Статті в журналах з теми "Lake Region (Vic )"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Lake Region (Vic ).
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 статей у журналах для дослідження на тему "Lake Region (Vic )".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Mishra, Vimal, Keith A. Cherkauer, and Laura C. Bowling. "Parameterization of Lakes and Wetlands for Energy and Water Balance Studies in the Great Lakes Region*." Journal of Hydrometeorology 11, no. 5 (October 1, 2010): 1057–82. http://dx.doi.org/10.1175/2010jhm1207.1.
Повний текст джерелаАнотація:
Abstract Lakes and wetlands are prevalent around the Great Lakes and play an important role in the regional water and energy cycle. However, simulating their impacts on regional-scale hydrology is still a major challenge and not widely attempted. In the present study, the Variable Infiltration Capacity (VIC) model is applied and evaluated with a physically based lake and wetland algorithm, which can simulate the effect of lakes and wetlands on the grid cell energy and water balance. The VIC model was calibrated at 10 U.S. Geological Survey (USGS) stream gauging stations against daily streamflow records for the period of 1985–95, and successfully evaluated for the period of 1996–2005. Single-grid sensitivity experiments showed that runoff, baseflow, and inundation area were sensitive to the lake model parameters. Simulations were also conducted to analyze the spatial and temporal variability of inundation area for the period of 1985–2005. Results indicated that water and energy fluxes were substantially affected when lakes and wetlands were included in model simulations. Domain-averaged annual mean evapotranspiration (ET) was increased by 5% while annual mean total runoff was decreased by 12% with lakes and wetlands. Latent heat flux increased while sensible heat flux decreased because of the inclusion of lakes and wetlands.
2
Amantai, Nigenare, and Jianli Ding. "Analysis on the Spatio-Temporal Changes of LST and Its Influencing Factors Based on VIC Model in the Arid Region from 1960 to 2017: An Example of the Ebinur Lake Watershed, Xinjiang, China." Remote Sensing 13, no. 23 (November 30, 2021): 4867. http://dx.doi.org/10.3390/rs13234867.
Повний текст джерелаАнотація:
LST (Land surface temperature) is an important indicator for monitoring dynamic changes in the earth’s resources and environment. However, the complexity of obtaining long-term, continuous LST data hinders the development of research on LST responses to meteorological factors or LUCC in areas where data is lacking. The objective of this research was to use the VIC-3L (Variable Infiltration Capacity) based on multi-source remote sensing data to simulate and explore spatio-temporal changes in the LST, to analyze the relationship between the LST and meteorological elements by using cross-wavelet transform (XWT) and wavelet coherence (WTC), the relationship between the LST and LUCC by using three-phase remote sensing images of LUCC. The following results were obtained. The annual average LST of the study area is increasing at a rate of 0.027 °C per year. The annual average LST level is relatively high in the central and eastern regions. The average temperature has an important influence on LST, which is mainly reflected in the period scale of 1~4a in 1963–1972, 1980–1996, and 2004–2010. The sharp decline in open shrubs may have exacerbated the increase in LST in the study area. This study provides a scientific reference for studying LST in arid areas.
3
Perales, K. Martin, Catherine L. Hein, Noah R. Lottig, and M. Jake Vander Zanden. "Lake water level response to drought in a lake-rich region explained by lake and landscape characteristics." Canadian Journal of Fisheries and Aquatic Sciences 77, no. 11 (November 2020): 1836–45. http://dx.doi.org/10.1139/cjfas-2019-0270.
Повний текст джерелаАнотація:
Climate change is altering hydrologic regimes, with implications for lake water levels. While lakes within lake districts experience the same climate, lakes may exhibit differential climate vulnerability regarding water level response to drought. We took advantage of a recent drought (∼2005–2010) and estimated changes in lake area, water level, and shoreline position on 47 lakes in northern Wisconsin using high-resolution orthoimagery and hypsographic curves. We developed a model predicting water level response to drought to identify characteristics of the most vulnerable lakes in the region, which indicated that low-conductivity seepage lakes found high in the landscape, with little surrounding wetland and highly permeable soils, showed the greatest water level declines. To explore potential changes in the littoral zone, we estimated coarse woody habitat (CWH) loss during the drought and found that drainage lakes lost 0.8% CWH while seepage lakes were disproportionately impacted, with a mean loss of 40% CWH. Characterizing how lakes and lake districts respond to drought will further our understanding of how climate change may alter lake ecology via water level fluctuations.
4
Wagner, B., H. Vogel, G. Zanchetta, and R. Sulpizio. "Environmental change within the Balkan region during the past ca. 50 ka recorded in the sediments from lakes Prespa and Ohrid." Biogeosciences 7, no. 10 (October 19, 2010): 3187–98. http://dx.doi.org/10.5194/bg-7-3187-2010.
Повний текст джерелаАнотація:
Abstract. Lakes Prespa and Ohrid, in the Balkan region, are considered to be amongst the oldest lakes in Europe. Both lakes are hydraulically connected via karst aquifers. From Lake Ohrid, several sediment cores up to 15 m long have been studied over the last few years. Here, we document the first long sediment record from nearby Lake Prespa to clarify the influence of Lake Prespa on Lake Ohrid and the environmental history of the region. Radiocarbon dating and dated tephra layers provide robust age control and indicate that the 10.5 m long sediment record from Lake Prespa reaches back to 48 ka. Glacial sedimentation is characterized by low organic matter content and absence of carbonates in the sediments, which indicate oligotrophic conditions in both lakes. Holocene sedimentation is characterized by particularly high carbonate content in Lake Ohrid and by particularly high organic matter content in Lake Prespa, which indicates a shift towards more mesotrophic conditions in the latter. Long-term environmental change and short-term events, such as related to the Heinrich events during the Pleistocene or the 8.2 ka cooling event during the Holocene, are well recorded in both lakes, but are only evident in certain proxies. The comparison of the sediment cores from both lakes indicates that environmental change affects particularly the trophic state of Lake Prespa due to its lower volume and water depth.
5
Benjamin, Stanley G., Tatiana G. Smirnova, Eric P. James, Eric J. Anderson, Ayumi Fujisaki-Manome, John G. W. Kelley, Greg E. Mann, Andrew D. Gronewold, Philip Chu, and Sean G. T. Kelley. "Inland lake temperature initialization via coupled cycling with atmospheric data assimilation." Geoscientific Model Development 15, no. 17 (September 5, 2022): 6659–76. http://dx.doi.org/10.5194/gmd-15-6659-2022.
Повний текст джерелаАнотація:
Abstract. Application of lake models coupled within earth-system prediction models, especially for predictions from days to weeks, requires accurate initialization of lake temperatures. Commonly used methods to initialize lake temperatures include interpolation of global sea-surface temperature (SST) analyses to inland lakes, daily satellite-based observations, or model-based reanalyses. However, each of these methods have limitations in capturing the temporal characteristics of lake temperatures (e.g., effects of anomalously warm or cold weather) for all lakes within a geographic region and/or during extended cloudy periods. An alternative lake-initialization method was developed which uses two-way-coupled cycling of a small-lake model within an hourly data assimilation system of a weather prediction model. The lake model simulated lake temperatures were compared with other estimates from satellite and in situ observations and interpolated-SST data for a multi-month period in 2021. The lake cycling initialization, now applied to two operational US NOAA weather models, was found to decrease errors in lake surface temperature from as much as 5–10 K vs. interpolated-SST data to about 1–2 K compared to available in situ and satellite observations.
6
Sato, Yota, Koji Fujita, Hiroshi Inoue, and Akiko Sakai. "Land- to lake-terminating transition triggers dynamic thinning of a Bhutanese glacier." Cryosphere 16, no. 6 (July 1, 2022): 2643–54. http://dx.doi.org/10.5194/tc-16-2643-2022.
Повний текст джерелаАнотація:
Abstract. There have been rapid increases in both the number and expansion of the proglacial lakes across High Mountain Asia. However, the relationship between proglacial lakes and glacier dynamics remains unclear in the Himalayan region. Here we present the surface elevation, flow-velocity changes, and proglacial lake expansion of Thorthormi and Lugge glaciers in the Lunana region, Bhutanese Himalaya, during the 2000–2018 period using photogrammetry and GPS survey data. The lake expansion and surface lowering rates and flow-velocity field of Lugge Glacier, a lake-terminating glacier, have remained approximately constant since 2000. Conversely, there have been accelerated proglacial lake expansion and a 2-fold increase in the thinning rate of Thorthormi Glacier since 2011, as well as a considerable speed-up in the flow-velocity field (>150 m a−1). We reveal that the lake formation and transition of Thorthormi Glacier from a land- to lake-terminating glacier have triggered glacier speed-up and rapid thinning via a positive (compressive) to negative (extensional) change in the emergence velocities. This study provides the first evidence of dynamic glacier changes that are associated with proglacial lake formation across the Himalayan region.
7
Wagner, B., H. Vogel, G. Zanchetta, and R. Sulpizio. "Environmental changes on the Balkans recorded in the sediments from lakes Prespa and Ohrid." Biogeosciences Discussions 7, no. 3 (May 10, 2010): 3365–92. http://dx.doi.org/10.5194/bgd-7-3365-2010.
