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Sample records for meromictic lake lake

  1. Bacterial Communities of Three Saline Meromictic Lakes in Central Asia

    PubMed Central

    Baatar, Bayanmunkh; Chiang, Pei-Wen; Rogozin, Denis Yu; Wu, Yu-Ting; Tseng, Ching-Hung; Yang, Cheng-Yu; Chiu, Hsiu-Hui; Oyuntsetseg, Bolormaa; Degermendzhy, Andrey G.; Tang, Sen-Lin

    2016-01-01

    Meromictic lakes located in landlocked steppes of central Asia (~2500 km inland) have unique geophysiochemical characteristics compared to other meromictic lakes. To characterize their bacteria and elucidate relationships between those bacteria and surrounding environments, water samples were collected from three saline meromictic lakes (Lakes Shira, Shunet and Oigon) in the border between Siberia and the West Mongolia, near the center of Asia. Based on in-depth tag pyrosequencing, bacterial communities were highly variable and dissimilar among lakes and between oxic and anoxic layers within individual lakes. Proteobacteria, Bacteroidetes, Cyanobacteria, Actinobacteria and Firmicutes were the most abundant phyla, whereas three genera of purple sulfur bacteria (a novel genus, Thiocapsa and Halochromatium) were predominant bacterial components in the anoxic layer of Lake Shira (~20.6% of relative abundance), Lake Shunet (~27.1%) and Lake Oigon (~9.25%), respectively. However, few known green sulfur bacteria were detected. Notably, 3.94% of all sequencing reads were classified into 19 candidate divisions, which was especially high (23.12%) in the anoxic layer of Lake Shunet. Furthermore, several hydro-parameters (temperature, pH, dissolved oxygen, H2S and salinity) were associated (P< 0.05) with variations in dominant bacterial groups. In conclusion, based on highly variable bacterial composition in water layers or lakes, we inferred that the meromictic ecosystem was characterized by high diversity and heterogenous niches. PMID:26934492

  2. Bacterial Communities of Three Saline Meromictic Lakes in Central Asia.

    PubMed

    Baatar, Bayanmunkh; Chiang, Pei-Wen; Rogozin, Denis Yu; Wu, Yu-Ting; Tseng, Ching-Hung; Yang, Cheng-Yu; Chiu, Hsiu-Hui; Oyuntsetseg, Bolormaa; Degermendzhy, Andrey G; Tang, Sen-Lin

    2016-01-01

    Meromictic lakes located in landlocked steppes of central Asia (~2500 km inland) have unique geophysiochemical characteristics compared to other meromictic lakes. To characterize their bacteria and elucidate relationships between those bacteria and surrounding environments, water samples were collected from three saline meromictic lakes (Lakes Shira, Shunet and Oigon) in the border between Siberia and the West Mongolia, near the center of Asia. Based on in-depth tag pyrosequencing, bacterial communities were highly variable and dissimilar among lakes and between oxic and anoxic layers within individual lakes. Proteobacteria, Bacteroidetes, Cyanobacteria, Actinobacteria and Firmicutes were the most abundant phyla, whereas three genera of purple sulfur bacteria (a novel genus, Thiocapsa and Halochromatium) were predominant bacterial components in the anoxic layer of Lake Shira (~20.6% of relative abundance), Lake Shunet (~27.1%) and Lake Oigon (~9.25%), respectively. However, few known green sulfur bacteria were detected. Notably, 3.94% of all sequencing reads were classified into 19 candidate divisions, which was especially high (23.12%) in the anoxic layer of Lake Shunet. Furthermore, several hydro-parameters (temperature, pH, dissolved oxygen, H2S and salinity) were associated (P< 0.05) with variations in dominant bacterial groups. In conclusion, based on highly variable bacterial composition in water layers or lakes, we inferred that the meromictic ecosystem was characterized by high diversity and heterogenous niches.

  3. An integrative study of a meromictic lake ecosystem in Antarctica

    PubMed Central

    Lauro, Federico M; DeMaere, Matthew Z; Yau, Sheree; Brown, Mark V; Ng, Charmaine; Wilkins, David; Raftery, Mark J; Gibson, John AE; Andrews-Pfannkoch, Cynthia; Lewis, Matthew; Hoffman, Jeffrey M; Thomas, Torsten; Cavicchioli, Ricardo

    2011-01-01

    In nature, the complexity and structure of microbial communities varies widely, ranging from a few species to thousands of species, and from highly structured to highly unstructured communities. Here, we describe the identity and functional capacity of microbial populations within distinct layers of a pristine, marine-derived, meromictic (stratified) lake (Ace Lake) in Antarctica. Nine million open reading frames were analyzed, representing microbial samples taken from six depths of the lake size fractionated on sequential 3.0, 0.8 and 0.1 μm filters, and including metaproteome data from matching 0.1 μm filters. We determine how the interactions of members of this highly structured and moderately complex community define the biogeochemical fluxes throughout the entire lake. Our view is that the health of this delicate ecosystem is dictated by the effects of the polar light cycle on the dominant role of green sulfur bacteria in primary production and nutrient cycling, and the influence of viruses/phage and phage resistance on the cooperation between members of the microbial community right throughout the lake. To test our assertions, and develop a framework applicable to other microbially driven ecosystems, we developed a mathematical model that describes how cooperation within a microbial system is impacted by periodic fluctuations in environmental parameters on key populations of microorganisms. Our study reveals a mutualistic structure within the microbial community throughout the lake that has arisen as the result of mechanistic interactions between the physico-chemical parameters and the selection of individual members of the community. By exhaustively describing and modelling interactions in Ace Lake, we have developed an approach that may be applicable to learning how environmental perturbations affect the microbial dynamics in more complex aquatic systems. PMID:21124488

  4. An integrative study of a meromictic lake ecosystem in Antarctica.

    PubMed

    Lauro, Federico M; DeMaere, Matthew Z; Yau, Sheree; Brown, Mark V; Ng, Charmaine; Wilkins, David; Raftery, Mark J; Gibson, John A E; Andrews-Pfannkoch, Cynthia; Lewis, Matthew; Hoffman, Jeffrey M; Thomas, Torsten; Cavicchioli, Ricardo

    2011-05-01

    In nature, the complexity and structure of microbial communities varies widely, ranging from a few species to thousands of species, and from highly structured to highly unstructured communities. Here, we describe the identity and functional capacity of microbial populations within distinct layers of a pristine, marine-derived, meromictic (stratified) lake (Ace Lake) in Antarctica. Nine million open reading frames were analyzed, representing microbial samples taken from six depths of the lake size fractionated on sequential 3.0, 0.8 and 0.1 μm filters, and including metaproteome data from matching 0.1 μm filters. We determine how the interactions of members of this highly structured and moderately complex community define the biogeochemical fluxes throughout the entire lake. Our view is that the health of this delicate ecosystem is dictated by the effects of the polar light cycle on the dominant role of green sulfur bacteria in primary production and nutrient cycling, and the influence of viruses/phage and phage resistance on the cooperation between members of the microbial community right throughout the lake. To test our assertions, and develop a framework applicable to other microbially driven ecosystems, we developed a mathematical model that describes how cooperation within a microbial system is impacted by periodic fluctuations in environmental parameters on key populations of microorganisms. Our study reveals a mutualistic structure within the microbial community throughout the lake that has arisen as the result of mechanistic interactions between the physico-chemical parameters and the selection of individual members of the community. By exhaustively describing and modelling interactions in Ace Lake, we have developed an approach that may be applicable to learning how environmental perturbations affect the microbial dynamics in more complex aquatic systems.

  5. Illuminating Microbial Dark Matter in Meromictic Sakinaw Lake

    PubMed Central

    Gies, Esther A.; Konwar, Kishori M.; Beatty, J. Thomas

    2014-01-01

    Despite recent advances in metagenomic and single-cell genomic sequencing to investigate uncultivated microbial diversity and metabolic potential, fundamental questions related to population structure, interactions, and biogeochemical roles of candidate divisions remain. Numerous molecular surveys suggest that stratified ecosystems manifesting anoxic, sulfidic, and/or methane-rich conditions are enriched in these enigmatic microbes. Here we describe diversity, abundance, and cooccurrence patterns of uncultivated microbial communities inhabiting the permanently stratified waters of meromictic Sakinaw Lake, British Columbia, Canada, using 454 sequencing of the small-subunit rRNA gene with three-domain resolution. Operational taxonomic units (OTUs) were affiliated with 64 phyla, including more than 25 candidate divisions. Pronounced trends in community structure were observed for all three domains with eukaryotic sequences vanishing almost completely below the mixolimnion, followed by a rapid and sustained increase in methanogen-affiliated (∼10%) and unassigned (∼60%) archaeal sequences as well as bacterial OTUs affiliated with Chloroflexi (∼22%) and candidate divisions (∼28%). Network analysis revealed highly correlated, depth-dependent cooccurrence patterns between Chloroflexi, candidate divisions WWE1, OP9/JS1, OP8, and OD1, methanogens, and unassigned archaeal OTUs indicating niche partitioning and putative syntrophic growth modes. Indeed, pathway reconstruction using recently published Sakinaw Lake single-cell genomes affiliated with OP9/JS1 and OP8 revealed complete coverage of the Wood-Ljungdahl pathway with potential to drive syntrophic acetate oxidation to hydrogen and carbon dioxide under methanogenic conditions. Taken together, these observations point to previously unrecognized syntrophic networks in meromictic lake ecosystems with the potential to inform design and operation of anaerobic methanogenic bioreactors. PMID:25172853

  6. Illuminating microbial dark matter in meromictic Sakinaw Lake.

    PubMed

    Gies, Esther A; Konwar, Kishori M; Beatty, J Thomas; Hallam, Steven J

    2014-11-01

    Despite recent advances in metagenomic and single-cell genomic sequencing to investigate uncultivated microbial diversity and metabolic potential, fundamental questions related to population structure, interactions, and biogeochemical roles of candidate divisions remain. Numerous molecular surveys suggest that stratified ecosystems manifesting anoxic, sulfidic, and/or methane-rich conditions are enriched in these enigmatic microbes. Here we describe diversity, abundance, and cooccurrence patterns of uncultivated microbial communities inhabiting the permanently stratified waters of meromictic Sakinaw Lake, British Columbia, Canada, using 454 sequencing of the small-subunit rRNA gene with three-domain resolution. Operational taxonomic units (OTUs) were affiliated with 64 phyla, including more than 25 candidate divisions. Pronounced trends in community structure were observed for all three domains with eukaryotic sequences vanishing almost completely below the mixolimnion, followed by a rapid and sustained increase in methanogen-affiliated (∼10%) and unassigned (∼60%) archaeal sequences as well as bacterial OTUs affiliated with Chloroflexi (∼22%) and candidate divisions (∼28%). Network analysis revealed highly correlated, depth-dependent cooccurrence patterns between Chloroflexi, candidate divisions WWE1, OP9/JS1, OP8, and OD1, methanogens, and unassigned archaeal OTUs indicating niche partitioning and putative syntrophic growth modes. Indeed, pathway reconstruction using recently published Sakinaw Lake single-cell genomes affiliated with OP9/JS1 and OP8 revealed complete coverage of the Wood-Ljungdahl pathway with potential to drive syntrophic acetate oxidation to hydrogen and carbon dioxide under methanogenic conditions. Taken together, these observations point to previously unrecognized syntrophic networks in meromictic lake ecosystems with the potential to inform design and operation of anaerobic methanogenic bioreactors. Copyright © 2014, American

  7. Sources of carbon and sulfur nutrition for consumers in three meromictic lakes of New York State

    NASA Technical Reports Server (NTRS)

    Fry, B.; Hayes, J. M. (Principal Investigator)

    1986-01-01

    The trophic importance of bacterioplankton as a source of carbon and sulfur nutrition for consumers in meromictic lakes was tested using stable carbon (delta 13C) and sulfur (delta 34S) isotopic measurements. Studies in three lakes near Syracuse, New York, showed that most consumers ultimately derive their C and S nutrition from a mixture of terrestrial detritus, phytoplankton, and littoral vegetation, rather than from bacterioplankton. Food webs in these meromictic lakes are thus similar to those in other lakes that lack dense populations of bacterioplankton.

  8. Groundwater flow patterns adjacent to a long-term stratified (meromictic) lake

    NASA Astrophysics Data System (ADS)

    Oz, I.; Shalev, E.; Gvirtzman, H.; Yechieli, Y.; Gavrieli, I.

    2011-08-01

    This paper examines, for the first time, the unique situation of a groundwater system adjacent to a long-term stratified (meromictic) lake. Using conceptual and numerical models, the configuration of groundwater interfaces between the three different water bodies (regional groundwater and upper and lower lake waters) and the flow patterns were quantitatively evaluated assuming a homogenous aquifer. A complex flow system, controlled by density difference, is created near the lake, where three circulation cells are developed. These results are different from the classic circulation cell that is found adjacent to nonstratified water bodies (lakes or oceans). Sensitivity analyses reveal that the results are sensitive to changes in thickness and density of the upper water mass of the lake. The Dead Sea, under its possible future meromictic conditions, serves as an ideal example of such a system. Thus, the model's results can be used as a preliminary assessment for groundwater behavior adjacent to the lake, if and when stratification will develop.

  9. Paleolimnology of Lake Tubutulik, an iron-meromictic Eocene Lake, eastern Seward Peninsula, Alaska

    USGS Publications Warehouse

    Dickinson, K.A.

    1988-01-01

    Sideritic lacustrine mudstone was found in drill core from a uranium deposit in the Death Valley area in the eastern part of the Seward Peninsula, Alaska. The precursor sediments for this rock were deposited in an unusual "iron-meromictic" Eocene lake, herein named Lake Tubutulik, which occupied part of the Boulder Creek basin, a structural graben that is probably a southern extension of the larger Death Valley basin. The Boulder Creek basin is bounded on the west by granite of the Late Cretaceous Darby Pluton, on the east by Precambrian to Paleozoic metasedimentary rocks. The lake basin was formed by basaltic flows that dammed the river valley of the ancestral Tubutulik River in early Eocene time. Lake Tubutulik contained a nearshore facies of fine-grained organic mud and an offshore facies of laminated sideritic mud. The offshore (profundal) laminated mudstone consists of alternating layers of authigenic siderite and detrital layers containing mostly quartz and clay minerals. Both lacustrine facies contain turbidities. The lacustrine sediments graded laterally into an onshore facies of colluvial and fluvial sandstone, paludal mudstone, and coal. The ancient lake apparently occupied a small deep basin in a tectonically active area of high relief. Meromixus was probably stabilized by reduced iron and bicarbonate dissolved in the monimolimnion. The intensity of meromixus decreased as the lake became shallower from sediment filling. The source of the iron, abundant in the monimolimnion of Lake Tubutulik, was probably the Eocene basalt. Based on carbon isotope analysis of the siderite, the dissolved bicarbonate in the profundal facies was largely inorganic. Sideritic carbon in one sample from the onshore paludal facies has an isotopic signature (??13C = +16.9) consistent with residual carbon formed during methanogenic fermentation. ?? 1988.

  10. Paleolimnology of Lake Tubutulik, an iron-meromictic Eocene Lake, eastern Seward Peninsula, Alaska

    NASA Astrophysics Data System (ADS)

    Dickinson, Kendell A.

    1988-01-01

    Sideritic lacustrine mudstone was found in drill core from a uranium deposit in the Death Valley area in the eastern part of the Seward Peninsula, Alaska. The precursor sediments for this rock were deposited in an unusual "iron-meromictic" Eocene lake, herein named Lake Tubutulik, which occupied part of the Boulder Creek basin, a structural graben that is probably a southern extension of the larger Death Valley basin. The Boulder Creek basin is bounded on the west by granite of the Late Cretaceous Darby Pluton, on the east by Precambrian to Paleozoic metasedimentary rocks. The lake basin was formed by basaltic flows that dammed the river valley of the ancestral Tubutulik River in early Eocene time. Lake Tubutulik contained a nearshore facies of fine-grained organic mud and an offshore facies of laminated sideritic mud. The offshore (profundal) laminated mudstone consists of alternating layers of authigenic siderite and detrital layers containing mostly quartz and clay minerals. Both lacustrine facies contain turbidities. The lacustrine sediments graded laterally into an onshore facies of colluvial and fluvial sandstone, paludal mudstone, and coal. The ancient lake apparently occupied a small deep basin in a tectonically active area of high relief. Meromixus was probably stabilized by reduced iron and bicarbonate dissolved in the monimolimnion. The intensity of meromixus decreased as the lake became shallower from sediment filling. The source of the iron, abundant in the monimolimnion of Lake Tubutulik, was probably the Eocene basalt. Based on carbon isotope analysis of the siderite, the dissolved bicarbonate in the profundal facies was largely inorganic. Sideritic carbon in one sample from the onshore paludal facies has an isotopic signature ( δ13C = +16.9) consistent with residual carbon formed during methanogenic fermentation.

  11. Estimation of lake water - groundwater interactions in meromictic mining lakes by modelling isotope signatures of lake water.

    PubMed

    Seebach, Anne; Dietz, Severine; Lessmann, Dieter; Knoeller, Kay

    2008-03-01

    A method is presented to assess lake water-groundwater interactions by modelling isotope signatures of lake water using meteorological parameters and field data. The modelling of delta(18)O and deltaD variations offers information about the groundwater influx into a meromictic Lusatian mining lake. Therefore, a water balance model is combined with an isotope water balance model to estimate analogies between simulated and measured isotope signatures within the lake water body. The model is operated with different evaporation rates to predict delta(18)O and deltaD values in a lake that is only controlled by weather conditions with neither groundwater inflow nor outflow. Comparisons between modelled and measured isotope values show whether the lake is fed by the groundwater or not. Furthermore, our investigations show that an adaptation of the Craig and Gordon model [H. Craig, L.I. Gordon. Deuterium and oxygen-18 variations in the ocean and the marine atmosphere. In Stable Isotopes in Oceanographic Studies and Paleotemperature, Spoleto, E. Tongiorgi (Ed.), pp. 9-130, Consiglio Nazionale delle Ricerche, Laboratorio di Geologia Nucleare, Pisa (1965).] to specific conditions in temperate regions seems necessary.

  12. Diversity, distribution and physiology of the aerobic phototrophic bacteria in the mixolimnion of a meromictic lake.

    PubMed

    Yurkova, Natalia; Rathgeber, Christopher; Swiderski, Jolantha; Stackebrandt, Erko; Beatty, J Thomas; Hall, Ken J; Yurkov, Vladimir

    2002-06-01

    The population of anoxygenic phototrophic bacteria in the aerobic zone of the meromictic Mahoney Lake was investigated using classical microbiological methods. This bacterial community was found to be very rich and diverse. Thirty-one new strains of the obligately aerobic phototrophic bacteria, and two new purple nonsulfur strains, were isolated in pure cultures and preliminarily characterized. The isolates contain a variety of carotenoids, bacteriochlorophyll a incorporated into pigment protein complexes, and are morphologically and physiologically diverse. These properties indicate a diversity of adaptations to the stratified environments of this meromictic lake. Phylogenetically all isolated strains belong to the alpha subclass of Proteobacteria.

  13. Microbial community diversity, structure and assembly across oxygen gradients in meromictic marine lakes, Palau.

    PubMed

    Meyerhof, Matthew S; Wilson, Jesse M; Dawson, Michael N; Michael Beman, J

    2016-12-01

    Microbial communities consume oxygen, alter biogeochemistry and compress habitat in aquatic ecosystems, yet our understanding of these microbial-biogeochemical-ecological interactions is limited by a lack of systematic analyses of low-oxygen ecosystems. Marine lakes provide an ideal comparative system, as they range from well-mixed holomictic lakes to stratified, anoxic, meromictic lakes that vary in their vertical extent of anoxia. We examined microbial communities inhabiting six marine lakes and one ocean site using pyrosequencing of 16S rRNA genes. Microbial richness and evenness was typically highest in the anoxic monimolimnion of meromictic lakes, with common marine bacteria present in mixolimnion communities replaced by anoxygenic phototrophs, sulfate-reducing bacteria and SAR406 in the monimolimnion. These sharp changes in community structure were linked to environmental gradients (constrained variation in redundancy analysis = 68%-76%) - particularly oxygen and pH. However, in those lakes with the steepest oxygen gradients, salinity and dissolved nutrients were important secondary constraining variables, indicating that subtle but substantive differences in microbial communities occur within similar low-oxygen habitats. Deterministic processes were a dominant influence on whole community assembly (all nearest taxon index values >4), demonstrating that the strong environmental gradients present in meromictic marine lakes drive microbial community assembly. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  14. Anaerobic Oxidation of Methane in a French meromictic lake (Lake Pavin): Who is responsible?

    NASA Astrophysics Data System (ADS)

    Grossi, V.; Attard, E.; Birgel, D.; Schaeffer, P.; Jézéquel, D.; Lehours, A.

    2012-12-01

    Methane is an important greenhouse gas and its biogeochemical cycle is of primary significance to the global carbon cycle. The Anaerobic Oxidation of Methane (AOM) has been estimated to be responsible for >90% of methane consumption. This biogeochemical process has been increasingly documented during the last two decades but the underlying microbial processes and their key agents remain incompletely understood. Freshwater lakes account for 2-10% of the total emissions of methane and are therefore an important part of the global methane cycle. Lake Pavin is a French meromictic crater lake with unusual hydrological characteristics: its morphology (depth >92m, mean diameter 750m) induce that waters below 60m are never mixed with overlying waters and remain permanently anoxic. The deep anoxic waters of Lake Pavin contain high concentrations (i.e. 4 mM) of methane but, contrary to other aquatic systems, almost no methane escapes from the lake. Previous biogeochemical and modeling studies suggest that methane is preferentially consumed within the oxic-anoxic transition zone (ca. 55-60 m depth) but that ca. 30% of methane oxidation occurs in the anoxic part of the lake. Phylogenetic (16S rRNA) analyses showed that ANME generally involved in AOM (ANME-1, -2 and -3) are not present in Lake Pavin. Other archaeal groups that do not have any cultured representatives so far appear well represented in the anoxic parts of the lake but their implication in AOM is not demonstrated. The analysis of lipid biomarkers using GC-MS and LC-MS revealed the presence of a low diversity of archaeal-specific biomarkers in the superficial sediments and in the anoxic waters of the lake. Archaeol and caldarcheaol (GDGT-0) are the two main archaeal core lipids detected; other biomarkers generally present in ANME such as pentamethylicosane or hydroxyarchaeol are not present. However, the stable carbon isotopic composition of archaeol (δ13C = -18‰) and of the biphytane chain of GDGT-0 (δ13C

  15. Sulfur-oxidizing bacteria in Soap Lake (Washington State), a meromictic, haloalkaline lake with an unprecedented high sulfide content.

    PubMed

    Sorokin, Dimitry Y; Foti, Mirjam; Pinkart, Holly C; Muyzer, Gerard

    2007-01-01

    Culture-dependent and -independent techniques were used to study the diversity of chemolithoautotrophic sulfur-oxidizing bacteria in Soap Lake (Washington State), a meromictic, haloalkaline lake containing an unprecedentedly high sulfide concentration in the anoxic monimolimnion. Both approaches revealed the dominance of bacteria belonging to the genus Thioalkalimicrobium, which are common inhabitants of soda lakes. A dense population of Thioalkalimicrobium (up to 10(7) cells/ml) was found at the chemocline, which is characterized by a steep oxygen-sulfide gradient. Twelve Thioalkalimicrobium strains exhibiting three different phenotypes were isolated in pure culture from various locations in Soap Lake. The isolates fell into two groups according to 16S rRNA gene sequence analysis. One of the groups was closely related to T. cyclicum, which was isolated from Mono Lake (California), a transiently meromictic, haloalkaline lake. The second group, consisting of four isolates, was phylogenetically and phenotypically distinct from known Thioalkalimicrobium species and unique to Soap Lake. It represented a new species, for which we suggest the name Thioalkalimicrobium microaerophilum sp. nov.

