Faculté des arts et des sciences – Département de sciences biologiques - Travaux et publications

URI permanent de cette collectionhttps://hdl.handle.net/1866/19204

Cette collection accueille les publications savantes et d’autres types de travaux d’auteur.e.s associé.e.s à cette unité. Voir aussi la collection Thèses et mémoires de l'unité.

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Enhancing chickpea growth via arbuscular mycorrhizal fungal inoculation : facilitating nutrient uptake and shifting potential pathogenic fungal communities
Basiru, Sulaimon; Aitsimhand, Khadija; Elfermi, Rachid; Khatour, Imad; Errafii, Khaoula; Legeay, Jean; Hijri, Mohamed; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Springer, 2024-11)
The plant mycobiome makes essential contributions to the host life cycle in both healthy and diseased states. Arbuscular mycorrhizal fungi (AMF) are the most widespread plant symbionts associated with plant roots, and they perform numerous functions that contribute to plants’ health and physiology. However, there exist many knowledge gaps in how the interactions between AMF and host plants’ root mycobiomes influence the performance of host plants. To this end, we inoculated a local chickpea cultivar grown in an agricultural soil under semi-controlled conditions with Rhizophagus irregularis. The plants were subjected to low or normal levels of phosphorus (P) fertilization. In addition to examining mycorrhizal colonization, plant biomass, and mineral nutrition, we sequenced the ITS region of the rDNA to assess the chickpea mycobiome and identify key fungal taxa potentially responding to AMF inoculation. Our results showed that AMF inoculation had a stronger effect on chickpea aboveground biomass, in addition to mineral nutrition; whereas P fertilization had a more profound effect on belowground traits. Specifically, AMF promoted shoot (p = 0.06), root (p = 0.001), and total aboveground biomass (p = 0.01), while P fertilization enhanced root biomass (p = 0.02), in addition to root diameter (p = 0.007), root volume (p = 0.01), and root length (p = 0.08). Furthermore, the total P (p = 0.05) and Na contents (p = 0.09) were enhanced in the aboveground biomass by AMF inoculation. ITS metabarcoding revealed Ascomycota as the dominant phylum in both roots and soil biotopes, followed by Basidiomycota, Chytridiomycota, Glomeromycota, Monoblepharomycota, Mucoromycota, and Rozellomycota. Ten ASVs were significantly impacted by AMF inoculation in chickpea roots, including important plant pathogens belonging to Didymella, Fusarium, Neocosmospora, and Stagonosporopsis. Surprisingly, a correlation was established between shoot biomass and some fungal taxa that were differentially abundant in roots. This study confirms the significance of AMF inoculation not for only improving chickpeas’ growth and mineral nutrition in semi-arid conditions but also for shaping plants’ fungal community composition, thereby promoting resilience against both biotic and abiotic stressors.
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Potential plant-to-plant transmission : shared endophytic bacterial community between ziziphus lotus and its parasite cuscuta epithymum
Radouane, Nabil; Errafii, Khaoula; Mouhib, Salma; Ait SiMhand, Khadija; Legeay, Jean; Hijri, Mohamed; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Springer, 2024)
Microbiota associated with host–parasite relationships offer an opportunity to explore interactions among plants, parasites, and microbes, thereby contributing to the overall complexity of community structures. The dynamics of ecological interactions between parasitic plants and their hosts in arid environments remain largely understudied, especially in Africa. This study aimed to examine the bacterial communities of Cuscuta epithymum L. (clover dodder), an epiphytic parasitic plant, and its host, Ziziphus lotus L. (jujuba),in an arid environment. Our goal was to uncover the ecological complexities of microbial communities within the framework of plant–plant interactions. We conducted a comprehensive analysis of the bacterial composition and diversity within populations of the C. epithymum parasite, the infected- and non-infected jujuba host, and their interface at the shoots of the host. This involved amplicon sequencing, targeting the V5–V6 regions of the 16S rRNA gene. A total of 5680 amplicon sequence variants (ASVs) were identified, with Pseudomonadota, Bacillota, and Actinobacteriota being prevalent phyla. Among the bacterial communities, three genera were dominant: Cutibacterium, Staphylococcus, and Acinetobacter. Interestingly, analyses of alpha- and beta-diversities revealed no significant difference between jujuba and its parasite, suggesting a shared shoot endophytic bacteriome. This finding advances our comprehension of microbial communities linked to plant–parasite interactions in the arid environments of Africa. Further studies on functional diversity and elucidation of the mechanisms by which bacterial communities transfer between host and parasite are needed.
