Biology subjects

Grosbois, G.

Publications and source records attributed to Grosbois, G..

3 recordsLinked to original sources

bioRxiv2026

Fish presence alters amphibian and zooplankton communities in kettle lakes, but not hydrological connectivity

Fishless lakes, critical drivers of biodiversity across freshwater landscapes, are becoming increasingly rare due to fish introductions. Although the impacts of fish introduction are well understood in high-elevation fishless lakes, their effects on fishless kettle lakes remain poorly understood. Many kettle lakes are disconnected from the surface water network and are therefore fishless. In this study, we examined how amphibian and zooplankton communities differ between fishless and fish-bearing kettle lakes by comparing 36 lakes in Quebec, Canada. Some kettle lakes are hydrologically connected to surrounding aquatic ecosystems, allowing natural colonization by fish. We therefore also evaluated how amphibian and zooplankton communities differ between connected and disconnected kettle lakes. Fish presence was associated with differences at each stage of the amphibian life cycle. Reproductive calls of adult amphibians were detected regardless of fish presence, indicating that reproduction occurred in all lake types. However, the presence of fish was associated with fewer amphibian egg masses and lower larval abundance, and the absence of salamanders at the larval stage. Small-bodied zooplankton were more abundant in fish-bearing lakes, while overall species richness was lower. In particular, Chaoborus americanus, a large top-predatory zooplankton species, was found exclusively in fishless lakes. In contrast to fish presence, hydrological connectivity had no significant effect on most communities, except for adult American toads, adult wood frogs, and mink frogs larvae, which responded positively to the interaction between fish presence and connectivity. Based on our results, we recommend avoiding fish stocking of kettle lakes to preserve essential reproductive habitats for amphibians, maintain refuges for sensitive zooplankton species, and safeguard the spatial heterogeneity that underpins landscape-scale biodiversity.

ecology↗

bioRxiv2025

Mining and e-waste recycling influence the spatial distribution of technology-critical elements, but not rare earth elements, in boreal lakes

Mining and more recent e-waste recycling have contributed trace elements (TEs) to the environment. However, the occurrence of emerging technology-critical elements (TCEs), including rare earth elements (REEs), remains poorly reported. Our study aims to i) investigate the spatial distribution of TEs, including TCEs, across different environmental matrices; ii) compare measured concentrations in water and sediment against environmental quality guidelines; and iii) assess potential risks to human health from fish consumption. In this study, we sampled water, sediment, and fish tissues (muscle and liver) across six boreal lakes near the historically mining region of Rouyn-Noranda, home to North Americas largest copper smelting and recycling facility (Horne Smelter). Concentrations of TEs (e.g., Cu, Se) were higher in lakes closest to the smelter. Similarly, some TCEs (i.e., Ti, Co, Tl) followed this same spatial distribution pattern, suggesting that their release may be linked to historical and current mining activities. Conversely, REEs displayed distinct spatial patterns, likely influenced by geological sources rather than pollution. Several TEs (e.g., Zn, Cd, Pb) exceeded Canadian water and sediment quality guidelines in lakes closer to the mining area. Muscle tissue from walleye or yellow perch showed Zn, Cd, or Pb concentrations above safety limits in at least one lake. This study highlights the importance of including emerging TCEs (e.g., Sr, Tl, Co) in biomonitoring programs. Our findings provide critical insights into the environmental distribution of TEs across multiple matrices of boreal lake ecosystems, contributing to global efforts in risk assessment and sustainable freshwater management in the context of growing electronic waste recycling. Highlights{blacksquare} First report of various TCEs and REEs in 3 matrices of boreal lakes {blacksquare}The spatial distribution of several newly reported TCEs is similar to that of historical TEs {blacksquare}REE concentrations are associated with geology rather than mining sources {blacksquare}Some TE concentrations in water and sediment are above guidelines in closest lakes {blacksquare}All lakes exceeded safety limits for at least one element (Zn, Cd, or Pb) in the muscle tissue of either walleye or yellow perch

ecology↗

bioRxiv2025

Live fast and die young: walleye populations adapt their life cycle to degraded lakes of the Canadian clay belt.

Despite its widespread distribution in North America, many populations of walleye (Sander vitreus) declined to the point where restoration measures, including restocking, are necessary. In this study, we compared population structure and dietary composition of walleye populations in two degraded lakes and two non-degraded lakes in the Abitibi-Temiscamingue region of Quebec, Canada. Food resources were assessed for walleye larvae, young-of-the-year, juveniles, and adults. Growth and relative abundance were also quantified for young-of-the-year, juvenile, and adult walleye. Young-of-the-year were more abundant and grew faster in degraded lakes compared to non-degraded controls, benefiting from high populations of spring zooplankton, which are a critical larval resource. The simplified food webs in degraded lakes lacked pollution-sensitive macroinvertebrates, which resulted in walleye diets being even more dominated by fish. Although juveniles and adults were equally or more abundant in degraded lakes compared to control lakes, premature adult mortality compromised population stability. We recommend focusing on improving adult fish habitat, manage for prey species, and review fishing regulations to enhance the survival of mature walleye and ensure sustainable populations.

ecology↗