Biology subjects

Monchamp, M.-E.

Publications and source records attributed to Monchamp, M.-E..

3 recordsLinked to original sources

bioRxiv2026

Threshold responses of multi-trophic freshwater communities to browning and eutrophication

Browning and eutrophication strongly influence aquatic ecosystems by altering nutrient dynamics, light availability, and food web structure. To investigate their combined effects on aquatic communities, we conducted a nine-week mesocosm experiment in a clear-water north-temperate lake, crossing dissolved organic carbon (DOC) and total phosphorus plus total nitrogen (TP+TN) enrichment treatments. Multi-trophic plankton communities (bacterioplankton, phytoplankton, and zooplankton) were monitored over time using environmental DNA (eDNA) marker gene amplicon sequencing. Beta-diversity analyses highlighted temporal and treatment-driven community restructuring, while PERMANOVA and Principal Response Curve analyses identified the treatments and taxa driving these changes. Our results show that elevated DOC favoured taxa associated with the microbial loop, while nutrient enrichment and lower DOC promoted the green pathway. Threshold responses across trophic levels were observed at 5-7 mg L-{superscript 1} DOC and 30-70 g L-{superscript 1} TP, marking the levels at which compositional shifts propagated through the food web. Overall, this study demonstrated how aquatic communities respond dynamically to browning and nutrient enrichment, offering insight into the mechanisms shaping multi-trophic interactions under a multiple stressor scenario. HighlightsO_LIBrowning and nutrient pulses drove coordinated shifts across bacterioplankton, phytoplankton, and zooplankton. C_LIO_LITemporal community succession and treatment effects were captured through beta-diversity and multivariate ordination analyses. C_LIO_LIThreshold responses propagated through the food web at 5-7 mg L-{superscript 1} DOC and 30-70 {micro}g L-{superscript 1} TP. C_LI Scientific Significance Statement TopicThis study provides insights into the interactive effects of browning and eutrophication on community composition shifts in freshwater ecosystems. Using a mesocosm experiment, we identified thresholds for dissolved organic carbon and total phosphorus + nitrogen concentrations that drove compositional changes across bacterial, phytoplankton, and zooplankton communities, as determined by environmental DNA amplicon sequencing data. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=133 SRC="FIGDIR/small/719940v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@d12f96org.highwire.dtl.DTLVardef@18b4426org.highwire.dtl.DTLVardef@271b94org.highwire.dtl.DTLVardef@183c1d6_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗

bioRxiv2021

Comparative analysis of zooplankton diversity in freshwaters: What can we gain from metagenomic analysis?

Molecular genetic approaches applied to environmental DNA have great potential for biodiversity research and ecosystem monitoring. A metagenome contains genetic information from all organisms captured in an environmental sample. It has been primarily used to study bacteria and archaea, but promising reports focusing on metazoan diversity are emerging. However, methodological uncertainties remain, and studies are required to validate the power and the limitations of such an approach when applied to macro-eukaryotes. Here, we analyzed water sample metagenomes to estimate zooplankton diversity in 22 freshwater lakes across Eastern Canada. We tested the coherence of data based on morphologically identified zooplankton taxa and molecular genetic data derived from shotgun sequencing of environmental DNA collected at the same time. RV coefficients showed a significant correlation between the relative abundance of zooplankton families derived from small subunit rRNA genes extracted from the metagenomes and morphologically identified zooplankton. However, differences in congruence with morphological counts were detected when varied bioinformatic approaches were applied to presence-absence data. This study presents one of the first diversity assessments of a group of aquatic metazoans using metagenomes and validates the coherence of the community composition derived from genetic and classical species surveys. Overall, our results suggest that metagenomics has the potential to be further developed to describe metazoan biodiversity in aquatic ecosystems, and to advance this area we provide key recommendations for workflow improvement.

ecology↗

bioRxiv2018

High dispersal levels and lake warming are emergent drivers of cyanobacterial community assembly over the Anthropocene

Disentangling the relative importance of deterministic and stochastic processes in shaping natural communities is central to ecology. Studies on community assembly over broad temporal and spatial scales in aquatic microorganisms are scarce. Here, we used 16S rDNA sequence data from lake sediments to test for community assembly patterns in cyanobacterial phylogenies across ten European peri-Alpine lakes and over a century of eutrophication and climate warming. We studied phylogenetic similarity in cyanobacterial assemblages over spatial and temporal distance, and environmental gradients, comparing detected patterns with theoretical expectations from deterministic and stochastic processes. We found limited evidence for deviation of lake communities from a random assembly model and no significant effects of geographic distance on phylogenetic similarity, suggesting no dispersal limitation and high levels of stochastic assembly. We did not detect a significant effect of phosphorus and nitrogen levels on deviation of community phylogenies from random. We found however a significant decay of phylogenetic similarity for non-random communities over a gradient of air temperature and water column stability. We show how phylogenetic data from sedimentary archives can improve our understanding of microbial community assembly processes, and support previous evidence that climate warming has been the strongest environmental driver of cyanobacterial community assembly over the Anthropocene.

ecology↗