Abstract：
AbstractFreshwater salinity regimes vary naturally and are changing in response to anthropogenic activities. Few insect species tolerate saline waters, and biodiversity losses are associated with increasing salinity in freshwater. We used radiotracers (22Na, 35SO4, and 45Ca) to examine ion uptake rates across concentration gradients in mayflies (Ephemeroptera), caddis flies (Trichoptera), and mosquitoes (Diptera) and made observations for some traits in seven other taxa representing mayflies, stone flies (Plecoptera), true flies (Diptera), and true bugs (Hemiptera). We further assessed the permeability of the cuticle to 3H2O influx and 22Na efflux when faced with deionized water in these same taxa. We hypothesized a relationship between uptake rates and reported saline tolerances, but our data did not support this hypothesis, likely because acclimatory responses were not part of this experimental approach. However, we found several common physiological traits across the taxa studied, including (i) ionic uptake rates that were always positively correlated with dissolved concentrations, (ii) generally low Ca uptake rates relative to other freshwater taxa, (iii) greater Na loss than Na uptake in dilute conditions, (iv) ion uptake that was more variable in ion-rich conditions than in dilute conditions, and (v) 3H2O influx that occurs quickly (but this rapidly exchangeable pool of body water accounts for a surprisingly small percentage of the water content of species tested). There remains much to learn about the physiology of these important organisms in the face of changing salinity regimes worldwide.
摘要：
摘要淡水盐度制度自然变化，并且随着人为活动而变化。很少有昆虫能耐受盐水，生物多样性的丧失与淡水中盐度的增加有关。我们使用了放射性示踪剂(22Na，35SO4和45Ca）以检查may蝇（星翅目）在浓度梯度上的离子吸收速率，卡迪斯苍蝇（毛翅目），和蚊子（双翅目），并对代表may蝇的其他七个分类群的一些特征进行了观察，石蝇（Plecoptera），真蝇（双翅目），和真正的bug（半翅目）。我们进一步评估了在这些相同的分类单元中面对去离子水时，表皮对3H2O流入和22Na流出的渗透性。我们假设摄取率和报告的盐耐受性之间的关系，但是我们的数据不支持这个假设，可能是因为适应反应不是这种实验方法的一部分。然而,我们在研究的类群中发现了几个共同的生理特征，包括（i）与溶解浓度始终呈正相关的离子吸收速率，（ii）相对于其他淡水分类群而言，钙的吸收率通常较低，（iii）在稀条件下，Na损失大于Na吸收，(iv)在富离子条件下的离子吸收比在稀条件下的变化更大，和（v）迅速发生的3H2O流入（但是这种可快速交换的体内水池占所测试物种的水含量的百分比很小）。面对全球不断变化的盐度制度，这些重要生物的生理学仍有很多需要了解的地方。
