Response of stream invertebrates to short-term salinization: A mesocosm approach

Salinization is a major and growing threat to freshwater ecosystems, yet its effects on aquatic invertebrates have been poorly described at a community-level. Here we use a controlled experimental setting to evaluate short-term stream community responses to salinization, under conditions designed to replicate the duration (72 h) and intensity (up to 5 mS cm−1) of salinity pulses common to Mediterranean rivers subjected to mining pollution during runoff events. There was a significant overall effect, but differences between individual treatments and the control were only significant for the highest salinity treatment. The community response to salinization was characterized by a decline in total invertebrate density, taxon richness and diversity, an increase in invertebrate drift and loss of the most sensitive taxa. The findings indicate that short-term salinity increases have a significant impact on the stream invertebrate community, but concentrations of 5 mS cm−1 are needed to produce a significant ecological response.

► Short-term salinization has a significant impact on the aquatic invertebrates.
► A significant short-term ecological response is registered at 5 mS cm−1.
► Salinization causes a decline in invertebrate density, richness and diversity.
► Biotic quality indices decline with increasing salinity and exposure time.