  16. Sulfur-Oxidizing Bacteria in Soap Lake (Washington State), a Meromictic, Haloalkaline Lake with an Unprecedented High Sulfide Content▿

    PubMed Central

    Sorokin, Dimitry Y.; Foti, Mirjam; Pinkart, Holly C.; Muyzer, Gerard

    2007-01-01

    Culture-dependent and -independent techniques were used to study the diversity of chemolithoautotrophic sulfur-oxidizing bacteria in Soap Lake (Washington State), a meromictic, haloalkaline lake containing an unprecedentedly high sulfide concentration in the anoxic monimolimnion. Both approaches revealed the dominance of bacteria belonging to the genus Thioalkalimicrobium, which are common inhabitants of soda lakes. A dense population of Thioalkalimicrobium (up to 107 cells/ml) was found at the chemocline, which is characterized by a steep oxygen-sulfide gradient. Twelve Thioalkalimicrobium strains exhibiting three different phenotypes were isolated in pure culture from various locations in Soap Lake. The isolates fell into two groups according to 16S rRNA gene sequence analysis. One of the groups was closely related to T. cyclicum, which was isolated from Mono Lake (California), a transiently meromictic, haloalkaline lake. The second group, consisting of four isolates, was phylogenetically and phenotypically distinct from known Thioalkalimicrobium species and unique to Soap Lake. It represented a new species, for which we suggest the name Thioalkalimicrobium microaerophilum sp. nov. PMID:17114324

  17. Protistan diversity in a permanently stratified meromictic lake (Lake Alatsee, SW Germany).

    PubMed

    Oikonomou, Andreas; Filker, Sabine; Breiner, Hans-Werner; Stoeck, Thorsten

    2015-06-01

    Protists play a crucial role for ecosystem function(ing) and oxygen is one of the strongest barriers against their local dispersal. However, protistan diversity in freshwater habitats with oxygen gradients received very little attention. We applied high-throughput sequencing of the V9 region (18S rRNA gene) to provide a hitherto unique spatiotemporal analysis of protistan diversity along the oxygen gradient of a freshwater meromictic lake (Lake Alatsee, SW Germany). In the mixolimnion, the communities experienced most seasonal structural changes, with Stramenopiles dominating in autumn and Dinoflagellata in summer. The suboxic interface supported the highest diversity, but only 23 OTUs95% (mainly Euglenozoa, after quality check and removal of operational taxonomic units (OTUs) with less than three sequences) were exclusively associated with this habitat. Eukaryotic communities in the anoxic monimolimnion showed the most stable seasonal pattern, with Chrysophyta and Bicosoecida being the dominant taxa. Our data pinpoint to the ecological role of the interface as a short-term 'meeting point' for protists, contributing to the coupling of the mixolimnion and the monimolimnion. Our analyses of divergent genetic diversity suggest a high degree of previously undescribed OTUs. Future research will have to reveal if this result actually points to a high number of undescribed species in such freshwater habitats. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  18. Molecular organic tracers of biogeochemical processes in a saline meromictic lake (Ace Lake)

    NASA Astrophysics Data System (ADS)

    Schouten, S.; Rijpstra, W. I. C.; Kok, M.; Hopmans, E. C.; Summons, R. E.; Volkman, J. K.; Sinninghe Damsté, J. S.

    2001-05-01

    The chemical structures, distribution and stable carbon isotopic compositions of lipids in a sediment core taken in meromictic Ace Lake (Antarctica) were analyzed to trace past biogeochemical cycling. Biomarkers from methanogenic archaea, methanotrophic bacteria and photosynthetic green sulfur bacteria were unambiguously assigned using organic geochemical understanding and by reference to what is known about the lake's present-day ecosystem. For instance, saturated and unsaturated 2,6,10,15,19-pentamethylicosane, archaeol and sn2-hydroxyarchaeol were derived from methanogenic archaea. Carotenoid analysis revealed chlorobactene and isorenieratene derived from the green-colored and brown-colored strains of the green sulfur bacteria (Chlorobiaceae); isotopic analyses showed that they were 13C-enriched. Phytenes appear to be derived from photoautotrophs that use the Calvin-Benson cycle, while phytane has a different source, possibly within the archaea. The most 13C-depleted compounds (ca. -55‰) identified were 4-methyl-5α-cholest-8(14)-en-3β-ol, identified using an authentic standard, and co-occurring 4-methylsteradienes: these originate from the aerobic methanotrophic bacterium Methylosphaera hansonii. Lipids of photoautotrophic origin, steranes and alkenones, are relatively depleted (ca. -28 to -36‰) whilst archaeal biomarkers are relatively enriched in 13C (ca. -17 to -25‰). The structural and carbon isotope details of sedimentary lipids thus revealed aspects of in situ biogeochemical processes such as methane generation and oxidation and phototrophic sulfide oxidation.

  19. [Anoxygenic phototrophic bacteria of the high-altitude meromictic Lake Gek-Gel, Azerbaijan].

    PubMed

    Lunina, O N; Kevbrina, M V; Akimov, V N; Pimenov, N V

    2008-01-01

    The anoxygenic phototrophic bacterial community of the high-altitude meromictic Lake Gek-Gel (Azerbaijan) was investigated in September 2003. The highest concentration of bacteriochlorophyll e (48 microg/l) was detected at a depth of 30 m; the peak of bacteriochlorophyll a (4.5 microg/l) occurred at 29 m. Phylogenetic analysis revealed that brown-colored green sulfur bacteria Chlorobium phaeobacteroides predominated in the lake. Nonsulfur purple bacteria phylogenetically close to Blastochloris sulfoviridis were found in insignificant amounts; these organisms have not been previously reported in Lake Gek-Gel.

  20. The sulfur cycle in a permanently meromictic haloalkaline lake

    NASA Astrophysics Data System (ADS)

    Pinkart, Holly C.; Simonsen, Brita; Peyton, Brent; Mormile, Melanie

    2006-08-01

    Soap Lake is a haloalkaline lake located in central Washington. This lake is a remnant of the Missoula flood events that created the landscape of western Montana, the southeastern portion of Washington state, and much of Oregon. It is 15,000 - 20,000 years old, and has maintained a stable meromixis for the last 10,000 years. This carbonate lake is characterized by a brackish mixolimnion, and a monimolimnion with a salinity of ~14%. The pH of both layers of the lake is approximately 10. Both layers also have a high concentration of dissolved sulfate, with the mineral mirabilite (Na IISO 4•10H IIO) found in the monimolimnion sediments. Sulfide concentrations in the monimolimnion exceed 100 mM. As part of the mission of the NSF Soap Lake Microbial Observatory, microorganisms involved in the sulfur cycle in this lake were studied in terms of their diversity and function. High rates of sulfate reduction were measured in both layers of the lake, with new species of sulfate-reducing bacteria seen in both areas. A particularly novel psychrophilic sulfur oxidizer was isolated from the monimolimnion. This organism has the ability to induce the formation of mirabilite, which was assumed to be an abiotically deposited evaporite mineral. This is the first evidence for a biogenic origin of this mineral. This leads to the possibility that related sulfate minerals, such as those reported on the Mars surface, may have a biogenic origin.

  1. Hydrogeochemistry of Big Soda Lake, Nevada: An alkaline meromictic desert lake

    USGS Publications Warehouse

    Kharaka, Y.K.; Robinson, S.W.; Law, L.M.; Carothers, W.W.

    1984-01-01

    Big Soda Lake, located near Fallon, Nevada, occupies an explosion crater rimmed by basaltic debris; volcanic activity apparently ceased within the last 10,000 years. This lake has been selected for a detailed multidisciplinary study that will ultimately cover the organic and inorganic hydrogeochemistry of water and sediments because the time at which chemical stratification was initiated is known (~1920) and chemical analyses are available for a period of more than 100 years. Detailed chemical analyses of the waters show that the lake is at present alkaline (pH = 9.7), chemically stratified (meromictic) and is extremely anoxic (total reduced sulfur-410 mg/L as H2S) below a depth of about 35 m. The average concentrations (in mg/L) of Na, K, Mg, Ca, NH3, H2S, alkalinity (as HCO3), Cl, SO4, and dissolved organics (as C) in waters of the upper layer (depth 0 to 32 m) are 8,100, 320, 150, 5.0, < 0.1, < 0.5, 4,100, 7,100, 5,800, and 20 respectively; in the deeper layer (depth 37 to 64 m) they are 27,000, 1,200, 5.6, 0.8, 45, 410, 24,000, 27,500, 6,800, and 60, respectively. Chemical and stable isotope analyses of the waters, ??13C and ??14C values of dissolved total carbonate from this lake and surface and ground waters in the area together with mineral-water equilibrium computations indicate that the waters in the lake are primarily meteoric in origin with the present chemical composition resulting from the following geochemical processes: 1. (1) evaporation and exchange with atmosphere, the dominant processes, 2. (2) mineral-water interactions, including dissolution, precipitation and ion exchange, 3. (3) inflow and outflow of ground water and 4. (4) biological activity of macro- and microorganisms, including sulfate reduction in the water column of the deeper layer at a very high rate of 6.6 ??mol L-1 day-1. ?? 1984.

  2. Distribution and diversity of microbial communities in meromictic soda Lake Doroninskoe (Transbaikalia, Russia) during winter

    NASA Astrophysics Data System (ADS)

    Matyugina, Evgeniya; Belkova, Natalia

    2015-11-01

    Meromictic soda and saline lakes are unique ecosystems characterized by the stability of physical, chemical and biological parameters, and they are distributed all over the world. Lakes located in regions with average annual negative air temperature are of particular interest because of the presence of two periods with intensive and dynamic processes: the so-called biological summer and the long ice season with the biological spring. Soda Lake Doroninskoe is located in Eastern Transbaikalia (51°14'N, 112°14'E) in the permafrost zone in an extreme continental climate, and is covered by ice for seven months per year. The structure and diversity of the microbial communities throughout the water column of the lake was studied by 16S rRNA gene amplicon metasequencing. Different species with specific functions were found to dominate at different depths. Metabolically flexible bacteria with a capacity to switch between anoxygenic photosynthesis and aerobic chemotrophic metabolism dominate in soda Lake Doroninskoe.

  3. A combined heat and water budget approach to quantify the groundwater inflow to a meromictic lake

    NASA Astrophysics Data System (ADS)

    Kettle, A.; Back, R.

    2012-04-01

    Groundwater exchange may have an important role in the mixing dynamics of certain lakes, in addition to the recognized effect of seasonally varying surface heat fluxes. However, the heat and mass fluxes associated with groundwater input to a lake are often difficult to measure and are poorly constrained. Permanent bottom anoxia in meromictic lakes is sometimes associated with significant inputs of surface water, which create a permanent upwelling system for phytoplankton blooms. In this contribution, we report the results of a 17 month experimental investigation of the heat and water budget of a meromictic lake in upstate New York. Fayetteville Green Lake is a good model system to conduct a combined heat and water budget analysis, with one outflow stream and a single inflow stream. The lake is contained in a relatively deep (~50m) flat-bottomed basin with a groundwater injection depth at ~20m at the base of the mixolimnion. The heat budget was formulated from data from regional meteorological stations and a vertical array of temperature sensors on a subsurface mooring. The mass budget was created from continuous measurements of lake stage and precipitation data. The results highlight that groundwater input has an important effect on the overall heat budget of the lake, with a critical role on the timing of the overturning of the mixolimnion in the spring and late autumn. Although lake heat budget studies have formerly been conducted to constrain the poorly-constrained evaporative term (latent heat) in the heat budget, our results suggest that groundwater exchange may dominate the surface latent heat flux of certain lakes.

  4. A combined heat and water budget approach to quantify the groundwater inflow to a meromictic lake

    NASA Astrophysics Data System (ADS)

    Kettle, Anthony; Back, Richard

    2013-04-01

    Groundwater exchange may have an important role in the mixing dynamics of certain lakes, and this may be comparable with near-surface mixing due to conventionally-defined surface radiation and turbulent heat fluxes. However, the heat and mass fluxes associated with groundwater input to a lake are often difficult to measure and are poorly constrained. Permanent bottom anoxia in meromictic lakes is sometimes associated with significant inputs of subsurface water, which creates a permanent upwelling system for phytoplankton blooms. This contribution presents the results of a 17 month experimental investigation of the heat and water budget of a meromictic lake in upstate New York. Fayetteville Green Lake is a good model system to conduct a combined heat and water budget analysis. It is a comparatively simple mass exchange system with one outflow stream and one significant inflow stream in addition to an important subsurface groundwater source. The lake is contained in a relatively deep (~50m) flat-bottomed basin with a groundwater injection depth at ~20m at the base of the mixolimnion. The heat budget was formulated from data from regional meteorological stations and a vertical array of temperature sensors on a subsurface mooring. The mass budget was created from continuous measurements of lake stage and precipitation data. The results highlight that groundwater input has an important effect on the overall heat budget of the lake, with an important role on the timing of the overturning of the mixolimnion in the spring and late autumn. Although lake heat budget studies have formerly been conducted to constrain the poorly-constrained evaporative term (latent heat) in the surface heat budget, the results of this study suggest that groundwater exchange may more important than the surface latent heat flux of certain lakes.

  5. Microbial Influences on Trace Metal Cycling in a Meromictic Lake, Fayetteville Green Lake, NY

    NASA Astrophysics Data System (ADS)

    Zerkle, A. L.; House, C.; Kump, L.

    2002-12-01

    Microorganisms can exist in aquatic environments at very high cell densities of up to 1011 cells/L, and can accumulate significant quantities of trace metals. Bacteria actively take up bioactive trace metals, including Fe, Zn, Mn, Co, Ni, Cu, and Mo, which function as catalytic centers in metalloproteins and metal-activated enzymes involved in virtually all cellular functions. In addition, bacteria may catalyze the release of trace metals from inorganic substrates by processes such as the reduction of iron and manganese oxides, suggesting that trace metal distributions within a natural environment dominated by microbial processes may be controlled primarily by microbial ecology. Fayetteville Green Lake (FGL), NY, is a permanently stratified meromictic lake that has a well-oxygenated surface water mass (mixolimnion) overlying a relatively stagnant, anoxic deep water mass (monimolimnion). A chemocline separates the water masses at around 20m depth, where oxygen concentrations decrease and sulfate and methane concentrations increase. In addition, previous studies have indicated that trace metals such as V, Cr, Co, Mn, and Fe reach elevated concentrations at the chemocline. Using fluorescent in situ hybridization (FISH) of FGL samples from depths of up to 40m with bacterial and archaeal probes, we have shown that fluctuating redox conditions within the FGL water column correlate with significant variations in the composition and distribution of microbial populations with depth. The mixolimnion is dominated by Eubacteria, with increasing concentrations of Archaea in the lower anoxic zone. Increases in microbial cell densities coincide with increases in trace metals at the chemocline, suggesting microbial activity may be responsible for trace metal release at this boundary. 16S rRNA PCR cloning techniques are currently being used to identify dominant microbial populations at various levels within the FGL water column. Future studies will focus on the potential for these

  6. Anaerobic microbial communities in Lake Pavin, a unique meromictic lake in France.

    PubMed

    Lehours, Anne-C; Bardot, Corinne; Thenot, Aurelie; Debroas, Didier; Fonty, Gerard

    2005-11-01

    The Bacteria and Archaea from the meromictic Lake Pavin were analyzed in samples collected along a vertical profile in the anoxic monimolimnion and were compared to those in samples from the oxic mixolimnion. Nine targeted 16S rRNA oligonucleotide probes were used to assess the distribution of Bacteria and Archaea and to investigate the in situ occurrence of sulfate-reducing bacteria and methane-producing Archaea involved in the terminal steps of the anaerobic degradation of organic material. The diversity of the complex microbial communities was assessed from the 16S rRNA polymorphisms present in terminal restriction fragment (TRF) depth patterns. The densities of the microbial community increased in the anoxic layer, and Archaea detected with probe ARCH915 represented the largest microbial group in the water column, with a mean Archaea/Eubacteria ratio of 1.5. Terminal restriction fragment length polymorphism (TRFLP) analysis revealed an elevated archaeal and bacterial phylotype richness in anoxic bottom-water samples. The structure of the Archaea community remained rather homogeneous, while TRFLP patterns for the eubacterial community revealed a heterogeneous distribution of eubacterial TRFs.

  7. Methanotrophy within the water column of a large meromictic tropical lake (Lake Kivu, East Africa)

    NASA Astrophysics Data System (ADS)

    Morana, C.; Borges, A. V.; Roland, F. A. E.; Darchambeau, F.; Descy, J.-P.; Bouillon, S.

    2015-04-01

    biomass in the oxycline, suggest that methanotrophic bacteria could potentially sustain a significant fraction of the pelagic food web in the deep, meromictic Lake Kivu.

  8. Contrasting taxonomic stratification of microbial communities in two hypersaline meromictic lakes

    PubMed Central

    Andrei, Adrian-Ştefan; Robeson, Michael S; Baricz, Andreea; Coman, Cristian; Muntean, Vasile; Ionescu, Artur; Etiope, Giuseppe; Alexe, Mircea; Sicora, Cosmin Ionel; Podar, Mircea; Banciu, Horia Leonard

    2015-01-01

    Hypersaline meromictic lakes are extreme environments in which water stratification is associated with powerful physicochemical gradients and high salt concentrations. Furthermore, their physical stability coupled with vertical water column partitioning makes them important research model systems in microbial niche differentiation and biogeochemical cycling. Here, we compare the prokaryotic assemblages from Ursu and Fara Fund hypersaline meromictic lakes (Transylvanian Basin, Romania) in relation to their limnological factors and infer their role in elemental cycling by matching taxa to known taxon-specific biogeochemical functions. To assess the composition and structure of prokaryotic communities and the environmental factors that structure them, deep-coverage small subunit (SSU) ribosomal RNA (rDNA) amplicon sequencing, community domain-specific quantitative PCR and physicochemical analyses were performed on samples collected along depth profiles. The analyses showed that the lakes harbored multiple and diverse prokaryotic communities whose distribution mirrored the water stratification patterns. Ursu Lake was found to be dominated by Bacteria and to have a greater prokaryotic diversity than Fara Fund Lake that harbored an increased cell density and was populated mostly by Archaea within oxic strata. In spite of their contrasting diversity, the microbial populations indigenous to each lake pointed to similar physiological functions within carbon degradation and sulfate reduction. Furthermore, the taxonomy results coupled with methane detection and its stable C isotope composition indicated the presence of a yet-undescribed methanogenic group in the lakes' hypersaline monimolimnion. In addition, ultrasmall uncultivated archaeal lineages were detected in the chemocline of Fara Fund Lake, where the recently proposed Nanohaloarchaeota phylum was found to thrive. PMID:25932617

  9. Contrasting taxonomic stratification of microbial communities in two hypersaline meromictic lakes.

    PubMed

    Andrei, Adrian-Ştefan; Robeson, Michael S; Baricz, Andreea; Coman, Cristian; Muntean, Vasile; Ionescu, Artur; Etiope, Giuseppe; Alexe, Mircea; Sicora, Cosmin Ionel; Podar, Mircea; Banciu, Horia Leonard

    2015-12-01

    Hypersaline meromictic lakes are extreme environments in which water stratification is associated with powerful physicochemical gradients and high salt concentrations. Furthermore, their physical stability coupled with vertical water column partitioning makes them important research model systems in microbial niche differentiation and biogeochemical cycling. Here, we compare the prokaryotic assemblages from Ursu and Fara Fund hypersaline meromictic lakes (Transylvanian Basin, Romania) in relation to their limnological factors and infer their role in elemental cycling by matching taxa to known taxon-specific biogeochemical functions. To assess the composition and structure of prokaryotic communities and the environmental factors that structure them, deep-coverage small subunit (SSU) ribosomal RNA (rDNA) amplicon sequencing, community domain-specific quantitative PCR and physicochemical analyses were performed on samples collected along depth profiles. The analyses showed that the lakes harbored multiple and diverse prokaryotic communities whose distribution mirrored the water stratification patterns. Ursu Lake was found to be dominated by Bacteria and to have a greater prokaryotic diversity than Fara Fund Lake that harbored an increased cell density and was populated mostly by Archaea within oxic strata. In spite of their contrasting diversity, the microbial populations indigenous to each lake pointed to similar physiological functions within carbon degradation and sulfate reduction. Furthermore, the taxonomy results coupled with methane detection and its stable C isotope composition indicated the presence of a yet-undescribed methanogenic group in the lakes' hypersaline monimolimnion. In addition, ultrasmall uncultivated archaeal lineages were detected in the chemocline of Fara Fund Lake, where the recently proposed Nanohaloarchaeota phylum was found to thrive.

  10. Biogeochemistry of natural gases in three alkaline, permanently stratified (meromictic) lakes

    SciTech Connect

    Oremland, R.S.; Miller, L.G. )

    1993-01-01

    Methane and associated light hydrocarbons are present as dissolved gases in the water columns of three alkaline, permanently stratified (meromictic) lakes: Big Soda Lake (Nevada), Mono Lake (California), and Soap Lake (Washington). Methane originates in the bottom sediments, but higher gaseous hydrocarbons (that is, gaseous hydrocarbons of higher molecular weight) have either microbial or thermal sources in the different lakes. Stable isotopic composition, hydrocarbon indices, radiocarbon dating, abundance-versus-depth profiles, and biological experiments indicate that methane is formed in the sediments by microbial processes. Methanogenesis and sulfate-reduction have much higher activity in the shallow littoral sediments than in the colder, more saline pelagic sediments of all three lakes. Methane-rich gas seeps are common in Mono Lake and emanate from a natural-gas deposit underlying the current lakebed. Seeps do not occur in either Big Soda Lake or Soap Lake. Ethane and higher alkanes are present in Big Soda Lake and Mono Lake, but are not present in significant quantities in Soap Lake. It is not clear if the presence of these higher alkanes is a consequence of biological activity, a result of mixing with thermogenic gases, or a combination of both factors. These results indicate the potential complexity and diversity encountered in studying light-hydrocarbon biogeochemistry in thermally and microbially active systems. Hence, in the case of methane, detailed multidisciplinary studies are often needed to determine its origin. For ethane and higher alkanes, there is currently a paucity of basic scientific information to allow for unequivocal identification of microbial and thermogenetic sources. 61 refs., 12 figs., 6 tabs.

  11. Depth distribution of microbial diversity in Mono Lake, a meromictic soda lake in California.

    PubMed

    Humayoun, Shaheen B; Bano, Nasreen; Hollibaugh, James T

    2003-02-01

    We analyzed the variation with depth in the composition of members of the domain Bacteria in samples from alkaline, hypersaline, and currently meromictic Mono Lake in California. DNA samples were collected from the mixolimnion (2 m), the base of the oxycline (17.5 m), the upper chemocline (23 m), and the monimolimnion (35 m). Composition was assessed by sequencing randomly selected cloned fragments of 16S rRNA genes retrieved from the DNA samples. Most of the 212 sequences retrieved from the samples fell into five major lineages of the domain Bacteria: alpha- and gamma-Proteobacteria (6 and 10%, respectively), Cytophaga-Flexibacter-Bacteroides (19%), high-G+C-content gram-positive organisms (Actinobacteria; 25%), and low-G+C-content gram-positive organisms (Bacillus and Clostridium; 19%). Twelve percent were identified as chloroplasts. The remaining 9% represented beta- and delta-Proteobacteria, Verrucomicrobiales, and candidate divisions. Mixolimnion and oxycline samples had low microbial diversity, with only 9 and 12 distinct phylotypes, respectively, whereas chemocline and monimolimnion samples were more diverse, containing 27 and 25 phylotypes, respectively. The compositions of microbial assemblages from the mixolimnion and oxycline were not significantly different from each other (P = 0.314 and 0.877), but they were significantly different from those of chemocline and monimolimnion assemblages (P < 0.001), and the compositions of chemocline and monimolimnion assemblages were not significantly different from each other (P = 0.006 and 0.124). The populations of sequences retrieved from the mixolimnion and oxycline samples were dominated by sequences related to high-G+C-content gram-positive bacteria (49 and 63%, respectively) distributed in only three distinct phylotypes, while the population of sequences retrieved from the monimolimnion sample was dominated (52%) by sequences related to low-G+C-content gram-positive bacteria distributed in 12 distinct

  12. Archaeal and bacterial community structures in the anoxic sediment of Antarctic meromictic lake Nurume-Ike

    NASA Astrophysics Data System (ADS)

    Kurosawa, Norio; Sato, Shota; Kawarabayasi, Yutaka; Imura, Satoshi; Naganuma, Takeshi

    2010-08-01

    Prokaryotic community structures in the anoxic sediment of the Antarctic meromictic Lake Nurume-Ike were revealed by sequence analysis of 16S rRNA gene clones. The archaeal clones obtained (205 total) consisted of only three phylotypes, and were dominantly affiliated with uncultured euryarchaeotes. Specifically, 93% of the clones were identified as marine benthic group-D archaeal phylotype. In contrast to the limited archaeal diversity, 53 phylotypes were detected within 312 bacterial clones. Major bacterial phylotypes were affiliated with α-Proteobacteria (20% of clones), d-Proteobacteria (9%), Planctmycetales (7%), and Cyanobacteria (7%). A small numbers of clones belonging to γ-Proteobacteria, Actinobacteria, Spirochaetes, Flavobacteria, and Verrucomicrobia were also found. A total of 53% of the bacterial clones, consisting of 13 phylotypes, could not be classified into any known group. These results indicated that the bacterial community of Lake Nurume-Ike sediment consisted of numerous phylogenetic groups and had a diversity comparable to the diversity of other Antarctic lakes communities previously reported. Interestingly, however, there were very few phylotypes shared between the communities of lakes Nurume-Ike and five other lakes located in the Vestfold Hills area. This is the first comprehensive study to analyze more than 500 16S rDNA clones for microbial community analysis of an Antarctic lake sediment sample, and the results significantly expand current views of bacterial diversity in Antarctic lakes.

