Tolerance to Copper and to Salinity in Daphnia longispina: Implications within a Climate Change Scenario

João Leitão,Amadeu M V M Soares,Rui Ribeiro,Isabel Lopes,Harald Auge

doi:10.1371/journal.pone.0068702

João Leitão, Amadeu M V M Soares + Show 3 more

Open Access

https://doi.org/10.1371/journal.pone.0068702

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Journal: PloS one	Publication Date: Aug 26, 2013
Citations: 42	License type: CC BY 4.0

Affiliation: University of Aveiro, University of Coimbra

Abstract

Considering IPPC climate change scenarios, it is pertinent to predict situations where coastal ecosystems already impacted with chemical contamination became exposed to an additional stressor under a future scenario of seawater intrusion. Accordingly, the present study aimed at evaluating if a negative association between tolerance to a metal and to saltwater exists among genotypes of a freshwater organism. For this, five clonal lineages of the cladoceran Daphnia longispina O.F. Müller, exhibiting a differential tolerance to lethal levels of copper, were selected. Each clonal lineage was exposed to lethal and sublethal concentrations of sodium chloride (assumed as a protective surrogate to evaluate the toxicity of increased salinity to freshwater organisms). Mortality, time to release the first brood and total number of neonates per female were monitored and the somatic growth rate and intrinsic rate of natural increase were computed for each clonal lineage. Data here obtained were compared with their lethal responses to copper and significant negative correlations were found. These results suggest that genetically eroded populations of D. longispina, due to copper or salinity, may be particularly susceptible to a later exposure to the other contaminant supporting the multiple stressors differential tolerance.

Highlights

At present, the rising of sea level is recognized as one of the major issues in environmental protection, especially when considering the conservation of biodiversity of low-lying coastal freshwater ecosystems [1]
It is pertinent to consider scenarios where coastal ecosystems are already impacted with chemical contamination, and that the biota inhabiting these ecosystems will be exposed to an additional stressor under a scenario of future seawater intrusion
It has been shown that if populations of freshwater organisms are exposed to chemical contamination, its genetic erosion may occur through the elimination of the most sensitive genotypes (e.g. [9,10,11,12,13,14,15])

Summary

Introduction

The rising of sea level is recognized as one of the major issues in environmental protection, especially when considering the conservation of biodiversity of low-lying coastal freshwater ecosystems [1]. Several works have been carried out to determine the sensitivity of freshwater species, inhabiting these ecosystems, to increased salinity and to understand what ecological changes may occur due to seawater intrusion [2,3,4,5]) Most of these works were focused on understanding the intrinsic sensitivity of tested organisms to increased salinity, induced by artificial seawater or by the use of one salt (usually NaCl, which is recognized as representing a worst case scenario; [6]), under optimal conditions It has been shown that if populations of freshwater organisms are exposed to chemical contamination, its genetic erosion may occur through the elimination of the most sensitive genotypes The extreme configuration of this later scenario would constitute the worst case: a negative correlation would lead to an increased risk of population extinction [14,16]

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