A trait database of stream invertebrates for the ecological risk assessment of single and combined effects of salinity and pesticides in South-East Australia

We compiled a database on a priori selected traits for South-East Australian freshwater macroinvertebrate families and used this data for the development of a biotic indicator for the detection of the effects of salinisation on freshwater communities (SPEARsalinity) and for the adaptation of the existing SPEARpesticides index for South-East Australian taxa. The SPEARsalinity indicator showed a reasonably high relationship (0.38 ≤ r2 ≤ 0.5) with salinity in terms of logarithmic electrical conductivity (log EC) using field biomonitoring data from 835 pools and riffle sites in Victoria and South Australia. Several other biotic indexes that were calculated for comparison purpose exhibited a lower relationship with log EC. In addition, SPEARsalinity was the only indicator that did not respond to other water quality variables and was therefore most selective. We used log EC data and modelled pesticide exposure for sites in Victoria in concert with SPEARsalinity and the existing SPEARpesticides index to assess whether pesticides interacts with effects of salinity on invertebrate communities and vice versa. No interaction with pesticides was found for the effect of log EC on SPEARsalinity, whereas EC interacted with the estimated pesticide exposure on the invertebrate communities. To foster the development of further trait-based ecological indicators, we suggest a conceptual model that predicts response traits based on the disturbance regime and disturbance mode of action of the stressor. Biotic indicators based on a priori selected traits represent a promising biomonitoring tool even for regions where ecological information is scarce.

Research highlights
► We compiled a trait database and developed a biotic indicator for salinisation.
► The indicator showed a good relationship with salinity.
► The indicator outperformed existing indicators.
► Salinity may modify effects of pesticides.
► We suggest a conceptual model for the development of further trait-based indicators.