  13. Culturable diversity of aerobic halophilic archaea (Fam. Halobacteriaceae) from hypersaline, meromictic Transylvanian lakes.

    PubMed

    Baricz, Andreea; Cristea, Adorján; Muntean, Vasile; Teodosiu, Gabriela; Andrei, Adrian-Ştefan; Molnár, Imola; Alexe, Mircea; Rakosy-Tican, Elena; Banciu, Horia Leonard

    2015-03-01

    Perennially stratified salt lakes situated in the Transylvanian Basin (Central Romania) were surveyed for the diversity of culturable halophilic archaea (Fam. Halobacteriaceae). The physical and chemical characteristics of the waters indicated that all the investigated lakes were meromictic and neutral hypersaline. Samples collected from upper, intermediate, and deeper water layers and sediments were used for the isolation of halophilic strains followed by 16S rRNA gene-based identification and phenotypic characterization. The phylogenetic analysis of the 16S rRNA gene sequences revealed that all 191 isolates reported in this study and 43 strains previously isolated were affiliated with the family Halobacteriaceae and classified to 18 genera. Haloferax was the most frequently isolated genus (~47 %), followed by Halobacterium spp. (~12 %), and Halorubrum spp. (~11 %). Highest culturable diversity was detected in Brâncoveanu Lake, the oldest and saltiest of all studied lakes, while the opposite was observed in the most stable and least human-impacted Fără Fund Lake. One strain from Ursu Lake might possibly constitute a novel Halorubrum species as shown by phylogenetic analysis. Several haloarchaeal taxa recently described in Asian (i.e., Iran, China) saline systems were also identified as inhabiting the Transylvanian salt lakes thus expanding our knowledege on the geographic distribution of Halobacteriaceae.

  14. Spatial and temporal distribution of archaeal diversity in meromictic, hypersaline Ocnei Lake (Transylvanian Basin, Romania).

    PubMed

    Baricz, Andreea; Coman, Cristian; Andrei, Adrian Stefan; Muntean, Vasile; Keresztes, Zsolt Gyula; Păuşan, Manuela; Alexe, Mircea; Banciu, Horia Leonard

    2014-03-01

    Saline, meromictic lakes with significant depth are usually formed as a result of salt mining activity. Ocnei Lake is one of the largest Transylvanian (Central Romania) neutral, hypersaline lake of man-made origin. We aimed to survey the seasonal dynamics of archaeal diversity in the water column of Ocnei Lake by employing microbiological methods as well as molecular techniques based on the sequence analysis of the 16S rRNA gene. We found that archaeal diversity in the water column increased with depth and salinity, with 8 OTUs being detected in the epilimnion compared to 21 found in the chemocline, and 32 OTUs in the monimolimnion. Down to 3.5 m depth, the archaeal community was markedly dominated by the presence of an unclassified archaeon sharing 93% sequence identity to Halogeometricum spp. At the chemocline, the shift in archaeal community composition was associated with an increase in salinity, the main factor affecting the vertical distribution of archaeal assemblages. It appears that the microoxic and hypersaline monimolimnion is populated by several major haloarchaeal taxa, with minor fluctuations in their relative abundances throughout all seasons. The culturable diversity was reasonably correlated to the dominant OTUs obtained by molecular methods. Our results indicate that Ocnei Lake represents a relatively stable extreme habitat, accommodating a diverse and putatively novel archaeal community, as 30% of OTUs could not be classified at the genus level.

  15. Local conditions structure unique archaeal communities in the anoxic sediments of meromictic Lake Kivu.

    PubMed

    Bhattarai, Susma; Ross, Kelly Ann; Schmid, Martin; Anselmetti, Flavio S; Bürgmann, Helmut

    2012-08-01

    Meromictic Lake Kivu is renowned for its enormous quantity of methane dissolved in the hypolimnion. The methane is primarily of biological origin, and its concentration has been increasing in the past half-century. Insight into the origin of methane production in Lake Kivu has become relevant with the recent commercial extraction of methane from the hypolimnion. This study provides the first culture-independent approach to identifying the archaeal communities present in Lake Kivu sediments at the sediment-water interface. Terminal restriction fragment length polymorphism analysis suggests considerable heterogeneity in the archaeal community composition at varying sample locations. This diversity reflects changes in the geochemical conditions in the sediment and the overlying water, which are an effect of local groundwater inflows. A more in-depth look at the archaeal community composition by clone library analysis revealed diverse phylogenies of Euryarchaeota and Crenarachaeota. Many of the sequences in the clone libraries belonged to globally distributed archaeal clades such as the rice cluster V and Lake Dagow sediment environmental clusters. Several of the determined clades were previously thought to be rare among freshwater sediment Archaea (e.g., sequences related to the SAGMEG-1 clade). Surprisingly, there was no observed relation of clones to known hydrogentrophic methanogens and less than 2 % of clones were related to acetoclastic methanogens. The local variability, diversity, and novelty of the archaeal community structure in Lake Kivu should be considered when making assumptions on the biogeochemical functioning of its sediments.

  16. [Sulfate reduction and methanogenesis in the Shira and Shunet meromictic lakes (Khakass Republic, Russia)].

    PubMed

    Kallistova, A Iu; Kevbrina, M V; Pimenov, N V; Rusanov, I I; Rogozin, D Iu; Wehrli, B; Nozhevnikova, A N

    2006-01-01

    The biogeochemical and molecular biological study of the chemocline and sediments of saline meromictic lakes Shira and Shunet (Khakass Republic, Russia) was performed. A marked increase in the rates of sulfate reduction and methanogenesis was revealed at the medium depths of the chemocline. The rates of these processes in the bottom sediments decreased with depth. The numbers of Bacteria, Archaea, and of sulfate-reducing bacteria (SRB) were determined by fluorescence in situ hybridization with rRNA specific oligonucleotide probes labeled with horseradish peroxidase and subsequent tyramide signal amplification. In the chemocline, both the total microbial numbers and those of Bacteria were shown to increase with depth. The archaea and SRB were present in almost equal numbers. In the lake sediments, a drastic decrease in microbial numbers with depth was revealed. SRB were found to prevail in the upper sediment layer and archaea in the lower one. This finding correlates with the measured rates of sulfate reduction and methanogenesis.

  17. Pyrosequencing analysis of the protist communities in a High Arctic meromictic lake: DNA preservation and change.

    PubMed

    Charvet, Sophie; Vincent, Warwick F; Comeau, André; Lovejoy, Connie

    2012-01-01

    High Arctic meromictic lakes are extreme environments characterized by cold temperatures, low nutrient inputs from their polar desert catchments and prolonged periods of low irradiance and darkness. These lakes are permanently stratified with an oxygenated freshwater layer (mixolimnion) overlying a saline, anoxic water column (monimolimnion). The physical and chemical properties of the deepest known lake of this type in the circumpolar Arctic, Lake A, on the far northern coast of Ellesmere Island, Canada, have been studied over the last 15 years, but little is known about the lake's biological communities. We applied high-throughput sequencing of the V4 region of the 18S ribosomal RNA gene to investigate the protist communities down the water column at three sampling times: under the ice at the end of winter in 2008, during an unusual period of warming and ice-out the same year, and again under the ice in mid-summer 2009. Sequences of many protist taxa occurred throughout the water column at all sampling times, including in the deep anoxic layer where growth is highly unlikely. Furthermore, there were sequences for taxonomic groups including diatoms and marine taxa, which have never been observed in Lake A by microscopic analysis. However, the sequences of other taxa such as ciliates, chrysophytes, Cercozoa, and Telonema varied with depth, between years and during the transition to ice-free conditions. These seasonally active taxa in the surface waters of the lake are thus sensitive to depth and change with time. DNA from these taxa is superimposed upon background DNA from multiple internal and external sources that is preserved in the deep, cold, largely anoxic water column.

  18. Vertical distribution of major sulfate-reducing bacteria in a shallow eutrophic meromictic lake.

    PubMed

    Kubo, Kyoko; Kojima, Hisaya; Fukui, Manabu

    2014-10-01

    The vertical distribution of sulfate-reducing bacteria was investigated in a shallow, eutrophic, meromictic lake, Lake Harutori, located in a residential area of Kushiro, Japan. A steep chemocline, characterized by gradients of oxygen, sulfide and salinity, was found at a depth of 3.5-4.0 m. The sulfide concentration at the bottom of the lake was high (up to a concentration of 10.7 mM). Clone libraries were constructed using the aprA gene, which encodes adenosine-5'-phosphosulfate reductase subunit A, in order to monitor sulfate-reducing bacteria. In the aprA clone libraries, the most abundant sequences were those from the Desulfosarcina-Desulfococcus (DSS) group. A primer set for a DSS group-specific 16S rRNA gene was used to construct another clone library, analysis of which revealed that the uncultured group of sulfate-reducing bacteria, SEEP SRB-1, accounted for nearly half of the obtained sequences. Quantification of the major bacterial groups by catalyzed reporter deposition-fluorescence in situ hybridization demonstrated that the DSS group accounted for 3.2-4.8% of the total bacterial community below the chemocline. The results suggested that the DSS group was one of the major groups of sulfate-reducing bacteria and that these presumably metabolically versatile bacteria might play an important role in sulfur cycling in Lake Harutori. Copyright © 2014 Elsevier GmbH. All rights reserved.

  19. Pyrosequencing analysis of the protist communities in a High Arctic meromictic lake: DNA preservation and change

    PubMed Central

    Charvet, Sophie; Vincent, Warwick F.; Comeau, André; Lovejoy, Connie

    2012-01-01

    High Arctic meromictic lakes are extreme environments characterized by cold temperatures, low nutrient inputs from their polar desert catchments and prolonged periods of low irradiance and darkness. These lakes are permanently stratified with an oxygenated freshwater layer (mixolimnion) overlying a saline, anoxic water column (monimolimnion). The physical and chemical properties of the deepest known lake of this type in the circumpolar Arctic, Lake A, on the far northern coast of Ellesmere Island, Canada, have been studied over the last 15 years, but little is known about the lake’s biological communities. We applied high-throughput sequencing of the V4 region of the 18S ribosomal RNA gene to investigate the protist communities down the water column at three sampling times: under the ice at the end of winter in 2008, during an unusual period of warming and ice-out the same year, and again under the ice in mid-summer 2009. Sequences of many protist taxa occurred throughout the water column at all sampling times, including in the deep anoxic layer where growth is highly unlikely. Furthermore, there were sequences for taxonomic groups including diatoms and marine taxa, which have never been observed in Lake A by microscopic analysis. However, the sequences of other taxa such as ciliates, chrysophytes, Cercozoa, and Telonema varied with depth, between years and during the transition to ice-free conditions. These seasonally active taxa in the surface waters of the lake are thus sensitive to depth and change with time. DNA from these taxa is superimposed upon background DNA from multiple internal and external sources that is preserved in the deep, cold, largely anoxic water column. PMID:23267353

  20. Quantitative analysis of biogeochemically controlled density stratification in an iron-meromictic lake

    NASA Astrophysics Data System (ADS)

    Nixdorf, E.; Boehrer, B.

    2015-11-01

    Lake stratification controls the cycling of dissolved matter within the water body. This is of particular interest in the case of meromictic lakes, where permanent density stratification of the deep water limits vertical transport, and a chemically different (reducing) milieu can be established. As a consequence, the geochemical setting and the mixing regime of a lake can stabilize each other mutually. We attempt a quantitative approach to the contribution of chemical reactions sustaining the density stratification. As an example, we chose the prominent case of iron meromixis in Waldsee near Doebern, a small lake that originated from near-surface underground mining of lignite. From a data set covering 4 years of monthly measured electrical conductivity profiles, we calculated summed conductivity as a quantitative variable reflecting the amount of electro-active substances in the entire lake. Seasonal variations followed the changing of the chemocline height. Coinciding changes of electrical conductivities in the monimolimnion indicated that a considerable share of substances, precipitated by the advancing oxygenated epilimnion, re-dissolved in the remaining anoxic deep waters and contributed considerably to the density stratification. In addition, we designed a lab experiment, in which we removed iron compounds and organic material from monimolimnetic waters by introducing air bubbles. Precipitates could be identified by visual inspection. Eventually, the remaining solutes in the aerated water layer looked similar to mixolimnetic Waldsee water. Due to its reduced concentration of solutes, this water became less dense and remained floating on nearly unchanged monimolimnetic water. In conclusion, iron meromixis as seen in Waldsee did not require two different sources of incoming waters, but the inflow of iron-rich deep groundwater and the aeration through the lake surface were fully sufficient for the formation of iron meromixis.

  1. Vertical structure of archaeal communities and the distribution of ammonia monooxygenase A gene variants in two meromictic High Arctic lakes.

    PubMed

    Pouliot, Jérémie; Galand, Pierre E; Lovejoy, Connie; Vincent, Warwick F

    2009-03-01

    The distribution of archaeal amoA and 16S rRNA genes was evaluated in two marine-derived, meromictic lakes in the Canadian High Arctic: Lake A and Lake C1 on the northern coast of Ellesmere Island. The amoA gene was recorded in both lakes, with highest copy numbers in the oxycline. Sequence analysis showed that amoA from the two lakes shared 94% similarity, indicating at least two phylogenetically distinct clusters. Clone libraries of archaeal 16S rRNA genes from Lake A revealed strong vertical differences in archaeal community diversity and composition down the water column. The oxic layer was dominated by one group of Euryarchaeota affiliated to the Lake Dagow Sediment (LDS) cluster. This group was absent from the oxycline, which had an extremely low archaeal diversity of two phylotypes. Both belonged to the Crenarchaeota Marine Group I (MGI), the marine group that has been linked to archaeal amoA; however, there was a low ratio of amoA to MGI copy numbers, suggesting that many MGI Archaea did not carry the amoA gene. The anoxic zone contained representatives of the RC-V (Rice Cluster-V) and LDS clusters of Euryarchaeota. These results show the strong vertical differentiation of archaeal communities in polar meromictic lakes, and they suggest archaeal nitrification within the oxycline of these highly stratified waters.

  2. Vertical distribution of nitrogen-fixing phylotypes in a meromictic, hypersaline lake.

    PubMed

    Steward, G F; Zehr, J P; Jellison, R; Montoya, J P; Hollibaugh, J T

    2004-01-01

    We investigated the diversity of nitrogenase genes in the alkaline, moderately hypersaline Mono Lake, California to determine (1) whether nitrogen-fixing (diazotrophic) populations were similar to those in other aquatic environments and (2) if there was a pattern of distribution of phylotypes that reflected redox conditions, as well as (3) to identify populations that could be important in N dynamics in this nitrogen-limited lake. Mono Lake has been meromictic for almost a decade and has steep gradients in oxygen and reduced compounds that provide a wide range of aerobic and anaerobic habitats. We amplified a fragment of the nitrogenase gene (nifH) from planktonic DNA samples collected at three depths representing oxygenated surface waters, the oxycline, and anoxic, ammonium-rich deep waters. Forty-three percent of the 90 sequences grouped in nifH Cluster I. The majority of clones (57%) grouped in Cluster III, which contains many known anaerobic bacteria. Cluster I and Cluster III sequences were retrieved at every depth indicating little vertical zonation in sequence types related to the prominent gradients in oxygen and ammonia. One group in Cluster I was found most often at every depth and accounted for 29% of all the clones. These sequences formed a subcluster that contained other environmental clones, but no cultivated representatives. No significant nitrogen fixation was detected by the 15N2 method after 48 h of incubation of surface, oxycline, or deep waters, suggesting that pelagic diazotrophs were contributing little to nitrogen fluxes in the lake. The failure to measure any significant nitrogen fixation, despite the detection of diverse and novel nitrogenase genes throughout the water column, raises interesting questions about the ecological controls on diazotrophy in Mono Lake and the distribution of functional genes in the environment.

  3. Roseicyclus mahoneyensis gen. nov., sp. nov., an aerobic phototrophic bacterium isolated from a meromictic lake.

    PubMed

    Rathgeber, Christopher; Yurkova, Natalia; Stackebrandt, Erko; Schumann, Peter; Beatty, J Thomas; Yurkov, Vladimir

    2005-07-01

    Eight strains of Gram-negative bacteria able to form ring-like cells were isolated from Mahoney Lake, a meromictic lake in south-central British Columbia, Canada. All strains were pink-purple and contained bacteriochlorophyll a incorporated into the light-harvesting 1 and 2 and reaction-centre pigment-protein complexes. Growth did not occur anaerobically under illuminated conditions; these strains were obligately aerobic, prompting their designation as members of the aerobic phototrophic bacteria. Physiological characterization revealed that these isolates share a similar tolerance to high levels of salinity and pH, as would be expected of bacteria from a highly saline lake; however, the strains exhibited marked differences in their ability to utilize organic substrates for aerobic heterotrophic growth. 16S rRNA sequence analysis showed that the strains are closely related to members of the non-phototrophic genera Octadecabacter (92.0-92.9%) and Ketogulonicigenium (92.2-92.6%), as well as to aerobic phototrophs of the genera Roseivivax (92.2-92.9%) and Roseovarius (91.7-92.4%) within the 'Alphaproteobacteria'. The DNA G+C content was 66.2 mol%. The unusual light-harvesting complex 2, the distinct morphological features and physiological traits of these strains as well as the phylogenetic data support the proposal of the novel genus and species Roseicyclus mahoneyensis gen. nov., sp. nov., with ML6(T) (=DSM 16097(T)=VKM B-2346(T)) as the type strain.

  4. Methanotrophy under Versatile Conditions in the Water Column of the Ferruginous Meromictic Lake La Cruz (Spain).

    PubMed

    Oswald, Kirsten; Jegge, Corinne; Tischer, Jana; Berg, Jasmine; Brand, Andreas; Miracle, María R; Soria, Xavier; Vicente, Eduardo; Lehmann, Moritz F; Zopfi, Jakob; Schubert, Carsten J

    2016-01-01

    Lakes represent a considerable natural source of methane to the atmosphere compared to their small global surface area. Methanotrophs in sediments and in the water column largely control methane fluxes from these systems, yet the diversity, electron accepting capacity, and nutrient requirements of these microorganisms have only been partially identified. Here, we investigated the role of electron acceptors alternative to oxygen and sulfate in microbial methane oxidation at the oxycline and in anoxic waters of the ferruginous meromictic Lake La Cruz, Spain. Active methane turnover in a zone extending well below the oxycline was evidenced by stable carbon isotope-based rate measurements. We observed a strong methane oxidation potential throughout the anoxic water column, which did not vary substantially from that at the oxic/anoxic interface. Both in the redox-transition and anoxic zones, only aerobic methane-oxidizing bacteria (MOB) were detected by fluorescence in situ hybridization and sequencing techniques, suggesting a close coupling of cryptic photosynthetic oxygen production and aerobic methane turnover. Additions of nitrate, nitrite and to a lesser degree iron and manganese oxides also stimulated bacterial methane consumption. We could not confirm a direct link between the reduction of these compounds and methane oxidation and we cannot exclude the contribution of unknown anaerobic methanotrophs. Nevertheless, our findings from Lake La Cruz support recent laboratory evidence that aerobic methanotrophs may be able to utilize alternative terminal electron acceptors under oxygen limitation.

  5. [Microbiological and isotopic-geochemical investigations of meromictic lakes in Khakasia in winter].

    PubMed

    Savvichev, A S; Rusanov, I I; Rogozin, D Iu; Zakharova, E E; Lunina, O N; Briantseva, I A; Iusupov, S K; Pimenov, N V; Degermendzhi, A G; Ivanov, M V

    2005-01-01

    Microbiological and isotopic-geochemical investigations of the brackish meromictic lakes Shira and Shunet were performed in the steppe region of Khakasia in winter. Measurements made with a submersed sensor demonstrated that one-meter ice transmits light in a quantity sufficient for oxygenic and anoxygenic photosynthesis. As in the summer season, in the community of phototrophic bacteria found in Lake Shira, the purple sulfur bacteria Amoebobacter purpureus dominated, whereas, in Lake Shunet, the green sulfur bacteria Pelodictyon luteolum were predominant. Photosynthetic production, measured using the radioisotopic method, was several times lower than that in summer. The rates of sulfate reduction and production and oxidation of methane in the water column and bottom sediments were also lower than those recorded in summer. The process of anaerobic methane oxidation in the sediments was an exception, being more intense in winter than in summer. The data from radioisotopic measurements of the rates of microbial processes correlate well with the results of determination of the isotopic composition of organic and mineral carbon (delta13C) and hydrogen sulfide and sulfate (delta34S) and suggest considerable seasonal variations in the activity of the microbial community in the water bodies investigated.

  6. Methanotrophy under Versatile Conditions in the Water Column of the Ferruginous Meromictic Lake La Cruz (Spain)

    PubMed Central

    Oswald, Kirsten; Jegge, Corinne; Tischer, Jana; Berg, Jasmine; Brand, Andreas; Miracle, María R.; Soria, Xavier; Vicente, Eduardo; Lehmann, Moritz F.; Zopfi, Jakob; Schubert, Carsten J.

    2016-01-01

    Lakes represent a considerable natural source of methane to the atmosphere compared to their small global surface area. Methanotrophs in sediments and in the water column largely control methane fluxes from these systems, yet the diversity, electron accepting capacity, and nutrient requirements of these microorganisms have only been partially identified. Here, we investigated the role of electron acceptors alternative to oxygen and sulfate in microbial methane oxidation at the oxycline and in anoxic waters of the ferruginous meromictic Lake La Cruz, Spain. Active methane turnover in a zone extending well below the oxycline was evidenced by stable carbon isotope-based rate measurements. We observed a strong methane oxidation potential throughout the anoxic water column, which did not vary substantially from that at the oxic/anoxic interface. Both in the redox-transition and anoxic zones, only aerobic methane-oxidizing bacteria (MOB) were detected by fluorescence in situ hybridization and sequencing techniques, suggesting a close coupling of cryptic photosynthetic oxygen production and aerobic methane turnover. Additions of nitrate, nitrite and to a lesser degree iron and manganese oxides also stimulated bacterial methane consumption. We could not confirm a direct link between the reduction of these compounds and methane oxidation and we cannot exclude the contribution of unknown anaerobic methanotrophs. Nevertheless, our findings from Lake La Cruz support recent laboratory evidence that aerobic methanotrophs may be able to utilize alternative terminal electron acceptors under oxygen limitation. PMID:27891115

  7. In situ determination of sulfide turnover rates in a meromictic alpine lake

    SciTech Connect

    Luethy, L.; Fritz, M.; Bachofen, R.

    2000-02-01

    A push-pull method, previously used in groundwater analyses, was successfully adapted for measuring sulfide turnover rates in situ at different depths in the meromictic Lake Cadagno. In the layer of phototrophic bacteria at about 12 m in depth net sulfide consumption was observed during the day, indicating active bacterial photosynthesis. During the night the sulfide turnover rates were positive, indicating a net sulfide production from the reduction of more-oxidized sulfur compounds. Because of lack of light, no photosynthesis takes place in the monimolimnion; thus, only sulfide formation is observed both during the day and the night. Sulfide turnover rates in the oxic mixolimnion were always positive as sulfide is spontaneously oxidized by oxygen and as the rates of sulfide oxidation depend on the oxygen concentrations present. Sulfide oxidation by chemolithotrophic bacteria may occur at the oxicline, but this cannot be distinguished from spontaneous chemical oxidation.

