Biology subjects

Leblond, M.

Publications and source records attributed to Leblond, M..

3 recordsLinked to original sources

bioRxiv2024

The 2023 wildfire season in Quebec: an overview of extreme conditions, impacts, lessons learned and considerations for the future.

The 2023 wildfire season in Quebec set records due to extreme warm and dry conditions, burning 4.5 million hectares and indicating persistent and escalating impacts associated with climate change. The study reviews the unusual weather conditions that led to the fires, discussing their extensive impacts on the forest sector, fire management, boreal caribou habitats, and particularly the profound effects on First Nation communities. The wildfires led to significant declines in forest productivity and timber supply, overwhelming fire management resources, and necessitating widespread evacuations. First Nation territories were dramatically altered, facing severe air quality issues and disruptions. While caribou impacts were modest across the province, the broader ecological, economical, and social repercussions were considerable. To mitigate future extreme wildfire seasons, the study suggests changes in forest management practices to increase forest resilience and resistance, adapting industrial structures to new timber supplies, and enhancing fire suppression and risk management strategies. It calls for a comprehensive, unified approach to risk management that incorporates the lessons from the 2023 fire season and accounts for ongoing climate change. The study underscores the urgent need for detailed planning and proactive measures to reduce the growing risks and impacts of wildfires in a changing climate.

ecology↗

bioRxiv2024

A difficult coexistence: resolving the iron-induced nitrification delay in groundwater filters

Rapid sand filters (RSF) are an established and widely applied technology for the removal of dissolved iron (Fe2+) and ammonium (NH +) in groundwater treatment. Most often, biological NH + oxidation is delayed and starts only upon complete Fe2+ depletion. However, the mechanism(s) responsible for the inhibition of NH + oxidation by Fe2+ or its oxidation (by)products remains elusive, hindering further process control and optimization. We used batch assays, lab-scale columns, and full-scale filter characterizations to resolve the individual impact of the main Fe2+ oxidizing mechanisms and the resulting products on biological NH + oxidation. Modelling of the obtained datasets allowed to quantitatively assess the hydraulic implications of Fe2+ oxidation. Dissolved Fe2+ and the reactive oxygen species formed as byproducts during Fe2+ oxidation had no direct effect on nitrification. The Fe3+ oxides on the sand grain coating, commonly assumed to be the main cause for inhibited nitrification, seemed instead to enhance nitrification by providing additional surface area for biofilm growth. Modelling allowed to exclude mass transfer limitations induced by accumulation of iron flocs and consequent filter clogging as the cause for delayed nitrification. We unequivocally identify the inhibition of NH +oxidizing organisms by the Fe3+ flocs generated during Fe2+ oxidation as the main cause for the commonly observed nitrification delay. The addition of Fe3+ flocs inhibited NH + oxidation both in batch and column tests, and the removal of Fe3+ flocs by backwashing completely re-established the NH + removal capacity, suggesting that the inhibition is reversible. In conclusion, our findings not only identify the iron form that causes the inhibition, albeit the biological mechanism remains to be identified, but also highlight the ecological importance of iron cycling in nitrifying environments. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=130 SRC="FIGDIR/small/581000v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@65ca28org.highwire.dtl.DTLVardef@bb3da3org.highwire.dtl.DTLVardef@cbd32dorg.highwire.dtl.DTLVardef@1956207_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightO_LIDissolved Fe2+ and reactive oxygen species do not affect NH + oxidation C_LIO_LIFe oxide coating aids sand grain colonization by NH +-oxidizing bacteria C_LIO_LIFe3+ flocs inhibit NH + oxidation by reducing the nitrifying capacity of AOB C_LIO_LIChanges in transport patterns due to clogging do not play a major role in NH + oxidation C_LIO_LIThe inhibition of NH4+ oxidation is reversible and reduced by backwashing C_LI

microbiology↗

bioRxiv2022

Existing caribou habitat and demographic models are poorly suited for Ring of Fire impact assessment: A roadmap for improving the usefulness, transparency, and availability of models for conservation

Decision making in conservation science often relies on the best available information. This may include using models that were not designed for purpose and are not accompanied by an assessment of limitations. To begin addressing these issues, we sought to reproduce, and evaluate the suitability of, the best available models for predicting impacts of proposed mining on boreal woodland caribou (Rangifer tarandus caribou) resource selection and demography in northern Ontario. We then evaluated their suitability for projecting the impacts of development in the Ring of Fire region. To aid in accessibility, we developed an R package for data preparation, analyses of resource selection, and demographic parameters. We found existing models were either ill suited, or lacking, for ongoing regional planning. The specificity of the regional resource selection model limited its usefulness for predicting impacts of development, and the high variability across caribou ranges limited the usefulness of a national aspatial demographic model for predicting range-specific impacts. Variability in model coefficients across caribou ranges suggests selection responses vary with habitat availability (i.e. a functional response) while demographic responses continue to decline with increasing disturbance. Models designed for forecasting that are continuously updated by range-specific demographic and habitat information, are required to better inform conservation decisions and ongoing policy and planning practices in the Ring of Fire region.

ecology↗