Response of stream macroinvertebrates to changes in salinity and the development of a salinity index

Abstract

Many streams and wetlands have been affected by increasing salinity, leading to significant changes in flora and fauna. The study investigates relationships between macroinvertebrate taxa and conductivity levels (µS cm−1) in Queensland stream systems. The analysed dataset contained occurrence patterns of frequently found macroinvertebrate taxa from edge (2580 samples) and riffle (1367 samples) habitats collected in spring and autumn over 8 years. Sensitivity analysis with predictive artificial neural network models and the taxon-specific mean conductivity values were used to assign a salinity sensitivity score (SSS) to each taxon (1—very tolerant, 5—tolerant, 10—sensitive). Salinity index (SI) based on the cumulative SSS was proposed as a measurement of change in macroinvertebrate communities caused by salinity increase. Changes in macroinvertebrate communities were observed at relatively low salinities, with SI rapidly decreasing to ~800–1000 µS cm−1 and decreasing further at a slower rate. Natural variability and water quality factors were ruled out as potential primary causes of the observed changes by using partial canonical correspondence analysis and subsets of the data with only good water quality.

Impact of potash mining in streams: the Llobregat basin (northeast Spain) as a case study

“…These findings align with those of previous studies, which reported that biological quality of salt polluted streams can be affected by conductivities as low as 1.5 mS cm -1 (Dunlop et al, 2005;Hart et al, 1991;Horrigan et al, 2005;Kefford et al, 2011), or even lower (Cormier et al, 2013;Kefford et al, 2011). Anyhow, the damage to the aquatic invertebrate community can be expected to increase with increasing conductivity (Berezina, 2003;Böhme, 2011;Braukmann and Böhme, 2011;Cañedo-Argüelles et al, 2012;Hart et al, 1991;Horrigan et al, 2005;Pinder et al, 2005;Piscart, 2005;Williams et al, 1999). It is important to notice the reduction in EPT taxa at sites P3 and P4, and IMMi-L, Iberian Mediterranean Multimetric Index, using qualitative data (Munné and Prat, 2009); IMMi-T, Iberian Mediterranean Multimetric Index, using quantitative data (Munné and Prat, 2009).…”

Effects of hydrologic connectivity on aquatic macroinvertebrate assemblages in different marsh types

“…Several abundant predators (Odonata: Aeshnidae, Libellulidae) in freshwater marsh were not observed in saline ponds although they have a relatively high salinity tolerance (i.e. between 5 and 14 ppt, Horrigan et al 2005). These findings suggest that SAV cover is an important habitat component for herbivorous groups but also that no single environmental trait is responsible for macroinvertebrate distribution patterns across marsh types.…”

“…Restriction of her bi vorous groups to the freshwater marsh seems to be partially a result of the salinity tolerance of individual taxa. Horrigan et al (2005Horrigan et al ( , 2007 found that the maximum salinity tolerance of taxa and FFGs, such as scrapers (e.g. Pyralidae), shredders (Scirtidae), piercers (Hydrophilidae) and collectors (Culicidae), was about 12 ppt.…”

Sub-lethal and chronic salinity tolerances of three freshwater insects: Cloeon sp. and Centroptilum sp. (Ephemeroptera: Baetidae)and Chironomus sp. (Diptera: Chironomidae)

“…For example, it has been reported that the abundance of halosensitive species (including mayflies and gastropods) is reduced at salt concentrations of 1500·mg·l -1 (~2.2·mS·cm ) following exposure to either a continuous or pulse release of saline water (Marshall and Bailey, 2004). Similarly, changes in macroinvertebrate community structures, from salt-sensitive taxa to salt tolerant taxa, were observed at salinities between 0.8-1.0·mS·cm -1 in Queensland streams (Horrigan et al, 2005). And in a study of the acute salinity tolerances of a range of macroinvertebrates from the Barwon River in Victoria, a wide range (5.5-76·mS·cm -1 ) of 72·h lethal concentrations (LC 50 ) was observed, which are the concentrations capable of killing 50% of individuals (Kefford et al, 2003).…”