Повний текст джерелаАнотація:
Abstract. Lakes Prespa and Ohrid on the Balkans are considered to be amongst the oldest lakes in Europe. Both lakes are hydraulically connected via karst aquifers. From Lake Ohrid, several up to ca. 15 m long sediment records were studied during the past years. In this study, a first long sediment record from Lake Prespa was studied in order to shed more light on the influence of Lake Prespa on Lake Ohrid and the environmental history of the region. Radiocarbon dating and the occurrence of 3 dated tephra layers provide a good age control and indicate that the 10.5 m long sediment record reaches back to 48 ka. The comparison of the results from this study with those from former studies of the Lake Ohrid cores indicates that Lake Prespa is more susceptible to environmental changes due to its lower volume and water depth. Glacial sedimentation is characterized by low organic matter contents and absence of carbonates in the sediments, which indicate oligotrophic conditions in both lakes. Holocene sedimentation is characterized by particularly high carbonate contents in Lake Ohrid and by particularly high organic matter contents in Lake Prespa, which indicate a shift towards more mesotrophic conditions in the latter. Long-term environmental changes and short-term events, such as the Heinrich events during the Pleistocene or the 8.2 cooling event during the Holocene, are well recorded in both lakes, but partly expressed in different proxies.
8
Rick, Brianna, Daniel McGrath, William Armstrong, and Scott W. McCoy. "Dam type and lake location characterize ice-marginal lake area change in Alaska and NW Canada between 1984 and 2019." Cryosphere 16, no. 1 (January 25, 2022): 297–314. http://dx.doi.org/10.5194/tc-16-297-2022.
Повний текст джерелаАнотація:
Abstract. Ice-marginal lakes impact glacier mass balance, water resources, and ecosystem dynamics and can produce catastrophic glacial lake outburst floods (GLOFs) via sudden drainage. Multitemporal inventories of ice-marginal lakes are a critical first step in understanding the drivers of historic change, predicting future lake evolution, and assessing GLOF hazards. Here, we use Landsat-era satellite imagery and supervised classification to semi-automatically delineate lake outlines for four ∼5-year time periods between 1984 and 2019 in Alaska and northwest Canada. Overall, ice-marginal lakes in the region have grown in total number (+183 lakes, 38 % increase) and area (+483 km2, 59 % increase) between the time periods of 1984–1988 and 2016–2019. However, changes in lake numbers and area were notably unsteady and nonuniform. We demonstrate that lake area changes are connected to dam type (moraine, bedrock, ice, or supraglacial) and topological position (proglacial, detached, unconnected, ice, or supraglacial), with important differences in lake behavior between the sub-groups. In strong contrast to all other dam types, ice-dammed lakes decreased in number (six fewer, 9 % decrease) and area (−51 km2, 40 % decrease), while moraine-dammed lakes increased (56 more, 26 % and +479 km2, 87 % increase for number and area, respectively) at a faster rate than the average when considering all dam types together. Proglacial lakes experienced the largest area changes and rate of change out of any lake position throughout the period of study and moraine-dammed lakes which experienced the largest increases are associated with clean-ice glaciers (<19 % debris cover). By tracking individual lakes through time and categorizing lakes by dam type, subregion, and topological position, we are able to parse trends that would otherwise be aliased if these characteristics were not considered. This work highlights the importance of such lake characterization when performing ice-marginal lake inventories and provides insight into the physical processes driving recent ice-marginal lake evolution.
9
Rempel, L. L., and D. G. Smith. "Postglacial fish dispersal from the Mississippi refuge to the Mackenzie River basin." Canadian Journal of Fisheries and Aquatic Sciences 55, no. 4 (April 1, 1998): 893–99. http://dx.doi.org/10.1139/f97-257.
Повний текст джерелаАнотація:
Wisconsinan glaciation had a profound impact on fish faunas in North America, and deglaciation led to the dispersal of approximately 28 species from the Mississippi glacial refuge into the Mackenzie River basin. A hypothesized dispersal 11 500 years ago via glacial lakes Agassiz and Peace is difficult to verify and hydrologic linkage between these lakes was sporadic and short lived. Geomorphic evidence indicates that glacial Lake Agassiz drained into the Mackenzie basin via the Clearwater River, Saskatchewan, 9900 years ago and created a second opportunity for fish dispersal northward. Fish distribution data indicate a 96% similarity between Mississippi species in the Mackenzie basin and species occupying the former Agassiz-Clearwater corridor. Fifteen species dispersed into the headwaters of the Clearwater River during hydrologic linkage to Lake Agassiz and are now isolated above an 18.5 m waterfall. Previous genetic data suggest lake trout (Salvelinus namaycush) used the Agassiz-Clearwater corridor for two-way dispersal between Beringia and the Great Lakes basin. Lake whitefish (Coregonus clupeaformis) populations of Mississippi origin are distinguished by a marker allele of glucose-3-phosphate dehydrogenase, G3PDH-1*b, that is absent from modern populations within the former Lake Peace region and the distribution of Mississippi whitefish across Canada is best resolved by our Agassiz-Clearwater dispersal hypothesis. Our research substantially alters the interpretation of fish biogeographic patterns in Canada and generates testable hypotheses for future studies.
10
Maurer, J. M., J. M. Schaefer, J. B. Russell, S. Rupper, N. Wangdi, A. E. Putnam, and N. Young. "Seismic observations, numerical modeling, and geomorphic analysis of a glacier lake outburst flood in the Himalayas." Science Advances 6, no. 38 (September 2020): eaba3645. http://dx.doi.org/10.1126/sciadv.aba3645.
Повний текст джерелаАнотація:
Glacial lake outburst floods (GLOFs) are a substantial hazard for downstream communities in vulnerable regions, yet unpredictable triggers and remote source locations make GLOF dynamics difficult to measure and quantify. Here, we revisit a destructive GLOF that occurred in Bhutan in 1994 and apply cross-correlation–based seismic analyses to track the evolution of the GLOF remotely (~100 kilometers from the source region). We use the seismic observations along with eyewitness reports and a downstream gauge station to constrain a numerical flood model and then assess geomorphic change and current state of the unstable lakes via satellite imagery. Coherent seismic energy is evident from 1 to 5 hertz beginning approximately 5 hours before the flood impacted Punakha village, which originated at the source lake and advanced down the valley during the GLOF duration. Our analysis highlights potential benefits of using real-time seismic monitoring to improve early warning systems.
11
Hengy, Miranda H., Dean J. Horton, Donald G. Uzarski, and Deric R. Learman. "Microbial community diversity patterns are related to physical and chemical differences among temperate lakes near Beaver Island, MI." PeerJ 5 (October 16, 2017): e3937. http://dx.doi.org/10.7717/peerj.3937.
Повний текст джерелаАнотація:
Lakes are dynamic and complex ecosystems that can be influenced by physical, chemical, and biological processes. Additionally, individual lakes are often chemically and physically distinct, even within the same geographic region. Here we show that differences in physicochemical conditions among freshwater lakes located on (and around) the same island, as well as within the water column of each lake, are significantly related to aquatic microbial community diversity. Water samples were collected over time from the surface and bottom-water within four freshwater lakes located around Beaver Island, MI within the Laurentian Great Lakes region. Three of the sampled lakes experienced seasonal lake mixing events, impacting either O2, pH, temperature, or a combination of the three. Microbial community alpha and beta diversity were assessed and individual microbial taxa were identified via high-throughput sequencing of the 16S rRNA gene. Results demonstrated that physical and chemical variability (temperature, dissolved oxygen, and pH) were significantly related to divergence in the beta diversity of surface and bottom-water microbial communities. Despite its correlation to microbial community structure in unconstrained analyses, constrained analyses demonstrated that dissolved organic carbon (DOC) concentration was not strongly related to microbial community structure among or within lakes. Additionally, several taxa were correlated (either positively or negatively) to environmental variables, which could be related to aerobic and anaerobic metabolisms. This study highlights the measurable relationships between environmental conditions and microbial communities within freshwater temperate lakes around the same island.
12
Evans, David O., and David H. Loftus. "Colonization of Inland Lakes in the Great Lakes Region by Rainbow Smelt, Osmerus mordax: Their Freshwater Niche and Effects on Indigenous Fishes." Canadian Journal of Fisheries and Aquatic Sciences 44, S2 (December 19, 1987): s249—s266. http://dx.doi.org/10.1139/f87-327.
Повний текст джерелаАнотація:
Rainbow smelt, Osmerus mordax, have colonized numerous inland lakes in eastern North America, primarily as a result of introductions by humans. Smelt often establish large populations in these lakes and influence indigenous fishes both directly (predation) and indirectly (competition). Smelt have a eurythermal life history, which results in spatial segregation of their larvae, juvenile, and adults, and are omnivorous feeders, eating a range of food types from zooplankton to fish. As a result, smelt interact strongly with a wide spectrum of prey and predator species. Effects on other species are mediated via food web interactions resulting in recruitment and growth changes in some species and redirection of energy flow and storage. Species most often affected are cold-water and cool-water species whose niches are most similar to juvenile and adult smelt. Increased growth rates of Atlantic salmon (Salmo salar) and lake trout (Salvelinus namaycush) and recruitment failure of lake whitefish (Coregonus clupeaformis) are the best documented responses to invasion by smelt. Many other species are probably also affected, although the effects vary greatly between lakes. Variation in the smelt metabolic niche (as expressed by relative growth efficiency) is due to variations in prey size and availability and is reflected in differences in smelt body size between lakes. Smelt body size, in turn, is related to the variable effects that they have on other species.
13
Carter, Sasha P., Helen A. Fricker, and Matthew R. Siegfried. "Antarctic subglacial lakes drain through sediment-floored canals: theory and model testing on real and idealized domains." Cryosphere 11, no. 1 (February 2, 2017): 381–405. http://dx.doi.org/10.5194/tc-11-381-2017.
