A large-scale assessment of lakes reveals a pervasive signal of land use on bacterial communities

Abstract

Lakes play a pivotal role in ecological and biogeochemical processes and have been described as “sentinels” of environmental change. Assessing “lake health” across large geographic scales is critical to predict the stability of their ecosystem services and their vulnerability to anthropogenic disturbances. The LakePulse research network is tasked with the assessment of lake health across gradients of land use on a continental scale. Bacterial communities are an integral and rapidly responding component of lake ecosystems, yet large-scale responses to anthropogenic activity remain elusive. Here, we assess the ecological impact of land use on bacterial communities from over 200 lakes covering more than 660,000 km2 across Eastern Canada. In addition to community variation between ecozones, land use across Eastern Canada also appeared to alter diversity, community composition, and network structure. Specifically, increasing anthropogenic impact within the watershed lowered diversity. Likewise, community composition was significantly correlated with agriculture and urban development within a watershed. Interaction networks showed decreasing complexity and fewer keystone taxa in impacted lakes. Moreover, we identified potential indicator taxa of high or low lake water quality. Together, these findings point to detectable bacterial community changes of largely unknown consequences induced by human activity within lake watersheds.

Seasonal Dynamics Are the Major Driver of Microbial Diversity and Composition in Intensive Freshwater Aquaculture

“…An additional seasonal factor that could affect water quality and subsequently the aquatic microbiome, is rainfall. During significant rain events, DARU receives runoff from the surrounding agricultural fields, carrying sediments, nutrients, fertilizers, pesticides and other soil-based compounds ( Maltby et al, 1995 ; Page et al, 1995 ; Mallin et al, 2009 ; Kraemer et al, 2020 ; Marmen et al, 2020 ). Unfortunately, we currently lack a quantitative budget of the water and nutrient inputs into the reservoir and fishponds, which is needed to test the hypothesis that rainwater runoff may be important at DARU.…”

Seasonal dynamics are the major driver of microbial diversity and composition in intensive freshwater aquaculture

“…An additional seasonal factor that could affect water quality and subsequently the aquatic microbiome, is rainfall. During significant rain events, DARU receives runoff from the surrounding agricultural fields, carrying sediments, nutrients, fertilizers, pesticides and other soil-based compounds (Kraemer et al, 2020; Mallin et al, 2009; Maltby et al, 1995; Marmen et al, 2020; Page et al, 1995). While we lack a quantitative budget of the water and nutrient inputs into the reservoir and fishponds, our results suggest that such runoff may be important at DARU.…”

Opening a next‐generation black box: Ecological trends for hundreds of species‐like taxa uncovered within a single bacterial >99% 16S rRNA operational taxonomic unit

“…Obviously, priB amplicon sequencing provides a possibility to study the mechanisms of community assembly in great detail. Furthermore, this method may provide an opportunity to measure the response of some important freshwater bacteria to environmental changes caused by anthropogenic impact (Kraemer et al, 2020)…”