarity. Intermediate body size showed a positive relationship with total phosphorus and a negative relationship with suspended solids. Significant associations were also observed between life cycle duration traits (short and long) and turbidity, suggesting reproductive responses to conditions of increased sedimentation. These results suggest that, although no overall improvements in water quality and taxonomy were detected, the analysis of functional traits highlighted ecological signals that conventional metrics overlooked in this dataset. Therefore, incorporating this complementary approach into monitoring programmes could improve the ecological assessment of restoration interventions in agricultural landscapes.