Accès libre
Spatially explicit predictions of food web structure from regional-level data
Dansereau, Gabriel; Barros, Ceres; Poisot, Timothée; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (The Royal Society, 2024-07-22)
Knowledge about how ecological networks vary across global scales iscurrently limited given the complexity of acquiring repeated spatial datafor species interactions. Yet, recent developments in metawebs highlightefficient ways to first document possible interactions within regionalspecies pools. Downscaling metawebs towards local network predictionsis a promising approach to using the current data to investigate thevariation of networks across space. However, issues remain in how torepresent the spatial variability and uncertainty of species interactions,especially for large-scale food webs. Here, we present a probabilisticframework to downscale a metaweb based on the Canadian mammalmetaweb and species occurrences from global databases. We investigatedhow our approach can be used to represent the variability of networksand communities between ecoregions in Canada. Species richness andinteractions followed a similar latitudinal gradient across ecoregions butsimultaneously identified contrasting diversity hotspots. Network motifsrevealed additional areas of variation in network structure compared withspecies richness and number of links. Our method offers the potentialto bring global predictions down to a more actionable local scale, andincreases the diversity of ecological networks that can be projected in space.This article is part of the theme issue 'Connected interactions: enrichingfood web research by spatial and social interactions.
Accès libre
Refining transcriptome gene catalogs by MS-validation of expressed proteins
Tse, Sirius P. K.; Beauchemin, Mathieu; Morse, David; Lo, Samuel C. L.; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Wiley, 2017-11-19)
Protein sequence identification by tandem mass spectroscopy (LC-MS/MS) identifies thousands of protein sequences even in complex mixtures, and provides valuable insight into the biological functions of different cells. For non-model organisms, transcriptomes are generally used to allow peptide identification, an important addition to their use as a gene catalog allowing the potential metabolic activities of cells to be determined. We used LC-MS/MS data to identify which of the six possible reading frames in the transcriptome was actually used by the cell to make protein, and asked whether this would have an impact on downstream analyses using the dataset. We combined results from several LC-MS/MS experiments designed to identify peptide sequences in extracts from the dinoflagellate Lingulodinium polyedra using a 74 655-sequence transcriptome. We compiled a list of 6628 translated nucleic acid sequences that contained the ensemble of peptide matches (termed MS-validated sequences) and assessed the similarity in downstream analyses between this data set and the 6628 nucleic acid sequences from which they were derived. When compared with BLASTx analyses of the DNA sequences, the MS-validated protein-sequences-analyzed using BLASTp showed differences in gene ontology, had more identified BLAST hits, and contained more KEGG pathway enzymes. The MS-validated protein sequences also differ from datasets containing longest open reading frame (ORF) protein sequences. We also note a poor correlation between the levels of protein and mRNA abundance, a comparison not previously performed for dinoflagellates. The differences observed between analyses of MS-validated protein sequence and nucleic acid sequence datasets suggest use of the former may provide a more accurate representation of cellular capacity than the latter. Developing MS-validated protein sequence datasets may also speed interpretation of MS-MS spectra in bottom up proteomics experiments.
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A transcriptome-based perspective of cell cycle regulation in dinoflagellates
Morse, David; Daoust, Philip; Benribague, Siham; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Elsevier, 2016-10-17)
Dinoflagellates are a group of unicellular and generally marine protists, of interest to many because of their ability to form the large algal blooms commonly called “red tides”. The large algal concentrations in these blooms require sustained cell replication, yet to date little is known about cell cycle regulation in these organisms. To address this issue, we have screened the transcriptomes of two dinoflagellates, Lingulodinium polyedrum and Symbiodinium sp., with budding yeast cell cycle pathway components. We find most yeast cell cycle regulators have homologs in these dinoflagellates, suggesting that the yeast model is appropriate for understanding regulation of the dinoflagellate cell cycle. The dinoflagellates are lacking several components essential in yeast, but a comparison with a broader phylogenetic range of protists reveals these components are usually also missing in other organisms. Lastly, phylogenetic analyses show that the dinoflagellates contain at least three cyclin-dependent kinase (CDK) homologs (belonging to the CDK1, CDK5 and CDK8 families), and that the dinoflagellate cyclins belong exclusively to the A/B type. This suggests that dinoflagellate CDKs likely play a limited role outside regulation of the cell cycle.