  8. In Situ Determination of Sulfide Turnover Rates in a Meromictic Alpine Lake

    PubMed Central

    Lüthy, Lucas; Fritz, Markus; Bachofen, Reinhard

    2000-01-01

    A push-pull method, previously used in groundwater analyses, was successfully adapted for measuring sulfide turnover rates in situ at different depths in the meromictic Lake Cadagno. In the layer of phototrophic bacteria at about 12 m in depth net sulfide consumption was observed during the day, indicating active bacterial photosynthesis. During the night the sulfide turnover rates were positive, indicating a net sulfide production from the reduction of more-oxidized sulfur compounds. Because of lack of light, no photosynthesis takes place in the monimolimnion; thus, only sulfide formation is observed both during the day and the night. Sulfide turnover rates in the oxic mixolimnion were always positive as sulfide is spontaneously oxidized by oxygen and as the rates of sulfide oxidation depend on the oxygen concentrations present. Sulfide oxidation by chemolithotrophic bacteria may occur at the oxicline, but this cannot be distinguished from spontaneous chemical oxidation. PMID:10653740

  9. Distribution of chloropigments in suspended particulate matter and benthic microbial mat of a meromictic lake, Lake Kaiike, Japan.

    PubMed

    Nakajima, Yoji; Okada, Hisatake; Oguri, Kazumasa; Suga, Hisami; Kitazato, Hiroshi; Koizumi, Yoshikazu; Fukui, Manabu; Ohkouchi, Naohiko

    2003-11-01

    We investigated the distribution of chloropigments in a small meromictic lake, Lake Kaiike, south-west Japan. In the water-column, concentrations of Chl a related to cyanobacteria, BChl a related to purple sulphur bacteria, and three types of BChl e homologues (BChls e1, e2 and e3) related to brown-coloured green sulphur bacteria, were maximal at the redox boundary. Below the redox boundary, absolute concentrations of Chl a and BChl a gradually decreased with depth, whereas BChls e remained rather constant. Suspended particulate matter (SPM) at the deeper region of the anoxic water-column was enriched in highly alkylated BChl e homologues compared with SPM at the redox boundary. The shift in the relative content of highly alkylated BChl e homologues beneath the boundary was associated with community related adaptation of brown-coloured green sulphur bacteria to changes in light quality/quantity, resulting from the optical absorption and reflectance of SPMs in the overlying water-column. Benthic microbial mats were characterized by high abundances of BChls e, in which highly alkylated homologues were substantially abundant. This suggests that the BChls e in the microbial mat may be derived from the low-light adapted brown-coloured green sulphur bacteria forming the bacterial mat.

  10. The geochemical cycling of trace elements in a biogenic meromictic lake

    USGS Publications Warehouse

    Balistrieri, L.S.; Murray, J.W.; Paul, B.

    1994-01-01

    The geochemical processes affecting the behavior and speciation of As, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in Hall Lake, Washington, USA, are assessed by examining dissolved and acid soluble particulate profiles of the elements and utilizing results from thermodynamic calculations. The water column of this meromictic lake is highly stratified and contains distinctive oxic, suboxic, and anoxic layers. Changes in the redox state of the water column with depth affect the distribution of all the elements studied. Most noticeable are increases in dissolved Co, Cr, Fe, Mn, Ni, Pb, and Zn concentrations across the oxic-suboxic boundary, increases in dissolved As, Co, Cr, Fe, Mn, and V concentrations with depth in the anoxic layer, significant decreases in dissolved Cu, Ni, Pb, and Zn concentrations in the anoxic region below the sulfide maximum, and large increases in acid soluble particulate concentrations of As, Cr, Cu, Fe, Mo, Ni, Pb, V, and Zn in the anoxic zone below the sulfide maximum. Thermodynamic calculations for the anoxic region indicate that all redox sensitive elements exist in their reduced forms, the primary dissolved forms of Cu, Ni, Pb, and Zn are metal sulfide solution complexes, and solid sulfide phases of Cu, Fe, Mo, and Pb are supersaturated. Calculations using a vertical diffusion and reaction model indicate that the oxidation rate constant for Mn(II) in Hall Lake is estimated to be 0.006 d-1 and is at the lower end of the range of microbial oxidation rates observed in other natural systems. The main geochemical processes influencing the distribution and speciation of trace elements in Hall Lake appear to be transformations of dissolved elements between their oxidation states (As, Cr, Cu, Fe, Mn, V), cocycling of trace elements with Mn and Fe (As, Co, Cr, Cu, Mo, Ni, Pb, V, Zn), formation of soluble metal sulfide complexes (Co, Cu, Ni, Pb, Zn), sorption (As, Co, Cr, Ni, V), and precipitation (Cu, Fe, Mn, Mo, Pb, Zn). ?? 1994.

  11. The geochemical cycling of trace elements in a biogenic meromictic lake

    SciTech Connect

    Balistrieri, L.S.; Murray, J.W.; Paul, B. )

    1994-10-01

    The geochemical processes affecting the behavior and speciation of As, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in Hall Lake, Washington, USA, are assessed by examining dissolved and acid soluble particulate profiles of the elements and utilizing results from thermodynamic calculations. The water column of this meromictic lake is highly stratified and contains distinctive oxic, suboxic, and anoxic layers. Changes in the redox state of the water column with depth affect the distribution of all the elements studied. Most noticeable are increases in dissolved Co, Cr, Fe, Mn, Ni, Pb, and Zn concentrations across the oxic-suboxic boundary, increases in dissolved As, Co, Cr, Fe, Mn, and V concentrations with depth in the anoxic layer, significant decreases in dissolved Cu, Ni, Pb, and Zn concentrations in the anoxic region below the sulfide maximum, and large increases in acid soluble particulate concentrations of As, Cr, Cu, Fe, Mo, Ni, Pb, V, and Zn in the anoxic zone below the sulfide maximum. Thermodynamic calculations for the anoxic region indicate that all redox sensitive elements exist in their reduced forms, the primary dissolved forms of Cu, Ni, Pb, and Zn are metal sulfide solution complexes, and solid sulfide phases of Cu, Fe, Mo, and Pb are supersaturated. Calculations using a vertical diffusion and reaction model indicate that the oxidation rate constant for Mn(II) in Hall Lake is estimated to be 0.006 d[sup [minus]1] and is at the lower end of the range of microbial oxidation rates observed in other natural systems. The main geochemical processes influencing the distribution and speciation of trace elements in Hall Lake appear to be transformations of dissolved elements between their oxidation states (As, Cr, Cu, Fe, Mn, V), cocycling of trace elements with Mn and Fe (As, Co, Cr, Cu, Mo, Ni, Pb, V, Zn), formation of soluble metal sulfide complexes (Co, Cu, Ni, Pb, Zn), sorption (As, Co, Cr, Ni, V), and precipitation (Cu, Fe, Mn, Mo, Pb, Zn).

  12. Grazing of the copepod Diaptomus connexus on purple sulphur bacteria in a meromictic salt lake.

    PubMed

    Overmann, J; Hall, K J; Northcote, T G; Beatty, J T

    1999-06-01

    A meromictic lake ecosystem (Mahoney Lake, BC, Canada) was investigated to elucidate the significance of chemocline bacteria in the total carbon cycle under natural conditions. In this lake, primary production by oxygenic phototrophs was insufficient to support the observed net secondary production of the calanoid copepod Diaptomus connexus and the rotifer Brachionus plicatilis, indicating the presence of additional food sources for consumers. Mahoney Lake harbours the densest population of phototrophic sulphur bacteria ever reported in a natural body of water. This layer is located at the interface between oxic and anoxic water layers and is dominated by the purple sulphur bacterium Amoebobacter purpureus. The transfer rates of A. purpureus carbon to D. connexus determined in stratified mesocosms were very low (0.71 ngC copepod(-1) day(-1)) and accounted for only 0.6% of the observed net biomass increase in the zooplankter. Stable stratification within the mesocosms prevented an upwelling of A. purpureus into the oxic part. However, measurements of carbon fluxes, infrared fluorescence microscopy and stable carbon analysis provided cumulative evidence that, under in situ conditions, the cell carbon of purple sulphur bacteria indeed enters the aerobic food chain via the grazing activity of D. connexus. Based on a two-source isotopic mixing model, A. purpureus represents at least 75-85% of the diet of D. connexus. Autumnal upwelling into oxic water layers and aggregation of A. purpureus cells appear to be the main factors determining the high carbon flux from purple sulphur bacteria to zooplankton under natural conditions, and most probably also play a key role in other aquatic ecosystems. Through this pathway, over 53% of the reduced organic matter of purple sulphur bacteria trapped in anoxic bottom waters is returned to the oxic realm.

  13. Spatio-temporal distribution of phototrophic sulfur bacteria in the chemocline of meromictic Lake Cadagno (Switzerland).

    PubMed

    Tonolla, Mauro; Peduzzi, Sandro; Hahn, Dittmar; Peduzzi, Raffaele

    2003-02-01

    Abstract In situ hybridization was used to study the spatio-temporal distribution of phototrophic sulfur bacteria in the permanent chemocline of meromictic Lake Cadagno, Switzerland. At all four sampling times during the year the numerically most important phototrophic sulfur bacteria in the chemocline were small-celled purple sulfur bacteria of two yet uncultured populations designated D and F. Other small-celled purple sulfur bacteria (Amoebobacter purpureus and Lamprocystis roseopersicina) were found in numbers about one order of magnitude lower. These numbers were similar to those of large-celled purple sulfur bacteria (Chromatium okenii) and green sulfur bacteria that almost entirely consisted of Chlorobium phaeobacteroides. In March and June when low light intensities reached the chemocline, cell densities of all populations, with the exception of L. roseopersicina, were about one order of magnitude lower than in August and October when light intensities were much higher. Most populations were evenly distributed throughout the whole chemocline during March and June, while in August and October a microstratification of populations was detected suggesting specific eco-physiological adaptations of different populations of phototrophic sulfur bacteria to the steep physico-chemical gradients in the chemocline of Lake Cadagno.

  14. Carotenoid biomarkers as an imperfect reflection of the anoxygenic phototrophic community in meromictic Fayetteville Green Lake.

    PubMed

    Meyer, K M; Macalady, J L; Fulton, J M; Kump, L R; Schaperdoth, I; Freeman, K H

    2011-07-01

    Organic biomarkers in marine sedimentary rocks hold important clues about the early history of Earth's surface environment. The chemical relicts of carotenoids from anoxygenic sulfur bacteria are of particular interest to geoscientists because of their potential to signal episodes of marine photic-zone euxinia such as those proposed for extended periods in the Proterozoic as well as brief intervals during the Phanerozoic. It is therefore critical to constrain the environmental and physiological factors that influence carotenoid production and preservation in modern environments. Here, we present the results of coupled pigment and nucleic acid clone library analyses from planktonic and benthic samples collected from a microbially dominated meromictic lake, Fayetteville Green Lake (New York). Purple sulfur bacteria (PSB) are abundant and diverse both in the water column at the chemocline and in benthic mats below oxygenated shallow waters, with different PSB species inhabiting the two environments. Okenone (from PSB) is an abundant carotenoid in both the chemocline waters and in benthic mats. Green sulfur bacteria and their primary pigment Bchl e are also represented in and below the chemocline. However, the water column and sediments are devoid of the green sulfur bacteria carotenoid isorenieratene. The unexpected absence of isorenieratene and apparent benthic production of okenone provide strong rationale for continued exploration of the microbial ecology of biomarker production in modern euxinic environments. © 2011 Blackwell Publishing Ltd.

  15. Identification of microbial communities involved in the methane cycle of a freshwater meromictic lake.

    PubMed

    Biderre-Petit, Corinne; Jézéquel, Didier; Dugat-Bony, Eric; Lopes, Filipa; Kuever, Jan; Borrel, Guillaume; Viollier, Eirc; Fonty, Gerard; Peyret, Pierre

    2011-09-01

    Lake Pavin is a meromictic crater lake located in the French Massif Central area. In this ecosystem, most methane (CH(4)) produced in high quantity in the anoxic bottom layers, and especially in sediments, is consumed in the water column, with only a small fraction of annual production reaching the atmosphere. This study assessed the diversity of methanogenic and methanotrophic populations along the water column and in sediments using PCR and reverse transcription-PCR-based approaches targeting functional genes, i.e. pmoA (α-subunit of the particulate methane monooxygenase) for methanotrophy and mcrA (α-subunit of the methyl-coenzyme M reductase) for methanogenesis as well as the phylogenetic 16S rRNA genes. Although methanogenesis rates were much higher in sediments, our results confirm that CH(4) production also occurs in the water column where methanogens were almost exclusively composed of hydrogenotrophic methanogens, whereas both hydrogenotrophs and acetotrophs were almost equivalent in the sediments. Sequence analysis of markers, pmoA and the 16S rRNA gene, suggested that Methylobacter may be an important group actively involved in CH(4) oxidation in the water column. Two main phylotypes were characterized, one of which could consume CH(4) under conditions where the oxygen amount is undetectable. FEMS Microbiology Ecology © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. No claim to original French government works.

  16. Potential sulfur metabolisms and associated bacteria within anoxic surface sediment from saline meromictic Lake Kaiike (Japan).

    PubMed

    Koizumi, Yoshikazu; Kojima, Hisaya; Fukui, Manabu

    2005-05-01

    The effects of light and of added electron donors and sulfur compounds on sulfur metabolisms in the microbial mat dilutions from the saline meromictic Lake Kaiike were investigated. Sulfide concentrations in the mat dilution without any electron donor gradually increased by approximately 0.6-1 mM in the dark. Additions of lactate, acetate, H(2)/CO(2), propionate and iso-butylate stimulated sulfide production, whereas benzoate did not, indicating the limitation of sulfate reduction by available electron donor concentrations. More sulfide was produced, without a decrease of sulfate, in an elemental sulfur-amended dilution than in a non-amended control. In contrast, the addition of a high concentration of sulfide slowed down sulfide production. After enrichment under various conditions, microbial communities in the dilutions were characterized by a denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene and sequencing. As a result, microorganisms affiliated with mesophilic sulfate-reducing bacteria group within the Deltaproteobacteria and the Epsilonproteobacteria were mainly enriched by the addition of electrons used in this study, suggesting that these microorganisms might play an important role in sulfur metabolisms within the surficial sediment of Lake Kaiike.

  17. Protistan grazing in a meromictic freshwater lake with anoxic bottom water.

    PubMed

    Oikonomou, Andreas; Pachiadaki, Maria; Stoeck, Thorsten

    2014-03-01

    Phagotrophic protists are an important mortality factor of prokaryotes in most aquatic habitats. However, no study has assessed protistan grazing as loss factor of bacterial biomass across the stratification gradient of a temperate freshwater meromictic lake. Protistan grazing effect was quantified in the mixolimnion, the transition zone, and the sulfidic anoxic monimolimnion of Lake Alatsee (Germany). Grazing experiments were performed using prey analogues from the natural prokaryotic assemblage. Daily grazing effect declined from the mixolimnion to the monimolimnion. Heterotrophic flagellates were phagotrophically active in all three water horizons and the main grazers in the monimolimnion. Pigmented flagellates accounted for 70% of total grazing in the mixolimnion and ciliates only for a small fraction of grazing in each depth. Prokaryotic biomass removal peaked in the interface, but protistan impact on the respective prokaryotic abundance was low. Grazing in the anoxic monimolimnion was negligible, with prokaryotic turnover rate being only 0.4% of standing stock. Our results support the assumption that protistan predation in anoxic waters is lower than in oxygenated ones and identify the interface as a microhabitat that supports high grazer biomass, pinpointing the importance of purple sulfur bacteria as carbon source for the upper mixolimnion and the bottom monimolimnion. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  18. Strong influence of the littoral zone on sedimentary lipid biomarkers in a meromictic lake.

    PubMed

    Bovee, R J; Pearson, A

    2014-11-01

    Planktonic sulfur bacteria growing in zones of photic zone euxinia (PZE) are important primary producers in stratified, sulfur-rich environments. The potential for export and burial of microbial biomass from anoxic photic zones remains relatively understudied, despite being of fundamental importance to interpreting the geologic record of bulk total organic carbon (TOC) and individual lipid biomarkers. Here we report the relative concentrations and carbon isotope ratios of lipid biomarkers from the water column and sediments of meromictic Mahoney Lake. The data show that organic matter in the central basin sediments is indistinguishable from material at the lake shoreline in both its lipid and carbon isotopic compositions. However, this material is not consistent with either the lipid profile or carbon isotope composition of biomass obtained directly from the region of PZE. Due to the strong density stratification and the intensive carbon and sulfur recycling pathways in the water column, there appears to be minimal direct export of the sulfur-oxidizing planktonic community to depth. The results instead suggest that basinal sediments are sourced via the littoral environment, a system that integrates an indigenous shoreline microbial community, the degraded remains of laterally rafted biomass from the PZE community, and detrital remains of terrigenous higher plants. Material from the lake margins appears to travel downslope, traverse the strong density gradient, and become deposited in the deep basin; its final composition may be largely heterotrophic in origin. This suggests an important role for clastic and/or authigenic minerals in aiding the burial of terrigenous and mat-derived organic matter in euxinic systems. Downslope or mineral-aided transport of anoxygenic, photoautotrophic microbial mats may have been a significant sedimentation process in early Earth history. © 2014 John Wiley & Sons Ltd.

  19. Methanotrophy within the water column of a large meromictic tropical lake (Lake Kivu, East Africa)

    NASA Astrophysics Data System (ADS)

    Morana, C.; Borges, A. V.; Roland, F. A. E.; Darchambeau, F.; Descy, J.-P.; Bouillon, S.

    2014-11-01

    The permanently stratified Lake Kivu is one of the largest freshwater reservoirs of dissolved methane (CH4) on Earth. Yet CH4 emissions from its surface to the atmosphere has been estimated to be 2 orders of magnitude lower than the CH4 upward flux to the mixed layer, showing that microbial CH4 oxidation is an important process within the water column. A combination of natural abundance carbon stable isotope analysis (δ13C) of several inorganic and organic carbon pools and 13CH4-labelling experiments was carried out during rainy and dry season to quantify (i) the contribution of CH4-derived carbon to the biomass, (ii) methanotrophic bacterial production (MBP), and (iii) methanotrophic bacterial growth efficiency (MBGE), defined as the ratio between MBP and gross CH4 oxidation. We also investigated the distribution and the δ13C of specific phospholipid fatty acids (PLFA), used as biomarkers for aerobic methanotrophs. Data revealed that methanotrophic organisms oxidized within the water column most of the upward flux of CH4 to the mixed layer and a significant amount of CH4-derived carbon was incorporated into the microbial biomass in the oxycline. Maximal MBP rates were measured in the oxycline, suggesting that CH4 oxidation was mainly driven by oxic processes. The MBGE was variable (2-50%) and negatively related to CH4 : O2 molar ratios. Thus, a comparatively smaller fraction of CH4-derived carbon was incorporated into the cellular biomass in deeper waters, at the bottom of the oxycline where oxygen was scarce. The aerobic methanotrophic community was clearly dominated by type I methanotrophs and no evidence was found for an active involvement of type II methanotrophs in CH4 oxidation in Lake Kivu. Vertically integrated over the water column, the MBP was equivalent to 16-58% of the average phytoplankton primary production. This relatively high magnitude of MBP, and the substantial contribution of CH4-derived carbon to the overall biomass in the oxycline, suggest

  20. Distribution, abundance and carbon isotopic composition of gaseous hydrocarbons in Big Soda Lake, Nevada: An alkaline, meromictic lake

    USGS Publications Warehouse

    Oremland, R.S.; Des Marais, D.J.

    1983-01-01

    Distribution and isotopic composition (??13C) of low molecular weight hydrocarbon gases were studied in Big Soda Lake (depth = 64 m), an alkaline, meromictic lake with permanently anoxic bottom waters. Methane increased with depth in the anoxic mixolimnion (depth = 20-35 m), reached uniform concentrations (55 ??M/l) in the monimolimnion (35-64 m) and again increased with depth in monimolimnion bottom sediments (>400 ??M/kg below 1 m sub-bottom depth). The ??13C[CH4] values in bottom sediment below 1 m sub-bottom depth (<-70 per mil) increased with vertical distance up the core (??13C[CH4] = -55 per mil at sediment surface). Monimolimnion ??13C[CH4] values (-55 to -61 per mil) were greater than most ??13C[CH4] values found in the anoxic mixolimnion (92% of samples had ??13C[CH4] values between -20 and -48 per mil). No significant concentrations of ethylene or propylene were found in the lake. However ethane, propane, isobutane and n-butane concentrations all increased with water column depth, with respective maximum concentrations of 260, 80, 23 and 22 nM/l encountered between 50-60 m depth. Concentrations of ethane, propane and butanes decreased with depth in the bottom sediments. Ratios of CH4 [C2H6 + C3H8] were high (250-620) in the anoxic mixolimnion, decreased to ~161 in the monimolimnion and increased with depth in the sediment to values as high as 1736. We concluded that methane has a biogenic origin in both the sediments and the anoxic water column and that C2-C4 alkanes have biogenic origins in the monimolimnion water and shallow sediments. The changes observed in ??13C[CH4] and CH4 (C2H6 + C3H8) with depth in the water column and sediments are probably caused by bacteria] processes. These might include anaerobic methane oxidation and different rates of methanogenesis and C2 to C4 alkane production by microorganisms. ?? 1983.

  1. Coupled reductive and oxidative sulfur cycling in the phototrophic plate of a meromictic lake.

    PubMed

    Hamilton, T L; Bovee, R J; Thiel, V; Sattin, S R; Mohr, W; Schaperdoth, I; Vogl, K; Gilhooly, W P; Lyons, T W; Tomsho, L P; Schuster, S C; Overmann, J; Bryant, D A; Pearson, A; Macalady, J L

    2014-09-01

    Mahoney Lake represents an extreme meromictic model system and is a valuable site for examining the organisms and processes that sustain photic zone euxinia (PZE). A single population of purple sulfur bacteria (PSB) living in a dense phototrophic plate in the chemocline is responsible for most of the primary production in Mahoney Lake. Here, we present metagenomic data from this phototrophic plate--including the genome of the major PSB, as obtained from both a highly enriched culture and from the metagenomic data--as well as evidence for multiple other taxa that contribute to the oxidative sulfur cycle and to sulfate reduction. The planktonic PSB is a member of the Chromatiaceae, here renamed Thiohalocapsa sp. strain ML1. It produces the carotenoid okenone, yet its closest relatives are benthic PSB isolates, a finding that may complicate the use of okenone (okenane) as a biomarker for ancient PZE. Favorable thermodynamics for non-phototrophic sulfide oxidation and sulfate reduction reactions also occur in the plate, and a suite of organisms capable of oxidizing and reducing sulfur is apparent in the metagenome. Fluctuating supplies of both reduced carbon and reduced sulfur to the chemocline may partly account for the diversity of both autotrophic and heterotrophic species. Collectively, the data demonstrate the physiological potential for maintaining complex sulfur and carbon cycles in an anoxic water column, driven by the input of exogenous organic matter. This is consistent with suggestions that high levels of oxygenic primary production maintain episodes of PZE in Earth's history and that such communities should support a diversity of sulfur cycle reactions. © 2014 John Wiley & Sons Ltd.

  2. Phototrophic Fe(II)-oxidation in the chemocline of a ferruginous meromictic lake.

    PubMed

    Walter, Xavier A; Picazo, Antonio; Miracle, Maria R; Vicente, Eduardo; Camacho, Antonio; Aragno, Michel; Zopfi, Jakob

    2014-01-01

    Precambrian Banded Iron Formation (BIF) deposition was conventionally attributed to the precipitation of iron-oxides resulting from the abiotic reaction of ferrous iron (Fe(II)) with photosynthetically produced oxygen. Earliest traces of oxygen date from 2.7 Ga, thus raising questions as to what may have caused BIF precipitation before oxygenic photosynthesis evolved. The discovery of anoxygenic phototrophic bacteria thriving through the oxidation of Fe(II) has provided support for a biological origin for some BIFs, but despite reports suggesting that anoxygenic phototrophs may oxidize Fe(II) in the environment, a model ecosystem of an ancient ocean where they are demonstrably active was lacking. Here we show that anoxygenic phototrophic bacteria contribute to Fe(II) oxidation in the water column of the ferruginous sulfate-poor, meromictic lake La Cruz (Spain). We observed in-situ photoferrotrophic activity through stimulation of phototrophic carbon uptake in the presence of Fe(II), and determined light-dependent Fe(II)-oxidation by the natural chemocline microbiota. Moreover, a photoferrotrophic bacterium most closely related to Chlorobium ferrooxidans was enriched from the ferruginous water column. Our study for the first time demonstrates a direct link between anoxygenic photoferrotrophy and the anoxic precipitation of Fe(III)-oxides in a ferruginous water column, providing a plausible mechanism for the bacterial origin of BIFs before the advent of free oxygen. However, photoferrotrophs represent only a minor fraction of the anoxygenic phototrophic community with the majority apparently thriving by sulfur cycling, despite the very low sulfur content in the ferruginous chemocline of Lake La Cruz.

