Intragenomic variation of rDNA internal transcribed spacers in the endemic Baikal sponge Lubomirskia baikalensis (Pallas, 1776) (Spongillida,Lubomirskiidae): Implications for Porifera barcoding

Baikal endemic sponges are a species group for which species identification is difficult and the taxonomy is insufficiently developed. The rDNA ITS (internal transcribed spacers) are practical molecular markers for sponges. However, intragenomic polymorphism of the ITS spacers has recently been detected in many organisms including marine and freshwater sponges. We for the first time demonstrate intragenomic polymorphism of the ITS region in the sponge family Lubomirskiidae. We identified 27 new ITS1 and ITS2 haplotypes. The level of intragenomic polymorphism of the ITS1 and ITS2 regions in Lubomirskia baikalensis was 0.1–2.0%, which overlaps with the intraspecific polymorphism of L. baikalensis and to the interspecific polymorphism within Lubomirskiidae. Thus, the detected level of intragenomic polymorphism of Lubomirskiidae suggests species identification of Baikal sponges using ITS sequences would be difficult. The reasons for the lack of concerted evolution of the ITS spacers in Lubomirskiidae may be hybridization or insufficient divergence time. Our work contributes to the development of sponge barcoding markers.     

The current problems of Lake Baikal ecosystem conservation

The greatest world reservoir of fresh water, the unique Lake Baikal, is at risk from anthropogenic influence. Three stages of economic activity in the lake region can be distinguished: (i) poor economic uses, (ii) increase of economic uses after the construction of the hydropower station dam on the outflow of the lake, and (iii) intensive increase of economic activity, characterized by the intensive use of mineral fertilizers, transportation, log rafting, growth of population around Baikal, mass development of tourism, the construction of the Baikal-Amur railroad and pulp combines. Chemical and biological pollution of the lake, fishing and hunting, the state of coasts and protected areas are discussed. The regions most affected are listed. The greater long-term influence is an increase in the mineralization of tributary waters due to forest cutting and land cultivation. Though the influence does not cause a decline in water quality, the properties of the Baikalian water in local sites of pollution can significantly differ from their initial state. The quality of water, however, is within the limits of requirements for fresh drinking water.     

Lake Baikal: Model for sustainable development of the territory

Created 20–30 million years ago, Lake Baikal is one of approximately 13 ancient lakes in the world. Lake Baikal is also the deepest lake in the world with 365 rivers flowing into it and holding a full 20% of the liquid fresh water on the surface of the Earth. The lake stretches from the south‐eastern section of Siberia to portions of northern Mongolia. Administratively, it is divided between three members of the Russian Federation: the Republic of Buryatia, Irkutsk Oblast and Chita Oblast. Lake Baikal and its catchment area are characterized by considerable biodiversity and by a vast richness of natural resources. Well over half of the 2615 plant and animal species found in the Baikal region are endemic. Lake Baikal’s unusual biota includes the Baikal seal (Phoca sibirica) which lives nowhere else on Earth and is separated by 3220 km from its nearest relative. These freshwater seals give birth to their young in snow dens on the lake’s ice. The Baikal region is a spectacular example of coexistence among different cultures and faiths over centuries. Over 1000 archaeological remains of past cultures have been found near Lake Baikal shores. Preserving the unique lake culture, values and ecological, ethnic and cultural traditions of the local people is one of the key elements in developing a model for sustainable development in the Baikal region. Lake Baikal is currently still considered clear and healthy overall, however the number and type of pollution sources are growing, and local pollution can be severe. The main sources of pollution in Lake Baikal are industrial wastes and atmospheric emissions from the Baikalsk pulp and paper mill, atmospheric emissions from nearby industrial facilities, excessive nutrient loads from farming and sediment and wastes that flow into Lake Baikal through the Selenga River. In May 1999, protection of Lake Baikal was codified in federal law for the first time. Progress is being made on a number of fronts despite the turbulent political transformations in Russia in the last 10 years. For instance, in the Irkutsk region, stakeholders have worked together to reduce the flow of unpurified drainage into the lake by 10 million m³ year^–1.     

