Abstract Approximately 5% of people in most countries have deafness or significant hearing loss. ... more Abstract Approximately 5% of people in most countries have deafness or significant hearing loss. This significant minority is underrepresented in mainstream universities across the world. Background information about deafness, relevant technology and its drawbacks, and the use of interpreters are discussed. The barriers to equitable representation of qualified Deaf academics in university settings are reviewed.
Los efectos antrópicos no deseados sobre los ecosistemas de agua dulce a nivel global son cada ve... more Los efectos antrópicos no deseados sobre los ecosistemas de agua dulce a nivel global son cada vez más frecuentes, generalizados y de mayor envergadura. Este hecho se traduce en una menor disponibilidad de agua para usos humanos que ha motivado la declaración por parte de las Naciones Unidas del período 2005-2015, como “Decenio Internacional para la Acción. El Agua, Fuente de Vida”(ONU 2005).
We are investigating whether variations in the nitrogen (delta symbol 15 N) and carbon (delta sym... more We are investigating whether variations in the nitrogen (delta symbol 15 N) and carbon (delta symbol 13 C) isotopic composition of largemouth bass (Micropterus salmoides) tissue can explain a significant amount of the variation in mercury concentrations in this top predator fish. The delta symbol 15 N and delta symbol 13 C values of tissues are integrated measures of diet assimilated over time, with consumers enriched in the heavier isotope relative to their diet.
We investigate whether variations in the nitrogen (d 15 N) and carbon (d 13 C) isotopic compositi... more We investigate whether variations in the nitrogen (d 15 N) and carbon (d 13 C) isotopic composition of largemouth bass (Micropterus salmoides) tissue can explain a significant amount of the variation in mercury concentrations in this top predator fish. The d 15 N and d 13 C values of tissues are integrated measures of diet assimilated over time, with consumers enriched in the heavier isotope relative to their diet.
Freshwater clams (Anodonta grandis simpsoniana) exposed to 51-55 ug⊙ L-1 of dissolved microcystin... more Freshwater clams (Anodonta grandis simpsoniana) exposed to 51-55 ug⊙ L-1 of dissolved microcystin-LR (MC-LR) in the laboratory for 3 days did not accumulate MC-LR equivalents (MC-LReq). However, clams placed in three eutrophic lakes with phytoplankton containing MC-LR (concentrations from below detection to 8.3 ug⊙ L-1 cellular toxin) for 12-28 days accumulated the toxin (24±7 to 527±330 ng⊙ g-1 MC-LReq; mean±SE).
The waterfront of historic Kingston, Ontario (pop: 113,000) has been used for industrial activiti... more The waterfront of historic Kingston, Ontario (pop: 113,000) has been used for industrial activities for over a century. More than 40 industries have existed within the inner harbour, and while many of these industries are no longer present, the properties that they operated on remain as potential sources of persistent contamination to the present day, including mercury.
Fish, benthic macroinvertebrates, macrophytes, biofilm, plankton, and terrestrial material were a... more Fish, benthic macroinvertebrates, macrophytes, biofilm, plankton, and terrestrial material were analyzed for stable nitrogen (δ15N) and carbon isotopes (δ13C) to study the food web structure of a double-basined, ultra-oligotrophic lake in northwest Patagonia.
Silver (Ag) ions are among the most toxic metallic ions to aquatic biota. In southern Argentina, ... more Silver (Ag) ions are among the most toxic metallic ions to aquatic biota. In southern Argentina, fish from Patagonian lakes have liver Ag concentrations [Ag] among the highest ever reported globally. Silver concentration in phytoplankton from Lake Moreno (1.82±3.00 μgg− 1 dry weight, DW) was found to be significantly higher than [Ag] in zooplankton (0.25±0.13 μgg− 1). Values in snails and decapods (0.60±0.28 μgg− 1 and 0.47±0.03 μgg− 1 respectively), were higher than in insect larvae (0.28±0.39 μgg− 1 for Trichoptera).
Hemimysis anomala, a littoral freshwater mysid native to the Ponto-Caspian region, is the newest ... more Hemimysis anomala, a littoral freshwater mysid native to the Ponto-Caspian region, is the newest invader to the Laurentian Great Lakes basin. Discovered in 2006, they have since been found in all of the Great Lakes (except Lake Superior) and have the potential to offset the dietary energy sink caused by invasive dreissenid mussels (Dreissena bugensis and D. polymorpha) in the littoral zone.