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Spatial organization of dinoflagellate genomes : novel insights and remaining critical questions
Lin, Senjie; Song, Bo; Morse, David; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Wiley, 2021-08-14)
As is true for many other aspects, genome architecture, evolution, and function in dinoflagellates are enigmatic and, in the meantime, continuous inspiration for scientific quests. Recent third-generation sequencing and Hi-C linkage analyses brought new insights into the spatial organization of symbiodiniacean genomes, revealing the topologically associated domains, discrete gene clusters and their cis and trans orientations, and relationships with transcription. Where do these new findings bring us in dinoflagellate genomics? Here, we aim to place these new results in the backdrop of the long history of research on this topic and in the context of what critical questions remain to be pursued in the future. The new data suggest, pending verification of other complete chromosome assemblies, a potential evolutionary trend in chromosome number decrease and length increase within the Symbiodiniaceae. While questions remain about the mechanics of the three-dimensional chromosome structure and cell cycle-related DNA replication, the mechanisms of gene transcription and genome size evolution, these latest findings set new starting points for further inquiries.
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A transcriptome-based perspective of meiosis in dinoflagellates
Morse, David; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Elsevier, 2019-08-01)
There is increasing interest in the possibility of sexual recombination in dinoflagellates, especially those symbiotic with coral, since recombination may be able to augment genetic diversity and reduce levels of coral bleaching. Several previous studies have addressed this in Symbiodinium by querying sequence databanks with a list of 51 genes termed a meiosis detection toolkit. Here, we have constructed an expanded list of 307 genes involved in meiosis in budding yeast. We find the genes involved in the major regulatory steps in yeast meiosis are also found in dinoflagellates, as are many of the genes involved in recombination. In contrast, few genes involved in forming the synaptonemal complex or forming spores are conserved. We further note that the meiosis-related genes absent in dinoflagellates are also as a general rule absent from other protists in the closely related apicomplexa and the ciliates. We conclude the symbiotic dinoflagellates are as able to undergo meiosis as are other protists.
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The main nitrate transporter of the dinoflagellate Lingulodinium polyedrum is constitutively expressed and not responsible for daily variations in nitrate uptake rates
Dagenais Bellefeuille, Steve; Morse, David; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Elsevier, 2016-04-22)
Dinoflagellates are unicellular eukaryotes capable of forming spectacular harmful algal blooms (HABs). Eutrophication of coastal waters by fertilizer runoff, nitrate in particular, has contributed to recent increases in the frequency, magnitude and geographic extent of HABs. Although physiological nitrate uptake and assimilation in dinoflagellates have often been measured in the field and in the laboratory, no molecular components involved in nitrate transport have yet been reported. This study reports the first identification and characterization of dinoflagellate nitrate transporters, found in the transcriptome of the bloom-forming Lingulodinium polyedrum. Of the 23 putative transporters found by BLAST searches, only members of the nitrate transporter 2 (NRT2) family contained all key amino acids known to be essential for nitrate transport. The dinoflagellate NRT2 sequences have 12 predicted transmembrane domains, as do the NRT2 sequences of bacteria, plants and fungi. The NRT2 sequences in Lingulodinium appear to have two different evolutionary origins, as determined by phylogenetic analyses. The most expressed transcript of all putative nitrate transporters was determined by RNA-Seq to be LpNRT2.1. An antibody raised against this transporter showed that the same amount of protein was found at different times over the light dark cycle and with different sources of N. Finally, global nitrate uptake was assessed using a 15N tracer, which showed that the process was not under circadian-control as previously suggested, but simply light-regulated.
