The development of a novel macroinvertebrate indexing tool for the determination of salinity effects in freshwater habitats

Salinisation is a global threat to freshwater habitats and predicted worsen with climate change. Increases in salinity can result substantial modification of biotic communities through both direct toxic effects indirect such as altering prey resources, competitive interactions, predator abundances, facilitating the spread invasive species. Traditional techniques determine salinity, point sampling chemical assessment, are typically periodic may not reveal intermittent changes concentration. Halo-stratification lack standardised depth collect data further complicates using these methods. More importantly, methods do show ecological impacts increases habitats. Complementing traditional biological assessments resolve issues. Pressure-specific indices aquatic macroinvertebrate community have long been used assess aspects habitats, although relatively few focussed on salinity. This paper presents Salinity Association Group Index (SAGI), novel index SAGI compatible derived from established survey employed by regulatory bodies for Water Framework Directive assessments, amongst others. The method integrates taxonomic resolution beyond family level taxon abundance weighting scoring matrix increase efficacy tool make best use publicly available data. Application case studies demonstrates positive, moderate strong correlation conductivity measure range correlations (R2 = 0.57–0.91) compares favourably pressure-specific, macroinvertebrate-based monitoring tools Europe WFD monitoring. Furthermore, shown be highly effective comparison alternative salinity-specific indices.