Taxonomic diversity and metabolic activity of microbial communities in rivers and estuarine waters of Southern Baikal in summer

We analyzed the diversity of bacterial communities, metabolic activity, pH, and anthropogenic impact in the water of the estuaries and estuarine waters of the rivers in Southern Baikal in 2018 with different chemical composition. The chemical composition of waters and values of total microbial count (TMC), organotrophic bacteria (OB), and bacterial production (BP) depended on the geographical position, length of the rivers, and their water quality. In rivers with water acidification, we did not detect an effect of pH on TMC, abundance of OB, or total amount of mesophilic aerobic and facultative anaerobic microorganisms (PC). In rivers with a discharge of untreated domestic sewage, there was an increase in the content of dissolved organic carbon (DOC), concentration of nutrients, number of fecal and mesophilic bacteria, and high metabolic activity of microorganisms. The value of bacterioplankton production reached 0.26 to 12.41 per day^?1; TMC – 0.155 ± 0.002 to 3.474 ± 0.044 million cells/mL. Using the massive parallel sequencing of fragments encoding the V2–V3 region of the 16S rRNA gene, we studied the diversity of bacteria and estimated the influence of chemical composition on the diversity of communities. As in other freshwater ecosystems and the pelagic zone of Lake Baikal, the members of freshwater Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, and Verrucomicrobia predominated in the estuaries and estuarine waters of the rivers. The obtained data on the number and diversity of hygiene indicator bacteria suggested fecal pollution of the rivers of Southern Baikal.     

Fractioning of petroleum hydrocarbons from seeped oil as a factor of purity preservation of water in Lake Baikal (Russia)

Polycyclic aromatic hydrocarbons (PAHs) and n-alkanes were found in five different types of oil-containing samples emanating from deep oil seeps in Lake Baikal, the deepest and oldest lake in the world containing 20% of the world’s surface freshwater. The n-alkanes were the dominant component of the seeped oil on the water surface. PAHs were minor compounds of the oil, but this group is included in a priority series of organic contaminants that are subject to environmental regulation. The set of studied samples from the seep included: (i) freshly-emitted oil on the lake surface, (ii) oil at the lake bottom, (iii) samples of asphalt towers at the lake bottom, (iv) oil from voids within the sediment core and (v) samples of water from different depths. High variability in the concentrations of n-alkanes and PAHs suggested the presence of oil fractionation at the sediment-water interface. A light fraction of oil enriched by n-alkanes migrates to the surface of the lake’s water column, where n-alkanes are biodegraded by the Baikal microbial community while heavy oil fractions remain at the lake bottom and form asphalt towers in which PAHs with maximum toxicity accumulate. In the lake’s photic water layer, PAHs from light oil can be accumulated by phytoplankton. In the lake’s water column, benzo[a]pyrene was not detected over their detection limit (0.1 ng/L). The Toxic Equivalent (TEQ) value of PAHs identified in the Baikal water ranged from 0.001 to 0.012 ng/L.     

Estimates of the remineralization and burial of organic carbon in Lake Baikal sediments

Sediment cores collected from several stations throughout Lake Baikal in water depths from 100 m off the Selenga River delta to the deepest basin of the lake (~1640 m), have been analyzed for sedimentary organic carbon, nitrogen, and the remineralized components in pore water. The organic carbon content of surface sediments generally varied from 2.3 to 3.2% by weight, and profiles typically showed an exponential decrease in both organic carbon and nitrogen in the upper 20–30 cm of the sediment column. Steady state models of organic matter diagenesis yield first order decomposition rate constants which range from 0.0009 to 0.022 y⁻¹. The calculated residence times for the metabolizable fraction of the organic matter in these sediments increases roughly with increasing water depth and is on the order of 50–300 years. Pore water concentration profiles were determined for dissolved inorganic carbon, dissolved organic carbon (DOC), methane, and dissolved ammonium. At depth (25–30 cm) methane concentrations ranged from 50 to 800 μmol L_pw⁻¹ and DOC from 400 to 900 μmol L_pw⁻¹. Estimation of carbon recycling rates based upon diffusion along pore water concentration gradients at the sediment-water interface, indicate that combined DOC and methane fluxes generally contribute <15% of the overall turnover of sedimentary organic carbon. Comparisons to Laurentian Great Lakes environments show trends in sediment deposition, organic matter remineralization, and the time scales of carbon recycling across nearly two orders of magnitude with the fraction of organic content buried generally decreasing with decreasing sedimentation rates.     

