Data from: Canopy facilitates seaweed recruitment on subtidal temperate reefs

Bennett&Wernberg_recruit facilitation_JEcol_raw data: Net recruitment rates (per 3.14 m2) and standardised net recruitment rates, of Scytothalia dorycarpa and Sargassum spp., into experimental plots of different canopy removal intensity). Collected in the field, at locations in southwestern Australia. 1. Facilitation through physical stress amelioration has been largely overlooked in subtidal marine ecosystems, where abiotic gradients are perceived to be benign. However, seemingly subtle changes in marine environmental conditions can alter community structure across vast areas, and therefore, the type of interactions and any refuge provided by marine foundation species. This could have substantial implications for community organization. 2. We measured net recruitment rates of subtidal seaweeds under experimentally modified canopy densities, across 1000 km of coastline, to examine the nature of interactions between seaweed canopies and recruits. 3. Contrary to expectations, facilitation, as evidenced by higher recruitment under canopies, was observed throughout all conditions for Scytothalia dorycarpa and under partial canopies at three of four locations for Sargassum spp., whilst competitive interactions remained prevalent for Sargassum under closed canopies. 4. Supply side dynamics were also of major importance to recruitment success for Scytothalia. For Sargassum, the interaction strength between recruits and the canopy became increasingly positive towards lower latitudes, suggesting the canopy environment was mitigating stress across the latitudinal climate gradient. 5. Synthesis. Positive interactions and stress amelioration play an important and previously unrecognized role in determining the recruitment success and viability of seaweeds in subtidal marine ecosystems. These results challenge long held paradigms about the general importance of canopy competition and force a rethink of how seaweed interactions affect habitat resilience to disturbances in subtidal ecosystems.Bennett&Wernberg招募促进实验（JEcol）原始数据：涵盖网翼藻（Scytothalia dorycarpa）与马尾藻属（Sargassum spp.）的净招募率（net recruitment rates，每3.14平方米）及标准化净招募率（standardised net recruitment rates），实验设置了不同冠层移除强度的实验样地（experimental plots）。数据采集自澳大利亚西南部的野外样点。 1. 物理胁迫缓解介导的促进作用在潮下带海洋生态系统（subtidal marine ecosystems）中长期被忽视，此前学界普遍认为该系统的非生物梯度（abiotic gradients）环境较为温和。然而，海洋环境条件的细微变化即可在大范围区域内改变群落结构，进而影响海洋基底物种（marine foundation species）所介导的种间相互作用类型与其所提供的庇护作用，这对群落组织模式可能产生深远影响。 2. 我们在跨越1000公里的海岸线范围内，通过实验调控冠层（canopy）密度，测量了潮下带海藻的净招募率，以探究海藻冠层与幼体之间的相互作用本质。 3. 与预期相悖的是：对于网翼藻，所有实验条件下均观测到冠层存在时招募率更高的促进效应；对于马尾藻属，在4个样点中的3个的部分冠层条件下也观测到该促进效应，而在完整冠层下马尾藻仍以竞争作用为主。 4. 供应侧动态（supply side dynamics）对网翼藻的招募成功同样至关重要。对于马尾藻属而言，幼体与冠层之间的相互作用强度随纬度降低逐渐转为正向，表明冠层环境在纬度气候梯度（latitudinal climate gradient）上缓解了胁迫压力。 5. 总结：正向相互作用与胁迫缓解在决定潮下带海洋生态系统中海藻的招募成功率与生存能力方面发挥着重要且此前未被认知的作用。本研究结果挑战了长期以来关于冠层竞争普遍重要性的生态范式（paradigms），促使我们重新思考海藻相互作用如何影响潮下带生态系统的栖息地恢复力（habitat resilience）以应对外界干扰（disturbances）。