Повний текст джерелаАнотація:
Abstract. Over the past decade, satellite observations of ice surface height have revealed that active subglacial lake systems are widespread under the Antarctic Ice Sheet, including the ice streams. For some of these systems, additional observations of ice-stream motion have shown that lake activity can affect ice-stream dynamics. Despite all this new information, we still have insufficient understanding of the lake-drainage process to incorporate it into ice-sheet models. Process models for drainage of ice-dammed lakes based on conventional R-channels incised into the base of the ice through melting are unable to reproduce the timing and magnitude of drainage from Antarctic subglacial lakes estimated from satellite altimetry given the low hydraulic gradients along which such lakes drain. We have developed an alternative process model, in which channels are mechanically eroded into the underlying deformable subglacial sediment. When applied to the known active lakes of the Whillans–Mercer ice-stream system, the model successfully reproduced both the inferred magnitudes and recurrence intervals of lake-volume changes, derived from Ice, Cloud and land Elevation Satellite (ICESat) laser altimeter data for the period 2003–2009. Water pressures in our model changed as the flood evolved: during drainage, water pressures initially increased as water flowed out of the lake primarily via a distributed system, then decreased as the channelized system grew, establishing a pressure gradient that drew water away from the distributed system. This evolution of the drainage system can result in the observed internal variability of ice flow over time. If we are correct that active subglacial lakes drain through canals in the sediment, this mechanism also implies that active lakes are typically located in regions underlain by thick subglacial sediment, which may explain why they are not readily observed using radio-echo-sounding techniques.
14
Rochette, Scott M., Patrick S. Market, Chad M. Gravelle, and Thomas A. Niziol. "A Case Study of Anomalous Snowfall with an Alberta Clipper." Advances in Meteorology 2017 (2017): 1–14. http://dx.doi.org/10.1155/2017/8406379.
Повний текст джерелаАнотація:
An Alberta clipper moved over western New York state on 11-12 January 2004, producing snowfall amounts of up to 27 cm in portions of the region during a roughly 12-h period. In addition, lightning and thunder were reported. Such systems, known primarily for their fast motion and relatively dry nature, are not generally associated with significant snowfalls. A postmortem analysis of this event, following an ingredients-based methodology, revealed that as the weak low approached the lower Great Lakes, it came under the influence of coupled 300-hPa jets that produced enhanced divergence and significant upward vertical motion over western New York, resulting in the enhanced convective snowfall over the region for a limited time. Instability and possible enhancement via the Great Lakes are also investigated, which show that while there was at least modest instability over the region during the time of heavy snowfall, lake enhancement was unlikely.
15
Wang, Qian, Xiangdong Yang, Nicholas John Anderson, and Xuhui Dong. "Direct versus indirect climate controls on Holocene diatom assemblages in a sub-tropical deep, alpine lake (Lugu Hu, Yunnan, SW China)." Quaternary Research 86, no. 1 (July 2016): 1–12. http://dx.doi.org/10.1016/j.yqres.2016.03.003.
Повний текст джерелаАнотація:
AbstractThe reconstruction of Holocene environmental changes in lakes on the plateau region of southwest China provides an understanding of how these ecosystems may respond to climate change. Fossil diatom assemblages were investigated from an 11,000-year lake sediment core from a deep, alpine lake (Lugu Hu) in southwest China, an area strongly influenced by the southwest (or the Indian) summer monsoon. Changes in diatom assemblage composition, notably the abundance of the two dominant planktonic species, Cyclotella rhomboideo-elliptica and Cyclostephanos dubius, reflect the effects of climate variability on nutrient dynamics, mediated via thermal stratification (internal nutrient cycling) and catchment-vegetation processes. Statistical analyses of the climateediatom interactions highlight the strong effect of changing orbitally-induced solar radiation during the Holocene, presumably via its effect on the lake’s thermal budget. In a partial redundancy analysis, climate (solar insolation) and proxies reflecting catchment process (pollen percentages, C/N ratio) were the most important drivers of diatom ecological change, showing the strong effects of climateecatchmentevegetation interactions on lake functioning. This diatom record reflects long-term ontogeny of the lake-catchment ecosystem and suggests that climatic changes (both temperature and precipitation) impact lake ecology indirectly through shifts in thermal stratification and catchment nutrient exports.
16
Black, Geoff A., J. Brian Dempson, and W. J. Bruce. "Distribution and postglacial dispersal of freshwater fishes of Labrador." Canadian Journal of Zoology 64, no. 1 (January 1, 1986): 21–31. http://dx.doi.org/10.1139/z86-005.
Повний текст джерелаАнотація:
The voluminous literature on the freshwater and diadromous fishes of Labrador is summarized in distributional maps. A total of 25 obligate freshwater spawning and one catadromous species has been reported. Fishes from Atlantic and Mississippi refugia probably invaded the region from the Great Lakes basin primarily via glacial Lake Barlow-Ojibway, crossing Quebec north of the Otish Mountain to the headwaters of the Churchill River system. Additional dispersal routes existed to the north and south. Euryhaline species from an Atlantic refugium first invaded coastal regions during postglacial depression and marine inundation. Remnants of these occur as landlocked populations. Labrador is divided into three major ichthyogeographic regions based on species distributions and dispersal opportunities. The Churchill River forms one region and is divided into three subregions. Upstream of Churchill Falls there is only one species, which dispersed across Quebec. Downstream areas, including accessible tributaries, have all of the common fishes present in Labrador. Less accessible watersheds south of Churchill River form the third subregion and are limited to fishes with better swimming abilities. The second major region is southeastern Labrador which has euryhaline fishes from Atlantic refugia and three species from Quebec. The third major region is loosely defined as northern Labrador (> 55°N) although it is one of decreasing numbers of species with increasing latitude.
17
Dunmire, Devon, Alison F. Banwell, Nander Wever, Jan T. M. Lenaerts, and Rajashree Tri Datta. "Contrasting regional variability of buried meltwater extent over 2 years across the Greenland Ice Sheet." Cryosphere 15, no. 6 (June 29, 2021): 2983–3005. http://dx.doi.org/10.5194/tc-15-2983-2021.
Повний текст джерелаАнотація:
Abstract. The Greenland Ice Sheet (GrIS) rapid mass loss is primarily driven by an increase in meltwater runoff, which highlights the importance of understanding the formation, evolution, and impact of meltwater features on the ice sheet. Buried lakes are meltwater features that contain liquid water and exist under layers of snow, firn, and/or ice. These lakes are invisible in optical imagery, challenging the analysis of their evolution and implication for larger GrIS dynamics and mass change. Here, we present a method that uses a convolutional neural network, a deep learning method, to automatically detect buried lakes across the GrIS. For the years 2018 and 2019 (which represent low- and high-melt years, respectively), we compare total areal extent of both buried and surface lakes across six regions, and we use a regional climate model to explain the spatial and temporal differences. We find that the total buried lake extent after the 2019 melt season is 56 % larger than after the 2018 melt season across the entire ice sheet. Northern Greenland has the largest increase in buried lake extent after the 2019 melt season, which we attribute to late-summer surface melt and high autumn temperatures. We also provide evidence that different processes are responsible for buried lake formation in different regions of the ice sheet. For example, in southwest Greenland, buried lakes often appear on the surface during the previous melt season, indicating that these meltwater features form when surface lakes partially freeze and become insulated as snowfall buries them. Conversely, in southeast Greenland, most buried lakes never appear on the surface, indicating that these features may form due to downward percolation of meltwater and/or subsurface penetration of shortwave radiation. We provide support for these processes via the use of a physics-based snow model. This study provides additional perspective on the potential role of meltwater on GrIS dynamics and mass loss.
18
Stivrins, Normunds, Ieva Grudzinska, Kati Elmi, Atko Heinsalu, and Siim Veski. "Determining reference conditions of hemiboreal lakes in Latvia, NE Europe: a palaeolimnological approach." Annales de Limnologie - International Journal of Limnology 54 (2018): 22. http://dx.doi.org/10.1051/limn/2018014.
Повний текст джерелаАнотація:
The current status of a lake can be evaluated via monitoring, but such data can only provide information about the last few decades to a century at best. In most cases, the natural state of a lake cannot be ascertained. This is even more challenging if the apparent anthropogenic effects on the environment over the last millennia are considered. We used data on fossil algae from five evenly distributed hemiboreal lakes in geographically different regions in Latvia, NE Europe to assess the amount of compositional change or turnover (i.e., the beta-diversity) in the algae datasets for the last 2000 years by using a Detrended Canonical Correspondence Analysis. Our results show that the algae turnover increases towards the present day with distinct shifts during times characterised by extensive and intensive agriculture establishment, and political and economic changes. Because the anthropogenic impact on the landscape and lakes before AD 1200 was relatively minor, we propose that algae composition at that time can be assumed to represent the natural reference conditions for most Latvian lakes.
19
Geyh, Mebus A., U. Schotterer, and M. Grosjean. "Temporal Changes of the 14C Reservoir Effect in Lakes." Radiocarbon 40, no. 2 (1997): 921–31. http://dx.doi.org/10.1017/s0033822200018890.