Comparative analysis of free-living and particle-associated bacterial communities of Lake Baikal during the ice-covered period

Free-living (FLC) and particle-associated (PAC) bacterial communities contribute differentially to the cycling of matter in the environment. In this work we have for the first time studied the taxonomic composition and diversity of FLC and PAC in the oligotrophic freshwater Lake Baikal during the under-ice plankton peak. The communities on the bottom ice surface and in the water column under the ice were studied. Analysis by light microscopy showed that the bottom surface of the ice was dominated by green algae Chlorella spp. A complex of microalgae developed in the water column: green algae Monoraphidium griffithii, Monoraphidium contortum, Chlorella spp., chrysophyte Dinobryon cylindricum, haptophyte Chrysochromulina parva, and diatom Synedra acus. Algal abundance on the ice sub-surface was several orders of magnitude higher than that in the water column. According to pyrosequencing data of the bacterial 16S rRNA V3-V4 region, diversity of FLC (as measured by Shannon, Simpson, Chao1 and ACE indices) was higher than that of PAC. Proteobacteria (Burkholderiaceae) dominated the FLC associated with ice; FLC of the water column under ice were dominated by Actinobacteria (Sporichthyaceae and Ilumatobacteraceae) and Verrucomicrobia (Methylacidiphilaceae). PAC associated with ice were dominated by Bacteroidetes (Flavobacteriaceae), while water column-associated PAC were dominated by Verrucomicrobia (FukuN18_freshwater_group, Methylacidiphilaceae) and cyanobacteria (Cyanobiaceae). The difference between free-living and particle-associated, as well as between water column and ice sub-surface bacterial communities, were explored on operational taxonomic unit (OTU) and phylotype levels.     

Groundwater contamination by sewage causes benthic algal outbreaks in the littoral zone of Lake Baikal (East Siberia)

Lake Baikal, an ancient lake in Siberia, contains more endemic species than any other lake in the world with most of them residing in the benthic littoral zone. Explosive growth of benthic Spirogyra, a filamentous green alga, began approximately in 2011 in localized coastal areas, with the most severe examples occurring near coastal towns that lack a wastewater treatment facility or have a malfunctioning system. At other sites (small settlements, harbors), however, the cause of its excess growth is less obvious. Multiple hypotheses have been offered including lake level fluctuations, climate warming, a relaxation of grazing pressure, and coastal eutrophication. We assessed these hypotheses using data on historical lake levels, water temperature, the spatial-temporal distribution of Spirogyra along inhabited and non-inhabited shorelines, and measurements of fecal coliform bacteria and nutrients in ground water, interstitial water, and lake water. These data suggest that groundwater contamination is the primary cause of coastal eutrophication. Most houses and buildings in small settlements around Lake Baikal lack septic tanks but use unlined cesspools to collect human waste. This untreated human waste enters groundwater via passive filtration through permeable soils and flows to the coastal zone where it drives excess growth of Spirogyra. Remediation — including installation of septic systems, modernization of existing sewage treatment plants in coastal towns, and the adoption of non-phosphate containing detergents — as well as a reconsideration of the federal monitoring system regarding the coastal zone is urgently needed to protect this extraordinary lake.     

First insights into the diversity and ecology of non-biting midges (Diptera: Chironomidae) of the unique ancient Skadar Lake basin (Montenegro/Albania)

In the present study, based on faunistic information collected during 2014 and 2015, in association with physical–chemical conditions of the collection sites, the environmental factors influencing the composition and distribution of chironomid assemblages were investigated. In total, 164 Chironomidae taxa reported in this study extended the existing checklist with 152 taxa newly found in the Skadar Lake basin. The comparison based on the list of species from the six large, well-studied European lakes showed that Lake Constance (Switzerland/Germany/Austria) is the most species-rich waterbody with 174 taxa, followed by Lake Skadar with 164 taxa. For pupal exuviae, the most species-rich site was situated in the centre of the small lake (north-western part of the Skadar Lake). A Canonical Correspondence Analysis (CCA) revealed that shallow coastal parts of the lake are much richer in species than the open, deeper parts of the lake. This first investigation since 1979 of non-biting midge species (including imagines) diversity will help to monitor biodiversity of the basin and to understand how protection programs influence biodiversity within the lake basin.     

