Addressing the recovery of feeding rates in post-exposure feeding bioassays: Cyathura carinata as a case study

Abstract

Post-exposure bioassays are used in environmental assessment as a cost-effective tool, but the effects of organism's recovery after exposure to pollutant has not yet been addressed in detail. The recoveries of post-exposure feeding rates after being exposed to two sublethal concentrations of cadmium during two different exposure periods (48h and 96h) were evaluated under laboratory conditions using the estuarine isopod Cyathura carinata. Results showed that feeding depression was a stable endpoint up to 24h after cadmium exposure, which is useful for ecotoxicological bioassays.

Previous stress causes a contrasting response to cadmium toxicity in the aquatic snail Potamopyrgus antipodarum: lethal and behavioral endpoints

“…A delayed mortality was found in P. antipodarum after short-term exposure to cadmium (48-96h) (Jensen and Forbes 2001 ). Other studies have shown similar trends (Zhao and Newman 2006 ; Pais-Costa et al 2015 ). Therefore, the inclusion of post-exposure/recovery periods after toxicant exposure is an improvement in the realism of laboratory bioassays, as it allows a better prediction of the fate of field populations (Zhao and Newman 2006 ; Pais-Costa et al 2015 ).…”

“…Other studies have shown similar trends (Zhao and Newman 2006 ; Pais-Costa et al 2015 ). Therefore, the inclusion of post-exposure/recovery periods after toxicant exposure is an improvement in the realism of laboratory bioassays, as it allows a better prediction of the fate of field populations (Zhao and Newman 2006 ; Pais-Costa et al 2015 ). In fact, in our study, the mortality among non-stressed animals at the highest cadmium concentration at the end of the recovery was more than twice that found at the end of the exposure period.…”

“…Post-exposure periods in laboratory bioassays allow the monitoring of the toxicant effects in a realistic way, since delayed effects are taken into account when calculating endpoints (Schill et al 2003 ; Alonso and Camargo 2009b ; Alonso et al 2010 ; Pais-Costa et al 2015 ; Xu et al 2021 ). In several previous studies, periods of post-exposure to toxicants had exhibited significant effects on survival, reproduction, growth, and behavior in different species, including P. antipodarum (Handy 1994 ; Jensen and Forbes 2001 ; Alonso and Camargo 2009b ; Alonso et al 2010 ; Azevedo-Pereira et al 2011 ; Pais-Costa et al 2015 ). The exposure of the freshwater amphipod Gammarus fossarum to cadmium for 5 days, followed by a recovery period of 15 days, showed that mortality occurred mainly in the first five days of recovery (Schill et al 2003 ).…”