Seasonal variation in mercury (Hg) concentrations and food web structure was assessed for eastern... more Seasonal variation in mercury (Hg) concentrations and food web structure was assessed for eastern Lake Ontario. Hg concentrations, measured in 6 species of invertebrates and 8 species of fishes, tended to be highest in the spring and lowest in the summer for most biota. Yellow perch (Perca flavescens) exhibited significant ontogenetic shifts in diet and Hg, although such patterns were not evident for other species. Food web structure, as indicated by stable isotope values (δ15N, δ13C) was not static.
We investigated the terrestrial influence on two chained deep ultraoligotrophic lakes of North Pa... more We investigated the terrestrial influence on two chained deep ultraoligotrophic lakes of North Patagonia (Argentina) through the seasonal analysis of two pelagic allochthonous indicators: i) water color, as a proxy of allochthonous dissolved organic matter in lakes; and ii) the color to chlorophyll a ratio (Color: Chla), as an indicator of the relationship between allochthonous and autochthonous carbon pools.
Mussels, Diplon chilensis, from Lake Moreno, a double-basined mountain lake in southern Argentina... more Mussels, Diplon chilensis, from Lake Moreno, a double-basined mountain lake in southern Argentina, is known to have elevated concentrations of chromium (Cr,> 25μgg− 1 dry weight DW) and arsenic (As, 35μgg− 1 DW), attributed to untreated sewage. To further understand the trophodynamics of Cr, As and cobalt (Co), we investigated concentrations and transfer throughout the food web in each basin of Lake Moreno.
This study focused on the value of deciduous leaves as biomonitors of total mercury (THg). Leaf s... more This study focused on the value of deciduous leaves as biomonitors of total mercury (THg). Leaf samples were collected from a range of deciduous species from five sampling sites in the province of Ontario, Canada. These included a site in the northwest (the Experimental Lakes Area, ELA), two sites in central Ontario (the town of Dorset and the Centre for Atmospheric Research Experiments, CARE), and two sites in the southeast (Sandbanks Provincial Park, SBPP and the City of Kingston). The sampled species exhibited distinctive species-specific differences with red oaks consistently having lower leaf THg concentrations than all maple species, while black and white ash leaves had the highest concentrations. Spatially, leaves collected across the distance between ELA and SBPP (~ 1500 km apart) had overlapping THg concentrations between 20 and 40 ng/g. Unexpectedly, leaves from urban parks of Kingston had considerably lower THg concentrations (< 25 ng/g) than the other sites, which suggested leaves may not reflect subtle gradients of atmospheric THg found under field conditions. Leaf THg increased with the growing season, with highest THg leaf concentrations found in early autumn just before senescence. Microspatial differences within a single tree, such as position on a branch are important, since higher mercury concentrations were associated with leaves positioned deeper into the canopy relative to outer leaves more exposed to wind turbulence and sunlight. Within any single leaf, THg concentrations were highest in the leaf tissue, and consistently distributed, while the vein and petiole tissue had lower THg concentrations. There was no relationship between THg concentrations and leaf area. Using deciduous tree leaves as regional temporal monitors of bioavailable mercury may be feasible, but careful selection of leaf sampling sites on the tree itself and the timing is of utmost importance for ensuring consistent and high quality biomonitoring data.
The Northern Patagonian Andean range shared by Chile and Argentina has numerous glacial oligotrop... more The Northern Patagonian Andean range shared by Chile and Argentina has numerous glacial oligotrophic lakes protected in a series of National Parks. Recent baseline surveys indicated that concentrations in muscle and liver tissues from various fish species from across Nahuel Huapi and Los Alerces National Parks in Argentina were comparable or higher than similar fish species from other parts of the world. As a result, Lake Moreno, in Nahuel Huapi National Park, was chosen to investigate multiple element sinks, trends, and transfer in a representative Patagonia aquatic food web. The metals and metalloids Ag, As, Ba, Br, Cs, Co, Cr, Fe, Hg, K, Na, Rb, Se, and Zn were analyzed in three size plankton fractions, submerged macrophytes, biofilm, insect larvae, amphipods, decapods, gastropods (snails), annelids (earthworms), and forage fish. Except for nanoplankton (10–53 μm; small-celled algae, rotifers) and microplankton (53–200 μm; larger algae, ciliates, zooplankton nauplii), which share elemental compositional similarities, each taxon category had its own distinctive compositional pattern, revealed by principal component analysis. Nano- and microplankton tend to be relatively elevated in some metals, including As, Co, Cr, Fe, Hg, Zn, and Rb, followed by biofilm. Shredder-scrapper Trichoptera (caddisflies) have higher concentration of most of the studied elements than other insect larvae taxa, especially carnivorous Odonata (Anisoptera, dragonflies), which were associated with lower elemental contents. Those trends point to an overall tendency for biodiminishing element concentrations with trophic level in the benthos of Lake Moreno.