洞庭湖湿地生态保护现状及对策

洞庭湖湿地是国际重要湿地,具有调蓄长江洪水、维系水域生态平衡、保护珍稀候鸟、繁衍生物多样性等功能,是长江流域重要的经济区。详细介绍了近5年来洞庭湖湿地生态保护所取得的成绩,指出了存在的问题,提出了进一步做好生态保护工作的对策。     

First data on lipids and microorganisms of deepwater endemic sponge Baikalospongia intermedia and sediments from hydrothermal discharge area of the Frolikha Bay (North Baikal,Siberia)

In this report, we study lipid components (fatty acids with various degrees of unsaturation, aldehydes and sterols) of deep-water sponges Baikalospongia intermedia and sediments sampled using deep-water manned submersibles “Mir” at a hydrothermal vent of Frolikha Bay at depths of 400–450 m. It was found that unsaturated fatty acids predominate in the FA-composition of the sponges: very long chain demospongic acid 26:3, as well as monounsaturated 24:1 and isomers of acids 16:1 and 18:1. Among the saturated fatty acids in addition to the stearic 18:0, palmitic 16:0 and heptadecanoic 17:0 acids, significant amounts of acids of microbial origin (iso-palmitic i16:0, isostearic i18:0, oxy-stearic 10 h18) were detected. Using the method of mass spectrometry of microbial markers, we conclude, that the main microbial components of sponges B. intermedia and sediments from Frolikha Bay are methanotrophic microorganisms.     

Fall diet and bathymetric distribution of deepwater sculpin (Myoxocephalus thompsonii) in Lake Huron

Deepwater sculpin Myoxocephalus thompsonii are an important component of Great Lake's offshore benthic food webs. Recent declines in deepwater sculpin abundance and changes in bathymetric distribution may be associated with changes in the deepwater food web of Lake Huron, particularly, decreased abundance of benthic invertebrates such as Diporeia. To assess how deepwater sculpins have responded to recent changes, we examined a fifteen-year time series of spatial and temporal patterns in abundance as well as the diets of fish collected in bottom trawls during fall of 2003, 2004, and 2005. During 1992–2007, deepwater sculpin abundance declined on a lake-wide scale but the decline in abundance at shallower depths and in the southern portion of Lake Huron was more pronounced. Of the 534 fish examined for diet analysis, 97% had food in the stomach. Mysis, Diporeia, and Chironomidae were consumed frequently, while sphaerid clams, ostracods, fish eggs, and small fish were found in only low numbers. We found an inverse relationship between prevalence of Mysis and Diporeia in diets that reflected geographic and temporal trends in abundance of these invertebrates in Lake Huron. Because deepwater sculpins are an important trophic link in offshore benthic food webs, declines in population abundance and changes in distribution may cascade throughout the food web and impede fish community restoration goals.     

Bathymetric distribution of chironomid larvae (Diptera: Chironomidae) in Lake Saiko,Japan

The distribution of benthic macroinvertebrate on 8 March 2009 was studied in Lake Saiko (73.2 m maximum depth). The average density of the benthic community for the entire lake was 19 583 individuals m^?2, being comprised of oligochaetes and chironomid larvae, with densities of 18 163 (92.8%) and 1274 (6.5%), respectively. The average wet weights of oligochaetes and chironomid larvae were 15.96 and 1.67 g m^?2, respectively. The oligochaetes inhabited the entire lake bottom, with their densities being higher in the transitional region (20–40 m) and deeper region (>40 m) than in the shallower region. However, the densities of chironomid larvae were low in the deeper region (>40 m), with only a few chironomid larvae being found in the centre of the lake (>60 m). The most abundant species (Micropsectra chuzeprima) exhibited the widest distribution (from 10.1 to 65.5 m depth), followed by Polypedilum nubeculosum. The results of this study also were compared to previous data on oligochaetes and chironomid larvae reported by Kitagawa (1973) . The density of these animals increased throughout the whole lake in 2009. However, the chironomid species compositions did not changed. The larval distribution pattern of chironomid changed since Kitagawa’s study, being distributed from 11 to 68 m in 1973. In contrast, almost all chironomid larvae were found in the transitional (e.g. M. chuzeprima) and shallower (e.g. Procladius choreus and P. nubeculosum) regions in 2009, with only a few individuals being observed in the deeper regions (>60 m). In contrast, the oligochaete density increased in the deeper regions. Large environmental changes must have affected the oligochaetes and chironomids densities, especially in the deeper regions with low dissolved oxygen concentrations. Consequently, the distribution pattern of oligochaetes and chironomids in the lake has changed. These study findings suggest the lake is experiencing increasing eutrophication.     