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Exploring dinoflagellate biology with high-throughput proteomics
Morse, David; Tse, Sirius P. K.; Lo, Samuel C. L.; Université de Montréal. Division de la gestion de documents et des archives (Elsevier, 2018-04-16)
Dinoflagellates are notorious for their ability to form the harmful algal blooms known as “red tides,” yet the mechanisms underlying bloom formation remain poorly understood. Despite recent advances in nucleic acid sequencing, which have generated transcriptomes from a wide range of species exposed to a variety of different conditions, measuring changes in RNA levels have not generally produced great insight into dinoflagellate cell biology or environmental physiology, nor do we have a thorough grasp on the molecular events underpinning bloom formation. Not only is the transcriptomic response of dinoflagellates to environmental change generally muted, but there is a markedly low degree of congruency between mRNA expression and protein expression in dinoflagellates. Herein we discuss the application of high-throughput proteomics to the study of dinoflagellate biology. By profiling the cellular protein complement (the proteome) instead of mRNA (the transcriptome), the biomolecular events that underlie the changes of phenotypes can be more readily evaluated, as proteins directly determine the structure and the function of the cell. Recent advances in proteomics have seen this technique become a high-throughput method that is now able to provide a perspective different from the more commonly employed nucleic acid sequencing. We suggest that the time is ripe to exploit these new technologies in addressing the many mysteries of dinoflagellate biology, such as how the symbiotic dinoflagellate inhabiting reef corals acclimate to increases in temperature, as well as how harmful algal blooms are initiated at the sub-cellular level. Furthermore, as dinoflagellates are not the only eukaryotes that demonstrate muted transcriptional responses, the techniques addressed within this review are amenable to a wide array of organisms.
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The level of pollination specialization affects the relationship between the shape of flowers and the bills of their hummingbird pollinators in Antillean Gesneriaceae
Faure, Julie; Martén-Rodríguez, Silvana; Clark, John L.; Joly, Simon; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (The University of Chicago Press, 2022-01-27)
Premise of research. Pollinators are known to impose strong selection on floral shape. Particularly well studied is the relationship between the flowers of hummingbird-pollinated plant species and the bills of their pollinators. However, no studies to date have evaluated whether these relationships vary according to the level of pollination specialization. Here, we quantify the relationship between the corolla shape of Antillean Gesneriaceae and the bills of their hummingbird pollinators for species with a specialist (one functional group of pollinators: hummingbirds) and a generalist (more than one functional group of pollinators: hummingbirds, bats, and insects) pollination strategy. Methodology. We used phylogenetic generalized least squares analyses on linear measurements and phylogenetic two blocks partial least squares on multivariate geometric morphometrics data to test whether and how the variation in the corolla shape of the Antillean Gesneriaceae is correlated to the shape of the bills of their hummingbird pollinators. Pivotal results. We found that corolla shape is correlated with the bill shape of the hummingbird pollinators but that the nature of this relationship differed between pollination specialists and generalists. For example, corolla curvature was positively correlated with bill curvature for specialists but not for generalists. Conclusions. Our study suggests that pollinators affect the evolution of flower shape but that the nature and strength of the selective pressures are affected by the pollinator guild of the pollinators in the Antillean Gesneriaceae.
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Increasing phytoremediation efficiency and reliability using novel omics approaches
Bell, Terrence H.; Joly, Simon; Pitre, Frédéric; Yergeau, Étienne; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Cell Press, 2014-04-12)
Phytoremediation is a cost-effective green alternative to traditional soil remediation technologies, but has experienced varied success in practice. The recent omics revolution has led to leaps in our understanding of soil microbial communities and plant metabolism, and some of the conditions that promote predictable activity in contaminated soils and heterogeneous environments. Combinations of omics tools and new bioinformatics approaches will allow us to understand integrated activity patterns between plants and microbes, and determine how this metaorganism can be modified to maximize growth, appropriate assembly of microbial communities, and, ultimately, phytoremediation activity. Here we provide an overview of how new omics-mediated discoveries can potentially be translated into an effective and reliable environmental technology.