Повний текст джерелаАнотація:
Conventional radiocarbon dates for sediment samples from aquatic systems and of coeval terrestrial samples deviate from each other due to the reservoir effect. The reservoir correction is usually assumed to be constant with time for a specific aquatic system. Our studies confirm that seasonal and secular changes are frequent and are governed by the limnological conditions. Lakes have two principal sources of 14C: atmospheric CO2 and the total dissolved inorganic carbon (TDIC) of the entering groundwater and runoff. The former has values of ca. 100 pMC; the latter usually has a 14C value well below 100 pMC. Atmospheric CO2 enters the lake by exchange via its surface. The proportions of these two kinds of input determine the magnitude of the reservoir correction in freshwater lakes. It is mainly a function of the volume/surface ratio of the lake and, consequently a function of the water depth. The surface of lakes with outflow does not change when sedimentation decreases the depth of the water. The depth of Schleinsee Lake in southern Germany has decreased from 30 to 15 m since ca. 9000 bp. As a result, the reservoir correction has decreased from ca. -1550 to -580 yr. In contrast, the depth of Lake Proscansko in Croatia increased with growth of the travertine dam and the reservoir correction changed from ca. -1790 to -2650 yr during the last 8800 yr. The largest fluctuations of lake levels occur in closed lakes in arid regions when the climate changes from humid to arid and vice versa. As a result, the reservoir correction of the 14C dates for the total organic fraction from Lejía Lake in the Atacama Desert of Chile varied between <-1800 yr and -4700 yr over a period of only 1800 yr between 11,500 and 9700 bp. The corresponding reservoir correction for the marl fraction is much higher. In summary, accurate and reliable 14C dating of lake sediments requires a study of the temporal changes of the reservoir effect by analysis of both the organic and marl fractions. The most reliable 14C dates are obtained from terrestrial plant remains.
20
Chapleau, François, and J. Andrew Cooper. "Variation in the preoperculomandibular canal of the johnny darter, Etheostoma nigrum, with associated zoogeographical considerations." Canadian Journal of Zoology 70, no. 12 (December 1, 1992): 2315–21. http://dx.doi.org/10.1139/z92-310.
Повний текст джерелаАнотація:
A total of 1267 specimens (from 87 stations) of the johnny darter, Etheostoma nigrum, were studied to examine the geographic variation in the numbers of pores on the preoperculomandibular canal. The pore count is bimodal for the total sample. These modes correspond to distinct geographic regions. Fishes from northern Ontario (west and north of Lake Nipigon), Manitoba, Saskatchewan, Minnesota, Wisconsin, Iowa, and the Upper Peninsula of Michigan usually have 7 or fewer pores (mode = 6). Populations from northern Ontario (east and south of Lake Nipigon), southern Ontario, Quebec, Illinois, Indiana, Kentucky, Tennessee, Maryland, Ohio, New York, Pennsylvania, West Virginia, Virginia, North Carolina, South Carolina, and the Lower Peninsula of Michigan have 8 or more pores (mode = 9). The differentiation between morphs predates their present distribution and the morphs probably occupied distinct geographic areas within the Mississippi refugium during the last glaciation. Etheostoma nigrum dispersed north, following two postglacial routes: (i) via the Mississippi River to Lake Agassiz (12 800 years BP) then eastward to the Hudson Bay and James Bay drainages via Lake Barlow–Ojibway (9500 years BP), and (ii) via a northeastern spread from the Great Lakes and Ohio River drainages to the St. Lawrence River and Ottawa River drainages (12 000 years BP).
21
Portilla, Karen, Elizabeth Velarde, Ellen Decaestecker, Franco Teixeira de Mello, and Koenraad Muylaert. "Potential Submerged Macrophytes to Mitigate Eutrophication in a High-Elevation Tropical Shallow Lake—A Mesocosm Experiment in the Andes." Water 15, no. 1 (December 26, 2022): 75. http://dx.doi.org/10.3390/w15010075.
Повний текст джерелаАнотація:
Submerged macrophytes promote water clarity in shallow lakes in temperate regions via zooplankton refuge, allelopathy, and nutrient competition with phytoplankton, thereby increasing zooplankton grazing. However, in high-altitude Andean ecosystems, these interactions in shallow lakes have received far less attention. To understand the role of submerged plants in a relatively cold ecosystem (typical for the Andean region), two 100 L experiments were conducted in Yahuarcocha Lake, which has a permanent cyanobacterial bloom. In our first experiment, we evaluated the response of the cyanobacteria bloom to different concentrations of Egeria densa (15%, 35%, and 45% PVI). In the second experiment, we investigated the interactions between E. densa (35% PVI), zooplankton, and the small-sized fish Poecilia reticulata as well as their impacts on phytoplankton. We found a strong reduction in cyanobacteria in the presence of E. densa, whereas P. reticulata promoted cyanobacteria dominance and zooplankton had a null effect on phytoplankton. Remarkably, the combination of E. densa, fish, and zooplankton substantially reduced the algae. Our findings showed that the cyanobacteria bloom decreased in the presence of E. densa, thereby increasing the water clarity in the high-elevation eutrophic ecosystem in the Andes. This effect depended on the plant volume inhabited and the small-sized fish biomass.
22
Michaud, Wendy K., Robert C. Perry, J. Brian Dempson, Milton Shears, and Michael Power. "Occurrence of Lake Chub, Couesius plumbeus, in Northern Labrador." Canadian Field-Naturalist 124, no. 2 (April 1, 2010): 113. http://dx.doi.org/10.22621/cfn.v124i2.1048.
Повний текст джерелаАнотація:
Lake Chub (Couesius plumbeus) were recently found in seven previously undocumented locations in northern Labrador. These populations represent the first recorded accounts of this species in the Labrador region north of the Churchill River drainage and east of the George River. Lake Chub likely invaded this region via dispersal routes provided by eastern spillways of glacial Lake Naskaupi.
23
Han, Rui, Xin Zhang, Jing Liu, Qifu Long, Laisheng Chen, Deli Liu, and Derui Zhu. "Microbial community structure and diversity within hypersaline Keke Salt Lake environments." Canadian Journal of Microbiology 63, no. 11 (November 2017): 895–908. http://dx.doi.org/10.1139/cjm-2016-0773.
Повний текст джерелаАнотація:
Keke Salt Lake is located in the Qaidamu Basin of China. It is a unique magnesium sulfate-subtype hypersaline lake that exhibits a halite domain ecosystem, yet its microbial diversity has remained unstudied. Here, the microbial community structure and diversity was investigated via high-throughput sequencing of the V3–V5 regions of 16S rRNA genes. A high diversity of operational taxonomic units was detected for Bacteria and Archaea (734 and 747, respectively), comprising 21 phyla, 43 classes, and 201 genera of Bacteria and 4 phyla, 4 classes, and 39 genera of Archaea. Salt-saturated samples were dominated by the bacterial genera Bacillus (51.52%–58.35% relative abundance), Lactococcus (9.52%–10.51%), and Oceanobacillus (8.82%–9.88%) within the Firmicutes phylum (74.81%–80.99%), contrasting with other hypersaline lakes. The dominant Archaea belonged to the Halobacteriaceae family, and in particular, the genera (with an abundance of >10% of communities) Halonotius, Halorubellus, Halapricum, Halorubrum, and Natronomonas. Additionally, we report the presence of Nanohaloarchaeota and Woesearchaeota in Qinghai–Tibet Plateau lakes, which has not been previously documented. Total salinity (especially Mg2+, Cl–, Na+, and K+) mostly correlated with taxonomic distribution across samples. These results expand our understanding of microbial resource utilization within hypersaline lakes and the potential adaptations of dominant microorganisms that allow them to inhabit such environments.
24
Hallett, Douglas J., Dana S. Lepofsky, Rolf W. Mathewes, and Ken P. Lertzman. "11 000 years of fire history and climate in the mountain hemlock rain forests of southwestern British Columbia based on sedimentary charcoal." Canadian Journal of Forest Research 33, no. 2 (February 1, 2003): 292–312. http://dx.doi.org/10.1139/x02-177.
Повний текст джерелаАнотація:
Little is known about the role of fire in the mountain hemlock (Tsuga mertensiana (Bong.) Carrière) rain forests of southern British Columbia. High-resolution analysis of macroscopic charcoal from lake sediment cores, along with 102 accelerator mass spectrometry (AMS) ages on soil charcoal, was used to reconstruct the long-term fire history around two subalpine lakes in the southern Coast and North Cascade Mountains. AMS ages on soil charcoal provide independent evidence of local fire around a lake and support the interpretation of peaks in lake sediment charcoal as distinct fire events during the Holocene. Local fires are rare, with intervals ranging from centuries to several millennia at some sites. Overall fire frequency varied continuously throughout the Holocene, suggesting that fire regimes are linked to climate via large-scale atmospheric circulation patterns. Fires were frequent between 11 000 and 8800 calendar years BP during the warm and dry early Holocene. The onset of humid conditions in the mid-Holocene, as rain forest taxa established in the region, produced a variable fire period until 3500 calendar years BP. A synchronous decrease in fire frequency from 3500 to 2400 calendar years BP corresponds to Neoglacial advances in the region and cool humid climate. A return of frequent fire between 2400 and 1300 calendar years BP suggests that prolonged summer drought occurred more often during this interval, which we name the Fraser Valley Fire Period. The present-day fire regime was established after 1300 calendar years BP.
25
Mulholland, Jake P., Jeffrey Frame, Stephen W. Nesbitt, Scott M. Steiger, Karen A. Kosiba, and Joshua Wurman. "Observations of Misovortices within a Long-Lake-Axis-Parallel Lake-Effect Snowband during the OWLeS Project." Monthly Weather Review 145, no. 8 (August 2017): 3265–91. http://dx.doi.org/10.1175/mwr-d-16-0430.1.
