Can isolated wetlands come to the trophic rescue of surrounding ecosystems? Investigating new pathways for food web connectivity

当生产性的“捐赠者”栖息地向生产性低下的“接受者”栖息地输送养分、能量和/或有机物时，就会发生食物网补贴。 这种材料的移动可以稳定食物网并提高整体生产率，但也会带来污染物。这些通量的研究和管理具有挑战性，因为它们与生态系统边界的传统概念不一致。 全球有超过 2000 万个小型湿地，其中许多湿地被人类认为无关紧要，因为它们很浅、与周围水体隔绝、在冬天完全冻结或干涸，而且缺乏鱼类。 因此，它们通常被视为简单的废物接收器，导致它们被社会低估，并且经常被排干、填满或退化。该研究计划挑战了这一观点，而是将它们视为重要的供体栖息地，通过大量有翅生物（即半水生昆虫（水船昆虫）和挺水昆虫（蠓虫））提供重要的食物网补贴。 这项补贴可能负责维持该地区以及世界其他寒冷或干燥地区的河流和湖泊的渔业生产，但对其质量知之甚少，包括健康（omega-3脂肪酸）和有害（汞）化合物。该计划将通过评估补贴的时间、幅度和营养质量来测试这些湿地是否对河流、湖泊和田野进行营养拯救。我的团队将研究这些通量在北美不同地区的变化，从加拿大北部的冰雪覆盖严重且夏季生长季节较短的环境，到美国南部的干旱环境，其中大多数湿地在夏末完全干燥。 我们还将确定这些昆虫是否将汞等污染物从湿地输送到河流，因为湿地是已知的汞甲基化热点。 最后，我们将评估水质变化如何影响昆虫群落组成，以及富营养化和盐碱化导致的湿地退化是否有利于迁徙或非迁徙类群。 总之，这项研究可以揭示保护加拿大和全球湿地的新原因。

Food web subsidies occur when a productive “donor” habitat sends nutrients, energy and/or organic matter to an unproductive “recipient” habitat. This movement of materials can stabilize food webs and enable higher overall productivity, but can also deliver contaminants. These fluxes are challenging to study and to manage because they are at odds with conventional notions of ecosystem boundaries. There are more than 20 million small wetlands across the globe, and many of these are deemed inconsequential by humans because they are shallow, isolated from surrounding waterbodies, freeze or dry out entirely in the winter, and lack fish. As such, they are regularly viewed as simple sinks for waste, leaving them undervalued by society and often drained, filled or degraded. This research program challenges that notion, and instead examines them as important donor habitats, providing a significant foodweb subsidy via a large flux of winged organisms namely semi-aquatic (waterboatmen) and emergent (midges) insects. It is possible that this subsidy is responsible for maintaining fisheries production in rivers and lakes both in this region and in other cold or dry regions of the world, but little is known about its quality, including both healthy (omega-3 fatty acids) and harmful (mercury) compounds.This program will test if these wetlands come to the trophic rescue of rivers, lakes and fields by evaluating the timing, magnitude, and nutritional quality of the subsidy. My team will examine how these fluxes change in different parts of North America, from northern Canadian environments where ice-cover is significant and the summer growing season is short, to arid environments in the southern United States where most wetlands dry completely in late summer. We will also determine if these insects deliver contaminants such as mercury from wetlands to rivers, because wetlands are known hotspots for mercury methylation. Finally, we will evaluate how changes in water quality affect insect community composition and whether wetland degradation from eutrophication and salinization favors migrant or non-migrant taxa. Together, this research could reveal new reasons to conserve wetlands in Canada and across the globe.