DISSERTATION RESEARCH: Abundance, trophic transfer, and cross-ecosystem movement of multiple cyanotoxins in arctic lakes

淡水湖为人类提供了至关重要的价值，从家庭、工业和农业的供水到主动和被动娱乐的机会。然而，湖栖蓝藻及其毒素--氰化毒素--日益受到关注，威胁到水产食物网的健康和淡水的安全使用。大多数对氰基毒素的研究都集中在温带和热带系统，浮游蓝藻表面有明显的水华。然而，并不是所有产生毒素的蓝藻都能形成表层水华，底栖蓝藻和水柱中非常小的单个细胞都能产生毒素，对消耗蓝藻的生物的丰度、影响以及毒素从湖泊向其周围陆地移动的可能性，尤其是在极地地区，人们了解得很少。到目前为止，极地淡水蓝藻是否产生氰化毒素以及氰化毒素通过极地水生食物网或进入陆地生态系统的程度在很大程度上尚不清楚。该项目将扩大我们对支持有毒蓝藻的生态系统类型的了解，并有助于评估哪些系统目前处于危险之中或未来可能面临危险。对海底蓝藻和水柱中非常小的单细胞产生的氰基毒素的研究将在格陵兰岛的湖泊和池塘中进行。为了补充正在进行的对最常见的氰基毒素的研究，研究人员将评估另外四种毒素的产生及其通过水生食物网和陆地生态系统的转移。因此，该项目将扩大与科学界和公共卫生界相关的氰化物的地理、分类范围和生态分布的知识。由这笔赠款资助的研究将使用先前从格陵兰西南部的19个湖泊和池塘收集的样本来(1)量化水生生态系统中另外四类氰毒素(Anatoxin-a、麻黄毒素、圆柱体精索蛋白和BMAA)的丰度，(2)估计氰毒素向陆地生态系统的转移，以便更全面地了解北极湖泊和附近陆地生境中生物毒素在生态系统内和跨生态系统的移动。初步数据表明，肝毒微囊藻毒素是由发菜属底栖蓝藻产生和释放的，也存在于远洋非水华浮游植物中。此外，微囊藻毒素正被转移到浮游动物和无脊椎动物幼虫体内。这项研究将把这些微囊藻毒素的分析扩展到陆地环境中，并调查食物链中是否存在另外四种氰基毒素。研究人员将调查毒素的产生、氰化毒素向湖泊中其他生物的转移，以及可能影响毒素从水生生态系统向陆地生态系统移动的几种机制(如出现的昆虫、气溶胶)。已经记录在案的氰化毒素在这些湖泊中的存在和移动表明，高纬度湖泊可以支持产毒蓝藻，我们可能低估了这些系统未来发展高水平毒性的潜力。

Freshwater lakes provide critical value human populations, from water supply for households, industry, and agriculture to opportunities for active and passive recreation. However, lake-dwelling cyanobacteria and their toxins, cyanotoxins, are of increasing concern, threatening the health of aquatic food webs and the safe uses of freshwaters. Most studies of cyanotoxins have focused on temperate and tropical systems with conspicuous surface blooms of planktonic cyanobacteria. However, not all toxin-producing cyanobacteria form surface blooms, both bottom-dwelling cyanobacteria and very small single cells in the water column, can produce toxins, and the abundance, impacts on organisms that consume the cyanobacteria, and the potential for toxins to move from lakes to the lands surrounding them is poorly understood, especially in polar regions. To date, very few studies have examined whether polar freshwater cyanobacteria produce cyanotoxins and the extent to which cyanotoxins move through polar aquatic food webs or into terrestrial ecosystems remains largely unknown. This project will expand our understanding of the types of ecosystems that support toxic cyanobacteria and contribute to the evaluation of which systems are currently at risk or may become at risk in the future. Studies of the cyanotoxins produced by both bottom-dwelling cyanobacteria and very small single cells in the water column will take place in lakes and ponds in Greenland. To complement ongoing studies of the most common class of cyanotoxin, the researchers will evaluate the production of four additional toxins and their transfer through aquatic food webs and into terrestrial ecosystems. As such, this project will expand the knowledge on the geographic and taxonomic range and ecological distribution of cyanotoxins relevant in both the scientific and public health communities.The research funded by this grant will use samples previously collected from 19 lakes and ponds in southwestern Greenland to (1) quantify the abundance of four additional classes of cyanotoxins (anatoxin-a, saxitoxins, cylindrospermosins, and BMAA) within the aquatic ecosystem and (2) estimate cyanotoxin transfer to terrestrial ecosystems in order to obtain a more complete picture of within- and across-ecosystem movement of biotoxins in Arctic lakes and nearby terrestrial habitats. Preliminary data suggest that hepatoxic microcystins are produced and released by benthic colonial cyanobacteria of the genus Nostoc and are also found in pelagic non-blooming phytoplankton. Moreover, microcystins are being transferred into zooplankton and invertebrate larvae. This research will extend these microcystin analyses into the terrestrial environment and investigate the presence of four additional cyanotoxins within the food web. The researchers will investigate toxin production, the transfer of cyanotoxins to other organisms in the lake, and several mechanisms (i.e., emerging insects, aerosols) that may influence the movement of toxins from the aquatic to terrestrial ecosystem. The already-documented presence and movement of cyanotoxins in these lakes demonstrate that high-latitude lakes can support toxigenic cyanobacteria, and that we may be underestimating the potential for these systems to develop high levels of toxicity in the future.