Повний текст джерелаАнотація:
Recent lake-effect snow field projects in the eastern Great Lakes region have revealed the presence of misovortices with diameters between 40 and 4000 m along cyclonic horizontal shear zones within long-lake-axis-parallel bands. One particular band in which an abundance of misovortices developed occurred on 7 January 2014. The leading hypothesis for lake-effect misovortexgenesis is the release of horizontal shearing instability (HSI). An analysis of three-dimensional dual-Doppler wind syntheses reveals that two criteria for HSI are satisfied along the horizontal shear zone, strongly suggesting that HSI was the likely cause of the misovortices in this case. Furthermore, the general lack of anticyclonic–cyclonic vortex couplets throughout the event reveal that tilting of horizontal vorticity into the vertical is of less importance compared to the release of HSI and subsequent strengthening via vortex stretching. A WRF simulation depicts misovortices along the horizontal shear zone within the simulated band. The simulated vortices display remarkable similarities to the observed vortices in terms of intensity, depth, spacing, and size. The simulated vortices persist over the eastern end of the lake; however, once the vortices move inland, they quickly dissipate. HSI criteria are also calculated from the WRF simulation and are satisfied along the shear zone. Competing hypotheses of misovortexgenesis are presented, with results indicating that the release of HSI is the likely mechanism of vortex formation.
26
Joshi, Susan M., and Leland J. Jackson. "How Might Changing Climate Limit Cyanobacteria Growth in Shallow Prairie Lakes? An Empirical Space-For-Time Evaluation of the Potential Role of Increasing Sulfate." Advances in Environmental and Engineering Research 3, no. 1 (November 20, 2021): 1. http://dx.doi.org/10.21926/aeer.2201007.
Повний текст джерелаАнотація:
Cyanobacteria blooms alter aquatic ecosystems and occur frequently in shallow prairie lakes, which are predicted to increase in salinity as the regional climate becomes hotter and drier. However, flat landscapes that experience depression bottom salinity with high concentrations of sulfate in addition to sodium and chloride, may mitigate nutrient increases or even inhibit cyanobacteria growth. Cyanobacteria can dominate shallow lakes with low N:P ratios because many cyanobacteria species fix dissolved N2, whether due to in-lake denitrification or exchange with the atmosphere, a process that requires molybdenum as an enzyme cofactor. Sulfate can compete with molybdate at cellular uptake sites, potentially limiting the competitive advantage of cyanobacteria. We studied 25 lakes located in a relatively limited geographic region of southern Alberta (Canada) and used a space-for-time analysis to model scenarios of increased sulfate concentrations under changing climate. Monthly, we measured nitrogen, phosphorus, sulfate, molybdenum, and cyanobacterial pigments and used mixed effects models to identify empirical relationships. Sulfate drives conductivity in the region and we found that most saline lakes we sampled are turbid lakes with high nutrients and high cyanobacteria biomass. In addition to phosphorus, molybdenum predicted cyanobacterial pigments in the top two models, showing a positive relationship with cyanobacterial biomass. We also found a negative relationship between sulfate concentration and cyanobacteria pigments, which suggests that as lakes get saltier, even with increased nutrients, there may not be an incremental increase in cyanobacteria biomass. Our results therefore suggest that competition between sulfate and molybdate may limit future cyanobacteria growth in shallow lakes and that with a warmer and drier climate it may not be inevitable that shallow lakes will continue to be dominated by cyanobacterial blooms, a hypothesis that could be tested directly via experimentation.
27
Svensson, Ola, Bernd Egger, Boye Gricar, Katie Woodhouse, Cock van Oosterhout, Walter Salzburger, Ole Seehausen, and George F. Turner. "Segregation of Species-Specific Male Attractiveness in F2 Hybrid Lake Malawi Cichlid Fish." International Journal of Evolutionary Biology 2011 (April 6, 2011): 1–7. http://dx.doi.org/10.4061/2011/426179.
Повний текст джерелаАнотація:
Among the huge radiations of haplochromine cichlid fish in Lakes Malawi and Victoria, closely related species are often reproductively isolated via female mate choice although viable fertile hybrids can be produced when females are confined only with heterospecific males. We generated F2 hybrid males from a cross between a pair of closely related sympatric cichlid fish from Lake Malawi. Laboratory mate choice experiments using microsatellite paternity analysis demonstrated that F2 hybrid males differed significantly in their attractiveness to females of the two parental species, indicating heritable variation in traits involved in mate choice that may contribute to reproductive isolation between these species. We found no significant correlation between male mating success and any measurement of male colour pattern. A simple quantitative genetic model of reproductive isolation suggests that there may be as few as two chromosomal regions controlling species-specific attractiveness. We propose that adaptive radiation of Lake Malawi cichlids could be facilitated by the presence of genes with major effects on mate choice and reproductive isolation.
28
Giambastiani, Yamuna, Riccardo Giusti, Lorenzo Gardin, Stefano Cecchi, Maurizio Iannuccilli, Stefano Romanelli, Lorenzo Bottai, Alberto Ortolani, and Bernardo Gozzini. "Assessing Soil Erosion by Monitoring Hilly Lakes Silting." Sustainability 14, no. 9 (May 7, 2022): 5649. http://dx.doi.org/10.3390/su14095649.
Повний текст джерелаАнотація:
Soil erosion continues to be a threat to soil quality, impacting crop production and ecosystem services delivery. The quantitative assessment of soil erosion, both by water and by wind, is mostly carried out by modeling the phenomenon via remote sensing approaches. Several empirical and process-based physical models are used for erosion estimation worldwide, including USLE (or RUSLE), MMF, WEPP, PESERA, SWAT, etc. Furthermore, the amount of sediment produced by erosion phenomena is obtained by direct measurements carried out in experimental sites. Data collection for this purpose is very complex and expensive; in fact, we have few cases of measures distributed at the basin scale to monitor this phenomenon. In this work, we propose a methodology based on an expeditious way to monitor the volume of hilly lakes with GPS, sonar sensor and aquatic drone. The volume is obtained by means of an automatic GIS procedure based on the measurements of lake depth and surface area. Hilly lakes can be considered as sediment containers. Time-lapse measurements make it possible to estimate the silting rate of the lake. The volume of 12 hilly lakes in Tuscany was measured in 2010 and 2018, and the results in terms of silting rate were compared with the estimates of soil loss obtained by RUSLE and MMF. The analyses show that all the lakes measured are subject to silting phenomena. The sediment estimated by the measurements corresponds well to the amount of soil loss estimated with the models used. The relationships found are significant and promising for a distributed application of the methodology, which allows rapid estimation of erosion phenomena. Substantial differences in the proposed comparison (mainly found in two cases) can be justified by particular conditions found on site, which are difficult to predict from the models. The proposed approach allows for a monitoring of basin-scale erosion, which can be extended to larger domains which have hilly lakes, such as, for example, the Tuscany region, where there are more than 10,000 lakes.
29
Bryanskaya, Alla V., Aleksandra A. Shipova, Alexei S. Rozanov, Oxana A. Kolpakova, Elena V. Lazareva, Yulia E. Uvarova, Vadim M. Efimov, et al. "Diversity and Metabolism of Microbial Communities in a Hypersaline Lake along a Geochemical Gradient." Biology 11, no. 4 (April 15, 2022): 605. http://dx.doi.org/10.3390/biology11040605.
Повний текст джерелаАнотація:
In the south of western Siberia (Russia), there are many unique and unexplored soda, saline, and freshwater lakes. In this study, the results are presented on microbial diversity, its metabolic potential, and their relation with a set of geochemical parameters for a hypersaline lake ecosystem in the Novosibirsk region (Oblast). The metagenomic approach used in this work allowed us to determine the composition and structure of a floating microbial community, the upper layer of silt, and the strata of bottom sediments in a natural saline lake via two bioinformatic approaches, whose results are in good agreement with each other. In the floating microbial community and in the upper layers of the bottom sediment, bacteria of the Proteobacteria (Gammaproteobacteria), Cyanobacteria, and Bacteroidetes phyla were found to predominate. The lower layers were dominated by Proteobacteria (mainly Deltaproteobacteria), Gemmatimonadetes, Firmicutes, and Archaea. Metabolic pathways were reconstructed to investigate the metabolic potential of the microbial communities and other hypothetical roles of the microbial communities in the biogeochemical cycle. Relations between different taxa of microorganisms were identified, as was their potential role in biogeochemical transformations of C, N, and S in a comparative structural analysis that included various ecological niches.
30
Xin, Wang, Tang Can, Wang Wei, and Li Ji. "Change Detection of Water Resources via Remote Sensing: An L-V-NSCT Approach." Applied Sciences 9, no. 6 (March 22, 2019): 1223. http://dx.doi.org/10.3390/app9061223.
Повний текст джерелаАнотація:
Aiming at the change detection of water resources via remote sensing, the non-subsampling contour transformation method combining a log-vari model and the Stractural Similarity of Variogram (VSSIM) model, namely log-vari and VSSIM based non-subsampled contourlet transform (L-V-NSCT) approach, is proposed. Firstly, a differential image construction method based on non-subsampled contourlet transform (NSCT) texture analysis is designed to extract the low-frequency and high-frequency texture features of the objects in the images. Secondly, the texture features of rivers, lakes and other objects in the images are accurately classified. Finally, the change detection results of regions of interest are extracted and evaluated. In this experiment, the L-V-NSCT approach is compared with other methods with the results showing the effectiveness of this method. The change in Dongting Lake is also analyzed, which can be used as a reference for relevant administrative departments.
31
Box, Jason E., and Kathleen Ski. "Remote sounding of Greenland supraglacial melt lakes: implications for subglacial hydraulics." Journal of Glaciology 53, no. 181 (2007): 257–65. http://dx.doi.org/10.3189/172756507782202883.
