Are fluorometric, taxonomic, and functional indicators of phytoplankton community structure linked to environmental typology of urban ponds and lakes?

ABSTRACTPhytoplankton 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.