Assessing the threat to Antarctic shallow marine ecosystems from hitchhikers on non-native kelp

长期以来，人类活动和航运一直被认为是对南极洲偏远和孤立的浅海生态系统“生物安全”的主要威胁(Chown等人，2015年)。然而，最近的研究表明，南大洋强烈的绕极风、洋流和锋面可能不会成为来自北方的自然殖民的障碍(Fraser等人，2018年)。亚南极(巴塔哥尼亚、福克兰群岛、新西兰和南半球中纬度岛屿)浅水海洋环境的特点往往是极其偏远岛屿上高度裸露的海岸(Griffiths&Waller，2016)。无冰的海岸线通常是由南极洲海带Durvillaea、巨囊藻和其他大型大型植物组成的密床。长期以来，南极浅海沿岸海洋群落一直被认为是由于数百公里的深海和南极环极洋流而与它们的亚北极邻居隔绝的。根据文献，任何时候都有超过7000万只海藻筏漂浮在南大洋上(Smith，2002)。这些活着的漂浮着的岛屿可以作为一系列来自原始沿海地区和在开阔海洋中采摘的候鸟物种的宿主。在风、洋流和风暴的推动下，这些木筏经常被引用为将新物种引入南极洲和亚南极岛屿的理论载体。我们发现了非本土海藻和被冲上南极海滩的广泛的“搭便车”客体，这让我们质疑这些物种传播障碍的渗透性(Avila等人，2020)。这是首次有证据表明，非本土物种在海藻筏上活着抵达南极大陆。在一些冷水地区，膜苔藓虫被发现是一种入侵和对生态有害的物种，这是它在南极洲的第一个记录(Avila等人，2020年)。成功的申请者将利用现有的数据和样本调查在智利南部、福克兰群岛、南乔治亚州和南极洲漂浮和搁浅的海藻上发现的群落，科学考察队(包括西班牙国家南极考察队巴塞罗那大学的合作伙伴)、旅游船和以前的考察队进行的机会主义收集。预计候选人将在南大西洋开展实地活动，以量化潜在的搭便车者，并进行生理实验。他们将与智利(Magallanes大学)的合作者/合作伙伴以及福克兰群岛的案例合作伙伴(南大西洋环境研究所-Saeri)合作。候选者将：确定该地区两种主要海藻--南极洲海藻和巨藻海藻--的物种及其丰度和在海藻植物上的位置。研究海带离开海岸对生活在海藻上的动植物的影响，模拟导致海带漂流的风暴的影响(在福克兰群岛和智利马哲伦群岛使用潜水潜水进行)。调查海藻物种的生物地理分布模式利用分类学和分子生物学方法；并将这与海洋模型和海带作为媒介的作用联系起来。了解南极和福克兰群岛本土物种对现在和未来极锋南部发现的条件的容忍能力(使用生理实验和IPCC气候情景)。利用从博士那里获得的知识进行风险评估，向科学家和政策制定者通报现在和未来极锋南部可能的候选物种和殖民中心。

Human activity and shipping have long been considered the principal threats to the "biosecurity" of the remote and isolated shallow marine ecosystems of Antarctica (Chown et al., 2015). However, recent work has shown that the Southern Ocean's strong, circumpolar winds, currents and fronts may not be a barrier to natural colonisation from the north (Fraser et al., 2018). The sub-Antarctic (Patagonia, the Falkland Islands, New Zealand and the mid-latitude islands of the Southern Hemisphere) shallow water marine environment is often characterised by highly exposed shores on extremely remote islands (Griffiths & Waller, 2016). The ice-free coastlines are often dominated by dense beds of the kelp Durvillaea antarctica, Macrocystis pyrifera and other large macrophytes. Antarctic shallow coastal marine communities were long thought to be isolated from their subAntarctic neighbours by hundreds of kilometres of deep ocean and the Antarctic Circumpolar Current.According to the literature, over 70 million kelp rafts are afloat in the Southern Ocean at any one time (Smith, 2002). These living, floating islands can play host to a range of passenger species from both their original coastal location and those picked in the open ocean. Driven by winds, currents and storms towards the coast of the continent, these rafts are often cited as theoretical vectors for the introduction of new species into Antarctica and the sub-Antarctic islands.Our discovery of non-native kelp and a wide range of 'hitchhiking' passenger organisms washed up on Antarctic beaches led us to question the permeability of these barriers to species dispersal (Avila et al., 2020). This is the first evidence of non-native species reaching the Antarctic continent alive on kelp rafts. One passenger species, the bryozoan Membranipora membranacea, is found to be an invasive and ecologically harmful species in some cold-water regions, and this is its first record from Antarctica (Avila et al., 2020).The successful applicant will investigate the communities found on floating and beached kelp from southern Chile, the Falkland Islands, South Georgia and Antarctica using existing data and samples, opportunistic collections by scientific expeditions (including partners from University of Barcelona on the Spanish National Antarctic Expeditions), tourist vessels and previous expeditions. The candidate will be expected to undertake a field campaign to the South Atlantic to quantify the potential hitchhikers and conduct physiological experiments. They will be working with collaborators/partners in Chile (University of Magallanes) and the CASE partner in the Falkland Islands (South Atlantic Environmental Research Institute - SAERI).The candidate will:Identify the species living on the two main species of kelp in the region, Durvillaea antarctica and Macrocystis pyrifera, and their abundance and location on the kelp plants.Examine the effect of kelp becoming dislodged from the shore on the fauna and flora that live on the kelp, simulating the effects of storms that lead to kelp rafting (undertaken using scuba diving in the Falkland Islands and potentially in Magellanic Chile).Investigate biogeographic distribution patterns in the species living on the kelp, using taxonomic and molecular methods; and relating this to oceanographic models and the role of kelp as a vector.Understanding the ability of sub-Antarctic and Falkland Island native species to tolerate conditions found south of the Polar Front both now and in the future (using physiological experiments and IPCC climate scenarios).Undertake a risk assessment, using knowledge gained from the PhD, to inform scientists and policy makers about the likely candidate species and centres of colonisation south of the Polar Front, both now and in the future.