Data: The roles of sea-ice, light and sedimentation in structuring shallow Antarctic benthic communities

Data repository for the paper:"The roles of sea-ice, light and sedimentation in structuring shallow Antarctic benthic communities"Graeme F. Clark, Jonathan S. Stark, Anne S. Palmer, Martin J. Riddle, Emma L. Johnston.PLoS ONEData are boulder communities (epifauna), annual light budgets, and sediment traps. See the paper for more details.ABSTRACTOn polar coasts, seasonal sea-ice duration strongly influences shallow marine environments by affecting environmental conditions, such as light, sedimentation, and physical disturbance. Sea-ice dynamics are changing in response to climate, but there is limited understanding of how this might affect shallow marine environments and benthos. Here we present a unique set of physical and biological data from a single region of Antarctic coast, and use it to gain insights into factors shaping polar benthic communities. At sites encompassing a gradient of sea-ice duration, we measured temporal and spatial variation in light and sedimentation and hard-substrate communities at different depths and substrate orientations. Biological trends were highly correlated with sea-ice duration, and appear to be driven by opposing gradients in light and sedimentation. As sea-ice duration decreased, there was increased light and reduced sedimentation, and concurrent shifts in community structure from invertebrate to algal dominance. Trends were strongest on shallower, horizontal surfaces, which are most exposed to light and sedimentation. Depth and substrate orientation appear to mediate exposure of benthos to these factors, thereby tempering effects of sea-ice and increasing biological heterogeneity. However, while light and sedimentation both varied spatially with sea-ice, their dynamics differed temporally. Light was sensitive to the site-specific date of sea-ice breakout, whereas sedimentation fluctuated at a regional scale coincident with the summer phytoplankton bloom. Sea-ice duration is clearly the overarching force structuring these shallow Antarctic benthic communities, but direct effects are imposed via light and sedimentation, and mediated by habitat characteristics.Data files:Boulder_community_data.csv- Percentage cover data for sessile organisms (invertebrates and algae) growing on boulder surfaces.- Columns 1 to 5 are sample attributes, columns 6 to 57 are measured variables (species or bare space).Light_budget_data.csv- Annual light budgets at each site, recorded by light meters.- Columns are site name and annual light budget (mol photons m-2 year-1)Sediment_trap_data.csv- Total sediment collected in sediment traps- Columns are site label, position in bay, replicate, dates deployed and retrieved, and the calculated sediment flux (g m-2 d-1)

本数据集为论文《海冰、光照与沉积作用在塑造南极浅海底栖群落（benthic communities）结构中的作用》的配套数据存储库，作者为Graeme F. Clark、Jonathan S. Stark、Anne S. Palmer、Martin J. Riddle、Emma L. Johnston，发表于PLoS ONE。数据集包含岩块（Boulder）表栖生物（epifauna）群落数据、年度光照预算数据以及沉积捕集器数据，详细信息请参阅原文。

【摘要】在极地海岸带，季节性海冰（sea-ice）持续时长通过调控光照、沉积作用（sedimentation）与物理扰动等环境条件，对浅海生态系统产生显著影响。当前海冰动力学因气候变化发生改变，但学界对其如何影响浅海环境与底栖生物的认知仍较为有限。本研究采集了南极海岸单一区域的独特物理与生物数据集，借此解析调控极地底栖群落结构的关键因子。研究在覆盖海冰持续时长梯度的多个采样点中，测定了不同深度与基底朝向的采样点处，光照与沉积作用的时空变化规律，以及硬质基底群落特征。生物学趋势与海冰持续时长呈现高度相关性，且其驱动机制表现为光照与沉积作用的反向梯度变化。随着海冰持续时长缩短，区域光照水平上升而沉积作用减弱，群落结构随之发生从无脊椎动物占优向藻类占优的转变。该趋势在浅海水平基底上最为显著，此类基底受光照与沉积作用的影响程度最高。水深与基底朝向可调节底栖生物对上述环境因子的暴露程度，进而削弱海冰的影响效应并提升生物群落的异质性。不过，尽管光照与沉积作用均随海冰时长呈现空间异质性，二者的时间动态却存在差异：光照水平对采样点专属的海冰消融日期极为敏感，而沉积作用则在区域尺度上随夏季浮游植物繁盛（phytoplankton bloom）期发生波动。研究结果表明，海冰持续时长是塑造南极浅海底栖群落的核心驱动因子，但其直接效应通过光照与沉积作用介导，并受生境特征（habitat characteristics）的调控。

### 数据文件说明
1. `Boulder_community_data.csv`：记录了岩块表面固着生物（sessile organisms，无脊椎动物与藻类）的盖度百分比数据。其中第1至5列为样本属性，第6至57列为实测变量（物种或裸空间占比）。
2. `Light_budget_data.csv`：记录了各采样点的年度光照预算，由光照计实时采集。数据列包括采样点名称与年度光照预算（单位：mol photons m⁻²·year⁻¹）。
3. `Sediment_trap_data.csv`：记录了沉积捕集器收集的总沉积物量。数据列包括采样点标签、海湾内位置、重复样本编号、部署与回收日期，以及计算得到的沉积物通量（单位：g m⁻²·d⁻¹）。