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Edge effects on vegetation in rights-of-way
Brisson, Jacques; Meilleur, Alain; Fortin, Marie-Josée; Bouchard, André; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Elsevier, 1997)
As a result of an increasing use of ecological methods for the control of vegetation in rights-of-way, it has become necessary to understand the natural processes that are likely to facilitate or hinder management objectives. Several factors may influence species composition within corridors, but edge effects ofthe vegetation immediately adjacent to the right-of-way is one ofthe mostimportant. To better measure and understand edge effects, we studied the spatial distribution of vegetation types on test right-of-way sites located in southern Quebec. Sampling was done along 133 transects located perpendicular to the right-of-way, with a distance of50 m between transects. Each transect consisted ofseven quadrats covering the vegetation within the corridor and two quadrats outside of the corridor. The results show that there is a strong edge effect on plant composition in the right-of-way corridor, especially when it is bordered by a forest. The edge effects result in a greater dominance of tree species and to a lesser extent a greater number of shrubs. Besides species richness, the species composition is also different at the edge of the right-of-way, with several species more likely to be found at the edge, while others occur more often in the central zone. There was little significant difference between north-facing and south-facing edges. Seed dispersal is assumed to be the main factor responsible for edge effects on plant composition. These results have implications on vegetation management in right-of-way corridors.
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Selecting herbaceous plant cover to control tree invasion in rights-of-way
de Blois, Sylvie; Brisson, Jacques; Bouchard, André; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Elsevier, 2002)
Following construction of a right-of-way, environmental regulation often requires the rapid restoration of a herbaceous plant cover to control erosion and/or attenuate visual impact. Herbaceous species can be selected with the added long-term goal of inhibiting tree invasion. We present a review of empirical evidence that can guide species selection. This review is based on an extensive survey and critical evaluation of relevant North American studies published in scientific papers, technical reports, and conference proceedings. Vegetation managers and scientists were also consulted for up-to-date information on on-going experiments. Observational and experimental evidence of inhibition in both natural and managed communities confirm that the biological control approach has significant potential. However, scientific evaluation of the long-term inhibition capacity of seeding mixtures is still rare. Ecological mechanisms favoring competitive ability are not always well understood but involve the sequestration of available resources and the modification of environmental conditions. Two approaches characterized experimental inhibition studies in rights-of-way. The first aims to test the interference potential of commercially available species commonly used in restoration, while the second favors the establishment of wild communities. Both approaches have their advantages and limitations, but several studies show that the establishment phase is crucial. Knowledge is lacking especially for the establishment of wild species. This review allowed us to identify 66 herbaceous species based on a critical assessment of the evidence provided. Besides inhibition potential, factors such as species availability and possible nuisance should also be considered.
Accès libre
The Haut-Saint-Laurent wilderness at the time of settlement based on Sellar’s History. Part I : Wildlife
Brisson, Jacques; Bouchard, André; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Société Historique de la Vallée de la Châteauguay = Chateauguay Valley Historical Society, 2004)
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The Haut-Saint-Laurent wilderness at the time of settlement based on Sellar’s History. Part II : Forests and wetlands.
Brisson, Jacques; Bouchard, André; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Société Historique de la Vallée de la Châteauguay = Chateauguay Valley Historical Society, 2006)
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The history and tree stratum of an old-growth forest of Haut-Saint-Laurent region, Quebec
Brisson, Jacques; Bergeron, Yves; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Natural Areas Association, 1992)
An old-growth forest of presettlement origin was recently discovered at the northern limit of the Eastern Deciduous Forest (sensu Braun 1950) of North America, in an area that is extensively affected by logging, land clearing, and agriculture. In a study of the disturbance history, forest composition, and dynamics of this old-growth forest, we found that (1) the preservation of the forest can be attributed to the initial settler’s lack of interest in exploiting it and to a strong sense of conservation by his descendants; (2) an American elm-black ash (Ultnus americana L.-Fraxinus nigra Marsh.) community occupies more hydric sites(approximately 15% ofthe forest) and a sugar maple -American beech (Acer saccharum Marsh.-Ftzgws grandifolia Ehrh.) community occurs on mesic sites; (3) larger canopy trees range in age from 150 to 300 years; (4) despite the absence of any major perturbation in the mesic portion of the site, the composition is not in equilibrium and beech is apparently increasing in abundance over the presently dominating maple; (5) the average tree growth has been very slow compared to that of trees in adjacent disturbed forests. Ecological information obtained from old-growth forests can contribute to decision making in management of natural areas.