Повний текст джерелаАнотація:
AbstractA supraglacial lake-depth retrieval function is developed, based on the correspondence between moderate-resolution imaging spectroradiometer (MODIS) reflectance and water depth measured during raft surveys. Individual lake depth, area and volume statistics, including short-term temporal changes for Greenland’s southwestern ablation region, were compiled for 2000–05. The maximum area of an individual lake was found to be 8.9 km2, the maximum volume 53.0 × 106 m3 and the maximum depth 12.2 m, sampling over 0.0625 km2 pixel areas. The total lake volume reaches >1 km3 in this region by July each year. The importance of melt lake reservoirs to Greenland ice-sheet flow may be a feedback between abrupt lake drainage events and ice dynamics. Lake-outburst volumes up to 31.5 × 106 m3 d−1 are capable of providing sufficient water via moulins to hydraulically pressurize the subglacial environment. Since the overburden pressure at the base of a flooded moulin is greater than that provided by ice, lake-outburst events seem capable of exerting sufficient upward force to lift the ice sheet locally, if water flow in the subglacial environment is constrained laterally. Considering a moulin with a 10 m2 cross-sectional area, basal pressurization can be maintained over lake-outburst episodes lasting hours to days.
32
Abubakar, Zakia, Fadhila Ali, Agnes Pinel, Oumar Traoré, Placide N'Guessan, Jean-Loup Notteghem, Frances Kimmins, Gnissa Konaté, and Denis Fargette. "Phylogeography of Rice yellow mottle virus in Africa." Journal of General Virology 84, no. 3 (March 1, 2003): 733–43. http://dx.doi.org/10.1099/vir.0.18759-0.
Повний текст джерелаАнотація:
The sequences of the coat protein gene of a representative sample of 40 isolates of Rice yellow mottle virus (RYMV) from 11 African countries were analysed. The overall level of nucleotide diversity was high ( ∼14 %). Great geographical distances between the sites where isolates were collected were consistently associated with high genetic distances. In contrast, a wide range of genetic distances occurred among isolates spread over short geographical distances. There was no evidence of long-range dispersal. RYMV diversity in relation to land area was eight times greater in East Africa than in West/Central Africa. West/Central African isolates with up to 9 % divergence belonged to a monophyletic group, whereas the East African isolates with up to 13 % divergence fell into distantly related groups. In East Africa, each Tanzanian strain had a specific and restricted geographical range, whereas West/Central African strains had large and partially overlapping geographical distributions. Overall, our results suggest an earlier RYMV diversification in East Africa and a later radiation in West/Central Africa. The West African situation was consistent with virus adaptation to savanna, forest and other ecological conditions. In contrast East Africa, as exemplified by the Tanzanian situation, with numerous physical barriers (mountain chains, sea channel, lakes), suggested that RYMV strains resulted from divergence under isolated conditions. For RYMV and for two other viruses, phylogenetic relationships were established between isolates from Madagascar and isolates from the Lake Victoria region.
33
Linke, Kristina, Irene Rückerl, Katharina Brugger, Renata Karpiskova, Julia Walland, Sonja Muri-Klinger, Alexander Tichy, Martin Wagner, and Beatrix Stessl. "Reservoirs of Listeria Species in Three Environmental Ecosystems." Applied and Environmental Microbiology 80, no. 18 (July 7, 2014): 5583–92. http://dx.doi.org/10.1128/aem.01018-14.
Повний текст джерелаАнотація:
ABSTRACTSoil and water are suggested to represent pivotal niches for the transmission ofListeria monocytogenesto plant material, animals, and the food chain. In the present study, 467 soil and 68 water samples were collected in 12 distinct geological and ecological sites in Austria from 2007 to 2009.Listeriawas present in 30% and 26% of the investigated soil and water samples, respectively. Generally, the most dominant species in soil and water samples wereListeria seeligeri,L. innocua, andL. ivanovii. The human- and animal-pathogenicL. monocytogeneswas isolated exclusively from 6% soil samples in regions A (mountainous region) and B (meadow). Distinct ecological preferences were observed forL. seeligeriandL. ivanovii, which were more often isolated from wildlife reserve region C (Lake Neusiedl) and from sites in proximity to wild and domestic ruminants (region A). The higherL. monocytogenesdetection and antibiotic resistance rates in regions A and B could be explained by the proximity to agricultural land and urban environment.L. monocytogenesmultilocus sequence typing corroborated this evidence since sequence type 37 (ST37), ST91, ST101, and ST517 were repeatedly isolated from regions A and B over several months. A higherL. monocytogenesdetection and strain variability was observed during flooding of the river Schwarza (region A) and Danube (region B) in September 2007, indicating dispersion via watercourses.
34
Slater, Greg F., Corey A. Goad, Matthew B. J. Lindsay, Kevin G. Mumford, Tara E. Colenbrander Nelson, Allyson L. Brady, Gerdhard L. Jessen, and Lesley A. Warren. "Isotopic and Chemical Assessment of the Dynamics of Methane Sources and Microbial Cycling during Early Development of an Oil Sands Pit Lake." Microorganisms 9, no. 12 (December 3, 2021): 2509. http://dx.doi.org/10.3390/microorganisms9122509.
Повний текст джерелаАнотація:
Water-capped tailings technology (WCTT) is a key component of the reclamation strategies in the Athabasca oil sands region (AOSR) of northeastern Alberta, Canada. The release of microbial methane from tailings emplaced within oil sands pit lakes, and its subsequent microbial oxidation, could inhibit the development of persistent oxygen concentrations within the water column, which are critical to the success of this reclamation approach. Here, we describe the results of a four-year (2015–2018) chemical and isotopic (δ13C) investigation into the dynamics of microbial methane cycling within Base Mine Lake (BML), the first full-scale pit lake commissioned in the AOSR. Overall, the water-column methane concentrations decreased over the course of the study, though this was dynamic both seasonally and annually. Phospholipid fatty acid (PLFA) distributions and δ13C demonstrated that dissolved methane, primarily input via fluid fine tailings (FFT) porewater advection, was oxidized by the water column microbial community at all sampling times. Modeling and under-ice observations indicated that the dissolution of methane from bubbles during ebullition, or when trapped beneath ice, was also an important source of dissolved methane. The addition of alum to BML in the fall of 2016 impacted the microbial cycling in BML, leading to decreased methane oxidation rates, the short-term dominance of a phototrophic community, and longer-term shifts in the microbial community metabolism. Overall, our results highlight a need to understand the dynamic nature of these microbial communities and the impact of perturbations on the associated biogeochemical cycling within oil sands pit lakes.
35
Prowse, Terry D., and Kirsten Brown. "Hydro-ecological effects of changing Arctic river and lake ice covers: a review." Hydrology Research 41, no. 6 (September 1, 2010): 454–61. http://dx.doi.org/10.2166/nh.2010.142.
Повний текст джерелаАнотація:
Freshwater ice is an integral part of the hydrologic regimes of cold environments. It controls the ecology of related aquatic systems and is important economically, through the facilitation of winter transport and via generation of extreme hydrologic events. Given projected changes in future climate, concern has been raised about related changes in freshwater ice. This paper reviews the status and trends in records of lake and river ice around the circumpolar North from traditional observations, remote sensing and paleo-sources. The temporal and spatial variability in trends are evaluated with relation to climatic conditions. Rapid changes experienced in freeze-up and break-up timing for high-latitude lakes, compared to those at more southerly locations, are particularly notable. Also considered are the nature and implications of changes in future freshwater-ice regimes that will have cascading effects on cold-region hydrology and a suite of hydro-ecological conditions including UV radiation receipts, habitat quality and availability, fisheries productivity and contaminant pathways. Overall, the duration and event timing of river and lake ice are proving to be useful indicators of climate change. Considering the scope and significance of ice-cover changes on northern hydro-ecology, a recommendation is made to place more emphasis on long-term and spatially diverse monitoring of freshwater ice.
36
Gao, Yanhong, Fei Chen, Gonzalo Miguez-Macho, and Xia Li. "Understanding precipitation recycling over the Tibetan Plateau using tracer analysis with WRF." Climate Dynamics 55, no. 9-10 (August 29, 2020): 2921–37. http://dx.doi.org/10.1007/s00382-020-05426-9.
Повний текст джерелаАнотація:
Abstract The precipitation recycling (PR) ratio is an important indicator that quantifies the land-atmosphere interaction strength in the Earth system’s water cycle. To better understand how the heterogeneous land surface in the Tibetan Plateau (TP) contributes to precipitation, we used the water-vapor tracer (WVT) method coupled with the Weather Research and Forecasting (WRF) regional climate model. The goals were to quantify the PR ratio, in terms of annual mean, seasonal variability and diurnal cycle, and to address the relationships of the PR ratio with lake treatments and precipitation amount. Simulations showed that the PR ratio increases from 0.1 in winter to 0.4 in summer when averaged over the TP with the maxima centered at the headwaters of three major rivers (Yangtze, Yellow and Mekong). For the central TP, the highest PR ratio rose to over 0.8 in August, indicating that most of the precipitation was recycled via local evapotranspiration in summer. The larger daily mean and standard deviation of the PR ratio in summer suggested a stronger effect of land-atmosphere interactions on precipitation in summer than in winter. Despite the relatively small spatial extent of inland lakes, the treatment of lakes in WRF significantly impacted the calculation of the PR ratio over the TP, and correcting lake temperature substantially improved both precipitation and PR ratio simulations. There was no clear relationship between PR ratio and precipitation amount; however, a significant positive correlation between PR and convective precipitation was revealed. This study is beneficial for the understanding of land-atmosphere interaction over high mountain regions.
