Phytoplankton bioindicators were used to assess environmental conditions in urban aquatic systems in a large Canadian city. Sampling was conducted during summers 2010 and 2011 in 20 urban waterbodies on the Island of Montreal (Quebec, Canada). We evaluated 4 indicators: (1) fluorometric estimates of the chlorophyll concentration of the total phytoplankton and of 4 spectral groups, (2) species richness, and (3) biovolumes of taxonomic and (4) functional groups of the microphytoplankton. We assessed how these indicators changed among types of urban waterbodies and determined the limnological features and/or management practices driving their spatial variation. Principal component analysis captured 48% of total environmental heterogeneity, and K-means clustering analyses defined 5 relevant types of waterbodies. Overall, 96 microphytoplankton species (γ diversity) were recorded, and species richness (α diversity) per waterbody varied from 1 to 27. Chlorophyll concentration of the total phytoplankton and the green algae spectral group, as well as the total biovolume of microphytoplankton, dinophytes, and of 2 functional groups (large flagellates, large colonies of green algae, and cyanobacteria) differed among waterbody types. Phytoplankton indicators based on in situ fluorometry and microphytoplankton biovolume of functional and taxonomic groups were fairly coherent and showed potential for monitoring. Implications of our findings are discussed in light of guiding future management practices to sustain biodiversity, ecological integrity, and water quality of urban waterbodies.

浮游植物生物指示剂用于评估加拿大大城市城市水生系统的环境条件。在2010年和2011年夏季，在蒙特利尔岛（加拿大魁北克）的20个城市水体中进行了采样。我们评估了4个指标：（1）对总浮游植物和4个光谱组的叶绿素浓度进行荧光测定，（2）物种丰富度，以及（3）微浮游植物的分类学生物量和（4）功能组。我们评估了这些指标在城市水体类型之间的变化，并确定了导致其空间变化的湖泊学特征和/或管理措施。主成分分析捕获了总环境异质性的48％，而K-均值聚类分析定义了5种相关的水体类型。总体上，记录了96种微浮游植物种类（γ多样性），每个水体的物种丰富度（α多样性）在1到27之间变化。总浮游植物和绿藻光谱组的叶绿素浓度，以及微浮游植物的总生物量，和2个功能组（大型鞭毛，绿藻大菌落和蓝细菌）在水体类型中有所不同。基于功能组和分类组的原位荧光法和微浮游植物生物量的浮游植物指标相当一致，并显示出监测的潜力。我们将根据指导未来的管理实践以维持城市水体的生物多样性，生态完整性和水质来讨论我们的发现的含义。