  3. Bacterial dissimilatory reduction of arsenate and sulfate in meromictic Mono Lake, California

    USGS Publications Warehouse

    Oremland, R.S.; Dowdle, P.R.; Hoeft, S.; Sharp, J.O.; Schaefer, J.K.; Miller, L.G.; Switzer, Blum J.; Smith, R.L.; Bloom, N.S.; Wallschlaeger, D.

    2000-01-01

    The stratified (meromictic) water column of alkaline and hypersaline Mono Lake, California, contains high concentrations of dissolved inorganic arsenic (~200 ??mol/L). Arsenic speciation changes from arsenate [As (V)] to arsenite [As (III)] with the transition from oxic surface waters (misolimnion) to anoxic bottom waters (monimolimnion). A radioassay was devised to measure the reduction of 73As (V) to 73As (III) and tested using cell suspensions of the As (V)-respiring Bacillus selenitireducens, which completely reduced the 73As (V). In field experiments, no significant activity was noted in the aerobic mixolimnion waters, but reduction of 73As (V) to 73As (III) was observed in all the monimolimnion samples. Rate constants ranged from 0.02 to 0.3/day, with the highest values in the samples from the deepest depths (24 and 28 m). The highest activities occurred between 18 and 21 m, where As (V) abundant (rate, ~5.9 ??mol/L per day). In contrast, sulfate reduction occurred at depths below 21 m, with the highest rates attained at 28 m (rate, ~2.3 ??mol/L per day). These results indicate that As (V) ranks second in importance, after sulfate, as an electron acceptor for anaerobic bacterial respiration in the water column. Annual arsenate respiration may mineralize as much as 14.2% of the pelagic photosynthetic carbon fixed during meromixis. When combined with sulfate-reduction data, anaerobic respiration in the water column can mineralize 32-55% of this primary production. As lakes of this type approach salt saturation, As (V) can become the most important electron acceptor for the biogeochemical cycling of carbon. Copyright (C) 2000 Elsevier Science Ltd.

  4. Phototrophic Fe(II)-oxidation in the chemocline of a ferruginous meromictic lake

    PubMed Central

    Walter, Xavier A.; Picazo, Antonio; Miracle, Maria R.; Vicente, Eduardo; Camacho, Antonio; Aragno, Michel; Zopfi, Jakob

    2014-01-01

    Precambrian Banded Iron Formation (BIF) deposition was conventionally attributed to the precipitation of iron-oxides resulting from the abiotic reaction of ferrous iron (Fe(II)) with photosynthetically produced oxygen. Earliest traces of oxygen date from 2.7 Ga, thus raising questions as to what may have caused BIF precipitation before oxygenic photosynthesis evolved. The discovery of anoxygenic phototrophic bacteria thriving through the oxidation of Fe(II) has provided support for a biological origin for some BIFs, but despite reports suggesting that anoxygenic phototrophs may oxidize Fe(II) in the environment, a model ecosystem of an ancient ocean where they are demonstrably active was lacking. Here we show that anoxygenic phototrophic bacteria contribute to Fe(II) oxidation in the water column of the ferruginous sulfate-poor, meromictic lake La Cruz (Spain). We observed in-situ photoferrotrophic activity through stimulation of phototrophic carbon uptake in the presence of Fe(II), and determined light-dependent Fe(II)-oxidation by the natural chemocline microbiota. Moreover, a photoferrotrophic bacterium most closely related to Chlorobium ferrooxidans was enriched from the ferruginous water column. Our study for the first time demonstrates a direct link between anoxygenic photoferrotrophy and the anoxic precipitation of Fe(III)-oxides in a ferruginous water column, providing a plausible mechanism for the bacterial origin of BIFs before the advent of free oxygen. However, photoferrotrophs represent only a minor fraction of the anoxygenic phototrophic community with the majority apparently thriving by sulfur cycling, despite the very low sulfur content in the ferruginous chemocline of Lake La Cruz. PMID:25538702

  5. Vertical Distribution of Functional Potential and Active Microbial Communities in Meromictic Lake Kivu.

    PubMed

    İnceoğlu, Özgul; Llirós, Marc; Crowe, Sean A; García-Armisen, Tamara; Morana, Cedric; Darchambeau, François; Borges, Alberto V; Descy, Jean-Pierre; Servais, Pierre

    2015-10-01

    The microbial community composition in meromictic Lake Kivu, with one of the largest CH4 reservoirs, was studied using 16S rDNA and ribosomal RNA (rRNA) pyrosequencing during the dry and rainy seasons. Highly abundant taxa were shared in a high percentage between bulk (DNA-based) and active (RNA-based) bacterial communities, whereas a high proportion of rare species was detected only in either an active or bulk community, indicating the existence of a potentially active rare biosphere and the possible underestimation of diversity detected when using only one nucleic acid pool. Most taxa identified as generalists were abundant, and those identified as specialists were more likely to be rare in the bulk community. The overall number of environmental parameters that could explain the variation was higher for abundant taxa in comparison to rare taxa. Clustering analysis based on operational taxonomic units (OTUs at 0.03 cutoff) level revealed significant and systematic microbial community composition shifts with depth. In the oxic zone, Actinobacteria were found highly dominant in the bulk community but not in the metabolically active community. In the oxic-anoxic transition zone, highly abundant potentially active Nitrospira and Methylococcales were observed. The co-occurrence of potentially active sulfur-oxidizing and sulfate-reducing bacteria in the anoxic zone may suggest the presence of an active yet cryptic sulfur cycle.

  6. Isotopic analyses (/sup 18/O, /sup 13/C, /sup 14/C) of two meromictic lakes in the Canadian Arctic Archipelago

    SciTech Connect

    Page, P.; Ouellet, M.; Hillaire-Marcel, C.; Dickman, M.

    1984-05-01

    Meromictic Lakes Garrow and Sophia in the Canadian Arctic Archipelago were sampled to establish the origin and age of their waters by isotopic studies. The sigma/sub SMOW//sup 18/O values reflect the permanent stratification of the waters in both lakes. The mixolimnia contain waters with an isotopic signal between -13.16 and -2.198%, coherent with the values of precipitation in these high latitudes. The short residence time of the water in this layer makes it possible to record episodic variations of the freshwater inputs to the lakes. In the chemoclines, the sigma/sup 18/O values increase to -10% concomitantly with a rise in chloride content to 42 g liter/sup -1/. This corresponds to a conservative mixing of surficial and deep waters. In the monimolimnia, hypersaline waters from brine production during permafrost growth in the watershed, according to a Rayleigh process. The brines drained toward the deepest part of each lake, after postglacial uplift, and became isolated. /sup 14/C dating of total inorganic carbon in the Lake Garrow monimolimnion gave an age of 2580 +/- 260 years B.P. In Lake Sophia, the deep waters exhibit recent /sup 14/C activity (121.4% modern carbon) that suggests recent infiltration of seawater into the lake basin.

  7. Co-occurrence of denitrification and nitrogen fixation in a meromictic lake, Lake Cadagno (Switzerland).

    PubMed

    Halm, Hannah; Musat, Niculina; Lam, Phyllis; Langlois, Rebecca; Musat, Florin; Peduzzi, Sandro; Lavik, Gaute; Schubert, Carsten J; Sinha, Bärbel; Singha, Bärbel; LaRoche, Julie; Kuypers, Marcel M M

    2009-08-01

    The nitrogen cycling of Lake Cadagno was investigated by using a combination of biogeochemical and molecular ecological techniques. In the upper oxic freshwater zone inorganic nitrogen concentrations were low (up to approximately 3.4 microM nitrate at the base of the oxic zone), while in the lower anoxic zone there were high concentrations of ammonium (up to 40 microM). Between these zones, a narrow zone was characterized by no measurable inorganic nitrogen, but high microbial biomass (up to 4 x 10(7) cells ml(-1)). Incubation experiments with (15)N-nitrite revealed nitrogen loss occurring in the chemocline through denitrification (approximately 3 nM N h(-1)). At the same depth, incubations experiments with (15)N(2)- and (13)C(DIC)-labelled bicarbonate, indicated substantial N(2) fixation (31.7-42.1 pM h(-1)) and inorganic carbon assimilation (40-85 nM h(-1)). Catalysed reporter deposition fluorescence in situ hybridization (CARD-FISH) and sequencing of 16S rRNA genes showed that the microbial community at the chemocline was dominated by the phototrophic green sulfur bacterium Chlorobium clathratiforme. Phylogenetic analyses of the nifH genes expressed as mRNA revealed a high diversity of N(2) fixers, with the highest expression levels right at the chemocline. The majority of N(2) fixers were related to Chlorobium tepidum/C. phaeobacteroides. By using Halogen In Situ Hybridization-Secondary Ion Mass Spectroscopy (HISH-SIMS), we could for the first time directly link Chlorobium to N(2) fixation in the environment. Moreover, our results show that N(2) fixation could partly compensate for the N loss and that both processes occur at the same locale at the same time as suggested for the ancient Ocean.

  8. Metagenome sequencing of the prokaryotic microbiota of the hypersaline and meromictic soap lake, washington.

    PubMed

    Hawley, Erik R; Hess, Matthias

    2014-01-23

    Soap Lake is a small saline lake in central eastern Washington that is sharply stratified into two layers. In addition to being highly alkaline (~pH 10), Soap Lake also contains high concentrations of sulfide. Here, we report the community profile of the prokaryotic microbiota associated with Soap Lake surface water.

  9. Lake

    ERIC Educational Resources Information Center

    Wien, Carol Anne

    2008-01-01

    The lake is blue black and deep. It is a glaciated finger lake, clawed out of rock when ice retracted across Nova Scotia in a northerly direction during the last ice age. The lake is narrow, a little over a mile long, and deep, 90 to 190 feet in places according to local lore, off the charts in others. The author loves to swim there, with a sense…

  10. Oxygen Minimum Zones in Miniature: Microbial Community Diversity, Activity, and Assembly Across Oxygen Gradients in Meromictic Marine Lakes, Palau

    NASA Astrophysics Data System (ADS)

    Beman, J. M.

    2016-02-01

    Oxygen minimum zones (OMZs) play a central role in biogeochemical cycles and are expanding as a consequence of climate change, yet our understanding of these changes is limited by a lack of systematic analyses of low-oxygen ecosystems. In particular, forecasting biogeochemical feedbacks to deoxygenation requires detailed knowledge of microbial community assembly and activity as oxygen declines. Marine `lakes'—isolated bodies of seawater surrounded by land—are an ideal comparative system, as they provide a pronounced oxygen gradient extending from well-mixed, holomictic lakes to stratified, meromictic lakes that vary in their extent of anoxia. We examined 13 marine lakes using pyrosequencing of 16S rRNA genes, quantitative PCR for nitrogen (N)- and sulfur (S)-cycling functional genes and groups, and N- and carbon (C)-cycling rate measurements. All lakes were inhabited by well-known marine bacteria, demonstrating the broad relevance of this study system. Microbial diversity was typically highest in the anoxic monimolimnion of meromictic lakes, with marine cyanobacteria, SAR11, and other common bacteria replaced by anoxygenic phototrophs, sulfate-reducing bacteria (SRBs), and SAR406 in the monimolimnion. Denitrifier nitrite reductase (nirS) genes were also detected alongside high abundances (>106 ml-1) of dissimilatory sulfite reductase (dsrA) genes from SRBs in the monimolimnion. Sharp changes in community structure were linked to environmental gradients (constrained variation in redundancy analysis=76%) and deterministic processes dominated community assembly at all depths (nearest taxon index values >4). These results indicate that oxygen is a strong, deterministic driver of microbial community assembly. We also observed enhanced N- and C-cycling rates along the transition from hypoxic to anoxic to sulfidic conditions, suggesting that microbial communities form a positive feedback loop that may accelerate deoxygenation and OMZ expansion.

  11. Morphological, Phylogenetic and Physiological Studies of Pico-Cyanobacteria Isolated from the Halocline of a Saline Meromictic Lake, Lake Suigetsu, Japan

    PubMed Central

    Ohki, Kaori; Yamada, Kazumasa; Kamiya, Mitsunobu; Yoshikawa, Shinya

    2012-01-01

    Small cyanobacteria (<2 μm, pico-cyanobacteria) are abundant in waters deeper than the oxic-anoxic zone in the halocline of a saline meromictic lake, Lake Suigetsu, Fukui, Japan. We have isolated 101 strains that were grouped into six groups by means of the phycobiliprotein composition and sequence homology of the intergenic spacer between the 16S and 23S rRNA genes. Significant growth was observed under weak green light (1.5 μmol m−2 s−1, approx. 460 to 600 nm), whereas the cells died under white light at even moderate intensities. The isolates grew in a wide range of salinities (0.2 to 3.2%). Tolerance to sulfide varied: four groups grew in medium containing sulfide, however, two groups did not. None of the isolates were capable of anoxygenic photosynthetic (PS-II independent photosynthetic) growth using sulfide as an electron donor. All groups were included within fresh and brackish water of Synechococcus/Cyanobium clade, but they were not monophyletic in the 16S rRNA gene-based phylogenetic tree. The physiological properties of pico-cyanobacteria showed that they had the ability to survive in unique physicochemical environments in the halocline of this saline meromictic lake. PMID:22791050

  12. Morphological, phylogenetic and physiological studies of pico-cyanobacteria isolated from the halocline of a saline meromictic lake, Lake Suigetsu, Japan.

    PubMed

    Ohki, Kaori; Yamada, Kazumasa; Kamiya, Mitsunobu; Yoshikawa, Shinya

    2012-01-01

    Small cyanobacteria (<2 µm, pico-cyanobacteria) are abundant in waters deeper than the oxic-anoxic zone in the halocline of a saline meromictic lake, Lake Suigetsu, Fukui, Japan. We have isolated 101 strains that were grouped into six groups by means of the phycobiliprotein composition and sequence homology of the intergenic spacer between the 16S and 23S rRNA genes. Significant growth was observed under weak green light (1.5 µmol m⁻² s⁻¹, approx. 460 to 600 nm), whereas the cells died under white light at even moderate intensities. The isolates grew in a wide range of salinities (0.2 to 3.2%). Tolerance to sulfide varied: four groups grew in medium containing sulfide, however, two groups did not. None of the isolates were capable of anoxygenic photosynthetic (PS-II independent photosynthetic) growth using sulfide as an electron donor. All groups were included within fresh and brackish water of Synechococcus/Cyanobium clade, but they were not monophyletic in the 16S rRNA gene-based phylogenetic tree. The physiological properties of pico-cyanobacteria showed that they had the ability to survive in unique physicochemical environments in the halocline of this saline meromictic lake.

  13. Spatial and temporal patterns in the microbial diversity of a meromictic soda lake in Washington State.

    PubMed

    Dimitriu, Pedro A; Pinkart, Holly C; Peyton, Brent M; Mormile, Melanie R

    2008-08-01

    The microbial community diversity and composition of meromictic Soap Lake were studied using culture-dependent and culture-independent approaches. The water column and sediments were sampled monthly for a year. Denaturing gradient gel electrophoresis of bacterial and archaeal 16S rRNA genes showed an increase in diversity with depth for both groups. Late-summer samples harbored the highest prokaryotic diversity, and the bacteria exhibited less seasonal variability than the archaea. Most-probable-number assays targeting anaerobic microbial guilds were performed to compare summer and fall samples. In both seasons, the anoxic samples appeared to be dominated by lactate-oxidizing sulfate-reducing prokaryotes. High numbers of lactate- and acetate-oxidizing iron-reducing bacteria, as well as fermentative microorganisms, were also found, whereas the numbers of methanogens were low or methanogens were undetectable. The bacterial community composition of summer and fall samples was also assessed by constructing 16S rRNA gene clone libraries. A total of 508 sequences represented an estimated >1,100 unique operational taxonomic units, most of which were from the monimolimnion, and the summer samples were more diverse than the fall samples (Chao1 = 530 and Chao1 = 295, respectively). For both seasons, the mixolimnion sequences were dominated by Gammaproteobacteria, and the chemocline and monimolimnion libraries were dominated by members of the low-G+C-content group, followed by the Cytophaga-Flexibacter-Bacteroides (CFB) group; the mixolimnion sediments contained sequences related to uncultured members of the Chloroflexi and the CFB group. Community overlap and phylogenetic analyses, however, not only demonstrated that there was a high degree of spatial turnover but also suggested that there was a degree of temporal variability due to differences in the members and structures of the communities.

  14. Methanobacterium lacus sp. nov., isolated from the profundal sediment of a freshwater meromictic lake.

    PubMed

    Borrel, Guillaume; Joblin, Keith; Guedon, Annie; Colombet, Jonathan; Tardy, Vincent; Lehours, Anne-Catherine; Fonty, Gérard

    2012-07-01

    An autotrophic, hydrogenotrophic methanogen, designated strain 17A1(T), was isolated from the profundal sediment of the meromictic Lake Pavin, France. The cells of the novel strain, which were non-motile, Gram-staining-negative rods that measured 2-15 µm in length and 0.2-0.4 µm in width, grew as filaments. Strain 17A1(T) grew in a mineral medium and its growth was stimulated by the addition of yeast extract, vitamins, acetate or rumen fluid. Penicillin, vancomycin and kanamycin reduced growth but did not completely inhibit it. Growth occurred at 14-41 °C (optimum 30 °C), at pH 5.0-8.5 (optimum pH 6.5) and with 0-0.4 M NaCl (optimum 0.1 M). The novel strain utilized H(2)/CO(2) and methanol/H(2) as substrates but not formate, acetate, methylamine/H(2), isobutanol or 2-propanol. Its genomic DNA G+C content was 37.0 mol%. In phylogenetic analyses based on 16S rRNA gene sequences, strain 17A1(T) appeared to be a member of the genus Methanobacterium, with Methanobacterium beijingense 8-2(T) (96.3% sequence similarity) identified as the most closely related established species. Based on phenotypic and phylogenetic data, strain 17A1(T) represents a novel species of methanogen within the genus Methanobacterium, for which the name Methanobacterium lacus sp. nov. is proposed. The type strain is 17A1(T) (=DSM 24406(T)=JCM 17760(T)).

  15. Isotopic analyses (/sup 18/O, /sup 13/C, /sup 14/C) of two meromictic lakes in the Canadian Arctic Archipelago

    SciTech Connect

    Page, P.; Ouellet, M.; Hillaire-Marcel, C.; Dickman, M.

    1984-05-01

    Meromictic Lakes Garrow and Sophia in the Canadian Arctic Archipelago were sampled to establish the origin and age of their water by isotopic studies. /sup 18/O values reflect the permanent stratification of the water in both lakes. The mixolimnia contain waters with an isotopic signal between -13.16 and -21.98%, coherent with the values for precipitation in these high latitudes. In the chemoclines, the delta/sup 18/O values increase to -10% concomitantly with a rise in chloride content to 42 g.liter/sup -1/. In the monimolimnia, hypersaline waters (up to 2.5 times the salinity of seawater) show negative delta/sup 18/O values (ca. -.08%). These waters result from brine production during permafrost growth in the watershed, according to a Rayleigh process. /sup 14/C dating of total inorganic carbon in the Lake Garrow monimolimnion gave an age of 2580 +/- 260 years BP. In Lake Sophia, the deep waters exhibit recent /sup 14/C activity that suggests recent infiltration of seawater into the lake basin.

  16. Partaking of Archaea to biogeochemical cycling in oxygen-deficient zones of meromictic saline Lake Faro (Messina, Italy).

    PubMed

    La Cono, Violetta; La Spada, Gina; Arcadi, Erika; Placenti, Francesco; Smedile, Francesco; Ruggeri, Gioacchino; Michaud, Luigi; Raffa, Carmen; De Domenico, Emilio; Sprovieri, Mario; Mazzola, Salvatore; Genovese, Lucrezia; Giuliano, Laura; Slepak, Vladlen Z; Yakimov, Michail M

    2013-06-01

    We used a combination of molecular and microbiological approaches to determine the activity, abundance and diversity of archaeal populations inhabiting meromictic saline Lake Faro (Messina, Italy). Analysis of archaeal 16S rRNA, amoA, accA and hbd genes and transcripts revealed that sub- and anoxic layers of Lake Faro are primarily inhabited by the organisms related to the clusters of Marine Group I.1a of Thaumarchaeota frequently recovered from oxygen-depleted marine ecosystems. These organisms dominated the metabolically active archaea down to the bottom of the lake, indicating their adaptation to recurrent changes in the levels of water column hypoxia. The upper microaerobic layer of Lake Faro redoxcline has the maximal rates of dark primary production much lower than those of other previously studied pelagic redoxclines, but comparable to the values of meso- and bathypelagic areas of Mediterranean Sea. Application of bacterial inhibitors, especially azide, significantly declined the CO2 fixation rates in the low interface and monimolimnion, whereas archaea-specific inhibitor had effect only in upper part of the redoxcline. Based on these findings, we hypothesize that dark bicarbonate fixation in suboxic zone of Lake Faro results mainly from archaeal activity which is affected by the predicted lack in oxygen in lower layers. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

  17. A Combined Molecular and Isotopic Study of Anoxygenic Photosynthesis in Meromictic Lakes of the Northwestern United States

    NASA Astrophysics Data System (ADS)

    Harris, J. H., IV; Gilhooly, W., III; Crane, E. J., III; Steinman, B.; Shelton, M. R.

    2014-12-01

    Sulfur isotope fractionations within the chemocline can be an indication of green and purple sulfur photosynthetic activity. This isotopic signal is, however, small and variable, on the order of +2-6‰ (Zerkle et al. 2009). It is therefore advantageous to investigate the environmental and ecological effects on this signal so that these influences can be taken into account when estimating the contribution of anoxygenic phototrophs to the sulfur cycle in aquatic environments. This project aims to investigate the ways in which anoxygenic phototroph community structure and lake water geochemistry impact the sulfur isotope fractionation expressed during anoxygenic photosynthesis in meromictic lakes. During the summer of 2013, water column profile analysis of six lakes in the Pacific Northwest (located in eastern Washington and western Montana) were conducted to assess photosynthetically available radiation, salinity, pH, temperature, dissolved solids, and specific conductivity. Water column samples were obtained to determine the sulfur isotopic composition of dissolved sulfate and sulfide, major ion and sulfide concentrations. Microbial samples were also collected for genetic sequencing. Initial results found green (e.g., Chlorobiaceae sp.) and purple (e.g., Lamprocystis purpurea) bacteria at the same depth in one of the study lakes. These data, in addition to the same suite of samples collected in the summer of 2014, provide insight into relationships between the isotopic composition of sulfur (in H2S, S0, and SO4), lake water chemistry, and the presence or absence of green and purple sulfur bacteria.

  18. Vertical distribution of Archaea and Bacteria in a meromictic lake as determined by fluorescent in situ hybridization.

    PubMed

    Lentini, Valeria; Gugliandolo, Concetta; Maugeri, Teresa L

    2012-01-01

    The prokaryotic cells distribution in the water column of the coastal saline meromictic Lake Faro (Messina, Italy) was investigated by microscopic counting techniques. Water samples were collected at a central station from the surface to the bottom, when waters were characterized by a marked stratification. A "red-water" layer, caused by a dense growth of photosynthetic sulfur bacteria, was present at a depth of 15 m, defining a transition area between oxic (mixolimnion) and anoxic (monimolimnion) layers. Fluorescently labeled 16S rRNA oligonucleotide, group-specific probes were used to determine the abundance of Bacteria and Archaea, and their subgroups, Green Sulfur Bacteria (GSB), Sulfate Reducing Bacteria (SRB), Cyanobacteria and Chromatium okenii, and Crenarchaeota and Euryarchaeota, as key elements of the microbial community. Bacteria decreased from surface to bottom, while Archaea increased with depth and reached the maximum value at 30 m, where they outnumbered the Bacteria. Bacteria and picophytoplankton prevailed in the mixolimnion. At the chemocline high numbers of prokaryotic cells were present, mainly represented by Cyanobacteria, Chromatium okenii and Euryarchaeota. GSB, SRB, and Crenarchaeota prevailed below the chemocline. Although Archaea constitute a minor fraction of microbial community, they could represent active contributors to the meromictic Lake Faro ecosystem.