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Biodiversite microfongique du Fagus grandifolia dans une forêt ancienne : bioindicateurs et structure mycosociologique
Vujanovic, Vladimir; Brisson, Jacques; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Ottawa Field Naturalists Club, 2001)
En Amérique du Nord, l’étude de la biodiversité des micromycètes dans les forêts anciennes représente un potentiel incontournable et largement inexploré. Le présent inventaire nous a permis de mettre en évidence la biodiversité microfongique, les bioindicateurs et la structure mycosociologique associée au hêtre à grandes feuilles (Fagus grandifolia) dans une forêt ancienne de l’est du Canada. La méthodologie utilisée s’appuie sur la stratégie proposée par le All-Taxa Biodiversity Inventory of Fungi (ATBIF). Plusieurs espèces s’avèrent des nouvelles mentions sur un hôte du genre Fagus. C’est le cas pour tous les membres de la sous-famille Phialostromatinae (Deuteromycota, Coelomycetes), soit quatre genres et cinq espèces, dont certaines pourraient être des espèces très rares ou menacées. Quatre associations, chacune étant associée à une partie spécifique de l’arbre, ont été déterminées. De plus, deux autres associations sont caractéristiques d’habitats particuliers dans la forêt. Notre étude supporte l’hypothèse selon laquelle les forets anciennes sont des écosystèmes en homéostasie qui constituent des réservoirs d’espèces microfongiques d’une grande diversité génétique. Outre la valeur intrinsèques de cette diversité exceptionnelle, les micromycètes ont également une valeur pratique potentielle, comme dans le contexte de la lutte biologique.
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Forked Three-awned Grass, Aristida basiramea Engelm. ex Vasey : a new addition to the flora of Quebec
Brisson, Jacques; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Ottawa Field Naturalists Club, 2004)
A population of Forked Three-awned Grass (Aristida basiramea Engelm. ex Vasey; Poaceae) was found for the first time in Quebec, on a sand barren of the Cazaville region (Haut-Saint-Laurent). The only other region where this species is known in Canada is on the southern side of Georgian Bay in Ontario.
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Une addition à la flore du Québec : Monarda punctata var. villicaulis (Lamiaceae)
Boudreault, Catherine; Brisson, Jacques; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (Ottawa Field Naturalists Club, 1994)
Une population de Monarde ponctuée (Monarda punctata var. villicaulis) fut trouvée pour la première fois au Québec, dans la région du Haut-Saint-Laurent. Cette population, qui comprend plus d’une centaine d’individus, déplace légèrement la limite nord de l’aire de répartition connue de l’espèce par 20 km.
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Effects of experimental thermocline and oxycline deepening on methylmercury bioaccumulation in a Canadian Shield lake
Perron, Tania; Chételat, John; Gunn, John; Beisner, Beatrix; Amyot, Marc; Université de Montréal. Faculté des arts et des sciences. Département de sciences biologiques (American Chemical Society, 2014-02-10)
Environmental disturbances like deforestation or climate change may influence lake thermal and oxic stratification, thereby modifying cycles of contaminants such as mercury (Hg). In a lake naturally separated into three basins, the thermocline and oxycline of an experimental basin were deepened by 4 and 3 m, respectively, to study the effect on the methylmercury (MeHg) accumulation. This treatment decreased hypolimnetic MeHg concentration by approximately 90%, zooplankton concentrations by 30 to 50%, and in some fish by 45%. A multiple linear regression indicated that oxycline depth significantly influenced hypolimnetic MeHg concentrations, with no significant effect of thermocline depth, anoxic water volume, interface area of oxic-anoxic water, and sediment area in contact with anoxic water. Fish MeHg decline varied, with a greater response by low oxygen-tolerant bullhead. Increased pelagic primary and secondary production likely caused zooplankton and fish MeHg decreases via algal and growth dilution. Environmental changes leading to oxycline deepening are therefore predicted to cause a decrease in MeHg bioaccumulation in similar Canadian Shield lakes. If associated ecosystem impacts related to the deepening treatment are deemed acceptable, then this experiment provides a potential remediation method for small lakes confronted with MeHg accumulation.

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