The effect of contaminants on mechanisms underlying invasive species impact

淡水生物多样性正受到一些全球变化驱动因素的威胁，包括水生污染造成的栖息地退化和入侵物种的扩散。众所周知，栖息地退化会增加入侵物种的成功，但发生这种情况的机制尚不清楚。这项研究的广泛目的是更好地理解物种入侵的非生物决定因素。这将通过比较一组本地入侵伽马科物种对潜在有毒元素(PTE)暴露的反应来完成。该项目的第一部分涉及确定合适的PTE浓度及其生物利用度。对欧洲各地淡水监测点的环境数据进行了分析，以开发一种在环境上切合实际的PTE混合物，供今后的研究使用。PTE混合物是通过从PTE列表中找到最普遍的污染物，它们与哪些其他污染物最相关，以及它们的浓度一起被发现的比率来确定的。这些符合环境现实的混合物将被用来观察不同Gammaridae物种的生物积累反应。Gammaridae将暴露在与环境相关的浓度较高的混合物中，通过电感耦合等离子体质谱分析确认摄取。下一个实验将着眼于伽马科对PTE的生态生理反应。将像以前一样监测暴露在PTE混合物中的Gammaridae的代谢率(即耗氧量)、血淋巴自控性和临界最高/最低温度。对整个物种的调查将确定入侵物种和本地物种的反应。接下来，我们将比较PTE暴露在侵袭性伽马科和本地伽马科中的行为变化和长期健康后果。将通过长期(即4-6个月)暴露在PTE中对Gammaridae进行检查，重点是它们的活动模式和较长期的健康影响(生存、生长、繁殖力)。此外，还将调查与繁殖力有关的配对和对生殖机会的竞争的影响。最后，我们将调查暴露在PTE下的入侵伽马科和本地伽马科通过行间和行内捕食对群落的影响。将观察到暴露在PTE中的伽马科对营养水平较低的‘猎物’物种和相同营养水平的‘中间捕食’物种的捕食行为。捕食者的功能反应将作为密度的函数来确定猎物的消耗率，将对捕食行为(项目组以前已经证明可以与入侵物种的影响联系在一起)与污染物暴露进行比较。

Freshwater biodiversity is under threat from a number of drivers of global change including habitat degradation by aquatic contamination and the spread of invasive species. Habitat degradation is known to increase the success of invasive species, however the mechanisms by which this occurs remain unclear. The broad aim of this study is to develop a better understanding of the abiotic determinants of species invasions. This will be done by comparing the responses of a suite of native to invasive Gammaridae species to potentially toxic element (PTE) exposure. The first part of this project involved determining suitable PTE concentrations and their bioavailability. Environmental data from freshwater monitoring sites across Europe were analysed to develop an environmentally realistic mixture of PTEs for use in future studies. The PTE mixture was determined by finding the most prevalent contaminants from the list of PTE's, which other contaminants they're most correlated with and the ratios at which their concentrations are found together.These environmentally realistic mixtures will be used to look at the bioaccumulation response of different Gammaridae species. Gammaridae will be exposed to the mixtures at environmentally relevant and elevated concentrations, with uptake confirmed via ICP-MS analysis. The next experiment will look at ecophysiological responses of Gammaridae to PTEs. Metabolic rate (i.e. oxygen consumption), haemolymph asmolarity and critical thermal maximum/minimums will be monitored in Gammaridae exposed to PTE mixtures as before. Investigation across the suite of species will determine responses in invasive and native species. Next we will compare the behavioural changes and longer-term fitness consequences of PTE exposure in invasive and native Gammaridae. Gammaridae will be examined through chronic (i.e. 4-6 months) exposure to PTEs with a focus on their activity patterns and longer-term fitness impacts (survival, growth, fecundity). Linked to fecundity, the effects of mate-pairing and competition for reproductive opportunities will also be investigated. Finally, we'll investigate community impacts via inter- and intraguild predation by invasive and native Gammaridae exposed to PTEs. The predatory behaviour of PTE exposed gammaridae towards lower trophic level 'prey' species and same trophic level 'interguild prey' species will be observed. Predator functional responses determining rates of prey consumption as a function of density will be modelled allowing for comparisons of predatory behaviour (which the project team have previously shown can be linked with invasive species impact) with respect to contaminant exposure.