Collaborative Research: Sea ice as a driver of Antarctic benthic macroalgal community composition and nearshore trophic connectivity

南极半岛西部已经成为了解南极洲和其他地方的冷水群落以及它们可能如何变化的模型。棕色巨藻(海藻)在该区域北部形成了广泛的海底森林，在为浅水社区提供物质结构和食物(碳)来源方面发挥了关键作用。然而，在安弗斯岛(度S纬度)和阿德莱德岛(S纬度67度)之间，这些大型藻类的数量和多样性明显减少。这可能是因为南部的栖息地在更长的时间内被更多的海冰覆盖，而海冰减少了到达藻类的光线。大型藻类覆盖率的减少无疑会影响食物链中的其他生物，但它如何改变海底群落的过程和组织尚不清楚。该项目将使用潜水、视频调查和藻类采集相结合的方法，定量记录安弗斯和阿德莱德群岛之间多个地点的大型藻类群落。海冰覆盖、光照水平等环境参数对群落结构的影响将被模型化，以确定哪些因素对群落结构的影响最大。对群落结构、食物网和碳流的影响将通过潜水和视频调查相结合的方式进行评估。更广泛的影响包括对研究生和博士后研究人员的培训，以及许多非正式的公共教育活动，包括讲座、向K-12小组做报告，以及各种基于社交媒体的考察。大型藻类群落在南极半岛西部以北更丰富和多样化，可能是因为与较短的海冰覆盖时间相关的更大的光照可获得性。该项目将确定藻类群落结构变化的原因和群落水平的后果。首先，将利用卫星海冰面积和水浊度数据选择、S和69 S之间的研究地点，在这些地点，年海冰覆盖范围是影响次表层光照水平的主要因素。然后，这些研究地点的大型藻类覆盖率的变化将通过潜水员进行的视频线条横断面调查来确定。在不同地点发现的物种的健康、生长和生理状态将通过样方抽样确定。将使用稳定同位素和脂肪酸生物标记物技术评估大型藻类衍生碳对食物网中常见无脊椎动物消费者的相对重要性。这将揭示跨海冰覆盖梯度的大型藻类丰度和物种组成的变化如何影响海底群落组成和整个食物网的碳流。总而言之，这项工作将有助于预测由于全球气候变化而导致的该地区海冰覆盖范围和持续时间的持续减少将如何影响近岸海底群落的结构。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The western Antarctic Peninsula has become a model for understanding cold water communities and how they may be changing in Antarctica and elsewhere. Brown macroalgae (seaweeds) form extensive undersea forests in the northern portion of this region where they play a key role in providing both physical structure and a food (carbon) source for shallow water communities. Yet between Anvers Island (64 degrees S latitude) and Adelaide Island (67 S latitude) these macroalgae become markedly less abundant and diverse. This is probably because the habitat to the south is covered by more sea ice for a longer period, and the sea ice reduces the amount of light that reaches the algae. The reduced macroalgal cover undoubtedly impacts other organisms in the food web, but the ways in which it alters sea-floor community processes and organization is unknown. This project will quantitatively document the macroalgal communities at multiple sites between Anvers and Adelaide Islands using a combination of SCUBA diving, video surveys, and algal collections. Sea ice cover, light levels, and other environmental parameters on community structure will be modelled to determine which factors have the largest influence. Impacts on community structure, food webs, and carbon flow will be assessed through a mixture of SCUBA diving and video surveys. Broader impacts include the training of graduate students and a postdoctoral researcher, as well as numerous informal public education activities including lectures, presentations to K-12 groups, and a variety of social media-based outreach.Macroalgal communities are more abundance and diverse to the north along the Western Antarctic Peninsula, perhaps due to the greater light availability that is associated with shorter period of sea-ice cover. This project will determine the causes and community level consequence of this variation in algal community structure. First, satellite data on sea ice extent and water turbidity will be used to select study sites between 64 S and 69 S where the extent of annual sea ice cover is the primary factor influencing subsurface light levels. Then, variations in macroalgal cover across these study sites will be determined by video line-transect surveys conducted by SCUBA divers. The health, growth, and physiological status of species found at the different sites will be determined by quadrat sampling. The relative importance of macroalgal-derived carbon to the common invertebrate consumers in the foodweb will be assessed with stable isotope and fatty acid biomarker techniques. This will reveal how variation in macroalgal abundance and species composition across the sea ice cover gradient impacts sea floor community composition and carbon flow throughout the food web. In combination, this work will facilitate predictions of how the ongoing reductions in extent and duration of sea ice cover that is occurring in the region as a result of global climate change will impact the structure of nearshore benthic communities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.