37
Steinhilber, M., and D. A. Neely. "A New Record of Deepwater Sculpin, Myoxocephalus thompsonii, in Northeastern Alberta." Canadian Field-Naturalist 120, no. 4 (October 1, 2006): 480. http://dx.doi.org/10.22621/cfn.v120i4.361.
Повний текст джерелаАнотація:
We present the first documented records of Deepwater Sculpin, Myoxocephalus thompsonii, from northern Alberta, and the second record for the province. Three specimens of Deepwater Sculpin were taken in gill nets set at 17 to 20 m depth in Colin Lake, Alberta, on 15 September 2001. Colin Lake, located in the Canadian Shield region of northeastern Alberta about 125 km northeast of Fort Chipewyan, drains into Lake Athabasca via the Colin River. The only other known Alberta population of Deepwater Sculpin inhabits Upper Waterton Lake in the southwestern corner of the province. This record is approximately 300 km SSE of the nearest verified record in the Northwest Territories and 400 km NW of the nearest verified record in Saskatchewan.
38
Cook, Benjamin D., Mark Adams, Peter B. Mather, and Jane M. Hughes. "Statistical phylogeographic tests of competing 'Lake Carpentaria hypotheses' in the mouth-brooding freshwater fish, Glossamia aprion (Apogonidae)." Marine and Freshwater Research 63, no. 5 (2012): 450. http://dx.doi.org/10.1071/mf11222.
Повний текст джерелаАнотація:
Glacial cycles during the Pleistocene reduced sea levels and created new land connections in northern Australia, where many currently isolated rivers also became connected via an extensive paleo-lake system, ‘Lake Carpentaria’. However, the most recent period during which populations of freshwater species were connected by gene flow across Lake Carpentaria is debated: various ‘Lake Carpentaria hypotheses’ have been proposed. Here, we used a statistical phylogeographic approach to assess the timing of past population connectivity across the Carpentaria region in the obligate freshwater fish, Glossamia aprion. Results for this species indicate that the most recent period of genetic exchange across the Carpentaria region coincided with the mid- to late Pleistocene, a result shown previously for other freshwater and diadromous species. Based on these findings and published studies for various freshwater, diadromous and marine species, we propose a set of ‘Lake Carpentaria’ hypotheses to explain past population connectivity in aquatic species: (1) strictly freshwater species had widespread gene flow in the mid- to late Pleistocene before the last glacial maximum; (2) marine species were subdivided into eastern and western populations by land during Pleistocene glacial phases; and (3) past connectivity in diadromous species reflects the relative strength of their marine affinity.
39
Arciszewski, Tim J. "Exploring the Influence of Industrial and Climatic Variables on Communities of Benthic Macroinvertebrates Collected in Streams and Lakes in Canada’s Oil Sands Region." Environments 8, no. 11 (November 16, 2021): 123. http://dx.doi.org/10.3390/environments8110123.
Повний текст джерелаАнотація:
Identifying and tracking the influence of industrial activities on streams and lakes is a priority for monitoring in Canada’s oil sands region (OSR). While differences in indicators are often found in waterbodies adjacent to mining facilities, the confounding influence of natural exposures to bitumen and other stressors can affect the identification of industrial effects. However, recent work suggests metrics of industrial activity at individual facilities, including production and fuel consumption, may be used in site-specific analyses to identify influence of the industry as a whole as well as individual operations. This study further examined the potential relationships between industrial and climatic variables on benthic communities from 13 streams and 4 lakes using publicly available data from the minable region and the Elastic Net (EN) variable selection technique. From the full set of possible industrial and climate variables, the EN commonly identified the negative influence of plant and fuel use of petroleum coke at the Suncor Basemine on benthic communities in streams and lakes. The fuel/plant use of petroleum coke at Suncor likely reflects the emission and regional deposition of delayed coke fly ash. Among the other industrial variables, crude bitumen production at Syncrude Mildred Lake and other facilities, steam injection rates, and petroleum coke stockpiling were also selected for some benthic invertebrate indices at some sites. Land disturbance metrics were also occasionally selected, but the analyses largely support the predominant influence of industrial facilities via (inferred) atmospheric pathways. While climate variables were also commonly selected by EN and follow-up work is needed, this study suggests that integrating industrial performance data into analyses of biota using a site-specific approach may have broad applicability in environmental monitoring in the OSR. More specifically, the approach used here may both resolve the long-standing challenge of natural confounding influences on monitoring the status of streams in the OSR and track the influence of industrial activities in biota below critical effect sizes.
40
Blanchfield, P. J., E. B. Taylor, and D. A. Watkinson. "Morphological and genetic analyses identify a new record of a glacial relict: pygmy whitefish (Prosopium coulterii) from northwestern Ontario." Canadian Journal of Zoology 92, no. 3 (March 2014): 267–71. http://dx.doi.org/10.1139/cjz-2013-0252.
Повний текст джерелаАнотація:
The pygmy whitefish (Prosopium coulterii (Eigenmann and Eigenmann, 1892)) is a glacial relict species with a disjunct North American distribution that, apart from its most easterly known location in Lake Superior, is predominantly found in northern and western regions of Canada. Here we report on a new finding of pygmy whitefish from Winnange Lake in northwestern Ontario that extends the range of this species ∼320 km from its most easterly distribution in Lake Superior and almost 1500 km east of the closest previously known western localities. Genetic analyses confirmed that the fish from Winnange Lake were most closely related to the lineage that includes fish from Lake Superior and likely also originated via postglacial dispersal from a refugium in the upper Mississippi – Missouri river system.
41
Coman, Melissa Anne, and Mathew Graeme Wells. "An oscillating bottom boundary layer connects the littoral and pelagic regions of Lake Opeongo, Canada." Water Quality Research Journal 47, no. 3-4 (August 1, 2012): 215–26. http://dx.doi.org/10.2166/wqrjc.2012.039.
Повний текст джерелаАнотація:
The movement of a thermocline can drive strong benthic currents, which can transport nutrients from sediments into the water column via pore water advection or sediment resuspension. We report field observations of near-shore benthic velocities and offshore thermocline movements in Lake Opeongo; a medium-sized lake typical of the Canadian Shield. We find that during large thermocline deflections there are sustained currents >6 cm s−1 in the near-shore benthic layer. The mean current was 1.75 cm s−1 and the maximum current is 10.3 cm s−1. At our site, the net transport is offshore even though the thermocline oscillates up and down so that currents are sometimes upslope and inshore. We estimate the excursion length of a water parcel over the 31-day deployment period, and determine that the mean daily excursion length is 630 m, with the maximum value being 2 km offshore. Given that the south arm of Lake Opeongo is 6 km long and 0.6 km wide, the predicted excursion length of water implies that there is strong connectivity between the sediment in the littoral zone, and the metalimnetic waters offshore. As Lake Opeongo is oligotrophic, any nutrient pulses from the sediment will be quickly taken up by the plankton.
42
EDLUND, MARK B. "Minnesota diatomists: The first 150 years." Phytotaxa 127, no. 1 (August 29, 2013): 10. http://dx.doi.org/10.11646/phytotaxa.127.1.5.
Повний текст джерелаАнотація:
Minnesota boasts over 12,000 lakes, most of glacial origin, three major continental drainage systems (Mississippi River to the Gulf of Mexico, Lake Superior via the other Great Lakes to the Atlantic Ocean, and the Red River of the North via the Nelson River, to Hudson Bay), and a diversity of landforms comprising seven major ecological regions. Such landscape and aquatic variability hosts a high diversity of diatoms, which have been studied for over 150 years. Diatom communities range from saline and eutrophic in the southwest agricultural lands, to oligotrophic and endemic forms in the cold waters of Lake Superior. Early diatom collections were distributed to reknowned diatomists such as C.G. Ehrenberg and H.L. Smith. Other botanists and phycologists, including Tilden, Eddy, and Drouet, were active in Minnesota but only rarely included diatoms in their studies. Interest in Minnesota diatoms increased in the latter half of the 20th century with taxonomic and floristic surveys (e.g., Czarnecki, Koppen, and Kingston) and the inclusion of diatoms in applied research efforts that set the groundwork for understanding post-glacial ecology, effects of Euroamerican settlement, impacts of climate, and the effects of acid precipitation. Important to these latter developments were the efforts of Dr. Herb Wright Jr., who invited several European diatomists (e.g., Florin, Battarbee, and Haworth) to work on paleoecological projects in and near Minnesota. Although not a diatomist per se, Wright's subsequent efforts to promote diatom research included the appointment of Platt Bradbury as a research associate and later John Kingston, Dick Brugam, and Brian Cumming. Students Sheri Fritz, Kate Laird, and Virginia Card completed diatom research for their doctoral degrees. These workers and others have left a legacy that continues to fuel several active labs in Minnesota that have used diatoms to develop water quality standards, assess and restore impaired waters, and understand the impacts of climate, management, and landuse change across the state.
43
Anyah, Richard O., Fredrick H. M. Semazzi, and Lian Xie. "Simulated Physical Mechanisms Associated with Climate Variability over Lake Victoria Basin in East Africa." Monthly Weather Review 134, no. 12 (December 1, 2006): 3588–609. http://dx.doi.org/10.1175/mwr3266.1.
