Roxane Maranger

Université de Montréal | UdeM · Department of Biological Sciences

Anthropogenic pressures, including urban and agricultural expansion, can negatively influence a lake’s capacity to provide aquatic ecosystem services (ES). However, identifying lakes most at risk of losing their ES requires integrating information on lake ecological state, global change threats, and ES demand. Here, we provide a social-ecological f...

Measuring freshwater submerged aquatic vegetation (SAV) biomass at large spatial scales is challenging, and no single technique can cost effectively accomplish this while maintaining accuracy. We propose to combine and intercalibrate accurate quadrat-scuba diver technique, fast rake sampling, and large-scale echosounding. We found that the overall...

Submerged aquatic vegetation (SAV) in lake littoral zones is an inland water wetland type that provides numerous essential ecosystem services, such as supplying food and habitat for fauna, regulating nutrient fluxes, stabilizing sediments, and maintaining a clear water state. However, little is known on how inland SAV quantities are changing global...

Different sources and fates control riverine dissolved organic matter (DOM) composition in catchments of contrasting land use and climate. However, assessing the changes in DOM composition together with nutrient forms along rivers exposed to these gradients remains rare. Here we quantified the spatial and temporal patterns in DOM components and nut...

Large rivers can retain a substantial amount of nitrogen (N), particularly in submerged aquatic vegetation (SAV) meadows that may act as disproportionate control points for N retention. However, the temporal variation of N retention in large rivers remains unknown since past measurements were snapshots in time. Using high‐frequency plants and NO3⁻...

Increasing the overall use efficiency of nitrogen (N) and phosphorus (P) resources in food production while minimizing losses to the environment are required to meet the dual challenge of food security and sustainability. Yet studies quantifying the overall performance of different agro-system types and how these have changed over time remain rare,...

Surface ocean eukaryotic phytoplankton biogeography can be determined as chlorophyll-a using remote sensing techniques yet evaluating its community composition remains limited. Given our ability to track site-specific chlorophyll-a concentration, we tested which factors influenced protistan functional trait distribution, and whether the distributio...

The microbial carbon pump (MCP) hypothesis suggests that successive transformation of labile dissolved organic carbon (DOC) by prokaryotes produces refractory DOC (RDOC) and contributes to the long-term stability of the deep ocean DOC reservoir. We tested the MCP by exposing surface water from a deep convective region of the ocean to epipelagic, me...

Measuring freshwater submerged aquatic (SAV) biomass at large spatial scales is challenging and no single technique can cost effectively accomplish this while maintaining accuracy. We propose to combine and intercalibrate accurate quadrat-scuba diver technique, fast rake sampling and large scale echosounding. We found that the relationship between...

Different sources and fates control riverine dissolved organic matter (DOM) composition in catchments of contrasting land use, and climate. However, assessing the changes in DOM composition together with nutrient forms along rivers exposed to these gradients remains rare. Here we quantified the spatial and temporal patterns in DOM components and nu...

Rivers are known to emit large amounts of greenhouse gases globally, however, few studies have evaluated the interacting influence of land use, within river features (for example, sites of major confluence, changes in shape), and hydrology on the coupled dynamics of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Here, we measured CO2,...

Natural and human features on land result in differential loadings of carbon (C), nitrogen (N), and phosphorus (P) to rivers that influence within ecosystem processing. However, little is known about how land use, together with seasonal changes in climate and hydrology, influence the relative proportions of C, N, and P in rivers. To evaluate the sp...

Lakes are important sources of greenhouse gases (GHGs) to the atmosphere. Factors controlling CO2, CH4 and N2O fluxes include eutrophication and warming, but the integrated influence of climate-warming-driven stratification, oxygen loss and resultant changes in bloom characteristics on GHGs are not well understood. Here we assessed the influence of...

Large-scale commercialization of the Haber-Bosch (HB) process is resulting in intensification of nitrogen (N) fertilizer use worldwide. Globally N fertilizer use is far outpacing that of phosphorus (P) fertilizer. Much of the increase in N fertilizers is also now in the form of urea, a reduced form of N. Incorporation of these fertilizers into agri...

Ecologists typically associate water quality with trophic status, where oligotrophic is considered excellent and presumably provides more aquatic ecosystem services. However, water quality is perceived differently among observers with different worldviews. For example, agriculture and public health sectors quantify the provisioning of aquatic ecosy...

Diverse prokaryotic communities consume and transform a broad suite of molecules in the dissolved organic matter (DOM) pool, which controls major biogeochemical cycles. Despite methodological advancements that provide increasingly more detailed information on the diversity of both prokaryotic communities and DOM components, understanding how these...

Excess reactive nitrogen (N) is linked to a myriad of environmental problems that carry large societal costs. Nitrogen footprint tools can help institutions understand how their direct and indirect activities are associated with N release to the environment through energy use, food, and transportation. However, little is known about how geographic...

Precise mapping of subsurface properties, especially soil parent material (SPM), is critical to understanding most geomorphic and hydrologic processes. Because spatial variability of the subsurface properties is highly correlated to the morphology of the earth's surface, DEMs and aerial/satellite imagery have been used successfully for lithological...

