Survival recovery rates by six clonal lineages of Daphnia longispina after intermittent exposures to copper. (February 2021)

• Record Type: Journal Article
• Authors: Venâncio, C.; Ribeiro, R.; Soares, A.M.V.M.; Lopes, I.
• Is Part Of: Chemosphere. Volume 264(2021)Part 1
• Publication Date: 2021-02
• Subjects: Sequential pulses -- Copper -- Metals -- Cladocera; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.128403
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Natural populations are commonly exposed to sequential pulses of contaminants. Accordingly, this study aimed at testing the existence of an association between the tolerance to lethal levels of copper (Cu) and the survival recovery ability from pulsed partially lethal copper exposures in six clonal lineages of Daphnia longispina . It was hypothesized that the most tolerant genotypes would be the ones exhibiting a faster survival recovery from a pulsed contaminant exposure. For each clonal lineage, the intensity of pulses corresponded to the respective concentration of Cu causing 30% of mortality after 24h of exposure (LC30, 24h ). The initial hypothesis was not corroborated: obtained results showed no association between survival recovery and lethal tolerance to Cu. Nevertheless, some patterns could be detected. Firstly, the most sensitive lineages to lethal levels of copper revealed a faster survival recovery from a first Cu pulse comparatively to the most tolerant ones, though they were the most sensitive to a second pulse exposure. Secondly, the most tolerant lineages, though being more tolerant to a second exposure, exhibited the lowest survival recovery capacity after exposure to a first pulse of Cu. However, differences in the survival recovery capacity of the six clonal lineages after the exposure to the two pulses of Cu were not observed. Increasing the duration of the recovery period from 24h to 72h did not significantly alter mortality rates, except for the most sensitive and most tolerant clonal lineages. The results here obtained suggests that standard lethality assays may sub-estimate the toxicity of chemicals under realistic exposure scenarios, since sequential pulses are not infrequent in natural conditions. Graphical abstract: Image 1 Highlights: Cu-tolerant lineages recovered later than sensitive ones after a Cu pulse with a similar lethal effect among clones. During recovery period, after a 24-h pulse, mortality continued to occur in all clonal lineages. After two sequential pulses, survival recovery rates were similar among all clonal lineages. Longer time periods between sequential pulses of Cu reduced mortality rates for all clonal lineages. No correlation existed between increased lethal tolerance to Cu and a faster survival recovery.