Environmental Monitoring and Science Division, Alberta Environment and Parks, T5J 5C6, Edmonton, Alberta, Canada.
Department of Biological Sciences, University of Alberta, T6G 2E9, Edmonton, Alberta, Canada.
Ecol Appl. 2020 Jul;30(5):e02102. doi: 10.1002/eap.2102. Epub 2020 Apr 1.
Multiple factors operating across different spatial and temporal scales affect β-diversity, the variation in community composition among sites. Disentangling the relative influence of co-occurring ecological drivers over broad biogeographic gradients and time is critical to developing mechanistic understanding of community responses to natural environmental heterogeneity as well as predicting the effects of anthropogenic change. We partitioned taxonomic β-diversity in phytoplankton communities across 75 north-temperate lakes and reservoirs in Alberta, Canada, using data-driven, spatially constrained null models to differentiate between spatially structured, spatially independent, and spuriously correlated associations with a suite of biologically relevant environmental variables. Phytoplankton β-diversity was largely independent of space, indicating spatial processes (e.g., dispersal limitation) likely play a minor role in structuring communities at the regional scale. Our analysis also identified seasonal differences in the importance of environmental factors, suggesting a general shift toward greater relevance of local, in-lake (e.g., nutrients and Secchi depth) over regional, atmospheric and catchment-level (e.g., monthly solar radiation and grassland coverage) drivers as the open-water growing season progressed. Several local and regional variables explained taxonomic variation jointly, reflecting climatic and land-use linkages (e.g., air temperature and water column stability or pastureland and nutrient enrichment) that underscore the importance of understanding how phytoplankton communities integrate, and may serve as sentinels of, broader anthropogenic changes. We also discovered similar community composition in natural and constructed water bodies, demonstrating rapid filtering of regional species to match local environmental conditions in reservoirs comparable to those in natural habitats. Finally, certain factors related to human footprint (e.g., cropland development) explained the composition of bloom-forming and/or toxic cyanobacteria more than the overall phytoplankton community, suggesting their heightened importance to integrated watershed management.
多种因素在不同的时空尺度上共同作用，影响着β多样性，即不同地点之间群落组成的变化。在广泛的生物地理梯度和时间范围内，理清共同存在的生态驱动因素的相对影响，对于理解群落对自然环境异质性的响应机制以及预测人为变化的影响至关重要。我们利用数据驱动的、受空间限制的零模型，对加拿大艾伯塔省 75 个北温带湖泊和水库的浮游植物群落的分类β多样性进行了划分，从而将其与一系列与生物相关的环境变量区分开来，这些变量具有空间结构、空间独立和虚假相关三种关系。浮游植物β多样性在很大程度上与空间无关，这表明空间过程（例如，扩散限制）可能在区域尺度上对群落结构的影响较小。我们的分析还确定了环境因素重要性的季节性差异，这表明随着开阔水面生长季节的推进，湖泊内部（例如，营养物质和塞奇深度）而非区域、大气和集水区（例如，每月太阳辐射和草地覆盖率）的驱动因素的相关性会逐渐增强。一些本地和区域变量共同解释了分类变化，反映了气候和土地利用之间的联系（例如，空气温度和水柱稳定性或草原和养分富化），这突出了了解浮游植物群落如何整合并可能作为更广泛人为变化的指示物的重要性。我们还发现自然和人工水体具有相似的群落组成，这表明在水库中，浮游植物能够迅速适应局部环境条件，与自然栖息地中的条件相匹配。最后，某些与人类足迹相关的因素（例如，耕地开发）比整体浮游植物群落更能解释形成水华和/或有毒蓝藻的组成，这表明它们对综合流域管理具有更高的重要性。
