Pesticide effects at the edge? Implications of downstream agrochemical pollution for organisms in refugia

根据过去二十年的几项研究，农药影响了溪流中的无脊椎动物群落，使耐受性的类群的相对丰度增加。在空间动力学和适应过程方面，我们对毒性效应的反应和长期后果的理解仍然不足。模型研究表明，就耐受性而言，对农药的遗传适应可能会传播到未受污染的斑块。然而，关于农药污染的下游效应对未受污染的上游区域的生物传播的可能性的实证研究很少。在这个项目中，我们将研究不同的无脊椎动物，农药效应在多大程度上可以传播给避难所的生物。该项目得益于一个全国性的农药监测方案（实施全国小水体农药监测），该方案提供高质量的农药数据、高分辨率的理化数据以及无脊椎动物和硅藻的组合数据，而无需额外费用。我们将在具有高农药毒性的农业场所和两个距离的避难所（避难所边缘和更远的上游）取样三种无脊椎动物，包括一种伽马虫、一种trichopteran和一种ephemeropteran。通过快速测试，我们将确定无脊椎动物的耐受性，这将使我们能够评估潜在的适应性。此外，我们将确定遗传多样性和能量储备。我们假设这种适应降低了遗传多样性，并传播到避难所边缘未受污染的斑块。此外，根据资源分配的概念，我们假设更高的耐受性与更高的能量分配到防御机制有关，导致与较低耐受性的生物体相比，能量储备更低。总体而言，该研究项目将大大增加对先前研究中在受污染栖息地斑块中观察到的更高耐受性的机制的理解（Shahid et al. 2018），并将推进我们对非污染地区生物和种群污染成本的评估。

Based on several studies in the last two decades, it is relatively well established that pesticides shape invertebrate assemblages in streams, with an increase in the relative abundance of tolerant taxa. Our understanding of the response and long-term consequences of toxicant effects is still deficient with respect to spatial dynamics and adaptation processes. Genetic adaptations to pesticides in terms of tolerance may propagate to non-polluted patches as shown in modelling studies. However, empirical studies on the potential of downstream effects of pesticide pollution to propagate to organisms in non-polluted upstream sections are scarce. In this project, we will examine for different invertebrates to which extent pesticide effects can propagate to organisms in refugia. The project profits from a nationwide pesticide monitoring programme (Implementation of the national monitoring of small water bodies for pesticides) that provides high quality pesticide data, high resolution physicochemical data as well as assemblage data on invertebrates and diatoms without extra costs. We will sample three invertebrate species, including a gammarid, a trichopteran and an ephemeropteran, in agricultural sites with high pesticide toxicity and in refugia at two distances (edge of refugia and further upstream). Using rapid tests, we will determine the tolerance of the invertebrates, which will enable us to evaluate potential adaptations. Moreover, we will determine the genetic diversity and energy reserves in gammarids. We hypothesise that the adaptation reduces genetic diversity and that this propagates to non-polluted patches at the edge of the refugium. Moreover, following the concept of resource allocation, we assume that a higher tolerance is associated with higher allocation of energy to defence mechanisms, resulting in lower energy reserves compared to less tolerant organisms. Overall, this research project will add considerably to the understanding of the mechanisms underlying a higher tolerance observed in polluted habitat patches in a previous study (Shahid et al. 2018) and it will advance our assessment of the costs of pollution for organisms and populations in non-polluted areas.