Department of Biology, University of Aveiro, Aveiro, Portugal.
PLoS One. 2013 Aug 26;8(8):e68702. doi: 10.1371/journal.pone.0068702. eCollection 2013.
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.
考虑到政府间气候变化专门委员会的气候变化情景，预测沿海生态系统在未来海水入侵情景下，在已经受到化学污染影响的情况下，又面临额外压力源的情况是很重要的。因此，本研究旨在评估淡水生物的基因型是否存在对金属和咸水的耐受性之间的负相关关系。为此，选择了对铜的致死水平表现出不同耐受性的枝角类动物长刺溞（Daphnia longispina O.F. Müller）的五个克隆谱系。每个克隆谱系都暴露在致死和亚致死浓度的氯化钠（被认为是评估增加盐度对淡水生物毒性的保护替代物）中。监测死亡率、首次产卵释放时间和每个雌性的新生儿总数，并计算每个克隆谱系的体增长率和自然增长率。将获得的数据与它们对铜的致死反应进行比较，发现了显著的负相关关系。这些结果表明，由于铜或盐度，基因侵蚀的长刺溞种群可能特别容易受到另一种污染物的后期暴露，从而支持多种压力源的差异耐受性。