Abstract Approximately 5% of people in most countries have deafness or significant hearing loss. ... more Abstract Approximately 5% of people in most countries have deafness or significant hearing loss. This significant minority is underrepresented in mainstream universities across the world. Background information about deafness, relevant technology and its drawbacks, and the use of interpreters are discussed. The barriers to equitable representation of qualified Deaf academics in university settings are reviewed.
Los efectos antrópicos no deseados sobre los ecosistemas de agua dulce a nivel global son cada ve... more Los efectos antrópicos no deseados sobre los ecosistemas de agua dulce a nivel global son cada vez más frecuentes, generalizados y de mayor envergadura. Este hecho se traduce en una menor disponibilidad de agua para usos humanos que ha motivado la declaración por parte de las Naciones Unidas del período 2005-2015, como “Decenio Internacional para la Acción. El Agua, Fuente de Vida”(ONU 2005).
We are investigating whether variations in the nitrogen (delta symbol 15 N) and carbon (delta sym... more We are investigating whether variations in the nitrogen (delta symbol 15 N) and carbon (delta symbol 13 C) isotopic composition of largemouth bass (Micropterus salmoides) tissue can explain a significant amount of the variation in mercury concentrations in this top predator fish. The delta symbol 15 N and delta symbol 13 C values of tissues are integrated measures of diet assimilated over time, with consumers enriched in the heavier isotope relative to their diet.
We investigate whether variations in the nitrogen (d 15 N) and carbon (d 13 C) isotopic compositi... more We investigate whether variations in the nitrogen (d 15 N) and carbon (d 13 C) isotopic composition of largemouth bass (Micropterus salmoides) tissue can explain a significant amount of the variation in mercury concentrations in this top predator fish. The d 15 N and d 13 C values of tissues are integrated measures of diet assimilated over time, with consumers enriched in the heavier isotope relative to their diet.
Freshwater clams (Anodonta grandis simpsoniana) exposed to 51-55 ug⊙ L-1 of dissolved microcystin... more Freshwater clams (Anodonta grandis simpsoniana) exposed to 51-55 ug⊙ L-1 of dissolved microcystin-LR (MC-LR) in the laboratory for 3 days did not accumulate MC-LR equivalents (MC-LReq). However, clams placed in three eutrophic lakes with phytoplankton containing MC-LR (concentrations from below detection to 8.3 ug⊙ L-1 cellular toxin) for 12-28 days accumulated the toxin (24±7 to 527±330 ng⊙ g-1 MC-LReq; mean±SE).
The waterfront of historic Kingston, Ontario (pop: 113,000) has been used for industrial activiti... more The waterfront of historic Kingston, Ontario (pop: 113,000) has been used for industrial activities for over a century. More than 40 industries have existed within the inner harbour, and while many of these industries are no longer present, the properties that they operated on remain as potential sources of persistent contamination to the present day, including mercury.
Fish, benthic macroinvertebrates, macrophytes, biofilm, plankton, and terrestrial material were a... more Fish, benthic macroinvertebrates, macrophytes, biofilm, plankton, and terrestrial material were analyzed for stable nitrogen (δ15N) and carbon isotopes (δ13C) to study the food web structure of a double-basined, ultra-oligotrophic lake in northwest Patagonia.
Silver (Ag) ions are among the most toxic metallic ions to aquatic biota. In southern Argentina, ... more Silver (Ag) ions are among the most toxic metallic ions to aquatic biota. In southern Argentina, fish from Patagonian lakes have liver Ag concentrations [Ag] among the highest ever reported globally. Silver concentration in phytoplankton from Lake Moreno (1.82±3.00 μgg− 1 dry weight, DW) was found to be significantly higher than [Ag] in zooplankton (0.25±0.13 μgg− 1). Values in snails and decapods (0.60±0.28 μgg− 1 and 0.47±0.03 μgg− 1 respectively), were higher than in insect larvae (0.28±0.39 μgg− 1 for Trichoptera).
Hemimysis anomala, a littoral freshwater mysid native to the Ponto-Caspian region, is the newest ... more Hemimysis anomala, a littoral freshwater mysid native to the Ponto-Caspian region, is the newest invader to the Laurentian Great Lakes basin. Discovered in 2006, they have since been found in all of the Great Lakes (except Lake Superior) and have the potential to offset the dietary energy sink caused by invasive dreissenid mussels (Dreissena bugensis and D. polymorpha) in the littoral zone.