Повний текст джерелаАнотація:
Abstract A fully coupled regional climate, 3D lake modeling system is used to investigate the physical mechanisms associated with the multiscale variability of the Lake Victoria basin climate. To examine the relative influence of different processes on the lake basin climate, a suite of model experiments were performed by smoothing topography around the lake basin, altering lake surface characteristics, and reducing or increasing the amount of large-scale moisture advected into the lake region through the four lateral boundaries of the model domain. Simulated monthly mean rainfall over the basin is comparable to the satellite (Tropical Rainfall Measuring Mission) estimates. Peaks between midnight and early morning hours characterize the simulated diurnal variability of rainfall over the four quadrants of the lake, consistent with satellite estimates, although the simulated peaks occur a little earlier. It is evident in the simulations with smoothed topography that the upslope/downslope flow generated by the mountains east of the lake and the land–lake breeze circulations play important roles in influencing the intensity, the location of lake/land breeze fronts, and the horizontal extent of the land–lake breeze circulation, as well as lake basin precipitation. When the lake surface is replaced with marsh (water hyacinth), the late night and early morning rainfall maximum located over the western sector of the lake is dramatically reduced. Our simulations also indicate that large-scale moisture transported via the prevailing easterly trades enhances lake basin precipitation significantly. This is in contrast to the notion advanced in some of the previous studies that Lake Victoria generates its own climate (rainfall) through precipitation–evaporation–reprecipitation recycling only.
44
Crisp, J. "Introduction. The refugee crisis in the Great Lakes region of Africa." Refugee Survey Quarterly 17, no. 2 (July 1, 1998): vi—xii. http://dx.doi.org/10.1093/rsq/17.2.vi.
Повний текст джерела
45
Bratina, Bonnie Jo, Bradley S. Stevenson, William J. Green, and Thomas M. Schmidt. "Manganese Reduction by Microbes from Oxic Regions of the Lake Vanda (Antarctica) Water Column." Applied and Environmental Microbiology 64, no. 10 (October 1, 1998): 3791–97. http://dx.doi.org/10.1128/aem.64.10.3791-3797.1998.
Повний текст джерелаАнотація:
ABSTRACT Depth profiles of metals in Lake Vanda, a permanently ice-covered, stratified Antarctic lake, suggest the importance of particulate manganese oxides in the scavenging, transport, and release of metals. Since manganese oxides can be solubilized by manganese-reducing bacteria, microbially mediated manganese reduction was investigated in Lake Vanda. Microbes concentrated from oxic regions of the water column, encompassing a peak of soluble manganese [Mn(II)], reduced synthetic manganese oxides (MnO2) when incubated aerobically. Pure cultures of manganese-reducing bacteria were readily isolated from waters collected near the oxic Mn(II) peak. Based on phylogenetic analysis of the 16S rRNA gene sequence, most of the isolated manganese reducers belong to the genusCarnobacterium. Cultures of a phylogenetically representative strain of Carnobacterium reduced synthetic MnO2 in the presence of sodium azide, as was seen in field assays. Unlike anaerobes that utilize manganese oxides as terminal electron acceptors in respiration, isolates of the genusCarnobacterium reduced Mn(IV) via a diffusible compound under oxic conditions. The release of adsorbed trace metals accompanying the solubilization of manganese oxides may provide populations of Carnobacterium with a source of nutrients in this extremely oligotrophic environment.
46
Vanderzalm, J. L., D. W. Page, and P. J. Dillon. "Application of a risk management framework to a drinking water supply augmented by stormwater recharge." Water Science and Technology 63, no. 4 (February 1, 2011): 719–26. http://dx.doi.org/10.2166/wst.2011.294.
Повний текст джерелаАнотація:
The Blue Lake is an important water resource for the city of Mount Gambier and the surrounding region, primarily as the drinking water supply source, but also as a tourist attraction. Mount Gambier’s stormwater is discharged directly via drainage wells into the unconfined, karstic Gambier Limestone aquifer, which in turn provides the majority of recharge to Blue Lake. Discharge of urban runoff to the aquifer commenced in the 1800s as a means of stormwater management, but is now recognised as contributing to the drinking water supply in Blue Lake. Recently, guidelines for managing the risks associated with water recycling and augmenting drinking water supplies have been developed. This paper examines the organic chemical hazards associated with a stormwater to potable recycling scheme as an example of the current risk management framework.
47
Crisp, J. "Introduction. The refugee crisis in the Great Lakes region of Africa." Refugee Survey Quarterly 17, no. 2 (July 1, 1998): vi—a—xii. http://dx.doi.org/10.1093/rsq/17.2.vi-a.
Повний текст джерела
48
Allen Curry, R. "Late glacial impacts on dispersal and colonization of Atlantic Canada and Maine by freshwater fishes." Quaternary Research 67, no. 2 (March 2007): 225–33. http://dx.doi.org/10.1016/j.yqres.2006.11.002.
Повний текст джерелаАнотація:
AbstractLate glacial scenarios of ice retreat and biogeography databases constrain the dispersal routes of obligate freshwater fishes into Atlantic Canada and Maine. Evidence indicates glacial ice covered the present-day mainland and offshore islands at 18,000 14C yr before present. Possible refugia for extirpated freshwater fishes were the exposed outer edge of the Grand Banks (east), exposed Georges Bank (south-Atlantic Refugium), and the Mississippi Refugium in the west. It is improbable that the region was recolonized from the offshore refugia. Rather, fishes recolonized from the east via the upper St. Lawrence River valley into the upper Saint John River, Maine (Lake Madawaska) from 11,000 to 12,000 14C yr BP. The short period of entry resulted in the low diversity of obligate freshwater species in the region. Lake Madawaska was breached and dispersal continued into the remainder of the region after 8000 14C yr BP. By 6000 14C yr BP, access routes to the east along low-lying coastal zones were blocked by rising sea levels, which isolated Prince Edward Island, Cape Breton Island, and most probably Nova Scotia. Natural dispersal across the region appeared complete by this time.
49
Halberstadt, Anna Ruth W., Colin J. Gleason, Mahsa S. Moussavi, Allen Pope, Luke D. Trusel, and Robert M. DeConto. "Antarctic Supraglacial Lake Identification Using Landsat-8 Image Classification." Remote Sensing 12, no. 8 (April 22, 2020): 1327. http://dx.doi.org/10.3390/rs12081327.
Повний текст джерелаАнотація:
Surface meltwater generated on ice shelves fringing the Antarctic Ice Sheet can drive ice-shelf collapse, leading to ice sheet mass loss and contributing to global sea level rise. A quantitative assessment of supraglacial lake evolution is required to understand the influence of Antarctic surface meltwater on ice-sheet and ice-shelf stability. Cloud computing platforms have made the required remote sensing analysis computationally trivial, yet a careful evaluation of image processing techniques for pan-Antarctic lake mapping has yet to be performed. This work paves the way for automating lake identification at a continental scale throughout the satellite observational record via a thorough methodological analysis. We deploy a suite of different trained supervised classifiers to map and quantify supraglacial lake areas from multispectral Landsat-8 scenes, using training data generated via manual interpretation of the results from k-means clustering. Best results are obtained using training datasets that comprise spectrally diverse unsupervised clusters from multiple regions and that include rock and cloud shadow classes. We successfully apply our trained supervised classifiers across two ice shelves with different supraglacial lake characteristics above a threshold sun elevation of 20°, achieving classification accuracies of over 90% when compared to manually generated validation datasets. The application of our trained classifiers produces a seasonal pattern of lake evolution. Cloud shadowed areas hinder large-scale application of our classifiers, as in previous work. Our results show that caution is required before deploying ‘off the shelf’ algorithms for lake mapping in Antarctica, and suggest that careful scrutiny of training data and desired output classes is essential for accurate results. Our supervised classification technique provides an alternative and independent method of lake identification to inform the development of a continent-wide supraglacial lake mapping product.
50
Adams, Cynthia R., Vicki S. Blazer, Jim Sherry, Robert Scott Cornman, and Luke R. Iwanowicz. "Phylogeographic Genetic Diversity in the White Sucker Hepatitis B Virus across the Great Lakes Region and Alberta, Canada." Viruses 13, no. 2 (February 12, 2021): 285. http://dx.doi.org/10.3390/v13020285.
Повний текст джерелаАнотація:
Hepatitis B viruses belong to a family of circular, double-stranded DNA viruses that infect a range of organisms, with host responses that vary from mild infection to chronic infection and cancer. The white sucker hepatitis B virus (WSHBV) was first described in the white sucker (Catostomus commersonii), a freshwater teleost, and belongs to the genus Parahepadnavirus. At present, the host range of WSHBV and its impact on fish health are unknown, and neither genetic diversity nor association with fish health have been studied in any parahepadnavirus. Given the relevance of genomic diversity to disease outcome for the orthohepadnaviruses, we sought to characterize genomic variation in WSHBV and determine how it is structured among watersheds. We identified WSHBV-positive white sucker inhabiting tributaries of Lake Michigan, Lake Superior, Lake Erie (USA), and Lake Athabasca (Canada). Copy number in plasma and in liver tissue was estimated via qPCR. Templates from 27 virus-positive fish were amplified and sequenced using a primer-specific, circular long-range amplification method coupled with amplicon sequencing on the Illumina MiSeq. Phylogenetic analysis of the WSHBV genome identified phylogeographical clustering reminiscent of that observed with human hepatitis B virus genotypes. Notably, most non-synonymous substitutions were found to cluster in the pre-S/spacer overlap region, which is relevant for both viral entry and replication. The observed predominance of p1/s3 mutations in this region is indicative of adaptive change in the polymerase open reading frame (ORF), while, at the same time, the surface ORF is under purifying selection. Although the levels of variation we observed do not meet the criteria used to define sub/genotypes of human and avian hepadnaviruses, we identified geographically associated genome variation in the pre-S and spacer domain sufficient to define five WSHBV haplotypes. This study of WSHBV genetic diversity should facilitate the development of molecular markers for future identification of genotypes and provide evidence in future investigations of possible differential disease outcomes.