Analysis of the correlations between environmental factors and rare cranes in the Poyang Lake region of China

Using survey data during 2001–2013 from a total of 38 lakes in the Poyang Lake region of China, we analyzed the inter-annual change in crane populations and the spatial distribution of crane species. Across the study sites, the total crane population was 6400 ± 2620 individuals during the period 2001–2013. Crane populations varied widely across the study sites: the largest crane population was observed on Bang Lake with an annual average of 2373, followed by Qi Lake, Dacha Lake, and Zhu Lake. The four main crane species, which were active on 50–80% of study lakes during the period of investigation, were G. leucogeranus, G. monacha, G. vipio, and G. grus. In particular, G. leucogeranus, G. monacha, and G. vipio were observed mainly in Poyang Lake National Nature Reserve and nearby lakes. G. grus was mostly observed in Poyang County. The largest populations of G. leucogeranus, G. vipio, and G. monacha were observed on Bang Lake, with annual averages of 1229, 985, and 88 birds, respectively. The largest G. grus population was observed on Qi Lake, with an annual average of 756 birds. We found that habitats for G. leucogeranus, G. monacha, and G. vipio were defined by similar environmental factors. In particular, increasing distance from roads had a positive impact on populations of these three species. By contrast, sedimentary total phosphorus content showed negative correlations with populations of all four main crane species, which implied that eutrophication could pose a threat to these rare crane species.     

Progress Toward the Rehabilitation of Lake Trout (Salvelinus namaycush) in South Bay,Lake Huron

Our objective was to evaluate the status of lake trout Salvelinus namaycush rehabilitation in South Bay, Lake Huron. Standardized surveys were conducted to quantify natural recruitment, annual mortality, and the contribution of wild-versus hatchery-origin lake trout. Some indicators suggest a high level of natural recruitment. The spawning population was comprised of multiple ages, and the mean age of spawners (8.4 years for females, 7.9 years for males) was at least 1 year older than the age at 50% maturity (5.8 years). Estimated annual total mortality rates (0.20–0.25) and sea-lamprey induced mortality rates (0.02) were less than maximum allowable values. The proportion of wild-origin fish captured was high among spawners but varied among sampling programs (42% in fall trap nets, 70% in fall gill nets, and 88% in summer gill nets). A strong year class (1997) could be tracked from 2001 to 2005. Few fish were captured from early (< 1996) or later (1999–2002) year classes. Possible explanations for low natural recruitment during these later years include declining spawning habitat quality caused by low water levels and/or invasion of non-native mussels (Dreissena spp.) and/or direct or indirect effects of alewife (Alosa pseudoharengus).     

Spatial genetic structure and recruitment dynamics of burbot (Lota lota) in Eastern Lake Michigan and Michigan tributaries

Burbot (Lota lota) are the only freshwater member of the Cod like (Lotidae) family that have a circumpolar distribution and occupy the widest geographic distribution of all Laurentian Great Lakes fish species. Information regarding burbot spatial genetic structure and recruitment dynamics is critical for the development of effective management strategies. Although burbot are a species of conservation concern throughout their range, little demographic or behavioral information exists. We estimated levels of genetic diversity within, and the degree of spatial population structure between samples collected from Lake Michigan and tributaries of the Manistee River, MI. Measures of genetic diversity across 10 microsatellite loci were moderately high. Disparities between adult groups sampled in Lake Michigan and the Manistee River were notable for observed heterozygosity (0.662 vs 0.488) and allelic richness (11.7 vs 6.6). Significant levels of inter-population variance in microsatellite allele frequencies (F_ST 0.154 to 0.208) were detected between Lake Michigan and the Manistee River samples. Results indicate reproductive isolation between what plausibly may be riverine and lacustrine spawning life history types. Pedigree analyses for three cohorts sampled in the Manistee River revealed that a sizeable number of adults contributed reproductively to multiple cohorts, indicating spawning philopatry. While data were collected from restricted areas in lacustrine and river habitats, analyses revealing microgeographic genetic structuring, potentially attributed to life history polymorphisms, have significant implications for burbot management in the Great Lakes.     