Seasonal variation in mercury (Hg) concentrations and food web structure was assessed for eastern... more Seasonal variation in mercury (Hg) concentrations and food web structure was assessed for eastern Lake Ontario. Hg concentrations, measured in 6 species of invertebrates and 8 species of fishes, tended to be highest in the spring and lowest in the summer for most biota. Yellow perch (Perca flavescens) exhibited significant ontogenetic shifts in diet and Hg, although such patterns were not evident for other species. Food web structure, as indicated by stable isotope values (δ15N, δ13C) was not static.
We investigated the terrestrial influence on two chained deep ultraoligotrophic lakes of North Pa... more We investigated the terrestrial influence on two chained deep ultraoligotrophic lakes of North Patagonia (Argentina) through the seasonal analysis of two pelagic allochthonous indicators: i) water color, as a proxy of allochthonous dissolved organic matter in lakes; and ii) the color to chlorophyll a ratio (Color: Chla), as an indicator of the relationship between allochthonous and autochthonous carbon pools.
Mussels, Diplon chilensis, from Lake Moreno, a double-basined mountain lake in southern Argentina... more Mussels, Diplon chilensis, from Lake Moreno, a double-basined mountain lake in southern Argentina, is known to have elevated concentrations of chromium (Cr,> 25μgg− 1 dry weight DW) and arsenic (As, 35μgg− 1 DW), attributed to untreated sewage. To further understand the trophodynamics of Cr, As and cobalt (Co), we investigated concentrations and transfer throughout the food web in each basin of Lake Moreno.
This study focused on the value of deciduous leaves as biomonitors of total mercury (THg). Leaf s... more This study focused on the value of deciduous leaves as biomonitors of total mercury (THg). Leaf samples were collected from a range of deciduous species from five sampling sites in the province of Ontario, Canada. These included a site in the northwest (the Experimental Lakes Area, ELA), two sites in central Ontario (the town of Dorset and the Centre for Atmospheric Research Experiments, CARE), and two sites in the southeast (Sandbanks Provincial Park, SBPP and the City of Kingston). The sampled species exhibited distinctive species-specific differences with red oaks consistently having lower leaf THg concentrations than all maple species, while black and white ash leaves had the highest concentrations. Spatially, leaves collected across the distance between ELA and SBPP (~ 1500 km apart) had overlapping THg concentrations between 20 and 40 ng/g. Unexpectedly, leaves from urban parks of Kingston had considerably lower THg concentrations (< 25 ng/g) than the other sites, which suggested leaves may not reflect subtle gradients of atmospheric THg found under field conditions. Leaf THg increased with the growing season, with highest THg leaf concentrations found in early autumn just before senescence. Microspatial differences within a single tree, such as position on a branch are important, since higher mercury concentrations were associated with leaves positioned deeper into the canopy relative to outer leaves more exposed to wind turbulence and sunlight. Within any single leaf, THg concentrations were highest in the leaf tissue, and consistently distributed, while the vein and petiole tissue had lower THg concentrations. There was no relationship between THg concentrations and leaf area. Using deciduous tree leaves as regional temporal monitors of bioavailable mercury may be feasible, but careful selection of leaf sampling sites on the tree itself and the timing is of utmost importance for ensuring consistent and high quality biomonitoring data.
The Northern Patagonian Andean range shared by Chile and Argentina has numerous glacial oligotrop... more The Northern Patagonian Andean range shared by Chile and Argentina has numerous glacial oligotrophic lakes protected in a series of National Parks. Recent baseline surveys indicated that concentrations in muscle and liver tissues from various fish species from across Nahuel Huapi and Los Alerces National Parks in Argentina were comparable or higher than similar fish species from other parts of the world. As a result, Lake Moreno, in Nahuel Huapi National Park, was chosen to investigate multiple element sinks, trends, and transfer in a representative Patagonia aquatic food web. The metals and metalloids Ag, As, Ba, Br, Cs, Co, Cr, Fe, Hg, K, Na, Rb, Se, and Zn were analyzed in three size plankton fractions, submerged macrophytes, biofilm, insect larvae, amphipods, decapods, gastropods (snails), annelids (earthworms), and forage fish. Except for nanoplankton (10–53 μm; small-celled algae, rotifers) and microplankton (53–200 μm; larger algae, ciliates, zooplankton nauplii), which share elemental compositional similarities, each taxon category had its own distinctive compositional pattern, revealed by principal component analysis. Nano- and microplankton tend to be relatively elevated in some metals, including As, Co, Cr, Fe, Hg, Zn, and Rb, followed by biofilm. Shredder-scrapper Trichoptera (caddisflies) have higher concentration of most of the studied elements than other insect larvae taxa, especially carnivorous Odonata (Anisoptera, dragonflies), which were associated with lower elemental contents. Those trends point to an overall tendency for biodiminishing element concentrations with trophic level in the benthos of Lake Moreno.
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