Connectivity among habitat patches in both natural and disturbed landscapes needs to be accounted for in conservation planning for biodiversity maintenance. Yet methods to assess connectivity are often limited, because simulating the dispersal of many species is computationally prohibitive, and current simulations make simplifying assumptions about...

Marine and freshwater prokaryotes feed primarily on bioavailable labile dissolved organic carbon (BDOCL), as well as the bioavailable fraction of the semilabile DOC (BDOCSL) pool. These fractions are operationally defined here as the DOC consumed within a month and greater than a month to a year and a half, respectively. Organic matter from these d...

Streams are important sites of elemental transformations due to the relatively high contact rates between flowing water and biogeochemically reactive sediments. Increased urbanization typically results in higher nutrient and carbon (C) inputs to streams from their watersheds and increased flow rates due to modification in channel form, reducing wit...

Ecologists typically associate water quality with trophic status where oligotrophic ecosystems have excellent water quality and presumably provide more aquatic ecosystem services. However water quality is perceived differently among worldviews. Aquatic ecosystem service provisioning to the public health and agriculture sectors is determined using s...

In this article, we challenge the notion that global warming stimulates organic matter mineralization and increases greenhouse gas emissions in lakes via direct temperature effects. We show that the interactive effects of warming and transparency loss due to eutrophication or browning overrides atmospheric warming alone. Thermal shielding enables a...

The distribution and quality of water resources vary dramatically across Canada, and human impacts such as land-use and climate changes are exacerbating uncertainties in water supply and security. At the national level, Canada has no enforceable standards for safe drinking water and no comprehensive water-monitoring program to provide detailed, tim...

Aquatic plants (macrophytes) are known to affect flow dynamics, contributing to flow resistance. Most studies on flow‐vegetation interactions are performed in laboratory flumes and focus on the flow field around plants, with little research at the level of vegetation patches in large aquatic ecosystems. In most hydrodynamic models, increased drag d...

We investigated the variability in ammonia oxidation (AO) rates and the presence of ammonia-oxidizing archaea and bacteria (AOB and AOA) over an annual cycle in the water column of a small, seasonnally ice covered, temperate shield lake. AO, the first step of nitrification, was measured in situ using ¹⁵N-labelled ammonium (NH4⁺) at 1% and 10% of ph...

Depth interpolated monthly variation in water temperature and dissolved oxygen. (DOCX)

Boxplot of seasonal delta N2O variation for the nitrification project. (DOCX)

Phylogenetic relationships. (DOCX)

Supplementary methods. Additional informations on DNA extraction, PCR amplification, sequencing and phylogenetic analysis. (DOCX)

Variation in NH4+, NO3-, N2O and chl a concentrations from lake sentinel bottom waters. (DOCX)

Informations on ammonia oxidation rates assays. (DOCX)

Simple linear regressions between ammonia oxidation rates and environmental variables. (DOCX)

Dataset for the lake sentinel project. (CSV)

Phosphorus (P) plays a crucial role in both agricultural production and water quality. There has been growing recognition of the importance of “legacy” P (surplus P that has accumulated in watersheds over time) for understanding contemporary water quality outcomes; however, little is known about how different watersheds respond to cumulative pressu...

Anthropogenic activities have led to increased transfers of nitrogen (N) and phosphorus (P) to surface waters where changes in the absolute amounts of N and P delivery, and in N:P ratios, threaten water quality. While models of riverine fluxes are increasingly good at predicting total annual nutrient loads, our understanding of which features of a...

Excess anthropogenic phosphorus in watersheds, transported with runoff, can result in aquatic eutrophication, a serious global water quality concern. Watersheds can retain phosphorus, especially in their soils, which can serve as a buffer against the effect of excessive use of phosphorus. However, whether there is a quantifiable threshold at which...

Declining water quality in reservoirs is of growing concern in many regions, yet there is still little understanding of long-term water quality trends in these systems. Across the landscape, reservoirs have diverse origins, functions, and operational strategies. In temperate environments, winter water-level drawdown is a common operational practice...

Université de Montréal (UdeM) is the largest of Montreal's four full scale universities : 33,770 undergraduate and 11,860 graduate students, 1925 professors and 5825 full-time equivalent employees. Its main campus is located in the heart of the city and is well served by public transit. Three small satellite campuses have also been considered in th...

Human activities have increased the global circulation of mercury, a potent neurotoxin. Mercury can be converted into methylmercury, which biomagnifies along aquatic food chains and leads to high exposure in fish-eating populations. Here we quantify temporal trends in the ocean-to-land transport of total mercury and methylmercury from fisheries and...

The “freshwater pipe” concept has improved our understanding of freshwater carbon (C) cycling, however, it has rarely been applied to macronutrients such as nitrogen (N) or phosphorus (P). Here, we synthesize knowledge of the processing of C, N, and P together in freshwaters from land to the ocean. We compared flux estimates into and out of the N a...

While excess phosphorus typically results in the eutrophication of inland waters, there is growing evidence that excess nitrogen (N) and the availability of different N forms influence phytoplankton community composition, often favoring potentially toxic genera. In this study, the environmental dynamics, phytoplankton community structure, and N upt...

