The molecular diversity of dissolved organic matter in forest streams across central Canadian boreal watersheds.

Small headwater streams can mobilize large amounts of terrestrially derived dissolved organic matter (DOM). While the molecular composition of DOM has important controls on biogeochemical cycles and carbon cycling, how stationary landscape metrics affect DOM composition is poorly understood, particularly in relation to non-stationary effects from hydrological changes across seasons. Here, we apply a combination of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and absorbance spectroscopy to characterize stream DOM from 13 diverse watersheds across the central Canadian boreal forests and statistically relate DOM compositional characteristics to landscape topography and hydrological metrics.

Mercury concentrations and export from small central Canadian boreal forest catchments before, during, and after forest harvest.

Northern boreal forests are a strong sink for mercury (Hg), a global contaminant of significant concern to wildlife and human health. Mercury stored in forest soils can be mobilized via runoff and erosion, and under suitable conditions can be methylated to its much more bioaccumulative form, methylmercury. Forest harvesting can affect the mobilization and methylation of Hg, though the direction and magnitude of the impact is unclear or conflicting across previous studies.

Impacts of forest harvesting on mercury concentrations and methylmercury production in boreal forest soils and stream sediment.

Methylmercury (MeHg) is the most neurotoxic and bioaccumulative form of mercury (Hg) present in the terrestrial and aquatic food sources of boreal ecosystems, posing potential risks to wildlife and human health. Harvesting impacts on Hg methylation and MeHg concentrations in forest soils and stream sediment are not fully understood. In this study, a field investigation was carried out in 4 harvested and 2 unharvested boreal forest watersheds, before and after harvest, to better understand impacts on Hg methylation and MeHg concentration in soils and stream sediment, including their responses to different forest management practices.

Watershed characteristics and chemical properties govern methyl mercury concentrations within headwater streams of boreal forests in Ontario, Canada.

Methyl mercury (MeHg) concentrations in boreal headwater streams are influenced by complex natural processes and disturbances such as forestry management. Understanding drivers of MeHg within boreal streams in Ontario, Canada, is of particular interest as there are legacy MeHg concerns. However, models accounting for the complexity of underlying processes have not yet been developed.

Alternative migratory strategies related to life history differences in the Walleye (Sander vitreus).

Background: While Pace of Life Syndrome predicts behavioural differences between individuals with differential growth and survival, testing these predictions in nature is challenging due to difficulties with measuring individual behaviour in the field. However, recent advances in acoustic telemetry technology have facilitated measurements of individual behaviour at scales not previously possible in aquatic ecosystems.

Methods: Using a Walleye (Sander vitreus) population inhabiting Black Bay, Lake Superior, we examine whether life history characteristics differ between more and less mobile individuals as predicted by Pace of Life Syndrome.

Differential gene expression associated with behavioral variation in ecotypes of Lake Superior brook trout (Salvelinus fontinalis).

Associations between behaviors and the development of different life history tactics have been documented in several species of salmon, trout, and charr. While it is well known that such behaviors are heritable the genes and molecular pathways connected to these behaviors remain unknown. We used an RNA-seq approach to identify genes and molecular pathways differentially regulated in brain tissue between "shy" and "bold" brook trout (Salvelinus fontinalis).

Climate and landscape conditions indirectly affect fish mercury levels by altering lake water chemistry and fish size.

Mercury pollution is a global environmental problem that threatens ecosystems, and negatively impacts human health and well-being. Mercury accumulation in fish within freshwater lakes is a complex process that appears to be driven by factors such as individual fish biology and water chemistry at the lake-scale, whereas, climate, and land-use/land-cover conditions within lake catchments can be influential at relatively larger scales. Nevertheless, unravelling the intricate network of pathways that govern how lake-scale and large-scale factors interact to affect mercury levels in fish remains an important scientific challenge.

Quantifying multiple pressure interactions affecting populations of a recreationally and commercially important freshwater fish.

The expanding human global footprint and growing demand for freshwater have placed tremendous stress on inland aquatic ecosystems. Aichi Target 10 of the Convention on Biological Diversity aims to minimize anthropogenic pressures affecting vulnerable ecosystems, and pressure interactions are increasingly being incorporated into environmental management and climate change adaptation strategies. In this study, we explore how climate change, overfishing, forest disturbance, and invasive species pressures interact to affect inland lake walleye (Sander vitreus) populations.

Effects of physicochemical surface characteristics of Listeria monocytogenes strains on attachment to glass.

Seven strains of Listeria monocytogenes frequently involved in foodborne disease (epidemic strains) and 14 sporadic strains were examined to compare the attachment and subsequent biofilm growth on glass slides at 37 degrees C. Epidemic strains at 3 h incubation had significantly higher attachment values than sporadic strains (P<0.001), but subsequent biofilm growth over 24 h was not dependent on initial attachment.

A comparison of AFLP and ERIC-PCR analyses for discriminating Escherichia coli from cattle, pig and human sources.

Amplified fragment length polymorphism (AFLP) and enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) genomic fingerprinting assays were compared for their ability to differentiate Escherichia coli isolates obtained from various host sources, and with respect to their pathogenicity. One hundred and ten verotoxigenic, enterotoxigenic and non-pathogenic E. coli isolates obtained from cattle, humans and pigs were used in this study.