  19. Methylosphaera hansonii gen. nov., sp. nov., a psychrophilic, group I methanotroph from Antarctic marine-salinity, meromictic lakes.

    PubMed

    Bowman, J P; McCammon, S A; Skerratt, J H

    1997-04-01

    Methanotrophic bacteria were enumerated and isolated from the chemocline and surface sediments of marine-salinity Antarctic meromictic lakes located in the Vestfold Hills, Antarctica (68 degrees S 78 degrees E). Most probable number (MPN) analysis indicated that at the chemocline of Ace Lake the methanotroph population made up only a small proportion of the total microbial population and was sharply stratified, with higher populations detected in the surface sediments collected at the edge of Ace Lake and Burton Lake. Methanotrophs were not detected in Pendant Lake. Only a single phenotypic group of methanotrophs was successfully enriched, enumerated and isolated into pure culture from the lake samples. Strains of this group were non-motile, coccoidal in morphology, did not form resting cells, reproduced by constriction, and required seawater for growth. The strains were also psychrophilic, with optimal growth occurring at 10-13 degrees C and maximum growth temperatures of 16-21 degrees C. The ribulose monophosphate pathway but not the serine pathway for incorporation of C1 compounds was detectable in the strains. The guanine plus cytosine (G + C) content of the genomic DNA was 43-46 mol%. Whole-cell fatty acid analysis indicated that 16:1 omega 8c (37-41%), 16:1 omega 6c (17-19%), 16:1 omega 7c (15-19%) and 16:0 (14-15%) were the major fatty acids in the strains. 16s rDNA sequence analysis revealed that the strains form a distinct line of descent in the family Methylococcaceae (group I methanotrophs), with the closest relative being the Louisiana Slope methanotrophic mytilid endosymbiont (91.8-92.3% sequence similarity). On the basis of polyphasic taxonomic characteristics the Antarctic lake isolates represent a novel group I methanotrophic genus with the proposed name Methylosphaera hansonii (type strain ACAM 549).

  20. [Dynamics of Purple Sulfur Bacteria in a Meromictic Saline Lake Shunet (Khakassia, Siberia) in 2007-2013].

    PubMed

    Rogozin, D Yu; Zykova, V V; Tarnovskii, M O

    2016-01-01

    According to the results of seasonal monitoring, in 2007-2013 purple sulfur bacteria morphologically similar to Thiocapsa sp. Shira_1 (AJ633676 in EMBL/GenBank) predominated in the anoxygenic phototrophic community of the water column of the meromictic Lake Shira (Khakassia, Siberia). No pronounced seasonal periodicity in the total cell number in the water column was revealed during the period of observation. In some years cell number during the period when the lake was covered with ice was reliably higher than in summer. The absence ofseasonal periodicity was probably due to the low amplitude of seasonal variations in temperature and illumination in the redox zone, resulting from its relatively deep location (12-16 m). The year-to-year dynamics was characterized by a reliable decrease of the total cell number in 2009-2010 and maxima in 2007 and 2011-2012. Canonical correlation analysis revealed that water temperature in the redox zone was the best predictor of the PSB abundance in Lake Shira. Water temperature, in turn, depended on the depth of mixing of the water column. Intense mixing in 2009-2011 was probably responsible for decreased PSB abundance in the lake. On the other hand, the absence of deep winter mixing, resulting in stable conditions in the chemocline, favored the preservation of relatively high PSB biomass. Prediction of circulation depth, which.depends mainly on the weather conditions and dynamics of the water level, is required for prediction of PSB abundance in Lake Shira. These results may be useful for paleolimnological reconstructions of the history of the lake based on the remnants of purple sulfur bacteria in bottom sediments.

  1. Diversity and community structure within anoxic sediment from marine salinity meromictic lakes and a coastal meromictic marine basin, Vestfold Hilds, Eastern Antarctica.

    PubMed

    Bowman, J P; Rea, S M; McCammon, S A; McMeekin, T A

    2000-04-01

    16S rDNA clone library analysis was used to examine the biodiversity and community structure within anoxic sediments of several marine-type salinity meromictic lakes and a coastal marine basin located in the Vestfolds Hills area of Eastern Antarctica. From 69 to 130 (555 total) 16S rDNA clones were analysed from each sediment sample, and restriction fragment length polymorphism (RFLP) and sequence analysis grouped the clones into 202 distinct phylotypes (a clone group with sequence similarity of >0.98). A number of phylotypes and phylotype groups predominated in all libraries, with a group of 10 phylotypes (31% of clones) forming a novel deep branch within the low G+C Gram-positive division. Other abundant phylotypes detected in several different clone libraries grouped with Prochlorococcus cyanobacteria, diatom chloroplasts, delta proteobacteria (Desulfosarcina group, Syntrophus and Geobacterl Pelobacter/Desulphuromonas group), order Chlamydiales (Parachlamydiaceae) and Spirochaetales (wall-less Antarctic spirochaetes). Most archaeal clones detected (3.1% of clones) belonged to a highly diverged group of Euryarchaeota clustering with clones previously detected in rice soil, aquifer sediments and hydrothermal vent material. Little similarity existed between the phylotypes detected in this study and other clone libraries based on marine sediment, suggesting that an enormous prokaryotic diversity occurs within marine and marine-derived sediments.

  2. Nitrogen cycling and N2O production in the water column of the ferruginous meromictic Lake La Cruz (Spain)

    NASA Astrophysics Data System (ADS)

    Tischer, Jana; Zopfi, Jakob; Frame, Caitlin H.; Jegge, Corinne; Kirsten, Oswald; Andreas, Brand; Miracle, Maria R.; Vicente, Eduardo; Lehmann, Moritz F.

    2016-04-01

    Ferruginous meromictic lakes are rare systems, considered potential modern analogues for an ancient Archean ferruginous Ocean. They may therefore represent valuable model ecosystems to study biogeochemical processes of early Earth history, in particular, the interaction between the iron (Fe) and other element cycles such as the complex nitrogen (N) cycle. In context of its exceptional water chemistry, we studied the N-cycling in the meromictic, ferruginous Lake La Cruz in the Central Iberian Ranges in Spain, combining i) general water column chemistry and detailed N speciation ii) stable isotope composition and intramolecular 15N distributions (site preference) of dissolved N2O and iii) 15N-isotope label incubation experiments, to identify and quantify biotic and abiotic N2O and N2 production pathways. Nitrification was identified as the main N2O production mechanism in the oxic zone, based on the N2O concentration profile and the isomeric composition of N2O (site preference = 24.7) at the depth of maximum concentration relative to the surface water. A second N2O peak of 23 nmol/L was observed within the chemocline, and relatively low values for the δ15N-N2O (-1.1) and a site preference of 16.1‰ with respect to the oxic water column suggest that here incomplete (nitrifier) denitrification is the dominant N2O production pathway. However, based on the bulk dual N-versus-O isotope signature, other production mechanisms cannot be excluded at this point. Within the anoxic water column, N2O is consumed quantitiatively to N2, consistent with 15N-NO3- incubation experiments, showing denitrification (and anammox) activity below the redox transition zone. The overlap of Fe and N-species (N2O, NO2-) in the water column is small, therefore abiotic N2O production is most likely negligible. The planned analysis of the NO3- and NH4+ isotopic signatures will provide further insight into the origin of N2O. Additionally, molecular biological analyses will provide information on

  3. Phylogenetic diversity of archaea and bacteria in the anoxic zone of a meromictic lake (Lake Pavin, France).

    PubMed

    Lehours, Anne-Catherine; Evans, Paul; Bardot, Corinne; Joblin, Keith; Gérard, Fonty

    2007-03-01

    The compositions of archaeal and bacterial populations at different depths (60 m [mixolimnion-chemocline interface], 70 m [chemocline-subchemocline interface], 90 m, and 92 m [the water-sediment interface]) in the anoxic zone of the water column in Lake Pavin, a freshwater permanently stratified mountain lake in France, were determined. Phylogenetic trees were constructed from sequences to assess archaeal and bacterial diversity at the four sites.

  4. Diversity and Dynamics of Active Small Microbial Eukaryotes in the Anoxic Zone of a Freshwater Meromictic Lake (Pavin, France).

    PubMed

    Lepère, Cécile; Domaizon, Isabelle; Hugoni, Mylène; Vellet, Agnès; Debroas, Didier

    2016-01-01

    Microbial eukaryotes play a crucial role in ecosystem functioning and oxygen is considered to be one of the strongest barriers against their local dispersal. However, diversity of microbial eukaryotes in freshwater habitats with oxygen gradients has previously received very little attention. We applied high-throughput sequencing (V4 region of the 18S rRNA gene) in conjunction with quantitative PCR (DNA and RNA) and fluorescent in situ hybridization (FISH) analyses, to provide an unique spatio-temporal analysis of microbial eukaryotes diversity and potential activity in a meromictic freshwater lake (lake Pavin). This study revealed a high genetic diversity of unicellular eukaryotes in the permanent anoxic zone of lake Pavin and allowed the discrimination of active vs. inactive components. Forty-two percent of the OTUs (Operational Taxonomic Units) are exclusively present in the monimolimnion, where Alveolata (Ciliophora and Dinophyceae) and Fungi (Dikarya and Chytrids) are the most active phyla and are probably represented by species capable of anaerobic metabolism. Pigmented eukaryotes (Haptophyceae and Chlorophyceae) are also present and active in this zone, which opens up questions regarding their metabolism.

  5. Diversity and Dynamics of Active Small Microbial Eukaryotes in the Anoxic Zone of a Freshwater Meromictic Lake (Pavin, France)

    PubMed Central

    Lepère, Cécile; Domaizon, Isabelle; Hugoni, Mylène; Vellet, Agnès; Debroas, Didier

    2016-01-01

    Microbial eukaryotes play a crucial role in ecosystem functioning and oxygen is considered to be one of the strongest barriers against their local dispersal. However, diversity of microbial eukaryotes in freshwater habitats with oxygen gradients has previously received very little attention. We applied high-throughput sequencing (V4 region of the 18S rRNA gene) in conjunction with quantitative PCR (DNA and RNA) and fluorescent in situ hybridization (FISH) analyses, to provide an unique spatio-temporal analysis of microbial eukaryotes diversity and potential activity in a meromictic freshwater lake (lake Pavin). This study revealed a high genetic diversity of unicellular eukaryotes in the permanent anoxic zone of lake Pavin and allowed the discrimination of active vs. inactive components. Forty-two percent of the OTUs (Operational Taxonomic Units) are exclusively present in the monimolimnion, where Alveolata (Ciliophora and Dinophyceae) and Fungi (Dikarya and Chytrids) are the most active phyla and are probably represented by species capable of anaerobic metabolism. Pigmented eukaryotes (Haptophyceae and Chlorophyceae) are also present and active in this zone, which opens up questions regarding their metabolism. PMID:26904006

  6. In situ analysis of sulfate-reducing bacteria related to Desulfocapsa thiozymogenes in the chemocline of meromictic Lake Cadagno (Switzerland)

    SciTech Connect

    Tonolla, M.; Demarta, A.; Peduzzi, S.; Hahn, D.; Peduzzi, R.

    2000-02-01

    Comparative sequence analysis of a 16S rRNA gene clone library from the chemocline of the meromictic Lake Cadagno (Switzerland) retrieved two clusters of sequences resembling sulfate-reducing bacteria within the family Desulfovibrionaceae. In situ hybridization showed that, similar to sulfate-reducing bacteria of the family Desulfobacteriaceae, bacteria of one cluster with similarity values to the closest cultured relatives of between 92.6 and 93.1% resembled free cells or cells loosely attached to other cells or debris. Bacteria of the second cluster closely related to Desulfocapsa thiozymogenes DSM7269 with similarity values between 97.9 and 98.4% were generally associated with aggregates of different small-celled phototrophic sulfur bacteria, suggesting a potential interaction between the two groups of bacteria.

  7. Stratification of Archaea in the deep sediments of a freshwater meromictic lake: vertical shift from methanogenic to uncultured archaeal lineages.

    PubMed

    Borrel, Guillaume; Lehours, Anne-Catherine; Crouzet, Olivier; Jézéquel, Didier; Rockne, Karl; Kulczak, Amélie; Duffaud, Emilie; Joblin, Keith; Fonty, Gérard

    2012-01-01

    As for lineages of known methanogens, several lineages of uncultured archaea were recurrently retrieved in freshwater sediments. However, knowledge is missing about how these lineages might be affected and structured according to depth. In the present study, the vertical changes of archaeal communities were characterized in the deep sediment of the freshwater meromictic Lake Pavin. For that purpose, an integrated molecular approach was performed to gain information on the structure, composition, abundance and vertical stratification of archaeal communities thriving in anoxic freshwater sediments along a gradient of sediments encompassing 130 years of sedimentation. Huge changes occurred in the structure and composition of archaeal assemblages along the sediment core. Methanogenic taxa (i.e. Methanosaeta and Methanomicrobiales) were progressively replaced by uncultured archaeal lineages (i.e. Marine Benthic Group-D (MBG-D) and Miscellaneous Crenarchaeal Group (MCG)) which are suspected to be involved in the methane cycle.

  8. Stratification of Archaea in the Deep Sediments of a Freshwater Meromictic Lake: Vertical Shift from Methanogenic to Uncultured Archaeal Lineages

    PubMed Central

    Borrel, Guillaume; Lehours, Anne-Catherine; Crouzet, Olivier; Jézéquel, Didier; Rockne, Karl; Kulczak, Amélie; Duffaud, Emilie; Joblin, Keith; Fonty, Gérard

    2012-01-01

    As for lineages of known methanogens, several lineages of uncultured archaea were recurrently retrieved in freshwater sediments. However, knowledge is missing about how these lineages might be affected and structured according to depth. In the present study, the vertical changes of archaeal communities were characterized in the deep sediment of the freshwater meromictic Lake Pavin. For that purpose, an integrated molecular approach was performed to gain information on the structure, composition, abundance and vertical stratification of archaeal communities thriving in anoxic freshwater sediments along a gradient of sediments encompassing 130 years of sedimentation. Huge changes occurred in the structure and composition of archaeal assemblages along the sediment core. Methanogenic taxa (i.e. Methanosaeta and Methanomicrobiales) were progressively replaced by uncultured archaeal lineages (i.e. Marine Benthic Group-D (MBG-D) and Miscellaneous Crenarchaeal Group (MCG)) which are suspected to be involved in the methane cycle. PMID:22927959

  9. Diversity of freshwater Epsilonproteobacteria and dark inorganic carbon fixation in the sulphidic redoxcline of a meromictic karstic lake.

    PubMed

    Noguerola, Imma; Picazo, Antonio; Llirós, Marc; Camacho, Antonio; Borrego, Carles M

    2015-07-01

    Sulfidic redoxclines are a suitable niche for the growth and activity of different chemo- and photolithotrophic sulphide-oxidizing microbial groups such as the Epsilonproteobacteria and the green sulfur bacteria (GSB). We have investigated the diversity, abundance and contribution to inorganic carbon uptake of Epsilonproteobacteria in a meromictic basin of Lake Banyoles. CARD-FISH counts revealed that Epsilonproteobacteria were prevalent at the redoxcline in winter (maximum abundance of 2 × 10(6) cells mL(-1), ≈60% of total cells) but they were nearly absent in summer, when GSB bloomed. This seasonal trend was supported by 16S rRNA gene pyrotag datasets, which revealed that the epsilonproteobacterial community was mainly composed of a member of the genus Arcobacter. In situ incubations using NaH(14)CO3 and MAR-CARD-FISH observations showed that this population assimilated CO2 in the dark, likely being mainly responsible for the autotrophic activity at the redoxcline in winter. Clone libraries targeting the aclB gene provided additional evidence of the potential capacity of these epsilonproteobacteria to fix carbon via rTCA cycle. Our data reinforce the key role of Epsilonproteobacteria in linking carbon and sulphur cycles, extend their influence to freshwater karstic lakes and raise questions about the actual contribution of chemolithotrophy at their redoxcline and euxinic water compartments.

  10. Early diagenetic processes of saline meromictic Lake Kai-ike, southwest Japan: III. Sulfur speciation and isotopes

    NASA Astrophysics Data System (ADS)

    Sakai, N.; Yamaguchi, K. E.; Oguri, K.

    2014-12-01

    Lake Kai-ike is a saline meromictic lake located along the coast of Kami-Koshiki Island. The lake is isolated from ocean by a gravel bar, through which seawater infiltrates by tidal pumping. The lake is permanently redox (density)-stratified with a mid-depth development of photic zone anoxia and a dense community of photosynthetic bacteria pinkish "bacterial plate". The early diagenesis of sulfur in sediments overlain by an anoxic water body was investigated using a sediment core (KAI4) from the lake. We determined abundance of various S-bearing species (i.e., Cr-reducible sulfide (= pyrite S: Spy), acid-volatile sulfide (AVS), sulfate sulfur (SSO4), elemental sulfur (S0), and organic sulfur) by an improved sequential extraction method. Here we focus on drastic and rapid changes on sulfur biogeochemistry found in the uppermost 5cm layer. With increasing depth, abundance of Spy increased but that of SSO4 and δ34S value of Spy (δ34Spy) decreased. These results suggest progressive formation of bacteriogenic pyrite. The δ34S values of SSO4 (δ34SSO4) ranged from 25.1 ‰ (at sediment surface) to 3.8 ‰ in the uppermost 5 cm layer. This δ34SSO4 decrease in the top 5 cm sediment suggests that SSO4 in the surface sediment inherits SO42- with elevated δ34S values (higher than typical seawater δ34S value of 21‰) in the water column, which is due to extensive bacterial sulfate reduction with preferential removal of low-δ34S sulfur as sulfide. In the lower part of the uppermost 5 cm layer, SO42- formed by oxidation of S0, AVS, and/or Spy with low-δ34S values by SO42--bearing seawater introduced by infiltration through the gravel bar. Increasing δ34Spy values with increasing depth suggest near complete consumption of SO42- by active bacterial sulfate reduction, and this process could be explained by Rayleigh distillation model. Early diagenesis of sulfur does occur in whole section of 25cm-long KAI4 core that accumulated for the last ~60 years (Yamaguchi et al

  11. Distribution, abundance and carbon isotopic composition of gaseous hydrocarbons in Big Soda Lake, Nevada - An alkaline, meromictic lake

    NASA Technical Reports Server (NTRS)

    Oremland, R. S.; Des Marais, D. J.

    1983-01-01

    The study of the distribution and isotopic composition of low molecular weight hydrocarbon gases at the Big Soda Lake, Nevada, has shown that while neither ethylene nor propylene were found in the lake, ethane, propane, isobutane and n-butane concentrations all increased with water column depth. It is concluded that methane has a biogenic origin in both the sediments and the anoxic water column, and that C2-C4 alkanes have biogenic origins in the monimolimnion water and shallow sediments. The changes observed in delta C-13/CH4/ and CH4/(C2H6 + C3H8) with depth in the water column and sedimeents are probably due to bacterial processes, which may include anaerobic methane oxidation and different rates of methanogenesis, and C2-to-C4 alkane production by microorganisms.

  12. Distribution, abundance and carbon isotopic composition of gaseous hydrocarbons in Big Soda Lake, Nevada - An alkaline, meromictic lake

    NASA Technical Reports Server (NTRS)

    Oremland, R. S.; Des Marais, D. J.

    1983-01-01

    The study of the distribution and isotopic composition of low molecular weight hydrocarbon gases at the Big Soda Lake, Nevada, has shown that while neither ethylene nor propylene were found in the lake, ethane, propane, isobutane and n-butane concentrations all increased with water column depth. It is concluded that methane has a biogenic origin in both the sediments and the anoxic water column, and that C2-C4 alkanes have biogenic origins in the monimolimnion water and shallow sediments. The changes observed in delta C-13/CH4/ and CH4/(C2H6 + C3H8) with depth in the water column and sedimeents are probably due to bacterial processes, which may include anaerobic methane oxidation and different rates of methanogenesis, and C2-to-C4 alkane production by microorganisms.

  13. Hypolimnetic dominance of epilimnetic dissolved inorganic carbon (DIC) δ13C and its relationship to isotopic covariance in the sedimentary record from a meromictic urban lake (Lake McCarrons, Minnesota, USA)

    NASA Astrophysics Data System (ADS)

    Myrbo, A.; Shapley, M.

    2011-12-01

    Water column stratification is an influential process in the lacustrine carbon cycle. In meromictic lakes with persistently anoxic bottom waters, the hypolimnetic processing and allocation of C may be more important than epilimnetic productivity in determining δ13C values of dissolved inorganic carbon (DIC), and by extension the δ13C values of organic and carbonate sedimentary components. In addition, hypolimnetic processes may be central to reconciling seemingly contradictory records from authigenic carbonates and autochthonous organic matter. Resolution of the biogeochemical and physical processes involved in determining mean δ13CDIC values and the direction and relative magnitude of δ13CDIC anomalies is critical to understanding the widely used sedimentary records of anoxic, meromictic lakes. It is likely that methanogenesis, advection via thermocline erosion, and ebullition of methane gas are key processes in the evolution of epilimnetic δ13CDIC values over time. Lake McCarrons (Minneapolis-St. Paul metropolitan area, population 3.4x106) provides an intriguing field setting for examining the effects of hypolimnetic processes on the lacustrine carbon cycle as represented in both the modern system and paleorecord. An isotope mass-balance model illuminates the observed systematic relationship between carbon and oxygen isotopic values of authigenic calcite (the poorly understood "isotopic covariance" of Talbot and others), and changes in the phasing of oscillations in the two records following the establishment of persistent hypolimnetic anoxia and stratification in the early 20th century. The model parameterizes simplified lake mixing, carbon allocation, and isotope fractionation processes, allowing examination of the sensitivity of sediment isotope trends in meromictic systems to changes in these limnologic characteristics, as well as tentative generalizations to other meromictic lake systems.

  14. Biogeochemical processes controlling density stratification in an iron-meromictic lake

    NASA Astrophysics Data System (ADS)

    Nixdorf, E.; Boehrer, B.

    2015-06-01

    Biogeochemical processes and mixing regime of a lake can control each other mutually. The prominent case of iron meromixis is investigated in Waldsee near Doebern, a small lake that originated from surface mining of lignite. From a four years data set of monthly measured electrical conductivity profiles, we calculated summed conductivity as a quantitative variable reflecting the amount of electro-active substances in the entire lake. Seasonal variations followed changing chemocline height. Coinciding changes of electrical conductivities in the monimolimnion indicated that a considerable share of substances, precipitated by the advancing oxygenated epilimnion, re-dissolved in the remaining anoxic deep waters and contributed considerably to the density stratification. In addition, we constructed a lab experiment, in which aeration of monimolimnetic waters removed iron compounds and organic material. Precipitates could be identified by visual inspection. Introduced air bubbles ascended through the water column and formed a water mass similar to the mixolimnetic Waldsee water. The remaining less dense water remained floating on the nearly unchanged monimolimnetic water. In conclusion, iron meromixis as seen in Waldsee did not require two different sources of incoming waters, but the inflow of iron rich deep groundwater and the aeration through the lake surface were fully sufficient.

  15. Quantifying, assessing and removing the extreme gas load from meromictic Guadiana pit lake, Southwest Spain.

    PubMed

    Boehrer, Bertram; Yusta, Iñaki; Magin, Katrin; Sanchez-España, Javier

    2016-09-01

    High gas charges in deep waters of lakes can represent a hazard to the lives of human beings and animals in the surrounding. As this danger was feared, we quantified the amount of dissolved gas in Guadiana pit lake (Las Herrerías, Huelva; southwest Spain) and documented the temporal evolution over a period of two years. Gas pressure due to dissolved gases, such as carbon dioxide, methane and nitrogen was measured. Based on these data, we assessed the risk and the associated danger of limnic eruptions from the lake and concluded that the present situation cannot be considered safe. By deploying a vertical pipe, the updraft of degassing water was tested and demonstrated: the pilot plant provided enough energy to drive a self-sustained flow. Such a system could be implemented to remove the extreme gas pressure from the deep water. Measurements of discharges could be extrapolated to indicate the size for an efficient plant for the gas removal. The construction of such a system would be technically and economically viable. A reintroduction of degassed water into the monimolimnion would be advisable.