Nitrate dual stable isotopes (δ¹⁵N and δ¹⁸O of NO3⁻) have proven to be a powerful technique to elucidate nitrogen (N) cycling pathways in aquatic systems. We applied this technique for the first time in the pelagic zone of a small temperate meso-eutrophic lake to identify the dominant N cycling pathways, and their spatial and temporal variability....

This perspective documents current thinking around climate actions in Canada by synthesizing scholarly proposals made by Sustainable Canada Dialogues (SCD), an informal network of scholars from all 10 provinces, and by reviewing responses from civil society representatives to the scholars’ proposals. Motivated by Canada’s recent history of repeated...

The renewed interest in trait-based approaches has offered a stimulating, conceptual framework for predicting species distributions, assessing community composition and determining biodiversity–ecosystem linkages. However, despite previous attempts to clarify trait terminology and its application, selecting ecologically meaningful traits that mecha...

In an era of increasingly multidisciplinary science, it is essential to identify the frontiers as well as the core of an inherently holistic discipline: ecosystem ecology. To achieve this, we led a series of town hall events at multiple scientific-society meetings over a two-year period followed by a workshop with a diverse set of ecosystem scienti...

Increasing air temperatures may result in stronger lake stratification, potentially altering nutrient and biogenic gas cycling. We assessed the impact of climate forcing by comparing the influence of stratification on oxygen, nutrients, and global-warming potential (GWP) of greenhouse gases (the sum of CH4, CO2, and N2O in CO2 equivalents) emitted...

Human activities have increased the flow of nitrogen (N) and phosphorus (P) over much of the Earth, leading to increased agricultural production, but also the degradation of air, soil, and water quality. Here we quantify the sources of anthropogenic N and P inputs to 76 watersheds of the St. Lawrence Basin (SLB) throughout the 20th century using NA...

Waste stabilisation ponds (WSPs) are highly enriched environments that may emit large quantities of greenhouse gases (GHG), including CO2, CH4 and N2O. However, few studies provide detailed reports on these emissions. In the present study, we investigated GHG emissions from WSPs in Western Australia and Quebec, Canada, and compared emissions to WSP...

This data compilation synthesizes 8609 individual observations and ranges of 13 traits from 201 freshwater and 191 marine crustacean taxa belonging to either Copepoda or Cladocera, two important zooplankton groups across all major aquatic habitats. Most data were gathered from the literature, with the balance being provided by zooplankton ecologist...

This data set is available through Ecological Archives: http://esapubs.org/archive/search.php We kindly ask users to cite this metadata source as: Hébert, M-P., Beisner, B. E., and Maranger, R. (2016) A compilation of quantitative functional traits for marine and freshwater crustacean zooplankton. Ecology 97(4): 1081-1081.

This data compilation synthesizes 8609 individual observations and ranges of 13 traits from 201 freshwater and 191 marine crustacean taxa belonging to either Copepoda or Cladocera, two important zooplankton groups across all major aquatic habitats. Most data were gathered from the literature, with the balance being provided by zooplankton ecologist...

The use of functional traits to characterize community composition has been proposed as a more effective way to link community structure to ecosystem functioning. Organismal morphology, body stoichiometry and physiology can be readily linked to large-scale ecosystem processes through functional traits that inform on interspecific and species-enviro...

Inland waters are important sites of nitrogen processing1,2, and represent a significant component of the global budget of nitrous oxide, a powerful greenhouse gas. Measurements have focused on nitrogen-rich temperate rivers, with low-nitrogen freshwater systems at high latitudes receiving less attention. Here we measured surface water nitrous oxid...

The use of functional traits to characterize community composition has been proposed as a more effective way to link community structure to ecosystem functioning. Organismal morphology, body stoichiometry and physiology can be readily linked to large-scale ecosystem processes through functional traits that inform on interspecific and species-enviro...

Here we harnessed the power of metaproteomics to assess the metabolic diversity and function of stratified aquatic microbial communities in the deep and expansive Lower St. Lawrence Estuary, located in Eastern Canada. Vertical profiling of the microbial communities through the stratified water column revealed differences in metabolic lifestyles and...

Mixotrophy is a valuable functional trait used by microbes when environmental conditions vary broadly or resources are limited. In the sunlit waters of the ocean, photoheterotrophy, a form of mixotrophy, is often mediated by proteorhodopsin (PR), a seven helices transmembrane protein binding the retinal chromophore. Altogether, they allow bacteria...

Large-scale commercialization of the Haber–Bosch (HB) process is resulting in intensification of nitrogen (N) fertilizer use worldwide. Globally N fertilizer use is far outpacing that of phosphorus (P) fertilizer. Much of the increase in N fertilizers is also now in the form of urea, a reduced form of N. Incorporation of these fertilizers into agri...

The nitrogen stable isotopic signature (d 15 N) of sediment is a powerful tool to understand eutrophication history, but its interpretation remains a challenge. In a large-scale comparative approach, we identified the most important drivers influencing surface sediments d 15 N of 65 lakes from two regions of Canada using proxies that reflect waters...