ORCID Profile
0000-0003-2723-5371
Current Organisation
University of Windsor Faculty of Science
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Publisher: Wiley
Date: 04-2006
Publisher: American Geophysical Union (AGU)
Date: 06-2021
DOI: 10.1029/2021JG006247
Abstract: Among its many impacts, climate warming is leading to increasing winter air temperatures, decreasing ice cover extent, and changing winter precipitation patterns over the Laurentian Great Lakes and their watershed. Understanding and predicting the consequences of these changes is impeded by a shortage of winter‐period studies on most aspects of Great Lake limnology. In this review, we summarize what is known about the Great Lakes during their 3–6 months of winter and identify key open questions about the physics, chemistry, and biology of the Laurentian Great Lakes and other large, seasonally frozen lakes. Existing studies show that winter conditions have important effects on physical, biogeochemical, and biological processes, not only during winter but in subsequent seasons as well. Ice cover, the extent of which fluctuates dramatically among years and the five lakes, emerges as a key variable that controls many aspects of the functioning of the Great Lakes ecosystem. Studies on the properties and formation of Great Lakes ice, its effect on vertical and horizontal mixing, light conditions, and biota, along with winter measurements of fundamental state and rate parameters in the lakes and their watersheds are needed to close the winter knowledge gap. Overcoming the formidable logistical challenges of winter research on these large and dynamic ecosystems may require investment in new, specialized research infrastructure. Perhaps more importantly, it will demand broader recognition of the value of such work and collaboration between physicists, geochemists, and biologists working on the world's seasonally freezing lakes and seas.
Publisher: Cold Spring Harbor Laboratory
Date: 25-06-2021
DOI: 10.1101/2021.06.23.21259176
Abstract: A wastewater surveillance program targeting a university residence hall was implemented during the spring semester 2021 as a proactive measure to avoid an outbreak of COVID-19 on c us. Over a period of 7 weeks from early February through late March 2021, wastewater originating from the residence hall was collected as grab s les 3 times per week. During this time, there was no detection of SARS-CoV-2 by RT-qPCR in the residence hall wastewater stream. Aiming to obtain a s le more representative of the residence hall community, a decision was made to use passive s lers beginning in late March onwards. Adopting a Moore Swab approach, SARS-CoV-2 was detected in wastewater s les on just two days after passive s lers were activated. These s les were also positive for the B.1.1.7 (Alpha) Variant of Concern (VOC) by RT-qPCR. The positive result triggered a public health case finding response including a mobile testing unit deployed to the residence hall the following day with testing of nearly 200 students and staff, which identified two laboratory-confirmed cases of B.1.1.7 variant COVID-19. These in iduals were re-located to a separate quarantine facility averting an outbreak on c us. Aggregating wastewater and clinical data, the c us wastewater surveillance program has yielded the first estimates of fecal shedding rates of the B.1.1.7 VOC of SARS-CoV-2 in in iduals from a non-clinical setting.
Publisher: Springer Science and Business Media LLC
Date: 09-11-2020
DOI: 10.1038/S41587-020-0718-6
Abstract: The reconstruction of bacterial and archaeal genomes from shotgun metagenomes has enabled insights into the ecology and evolution of environmental and host-associated microbiomes. Here we applied this approach to ,000 metagenomes collected from erse habitats covering all of Earth’s continents and oceans, including metagenomes from human and animal hosts, engineered environments, and natural and agricultural soils, to capture extant microbial, metabolic and functional potential. This comprehensive catalog includes 52,515 metagenome-assembled genomes representing 12,556 novel candidate species-level operational taxonomic units spanning 135 phyla. The catalog expands the known phylogenetic ersity of bacteria and archaea by 44% and is broadly available for streamlined comparative analyses, interactive exploration, metabolic modeling and bulk download. We demonstrate the utility of this collection for understanding secondary-metabolite biosynthetic potential and for resolving thousands of new host linkages to uncultivated viruses. This resource underscores the value of genome-centric approaches for revealing genomic properties of uncultivated microorganisms that affect ecosystem processes.
Publisher: American Geophysical Union (AGU)
Date: 12-2005
DOI: 10.1029/2005GB002494
Publisher: American Geophysical Union (AGU)
Date: 12-2005
DOI: 10.1029/2005GB002476
Publisher: Springer Science and Business Media LLC
Date: 17-03-2004
DOI: 10.1038/NATURE02437
Abstract: Iron supply has a key role in stimulating phytoplankton blooms in high-nitrate low-chlorophyll oceanic waters. However, the fate of the carbon fixed by these blooms, and how efficiently it is exported into the ocean's interior, remains largely unknown. Here we report on the decline and fate of an iron-stimulated diatom bloom in the Gulf of Alaska. The bloom terminated on day 18, following the depletion of iron and then silicic acid, after which mixed-layer particulate organic carbon (POC) concentrations declined over six days. Increased particulate silica export via sinking diatoms was recorded in sediment traps at depths between 50 and 125 m from day 21, yet increased POC export was not evident until day 24. Only a small proportion of the mixed-layer POC was intercepted by the traps, with more than half of the mixed-layer POC deficit attributable to bacterial remineralization and mesozooplankton grazing. The depletion of silicic acid and the inefficient transfer of iron-increased POC below the permanent thermocline have major implications both for the biogeochemical interpretation of times of greater iron supply in the geological past, and also for proposed geo-engineering schemes to increase oceanic carbon sequestration.
Publisher: Springer Science and Business Media LLC
Date: 10-2000
DOI: 10.1038/35037500
Abstract: Changes in iron supply to oceanic plankton are thought to have a significant effect on concentrations of atmospheric carbon dioxide by altering rates of carbon sequestration, a theory known as the 'iron hypothesis'. For this reason, it is important to understand the response of pelagic biota to increased iron supply. Here we report the results of a mesoscale iron fertilization experiment in the polar Southern Ocean, where the potential to sequester iron-elevated algal carbon is probably greatest. Increased iron supply led to elevated phytoplankton biomass and rates of photosynthesis in surface waters, causing a large drawdown of carbon dioxide and macronutrients, and elevated dimethyl sulphide levels after 13 days. This drawdown was mostly due to the proliferation of diatom stocks. But downward export of biogenic carbon was not increased. Moreover, satellite observations of this massive bloom 30 days later, suggest that a sufficient proportion of the added iron was retained in surface waters. Our findings demonstrate that iron supply controls phytoplankton growth and community composition during summer in these polar Southern Ocean waters, but the fate of algal carbon remains unknown and depends on the interplay between the processes controlling export, remineralisation and timescales of water mass subduction.
Publisher: Springer Science and Business Media LLC
Date: 18-11-2020
DOI: 10.1038/S41587-020-00769-4
Abstract: An amendment to this paper has been published and can be accessed via a link at the top of the paper.
No related grants have been discovered for Robert McKay.