  16. Dynamics of the anoxygenic phototrophic community in meromictic Fayetteville Green Lake (NY) and the associated sedimentary pigment record

    NASA Astrophysics Data System (ADS)

    Meyer, K. M.; Fulton, J. M.; Hunter, S.; Macalady, J. L.; Kump, L.; Freeman, K. H.

    2012-12-01

    Photosynthetic pigments and their diagenetic products in marine sedimentary rocks hold important clues about recent and ancient variability in the Earth's surface environment. The chemical relicts of carotenoids from anoxygenic sulfur bacteria are of particular interest to geoscientists because of their potential to signal episodes of marine photic-zone euxinia such as those proposed for extended periods in the Proterozoic as well as brief intervals during the Phanerozoic. It is therefore critical to constrain the environmental and physiological factors that influence carotenoid production and preservation in modern environments. Our work in redox stratified, microbially dominated Fayetteville Green Lake (New York) has spanned the past decade and included seasonal (2005-2006) and monthly (2011) pigment monitoring in the water column, as well as a coupled pigment and nucleic acid clone library analyses from planktonic and benthic samples in 2006. Populations of photosynthetic bacteria in the water column are dynamic on monthly and annual scales. In 2011, purple sulfur bacteria (PSB) and green sulfur bacteria (GSB) were most abundant in spring and fall, respectively, responding to environmental conditions. PSB are diverse both at the chemocline and in benthic mats below oxygenated shallow waters, with different PSB species inhabiting the two environments. Okenone (from PSB) is an abundant carotenoid in both the chemocline waters and in benthic mats. GSB and their primary pigment Bchl e are also represented in and below the chemocline. However, the water column and sediments contain only trace concentrations of the GSB carotenoid isorenieratene, with concentrations relative to Bchl e being at least two orders of magnitude lower than we have observed in other meromictic lakes. Sediments deposited over the past ~550 years also reveal decadal to centennial scale variability in pigment production in the water column, possibly associated with hypothesized climatic and

  17. Suigetsumonas clinomigrationis gen. et sp. nov., a Novel Facultative Anaerobic Nanoflagellate Isolated from the Meromictic Lake Suigetsu, Japan.

    PubMed

    Okamura, Takahiko; Kondo, Ryuji

    2015-09-01

    A novel facultative anaerobic bacterivorous nanoflagellate was isolated from the water just below the permanent oxic-anoxic interface of the meromictic Lake Suigetsu, Japan. We characterized the isolate using light and transmission electron microscopy and molecular phylogenetic analyses inferred from 18S rDNA sequences. The phylogenetic analyses showed that the isolate belonged to class Placididea (stramenopiles). The isolate showed key ultrastructural features of the Placididea, such as flagellar hairs with two unequal terminal filaments, microtubular root 2 changing in shape from an arced to an acute-angled shape, and a lack of an x-fiber in root 2. However, the isolate had a single helix in the flagellar transition region, which is a double helix in the two known placidid nanoflagellates Placidia cafeteriopsis and Wobblia lunata. Moreover, the isolate had different intracellular features compared with these two genera, such as the arrangement of basal bodies, the components of the flagellar apparatus, the number of mitochondria, and the absence (or presence) of paranuclear bodies. The 18S rDNA sequence was also phylogenetically distant from the clades of the known Placididae W. lunata and P. cafeteriopsis. Consequently, the newly isolated nanoflagellate was described as Suigetsumonas clinomigrationis gen. et sp. nov. Copyright © 2015 Elsevier GmbH. All rights reserved.

  18. Predation impact of ciliated and flagellated protozoa during a summer bloom of brown sulfur bacteria in a meromictic coastal lake.

    PubMed

    Saccà, Alessandro; Borrego, Carles M; Renda, Rossella; Triadó-Margarit, Xavier; Bruni, Vivia; Guglielmo, Letterio

    2009-10-01

    Anaerobic phagotrophic protozoa may play an important role in the carbon flux of chemically stratified environments, especially when phototrophic sulfur bacteria account for a high proportion of the primary production. To test this assumption, we investigated the vertical and temporal distribution of microbial heterotrophs and of autotrophic picoplankton throughout the water column of the meromictic coastal lake Faro (Sicily, Italy), in the summer of 2004, coinciding with a bloom of brown-colored green sulfur bacteria. We also assessed the grazing impact of ciliated and flagellated protozoa within the sulfur bacteria plate using a modification of the fluorescently labeled bacteria uptake approach, attempting to minimize the biases intrinsic to the technique and to preserve the in situ anoxic conditions. Significant correlations were observed between ciliate biomass and bacteriochlorophyll e concentration, and between heterotrophic nanoflagellate biomass and chlorophyll a concentration in the water column. The major predators of anaerobic picoplankton were pleuronematine ciliates and cryptomonad flagellates, with clearances of 26.6 and 9.5 nL per cell h(-1), respectively, and a cumulative impact on the picoplankton gross growth rate ranging between 36% and 72%. We concluded that protozoan grazing channels a large proportion of anaerobic picoplankton production to higher trophic levels without restraining photosynthetic bacteria productivity.

  19. Biogeochemical processes in the saline meromictic Lake Kaiike, Japan: implications from molecular isotopic evidences of photosynthetic pigments.

    PubMed

    Ohkouchi, Naohiko; Nakajima, Yoji; Okada, Hisatake; Ogawa, Nanako O; Suga, Hisami; Oguri, Kazumasa; Kitazato, Hiroshi

    2005-07-01

    Stable carbon and nitrogen isotopic compositions were determined for individual photosynthetic pigments isolated and purified from the saline meromictic Lake Kaiike, Japan, to investigate species-independent biogeochemical processes of photoautotrophs in the natural environment. In the anoxic monimolimnion and benthic microbial mats, the carbon isotopic compositions of BChls e and isorenieratene related to brown-coloured strains of green sulfur bacteria are substantially ( approximately 10 per thousand) depleted in (13)C relative to those found in the chemocline. In conjunction with 16S rDNA evidence reported previously, it strongly suggests that Pelodyctyon luteolum inhabited and photosynthesized in the anoxic monimolimnion and benthic microbial mats by using (13)C-depleted regenerated CO(2). By contrast, both Chl a and BChl a in the monimolimnion and microbial mats have similar isotopic compositions as they do in the chemocline, implying that the source organisms live only in the chemocline. In the chemocline, the nitrogen isotopic compositions of BChl e homologues ranges from -7.7 to-6.5 per thousand, whereas that of BChl a is -2.1 per thousand. These isotopic compositions suggest that green sulfur bacteria Chlorobium phaeovibrioides would conduct nitrogen fixation in the chemocline, whereas purple sulfur bacteria Halochromatium sp. and cyanobacteria Synechococcus sp. may assimilate nitrite.

  20. Seasonal changes in the chemistry and biology of a meromictic lake (Big Soda Lake, Nevada, U.S.A.)

    USGS Publications Warehouse

    Cloern, J.E.; Cole, B.E.; Oremland, R.S.

    1983-01-01

    Big Soda Lake is an alkaline, saline lake with a permanent chemocline at 34.5 m and a mixolimnion that undergoes seasonal changes in temperature structure. During the period of thermal stratification, from summer through fall, the epilimnion has low concentrations of dissolved inorganic nutrients (N, Si) and CH4, and low biomass of phytoplankton (chlorophyll a ca. 1 mgm -3). Dissolved oxygen disappears near the compensation depth for algal photosynthesis (ca. 20 m). Surface water is transparent so that light is present in the anoxic hypolimnion, and a dense plate of purple sulfur photosynthetic bacteria (Ectothiorhodospira vacuolata) is present just below 20 m (Bchl a ca. 200 mgm-3). Concentrations of N H4+, Si, and CH4 are higher in the hypolimnion than in the epilimnion. As the mixolimnion becomes isothermal in winter, oxygen is mixed down to 28 m. Nutrients (NH4+, Si) and CH4 are released from the hypolimnion and mix to the surface, and a diatom bloom develops in the upper 20 m (chlorophyll a > 40 mgm-3). The deeper mixing of oxygen and enhanced light attenuation by phytoplankton uncouple the anoxic zone and photic zone, and the plate of photosynthetic bacteria disappears (Bchl a ca.10mgm-3). Hence, seasonal changes in temperature distribution and mixing create conditions such that the primary producer community is alternately dominated by phytoplankton and photosynthetic bacteria: the phytoplankton may be nutrient-limited during periods of stratification and the photosynthetic bacteria are light-limited during periods of mixing. ?? 1983 Dr W. Junk Publishers.

  1. Dynamics of the methane profile through the water column of meromictic Fayetteville Green Lake, N.Y

    NASA Astrophysics Data System (ADS)

    McClure, B. E.; Havig, J. R.; Sowers, T. A.; Hamilton, T. L.; McCormick, M.; Kump, L. R.

    2013-12-01

    Green Lake in Fayetteville, N.Y. is a meromictic lake with a chemocline approximately 21 meters below the surface where redox chemistry shifts from micro-aerobic to euxinic, and a purple- and green- sulfur bacterial plate is a predominant feature. Historic data, mirrored by our recent (November 2012) high-resolution sampling and analysis, document a monimolimnion methane concentration profile that increases nearly linearly with depth to the bottom sediments. Gas chromatography (GC) and Flame Ionization Detection (FID) analyses reveal concentrations exceeding20 μM CH4 at 30 cm depth in the sediments, lower concentrations ranging from ~5 μM CH4 at 44 m to 1.5 μM CH4 at 21.75 m in the water column, and decreased concentrations with an average of 0.12 μM CH4 from 21 m through the chemocline and the oxic zone, demonstrating a diffusive trend from sediments to the chemocline. However, our findings exhibit a departure from linearity from 21-30 meters in which methane concentrations were higher than expected if the sediments were the sole source of methane. We incubated biomass collected from 24 m (June 2013) to examine the source of this unexpected ';hump' in methane concentrations in the water column. To date, no methane production has been observed. Isotopic analysis for δ 13C in CH4 of seven water samples collected from depths above, below and in the methane ';hump' indicate that methane present in the water column is biogenic. Furthermore, the δ 13C values observed, approximately -100‰, indicate biologically- mediated cycling of methane. δ13C values of dissolved inorganic carbon (DIC) indicate input of oxidized methane. These findings suggest that two sources of methane with similar isotopic compositions exist, one diffusing from lake-bottom sediments and the other laterally injected from seeps at or near the chemocline, with consumption near the base of the chemocline. Coupled geochemical analyses show that sulfide and ammonia exhibit a similar concentration

  2. Intensive cryptic microbial iron cycling in the low iron water column of the meromictic Lake Cadagno.

    PubMed

    Berg, Jasmine S; Michellod, Dolma; Pjevac, Petra; Martinez-Perez, Clara; Buckner, Caroline R T; Hach, Philipp F; Schubert, Carsten J; Milucka, Jana; Kuypers, Marcel M M

    2016-12-01

    Iron redox reactions play an important role in carbon remineralization, supporting large microbial communities in iron-rich terrestrial and aquatic sediments. Stratified water columns with comparably low iron concentrations are globally widespread, but microbial iron cycling in these systems has largely been ignored. We found evidence for unexpectedly high iron turnover rates in the low (1-2 µmol·l(-1) ) iron waters of Lake Cadagno. Light-dependent, biological iron oxidation rates (1.4-13.8 µmol·l(-1) ·d(-1) ) were even higher than in ferruginous lakes with well-studied microbial iron cycles. This photoferrotrophic iron oxidation may account for up to 10% of total primary production in the chemocline. Iron oxides could not be detected and were presumably reduced immediately by iron-reducing microorganisms. Sequences of putative iron oxidizers and reducers were retrieved from in situ 16S rRNA gene amplicon libraries and some of these bacteria were identified in our enrichment cultures supplemented with Fe(II) and FeS. Based on our results, we propose a model in which iron is oxidized by photoferrotrophs and microaerophiles, and iron oxides are immediately reduced by heterotrophic iron reducers, resulting in a cryptic iron cycle. We hypothesize that microbial iron cycling may be more prevalent in water column redoxclines, especially those within the photic zone, than previously believed. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  3. Tracking photosynthetic sulfide oxidation in a meromictic lake using sulfate δ34S and δ18O

    NASA Astrophysics Data System (ADS)

    Gilhooly, W. P.; Reinhard, C.; Lyons, T. W.; Glass, J. B.

    2012-12-01

    Phototrophic sulfur bacteria oxidize sulfide and fix carbon dioxide in the presence of sunlight without producing oxygen. Environmental conditions in the Paleo- and Mesoproterozoic, when atmospheric oxygen concentrations were at low levels and portions of the oceans were anoxic and sulfidic (euxinic), were conducive to widespread carbon fixation by anoxygenic photosynthesis. This pathway may have helped sustain euxinic conditions in the Proterozoic water column. With limited organic biomarker and geochemical evidence for widespread production of anoxygenic phototrophs, however, additional proxies are needed to fingerprint paleoecological and biogeochemical signals associated with photic zone euxinia. Paired δ34S and δ18O from ancient sulfates (gypsum, barite, or CAS) may offer an added constraint on the history and ecological dominance of photosynthetic S-oxidation. Sulfate-oxygen can fractionate during sulfate reduction, but the extent of isotopic enrichment is controlled either by kinetic isotope effects imparted during intracellular enzymatic steps or equilibrium oxygen exchange with ambient water. An improved understanding of these processes can be gained from modern natural environments. Mahoney Lake is a density-stratified lake located within the White Lake Basin of British Columbia. The euxinic water column supports a dense plate of purple sulfur bacteria (Amoebobacter purpureus) that thrives where free sulfide intercepts the photic zone at ~7 m water depth. We analyzed the isotopic composition of sulfate (δ34SSO4 and δ18OSO4), sulfide (δ34SH2S), and water (δ18OH2O) to track the potentially coupled processes of dissimilatory sulfate reduction and phototrophic sulfide oxidation within this meromictic lake. Large isotopic offsets observed between sulfate and sulfide within the monimolimnion (δ34SSO4-H2S = 51‰) and within pore waters along the oxic margin (δ34SSO4-H2S >50‰) are consistent with sulfate reduction in both the sediments and the anoxic

  4. Speciation, reactivity, and cycling of Fe and Pb in a meromictic lake

    SciTech Connect

    Taillefert, M.; Lienemann, C.P.; Gaillard, J.F.; Perret, D.

    2000-01-01

    A suite of analytical techniques were combined to study the chemical speciation of Fe and Pb in the water column of a lake characterized by a biogenic meromixis (Paul Lake, MI). Depth profiles of Fe{sup 2+} and dissolved Pb display significant concentration gradients below the chemocline, i.e., they increase from below detection limit to ca. 100 {micro}M for Fe{sup 2+} and 2 nM for Pb{sub d}. Significant correlations between particulate organic matter, hydrous iron oxides, and particulate Pb suggest that Pb is scavenged by Fe-rich particles formed at the oxic-anoxic transition. Transmission electron microscopy shows that particles of hydrous iron oxides form complex aggregates with natural organic matter at and below the oxic-anoxic transition. Experiments with batch reactors show that these organo-mineral moieties remove Pb rapidly during their formation. Thermodynamic calculations predict that FeS nor PbS are respectively saturated and oversaturated in the monimolimnion, although the presence of neither FeS nor PbS was observed. This suggests that the solubilities of Fe and Pb are influenced by complexation. Voltammetric experiments on filtered samples show that Pb is weakly complexed in the mixolimnion and strongly complexed in the monimolimnion. A conditional stability constant for Pb complexation is determined using metal titration curves assuming a simple 1:1 stoichiometry and gives logK{sub cond} = 9.4 {+-} 0.8 M{sup {minus}1} in the monimolimnion. These speciation results are confirmed by ion exchange chromatography, which demonstrates that more than 98% of Pb is complexed by natural organic matter.

  5. Spatial and Temporal Patterns in the Microbial Diversity of a Meromictic Soda Lake in Washington State▿ †

    PubMed Central

    Dimitriu, Pedro A.; Pinkart, Holly C.; Peyton, Brent M.; Mormile, Melanie R.

    2008-01-01

    The microbial community diversity and composition of meromictic Soap Lake were studied using culture-dependent and culture-independent approaches. The water column and sediments were sampled monthly for a year. Denaturing gradient gel electrophoresis of bacterial and archaeal 16S rRNA genes showed an increase in diversity with depth for both groups. Late-summer samples harbored the highest prokaryotic diversity, and the bacteria exhibited less seasonal variability than the archaea. Most-probable-number assays targeting anaerobic microbial guilds were performed to compare summer and fall samples. In both seasons, the anoxic samples appeared to be dominated by lactate-oxidizing sulfate-reducing prokaryotes. High numbers of lactate- and acetate-oxidizing iron-reducing bacteria, as well as fermentative microorganisms, were also found, whereas the numbers of methanogens were low or methanogens were undetectable. The bacterial community composition of summer and fall samples was also assessed by constructing 16S rRNA gene clone libraries. A total of 508 sequences represented an estimated >1,100 unique operational taxonomic units, most of which were from the monimolimnion, and the summer samples were more diverse than the fall samples (Chao1 = 530 and Chao1 = 295, respectively). For both seasons, the mixolimnion sequences were dominated by Gammaproteobacteria, and the chemocline and monimolimnion libraries were dominated by members of the low-G+C-content group, followed by the Cytophaga-Flexibacter-Bacteroides (CFB) group; the mixolimnion sediments contained sequences related to uncultured members of the Chloroflexi and the CFB group. Community overlap and phylogenetic analyses, however, not only demonstrated that there was a high degree of spatial turnover but also suggested that there was a degree of temporal variability due to differences in the members and structures of the communities. PMID:18552187

  6. Behavior of dissolved manganese and other trace elements across the oxic/euxinic transition of a meromictic lake, Fayetteville Green Lake, New York, USA

    NASA Astrophysics Data System (ADS)

    Havig, J. R.; McCormick, M.; Bachan, A.; Kump, L. R.

    2014-12-01

    High-depth-resolution sampling of stratified water bodies is often problematic, due to scale and/or accessibility (e.g. the Black Sea or remote lakes). In contrast, Fayetteville Green Lake (FGL), N.Y. is an easily accessible, 53 m deep meromictic system with an oxic upper mixolimnion (dissolved oxygen ~ 350 µM) and a euxinic lower monimolimnion (total sulfide ~1 mM). The accessibility and stability of FGL provides a unique opportunity for high-resolution sampling of a permanently stratified water column, allowing better characterization of the changes in concentration of biologically important trace elements within the framework of major element geochemistry. High-resolution (0.2 - 0.5m) sampling of FGL at various times of year reveals concentration shifts between the oxic and euxinic zone. For Mn, Fe, and Co, dissolved (< 0.2 µm) concentrations are lower in the oxic zone (~ 10 nM, 20 nM, and 1.5 nM, respectively), and higher in the euxinic zone (~ 6000 nM, 200 nM, and 8 nM). Ni and V exhibit little to no difference between the oxic and euxinic zones (~ 90 and 20 nM, respectively), and Zn shows a small decrease with depth (from ~1600 to 1300 nM). Of the elements analyzed, Mo is the only one that exhibits a large decrease from the oxic to euxinic zones (from ~ 180 to 10 nM). The 4-m chemocline between the oxic and euxinic zones over which dramatic changes in trace element concentration occur in FGL is where peak concentrations for several elements are found, including Fe (3.2 μM), Zn (3.1 μM), Co (86 nM), and V (72 nM). The largest peak is observed for Mn, with a peak concentration of 61 μM, and a transition zone that extends well into the overlying mixolimnion and mirrors the decline in oxygen concentration. Manganese concentration peaks in chemoclines have been observed in a variety of stratified systems that exhibit a gap between the decrease in dissolved oxygen and the increase in sulfide concentration, presumably the result of limited vertical mixing and

  7. Molecular identification of an uncultured bacterium ("morphotype R") in meromictic Lake Cadagno, Switzerland.

    PubMed

    Tonolla, Mauro; Bottinelli, Michele; Demarta, Antonella; Peduzzi, Raffaele; Hahn, Dittmar

    2005-07-01

    Comparative sequence analysis of almost complete 16S rRNA genes of members of the Desulfobacteriaceae retrieved from two gene clone libraries of uncultured bacteria of the chemocline of Lake Cadagno, Switzerland, resulted in the molecular identification of nine sequences, with a tight cluster of five sequences that represented at least three different populations of bacteria with homology values of 95% and 93% to their closest cultured relatives Desulfomonile tiedjei and Desulfomonile limimaris, respectively. In situ hybridization with probes DsmA455 targeting two subpopulations and DsmB455 targeting one subpopulation, detected bacteria with a peculiar morphology previously described as "morphotype R". The individual probes detected about the same number of cells in all samples and together added up to represent all cells of "morphotype R" suggesting that the basic ecophysiological requirements of the subpopulations might be similar. In the monimolimnion, "morphotype R" cells accounted for up to 29% of all Bacteria and entirely represented the Desulfobacteriaceae, the most prominent sulfate-reducing bacteria. In the sediment, "morphotype R" was similarly prominent in the upper cm only where it represented all Desulfobacteriaceae and up to 50% of all Bacteria. Numbers and importance within the Desulfobacteriaceae and Bacteria declined significantly with depth in sediments suggesting potential effects of changing environmental conditions on the fate of "morphotype R".

  8. Emission and oxidation of methane in a meromictic, eutrophic and temperate lake (Dendre, Belgium).

    PubMed

    Roland, Fleur A E; Darchambeau, François; Morana, Cédric; Bouillon, Steven; Borges, Alberto V

    2017-02-01

    We sampled the water column of the Dendre stone pit lake (Belgium) in spring, summer, autumn and winter. Depth profiles of several physico-chemical variables, nutrients, dissolved gases (CO2, CH4, N2O), sulfate, sulfide, iron and manganese concentrations and δ(13)C-CH4 were determined. We performed incubation experiments to quantify CH4 oxidation rates, with a focus on anaerobic CH4 oxidation (AOM), without and with an inhibitor of sulfate reduction (molybdate). The evolution of nitrate and sulfate concentrations during the incubations was monitored. The water column was anoxic below 20 m throughout the year, and was thermally stratified in summer and autumn. High partial pressure of CO2 and CH4 and high concentrations of ammonium and phosphate were observed in anoxic waters. Important nitrous oxide and nitrate concentration maxima were also observed (up to 440 nmol L(-1) and 80 μmol L(-1), respectively). Vertical profiles of δ(13)C-CH4 unambiguously showed the occurrence of AOM. Important AOM rates (up to 14 μmol L(-1) d(-1)) were observed and often co-occurred with nitrate consumption peaks, suggesting the occurrence of AOM coupled with nitrate reduction. AOM coupled with sulfate reduction also occurred, since AOM rates tended to be lower when molybdate was added. CH4 oxidation was mostly aerobic (∼80% of total oxidation) in spring and winter, and almost exclusively anaerobic in summer and autumn. Despite important CH4 oxidation rates, the estimated CH4 fluxes from the water surface to the atmosphere were high (mean of 732 μmol m(-2) d(-1) in spring, summer and autumn, and up to 12,482 μmol m(-2) d(-1) in winter).

  9. Biogeochemistry of a large, meromictic tropical lake (Lake Kivu, East Africa): insights from a stable isotope study covering an annual cycle

    NASA Astrophysics Data System (ADS)

    Morana, Cedric; Darchambeau, François; Muvundja, Fabrice; Roland, Fleur; Kelemen, Zita; Commarieu, Marc-Vincent; Leporcq, Bruno; Alunga, Georges; Masilya, Pascal; Descy, Jean-Pierre; Borges, Alberto V.; Bouillon, Steven

    2014-05-01

    Lake Kivu (East Africa) is a large (2370 km2) and deep (maximum depth of 485 m) meromictic lake. Its vertical structure consists of an oxic and nutrient-poor mixed layer down to 70 m maximum, and a permanently anoxic monimolimnion rich in dissolved gases (methane and carbon dioxide) and nutrients. Seasonal variation of the vertical position of the oxic-anoxic interface is driven by contrasting air humidity and wind speed regimes between rainy (October-May) and dry (June-September) seasons. The latter is characterized by a deepening of the oxic zone, and an increased input of dissolved gases and inorganic nutrients. The mean annual photic depth is 18 m, but water transparency slightly decreases during the dry season. In this study, we present a comprehensive data set covering a full annual cycle at a fortnightly resolution, which combine hydrochemical data, δ13C and δ15N measurements of particulate organic carbon and nitrogen (POC, PN) and zooplankton, δ13C of dissolved organic and inorganic carbon (DOC, DIC), nutrients and gases (CH4) concentrations, phytoplankton biomass and composition. In the euphotic zone, phytoplankton biomass was constant during the rainy season, but doubled during the dry season. In contrast, δ13C-DIC increased linearly with time during the rainy season, deviating from the values expected at isotopic equilibrium with the atmosphere, then suddenly decreased in the dry season due to the vertical mixing with 13C-depleted DIC. Results of mass-balance calculations indicate that the δ13C-DIC increase reflects the net autotrophic status of the mixed layer. Irrespective of the season, the δ13C-POC signatures were constant from the surface to the oxic-anoxic interface, then showed a local and abrupt excursion to values as low as -40o reflecting the incorporation of a 13C-depleted source in the POC. While the large pool of DIC is the main carbon source for POC in surface waters, CH4 contributes significantly to C fixation at the oxic

  10. Molecular analysis of the sulfate reducing and archaeal community in a meromictic soda lake (Mono Lake, California) by targeting 16S rRNA, mcrA, apsA, and dsrAB genes.

