Freshwater Bacterioplankton Metacommunity Structure Along Urbanization Gradients in Belgium

Abstract

Urbanization is transforming and fragmenting natural environments worldwide, driving changes in biological communities through alterations in local environmental conditions as well as by changing the capacity of species to reach specific habitats. While the majority of earlier studies have been performed on higher plants and animals, it is crucial to increase our insight on microbial responses to urbanization across different spatial scales. Here, using a metacommunity approach, we evaluated the effects of urbanization on bacterioplankton communities in 50 shallow ponds in Belgium (Flanders region), one of the most urbanized areas in Northwest Europe. We estimated the relative importance of local environmental factors (35 abiotic and biotic variables), regional spatial factors and urbanization (built-up area) quantified at two spatial scales (200 m × 200 m and 3 km × 3 km). We show that urbanization at local or regional scales did not lead to strong changes in community composition and taxon diversity of bacterioplankton. Urbanization at regional scale (3 km × 3 km) explained only 2% of community composition variation while at local scale (200 m × 200 m), no effect was detected. Local environmental factors explained 13% (OTUs with relative abundance ≥ 0.1%) to 24% (12 dominant OTUs -≥ 1%) of community variation. Six local environmental variables significantly explained variation in bacterioplankton community composition: pH, alkalinity, conductivity, total phosphorus, abundance of Daphnia and concentration of copper (Cu), of which pH was partly mediated by urbanization. Our results indicate that environmental rather than spatial factors accounted for the variation in bacterioplankton community structure, suggesting that species sorting is the main process explaining bacterioplankton community assembly. Apparently, urbanization does not have a direct and strong effect on bacterioplankton metacommunity structure, probably due to the capacity of these organisms to adapt toward and colonize habitats with different environmental conditions and due to their fast adaptation and metabolic versatility. Thus, bacterioplankton communities inhabiting shallow ponds may be less affected by environmental conditions resulting from urbanization as compared to the impacts previously described for other taxa.

Patterns of Structural and Functional Bacterioplankton Metacommunity along a River under Anthropogenic Pressure

“…The lowest average number of OTUs was recorded in the lower, urbanized river course. Hanashiro et al [55] suggest that urbanization does not have a direct impact on the bacterioplankton metacommunity structure and that environmental rather than spatial factors contribute to its variability. The fact that only small differences in microbial biodiversity were observed may also be connected with the biotic homogenization of the studied river, resulting from the anthropogenic modification of this ecosystem [56].…”

Trait-Environment Relationships Reveal the Success of Alien Plants Invasiveness in an Urbanized Landscape

“…In addition, urban landscapes are highly modified and undergo rapid human–urban expansion [ 76 , 81 , 82 , 83 ]. This expansion can greatly change the composition dynamics of species [ 84 , 85 ], as well as increase the connection of water bodies spread throughout urban environments [ 86 , 87 ], leading to more homogenization in species composition. Moreover, urban landscapes with fast-growing modifications are expected to be under climatic changes, such as drought stress, longer and drier periods with water shortage, and extremely hot weather conditions during summer time, with more frequent temperature extremes up to 100 °C [ 88 , 89 ].…”

Metabolic Potential of Some Functional Groups of Bacteria in Aquatic Urban Systems

“…These are particularly important factors in determining the seasonal dynamics of biological communities, especially microbial communities. The development of heterotrophic bacteria is dependent on both variations in temperature and pH [12], as well as factors that characterize water quality (conductivity, TDS, ORP, turbidity) [25]. Enzymatic activity measured in the sediment of Lake Erhai (China) showed significant positive correlations with the temperature measured in the water column [26].…”