Current standardized laboratory test protocols use model species that have limitations
to accurately assess native species responses to stressors. We developed and tested a novel acute
in situ protocol for testing field-collected organisms. We used Asellus aquaticus and NaCl as a
reference toxicant to test for the effects of location (laboratory vs. in situ), medium (synthetic vs. field
water), substrate (presence vs. absence), and protocol replicability. We further tested the protocol
using groundwater-adapted isopods: Proasellus assaforensis for the effect of location, P. cavaticus of
medium and P. lusitanicus of substrate. Our results showed that A. aquaticus’ lethality obtained
with the novel acute in situ protocol did not significantly differ from those from laboratory testing.
However, laboratory tested P. assaforensis showed a higher sensitivity, suggesting that its acclimation
to laboratory conditions might have pernicious effects. A. aquaticus and P. cavaticus showed a higher
mortality using synthetic medium in situ and under laboratory conditions, which overestimated the
stressor’s effect. Besides, substrate use had no significant effect. The novel acute in situ protocol
allows the use of native species under realistic scenarios. It is particularly well adapted for assessing
the risk of groundwater ecosystems but it can be applied to a wide range of ecosystems.info:eu-repo/semantics/publishedVersio