Community structure and distribution of Ephemeroptera and Plecoptera larvae in lowland karst rivers in Slovenia

Abstract

Mayfly and stonefly larval community compositions were investigated in lowland karst rivers. From January to December 2005, 49 benthos samples were taken using a multi-habitat approach. Environmental variables were measured in about monthly intervals. Altogether, 26 mayfly taxa (20 species) and 17 stonefly taxa (13 species) were recorded. Eight species were common, whereas 16 taxa were rare. Only Baetis rhodani and Ephemerella ignita occurred frequently at all sites. Significant differences were observed among sampling sites in diversity and richness metrics but neither in abundance nor in values of index of biocenotic regions. Spatial and seasonal differences amongst assemblages were determined by NMS. The relationship between mayfly and stonefly assemblage structure and seasonally varied environmental factors were investigated using canonical correspondence analysis (CCA). Mayfly and stonefly larval taxa distribution was best correlated to an eutrophication gradient represented by conductivity, nitrate concentration and dissolved oxygen concentration.

Keywords:

• mayflies
• stoneflies
• diversity
• multivariate analysis
• lowland karst river
• karst spring
• Slovenia