Spatial ecology of Bay of Quinte walleye (Sander vitreus): Annual timing,extent, and patterns of migrations in eastern Lake Ontario

Walleye (Sander vitreus) are the top nearshore predator in the Bay of Quinte and eastern Lake Ontario, where they have strong ecological and socio-economic impacts. The population is known to migrate seasonally; however, the precise timing and extent are not well defined. This study used acoustic telemetry to provide a fisheries-independent measure of timing, extent, and seasonal distribution of migration in Lake Ontario and to examine the influence of sex, spawning river, size, and year. Annual detection histories were used to determine the timing of migrations into and out of the spawning rivers, departure from the Bay of Quinte post-spawn, and the pre-spawn return to the Bay of Quinte. Sequence analysis was subsequently used to examine how fish occupy defined regions of eastern Lake Ontario annually and identify patterns in migration strategy. Spawning site fidelity was high for both rivers (91–97%) and annual residency within the Bay of Quinte was low (9.5%). Females spent less time in spawning rivers, migrated to the main lake earlier, and generally travelled further than males. Larger fish also migrated to the main lake first and travelled further, and differences in timing between spawning rivers were minor. Annual differences in timing were observed and were most likely related to environmental differences between years. Cluster analysis was used to identify groups of fish which utilized unique annual migration strategies and demonstrated sex and size had an important influence on the variability in annual spatial occupancy, but the importance of spawning river and year was minimal.     

Phylogenetic relationships and historical population reconstruction of Asian members of the genus Epischura (Copepoda,Calanoida)

We have reconstructed major demographic and phylogenetic events for two closely related copepod species: Epischura baikalensis Sars, 1900 (Copepoda, Calanoida), a key endemic species of the plankton community from Lake Baikal, and E. chankensis Rylov, 1928, a key zooplankton species from Lake Khanka. The reconstructions were based on the nucleotide sequences of mitochondrial DNA (mtDNA) cytochrome oxidase subunit 1 (CO1) using the BEAST software package and recently identified calibrations for the Baikal amphipods Gmelinoides fasciatus. The time span to a common ancestor for E. baikalensis and E. chankensis is 13.7 million years (95% confidence interval is 8.3–21.4 million years. Both species studied have experienced abrupt changes in the effective population size in the past. These changes are likely associated with climate and geological shifts in their habitat areas. For E. baikalensis, these changes can be associated with alternating glacier and interglacial periods as well as an increase in depth of Lake Baikal; for E. chankensis with formation and increase in the area of Lake Khanka, which was also due to climate and geological shifts in the Khanka basin.     

鄱阳湖入江水道总磷时空分布规律及采砂影响简析

为了探讨鄱阳湖入江水道的总磷时空分布规律,区分水文自然节律与采砂影响的主次关系,结合区间纳污情况,对老爷庙、星子及蛤蟆石断面的总磷监测数据进行了时空变化的数理统计分析.结果表明:由于入湖水量差异导致水体自净能力与纳污能力的变化,鄱阳湖入江水道主要断面的总磷指标存在"丰水期优于枯水期"的周期性波动规律;老爷庙-星子段总磷浓度总体呈现优化趋势;星子-蛤蟆石段则呈劣化趋势;鄱阳湖采砂相关作业对断面水质存在一定的影响,但其本质是底泥扰动带来的内源性污染迁移,其影响较入湖排污带来的外源性污染要小.研究结果有助于更加理性地分析采砂对水质的影响.     

Development of the Great Lakes Ice-circulation Model (GLIM): Application to Lake Erie in 2003–2004

To simulate ice and water circulation in Lake Erie over a yearly cycle, a Great Lakes Ice-circulation Model (GLIM) was developed by applying a Coupled Ice-Ocean Model (CIOM) with a 2-km resolution grid. The hourly surface wind stress and thermodynamic forcings for input into the GLIM are derived from meteorological measurements interpolated onto the 2-km model grids. The seasonal cycles for ice concentration, thickness, velocity, and other variables are well reproduced in the 2003/04 ice season. Satellite measurements of ice cover were used to validate GLIM with a mean bias deviation (MBD) of 7.4%. The seasonal cycle for lake surface temperature is well reproduced in comparison to the satellite measurements with a MBD of 1.5%. Additional sensitivity experiments further confirm the important impacts of ice cover on lake water temperature and water level variations. Furthermore, a period including an extreme cooling (due to a cold air outbreak) and an extreme warming event in February 2004 was examined to test GLIM's response to rapidly-changing synoptic forcing.