    PubMed

    Scholten, J C M; Joye, S B; Hollibaugh, J T; Murrell, J C

    2005-07-01

    Sulfate reduction is the most important process involved in the mineralization of carbon in the anoxic bottom waters of Mono Lake, an alkaline, hypersaline, meromictic Lake in California. Another important biogeochemical process in Mono Lake is thought to be sulfate-dependent methane oxidation (SDMO). However little is known about what types of organisms are involved in these processes in Mono Lake. Therefore, the sulfate-reducing and archaeal microbial community in Mono Lake was analyzed by targeting 16S rRNA, methyl-coenzyme M reductase (mcrA), adenosine-5'-phosphosulfate (apsA), and dissimilatory sulfite reductase (dsrAB) genes to investigate the sulfate-reducing and archaeal community with depth. Most of the 16S rRNA gene sequences retrieved from the samples fell into the delta-subdivision of the Proteobacteria. Phylogenetic analyses suggested that the clones obtained represented sulfate-reducing bacteria, which are probably involved in the mineralization of carbon in Mono Lake, many of them belonging to a novel line of descent in the delta-Proteobacteria. Only 6% of the sequences retrieved from the samples affiliated to the domain Euryarchaeota but did not represent Archaea, which is considered to be responsible for SDMO [Orphan et al. 2001: Appl Environ Microbiol 67:1922-1934; Teske et al.: Appl Environ Microbiol 68:1994-2007]. On the basis of our results and thermodynamic arguments, we proposed that SDMO in hypersaline environments is presumably carried out by SRB alone. Polymerase chain reaction (PCR) amplifications of the mcrA-, apsA-, and dsrAB genes in Mono Lake samples were, in most cases, not successful. Only the PCR amplification of the apsA gene was partially successful. The amplification of these functional genes was not successful because there was either insufficient "target" DNA in the samples, or the microorganisms in Mono Lake have divergent functional genes.

  11. Biogeochemical processes involving dissolved CO2 and CH4 at Albano, Averno, and Monticchio meromictic volcanic lakes (Central-Southern Italy)

    NASA Astrophysics Data System (ADS)

    Cabassi, Jacopo; Tassi, Franco; Vaselli, Orlando; Fiebig, Jens; Nocentini, Matteo; Capecchiacci, Francesco; Rouwet, Dmitri; Bicocchi, Gabriele

    2013-01-01

    This paper focuses on the chemical and isotopic features of dissolved gases (CH4 and CO2) from four meromictic lakes hosted in volcanic systems of Central-Southern Italy: Lake Albano (Alban Hills), Lake Averno (Phlegrean Fields), and Monticchio Grande and Piccolo lakes (Mt. Vulture). Deep waters in these lakes are characterized by the presence of a significant reservoir of extra-atmospheric dissolved gases mainly consisting of CH4 and CO2. The δ13C-CH4 and δD-CH4 values of dissolved gas samples from the maximum depths of the investigated lakes (from -66.8 to -55.6 ‰ V-PDB and from -279 to -195 ‰ V-SMOW, respectively) suggest that CH4 is mainly produced by microbial activity. The δ13C-CO2 values of Lake Grande, Lake Piccolo, and Lake Albano (ranging from -5.8 to -0.4 ‰ V-PDB) indicate a significant CO2 contribution from sublacustrine vents originating from (1) mantle degassing and (2) thermometamorphic reactions involving limestone, i.e., the same CO2 source feeding the regional thermal and cold CO2-rich fluid emissions. In contrast, the relatively low δ13C-CO2 values (from -13.4 to -8.2 ‰ V-PDB) of Lake Averno indicate a prevalent organic CO2. Chemical and isotopic compositions of dissolved CO2 and CH4 at different depths are mainly depending on (1) CO2 inputs from external sources (hydrothermal and/or anthropogenic); (2) CO2-CH4 isotopic exchange; and (3) methanogenic and methanotrophic activity. In the epilimnion, vertical water mixing, free oxygen availability, and photosynthesis cause the dramatic decrease of both CO2 and CH4 concentrations. In the hypolimnion, where the δ13C-CO2 values progressively increase with depth and the δ13C-CH4 values show an opposite trend, biogenic CO2 production from CH4 using different electron donor species, such as sulfate, tend to counteract the methanogenesis process whose efficiency achieves its climax at the water-bottom sediment interface. Theoretical values, calculated on the basis of δ13C-CO2 values, and

  12. Distribution of Dehalococcoidia in the Anaerobic Deep Water of a Remote Meromictic Crater Lake and Detection of Dehalococcoidia-Derived Reductive Dehalogenase Homologous Genes.

    PubMed

    Biderre-Petit, Corinne; Dugat-Bony, Eric; Mege, Mickaël; Parisot, Nicolas; Adrian, Lorenz; Moné, Anne; Denonfoux, Jérémie; Peyretaillade, Eric; Debroas, Didier; Boucher, Delphine; Peyret, Pierre

    2016-01-01

    Here we describe the natural occurrence of bacteria of the class Dehalococcoidia (DEH) and their diversity at different depths in anoxic waters of a remote meromictic lake (Lake Pavin) using 16S rRNA gene amplicon sequencing and quantitative PCR. Detected DEH are phylogenetically diverse and the majority of 16S rRNA sequences have less than 91% similarity to previously isolated DEH 16S rRNA sequences. To predict the metabolic potential of detected DEH subgroups and to assess if they encode genes to transform halogenated compounds, we enriched DEH-affiliated genomic DNA by using a specific-gene capture method and probes against DEH-derived 16S rRNA genes, reductive dehalogenase genes and known insertion sequences. Two reductive dehalogenase homologous sequences were identified from DEH-enriched genomic DNA, and marker genes in the direct vicinity confirm that gene fragments were derived from DEH. The low sequence similarity with known reductive dehalogenase genes suggests yet-unknown catabolic potential in the anoxic zone of Lake Pavin.

  13. Dominance of green sulfur bacteria in the chemocline of the meromictic Lake Suigetsu, Japan, as revealed by dissimilatory sulfite reductase gene analysis.

    PubMed

    Mori, Yumi; Kataoka, Takafumi; Okamura, Takahiko; Kondo, Ryuji

    2013-05-01

    This study investigated the spatiotemporal abundance and diversity of the α-subunit of the dissimilatory sulfite reductase gene (dsrA) in the meromictic Lake Suigetsu for assessing the sulfur-oxidizing bacterial community. The density of dsrA in the chemocline reached up to 3.1 × 10(6) copies ml(-1) in summer by means of quantitative real-time PCR and it was generally higher than deeper layers. Most of the dsrA clones sequenced were related to green sulfur bacteria such as Chlorobium phaeovibrioides, C. limicola, and C. luteolum. Below the chemocline of the lake, we also detected other dsrA clones related to the purple sulfur bacterium Halochromatium salexigens and some branching lineages of diverse sequences that were related to chemotrophic sulfur bacterial species such as Magnetospirillum gryphiswaldense, Candidatus Ruthia magnifica, and Candidatus Thiobios zoothamnicoli. The abundance and community compositions of sulfur-oxidizing bacteria changed depending on the water depth and season. This study indicated that the green sulfur bacteria dominated among sulfur-oxidizing bacterial population in the chemocline of Lake Suigetsu and that certain abiotic environmental variables were important factors that determined sulfur bacterial abundance and community structure.

  14. Distribution of Dehalococcoidia in the Anaerobic Deep Water of a Remote Meromictic Crater Lake and Detection of Dehalococcoidia-Derived Reductive Dehalogenase Homologous Genes

    PubMed Central

    Biderre-Petit, Corinne; Dugat-Bony, Eric; Mege, Mickaël; Parisot, Nicolas; Adrian, Lorenz; Moné, Anne; Denonfoux, Jérémie; Peyretaillade, Eric; Debroas, Didier; Boucher, Delphine; Peyret, Pierre

    2016-01-01

    Here we describe the natural occurrence of bacteria of the class Dehalococcoidia (DEH) and their diversity at different depths in anoxic waters of a remote meromictic lake (Lake Pavin) using 16S rRNA gene amplicon sequencing and quantitative PCR. Detected DEH are phylogenetically diverse and the majority of 16S rRNA sequences have less than 91% similarity to previously isolated DEH 16S rRNA sequences. To predict the metabolic potential of detected DEH subgroups and to assess if they encode genes to transform halogenated compounds, we enriched DEH-affiliated genomic DNA by using a specific-gene capture method and probes against DEH-derived 16S rRNA genes, reductive dehalogenase genes and known insertion sequences. Two reductive dehalogenase homologous sequences were identified from DEH-enriched genomic DNA, and marker genes in the direct vicinity confirm that gene fragments were derived from DEH. The low sequence similarity with known reductive dehalogenase genes suggests yet-unknown catabolic potential in the anoxic zone of Lake Pavin. PMID:26734727

  15. Psychrosinus fermentans gen. nov., sp. nov., a lactate-fermenting bacterium from near-freezing oxycline waters of a meromictic Antarctic lake.

    PubMed

    Sattley, W Matthew; Jung, Deborah O; Madigan, Michael T

    2008-10-01

    A novel, obligately anaerobic, fermentative bacterium, strain FCF9, was isolated from a 9-m water sample from permanently ice-covered, meromictic Lake Fryxell, Antarctica. A phylogenetic analysis based on 16S rRNA gene sequence identity clustered the Antarctic isolate within the Sporomusa-Pectinatus-Selenomonas phyletic group, where it was most closely related to Pelosinus fermentans (95.5% sequence identity). However, unlike species of Pelosinus, strain FCF9 was psychrophilic, with growth occurring optimally near 15 degrees C, and endospores were not produced. The metabolism of the new organism was strictly fermentative. The substrates fermented by strain FCF9 included only lactate and a few related organic acids. The major products from lactate fermentation were acetate and propionate. On the basis of phylogenetic, morphological, and physiological criteria, strain FCF9(T) is proposed as the type strain of a novel genus and species of psychrophilic-fermenting bacteria, Psychrosinus fermentans gen. nov., sp. nov.

  16. Green River iaminites: does the playa-lake model really invalidate the stratified-lake model

    SciTech Connect

    Boyer, B.W.

    1982-06-01

    Proponents of the playa-lake model have proposed deposition of most of the Green River Formation microlaminated carbonates (including oil shales) in lakes that were not perennially stratified (meromictic). However, there is a variety of evidence favoring a meromictic depositional environment: (1) close similarity of much of the lamination to varves in modern meromictic lakes, (2) evidence that hydrologic events favoring development of meromixis (chemical stratification) occurred prior to deposition of major accumulations of oil shale, (3) mutually exclusive distribution of fossil nekton (especially fish) and normal lacustrine benthos (including mollusks), and (4) analogy with a Quaternary playa that became a meromictic lake following increased inflow. The playa-lake model is untenable for the typical fish-bearing, kerogen-rich microlaminated sediments. These laminites were probably deposited in a large ectogenic meromictic lake - a chemically stratified lake that formed when increased fresh-water inflow ''drowned'' a saline playa complex.

  17. Distribution and diversity of bacteria in a saline meromictic lake as determined by PCR-DGGE of 16S rRNA gene fragments.

    PubMed

    Gugliandolo, Concetta; Lentini, Valeria; Maugeri, Teresa L

    2011-01-01

    The variations in vertical distribution and composition of bacteria in the meromictic Lake Faro (Messina, Italy) were analysed by culture-independent methods in two different mixing conditions. Water samples were collected from a central station from the surface to the bottom (30 m depth) on two different sampling dates--the first characterised by a well-mixed water mass and the second by a marked stratification. A 'red-water' layer, caused by a dense growth of photosynthetic sulphur bacteria, was present at a depth of 25 m in December 2005 and at 15 m in August 2006, defining two different zones in terms of their physicochemical properties. The vertical distribution of bacterioplankton showed that the interface zones were more densely populated than others. In both sampling periods, the highest numbers of live cells were observed within 'red water' layers. The dominant phylotypes of the bacterial community were determined by sequencing the Denaturing Gradient Gel Electrophoresis (DGGE) bands resulting from PCR amplification of 16S rRNA gene fragments. The number of DGGE bands, considered indicative of the total species richness, did not vary predictably across the two different sampling periods. Proteobacteria (α-, γ-, δ- and ε subclass members), Cytophaga-Flavobacterium-Bacteroides, green sulphur bacteria and Cyanobacteria were retrieved from Lake Faro. Most of the bands showed DNA sequences that did not match with other previously described organisms, suggesting the presence of new indigenous bacterial phylotypes.

  18. Powering up the ``biogeochemical engine'': The impact of exceptional ventilation of a deep meromictic lake on the lacustrine redox, nutrient, and methane balances

    NASA Astrophysics Data System (ADS)

    Lehmann, Moritz; Simona, Marco; Wyss, Silvia; Blees, Jan; Frame, Caitlin; Niemann, Helge; Veronesi, Mauro; Zopfi, Jakob

    2015-08-01

    The Lake Lugano North Basin has been meromictic for several decades, with anoxic waters below 100m depth. Two consecutive cold winters in 2005 and 2006 induced exceptional deep mixing, leading to a transient oxygenation of the whole water column. With the ventilation of deep waters and the oxidation of large quantities of reduced solutes, the lake's total redox-balance turned positive, and the overall hypolimnetic oxygen demand of the lake strongly decreased. The disappearance of 150 t dissolved phosphorous (P) during the first ventilation in March 2005 is attributed to the scavenging of water-column-borne P by newly formed metal oxyhydroxides and the temporary transfer to the sediments. The fixed nitrogen (N) inventory was reduced by ~30% (~1000 t). The water-column turnover induced the nitratation of the previously NO3--free deep hypolimnion by oxidation of large amounts of legacy NH4+ and by mixing with NO3--rich subsurface water masses. Sediments with a strong denitrifying potential, but NO3--starved for decades, were brought in contact with NO3--replete waters, invigorating benthic denitrification and rapid fixed N loss from the lake in spite of the overall more oxygenated conditions. Similarly, a large microbial aerobic CH4 oxidation (MOx) potential in the hypolimnion was capitalized with the ventilation of the deep basin. Almost all CH4, which had been built up over more than 40 years (~2800 t), was removed from the water column within 30 days. However, boosted MOx could only partly explain the disappearance of the CH4. The dominant fraction (75%) of the CH4 evaded to the atmosphere, through storage flux upon exposure of anoxic CH4-rich water to the atmosphere. As of today, the North Basin seems far from homeostasis regarding its fixed N and CH4 budgets, and the deep basin's CH4 pool is recharging at a net production rate of ~66 t y-1. The size of impending CH4 outbursts will depend on the frequency and intensity of exceptional mixing events in the future.

  19. Combining sedimentological, trace metal (Mn, Mo) and molecular evidence for reconstructing past water-column redox conditions: The example of meromictic Lake Cadagno (Swiss Alps)

    NASA Astrophysics Data System (ADS)

    Wirth, Stefanie B.; Gilli, Adrian; Niemann, Helge; Dahl, Tais W.; Ravasi, Damiana; Sax, Nadja; Hamann, Yvonne; Peduzzi, Raffaele; Peduzzi, Sandro; Tonolla, Mauro; Lehmann, Moritz F.; Anselmetti, Flavio S.

    2013-11-01

    Here, we present sedimentological, trace metal, and molecular evidence for tracking bottom water redox-state conditions during the past 12,500 years in nowadays sulfidic and meromictic Lake Cadagno (Switzerland). A 10.5 m long sediment core from the lake covering the Holocene period was investigated for concentration variations of the trace metals Mn and Mo (XRF core scanning and ICP-MS measurements), and for the presence of anoxygenic phototrophic sulfur bacteria (carotenoid pigment analysis and 16S rDNA real time PCR). Our trace metal analysis documents an oxic-intermediate-sulfidic redox-transition period beginning shortly after the lake formation ˜12.5 kyr ago. The oxic period is characterized by low sedimentary Mn and Mo concentrations, as well as by the absence of any remnants of anoxygenic phototrophic sulfur bacteria. Enhanced accumulation/preservation of Mn (up to 5.6 wt%) in the sediments indicates an intermediate, Mn-enriched oxygenation state with fluctuating redox conditions during a ˜2300-year long transition interval between ˜12.1 and 9.8 kyr BP. We propose that the high Mn concentrations are the result of enhanced Mn2+ leaching from the sediments during reducing conditions and subsequent rapid precipitation of Mn-(oxyhydr)oxide minerals during episodic and short-term water-column mixing events mainly due to flood-induced underflows. At 9800 ± 130 cal yr BP, a rapid transition to fully sulfidic conditions is indicated by the marked enrichment of Mo in the sediments (up to 490 ppm), accompanied by an abrupt drop in Mn concentrations and the increase of molecular biomarkers that indicate the presence of anoxygenic photosynthetic bacteria in the water column. Persistently high Mo concentrations >80 ppm provide evidence that sulfidic conditions prevailed thereafter until modern times, without any lasting hypolimnetic ventilation and reoxygenation. Hence, Lake Cadagno with its persistently stable chemocline offers a framework to study in great

  20. Carbon and Sulfur Cycling below the Chemocline in a Meromictic Lake and the Identification of a Novel Taxonomic Lineage in the FCB Superphylum, Candidatus Aegiribacteria.

    PubMed

    Hamilton, Trinity L; Bovee, Roderick J; Sattin, Sarah R; Mohr, Wiebke; Gilhooly, William P; Lyons, Timothy W; Pearson, Ann; Macalady, Jennifer L

    2016-01-01

    Mahoney Lake in British Columbia is an extreme meromictic system with unusually high levels of sulfate and sulfide present in the water column. As is common in strongly stratified lakes, Mahoney Lake hosts a dense, sulfide-oxidizing phototrophic microbial community where light reaches the chemocline. Below this "plate," the euxinic hypolimnion is anoxic, eutrophic, saline, and rich in sulfide, polysulfides, elemental sulfur, and other sulfur intermediates. While much is known regarding microbial communities in sunlit portions of euxinic systems, the composition and genetic potential of organisms living at aphotic depths have rarely been studied. Metagenomic sequencing of samples from the hypolimnion and the underlying sediments of Mahoney Lake indicate that multiple taxa contribute to sulfate reduction below the chemocline and that the hypolimnion and sediments each support distinct populations of sulfate reducing bacteria (SRB) that differ from the SRB populations observed in the chemocline. After assembling and binning the metagenomic datasets, we recovered near-complete genomes of dominant populations including two Deltaproteobacteria. One of the deltaproteobacterial genomes encoded a 16S rRNA sequence that was most closely related to the sulfur-disproportionating genus Dissulfuribacter and the other encoded a 16S rRNA sequence that was most closely related to the fatty acid- and aromatic acid-degrading genus Syntrophus. We also recovered two near-complete genomes of Firmicutes species. Analysis of concatenated ribosomal protein trees suggests these genomes are most closely related to extremely alkaliphilic genera Alkaliphilus and Dethiobacter. Our metagenomic data indicate that these Firmicutes contribute to carbon cycling below the chemocline. Lastly, we recovered a nearly complete genome from the sediment metagenome which represents a new genus within the FCB (Fibrobacteres, Chlorobi, Bacteroidetes) superphylum. Consistent with the geochemical data, we found

  1. [Microbiological and isotopic geochemical investigation of Lake Kislo-Sladkoe, a meromictic water body at the Kandalaksha Bay Shore (White Sea)].

    PubMed

    Savvichev, A S; Lunina, O N; Rusanov, I I; Zakharova, E E; Veslopolova, E F; Ivanov, M V

    2014-01-01

    Microbiological, biogeochemical, and isotopic geochemical investigation of Lake Kislo-Sladkoe (Polusolenoe in early publications) at the Kandalaksha Bay shore (White Sea) was carried out in September 2010. Lake Kislo-Sladkoe was formed in the mid-1900s out of a sea gulf due to a coastal heave. At the time of investigation, the surface layer was saturated with oxygen, while near-bottom water contained sulfide (up to 32 mg/L). Total number of microorganisms was high (12.3 x 10(6) cells/mL on average). Light CO2 fixation exhibited two pronounced peaks. In the oxic zone, the highest rates of photosynthesis were detected at 1.0 and 2.0 m. The second, more pronounced peak of light CO2 fixation was associated with activity of anoxygenic phototrophic bacteria in the anoxic layer at the depth of 2.9 m (413 μg C L(-1) day(-1)). Green-colored green sulfur bacteria (GSB) predominated in the upper anoxic layer (2.7-2.9 m), their numbers being as high as 1.12 x 10(4) cells/mL, while brown-colored GSB predominated in the lower horizons. The rates of both sulfate reduction and methanogenesis peaked in the 2.9 m horizon (1690 μg S L(-1) day(-1) and 2.9 μL CH4 L(-1) day(-1)). The isotopic composition of dissolved methane from the near-bottom water layer (δ13C (CH4) = -87.76 per thousand) was significantly lighter than in the upper horizons (δ13C (CH4) = -77.95 per thousand). The most isotopically heavy methane (δ13C (CH4) = -72.61 per thousand) was retrieved from the depth of 2.9 m. The rate of methane oxidation peaked in the same horizon. As a result of these reactions, organic matter (OM) carbon of the 2.9 m horizon became lighter (-36.36 per thousand), while carbonate carbon became heavier (-7.56 per thousand). Thus, our results demonstrated that Lake Kislo-Sladkoe is a stratified meromictic lake with active microbial cycles of carbon and sulfur. Suspended matter in the water column was mostly of autochthonous origin. Anoxygenic photosynthesis coupled to utilization of

  2. Carbon and Sulfur Cycling below the Chemocline in a Meromictic Lake and the Identification of a Novel Taxonomic Lineage in the FCB Superphylum, Candidatus Aegiribacteria

    PubMed Central

    Hamilton, Trinity L.; Bovee, Roderick J.; Sattin, Sarah R.; Mohr, Wiebke; Gilhooly, William P.; Lyons, Timothy W.; Pearson, Ann; Macalady, Jennifer L.

    2016-01-01

    Mahoney Lake in British Columbia is an extreme meromictic system with unusually high levels of sulfate and sulfide present in the water column. As is common in strongly stratified lakes, Mahoney Lake hosts a dense, sulfide-oxidizing phototrophic microbial community where light reaches the chemocline. Below this “plate,” the euxinic hypolimnion is anoxic, eutrophic, saline, and rich in sulfide, polysulfides, elemental sulfur, and other sulfur intermediates. While much is known regarding microbial communities in sunlit portions of euxinic systems, the composition and genetic potential of organisms living at aphotic depths have rarely been studied. Metagenomic sequencing of samples from the hypolimnion and the underlying sediments of Mahoney Lake indicate that multiple taxa contribute to sulfate reduction below the chemocline and that the hypolimnion and sediments each support distinct populations of sulfate reducing bacteria (SRB) that differ from the SRB populations observed in the chemocline. After assembling and binning the metagenomic datasets, we recovered near-complete genomes of dominant populations including two Deltaproteobacteria. One of the deltaproteobacterial genomes encoded a 16S rRNA sequence that was most closely related to the sulfur-disproportionating genus Dissulfuribacter and the other encoded a 16S rRNA sequence that was most closely related to the fatty acid- and aromatic acid-degrading genus Syntrophus. We also recovered two near-complete genomes of Firmicutes species. Analysis of concatenated ribosomal protein trees suggests these genomes are most closely related to extremely alkaliphilic genera Alkaliphilus and Dethiobacter. Our metagenomic data indicate that these Firmicutes contribute to carbon cycling below the chemocline. Lastly, we recovered a nearly complete genome from the sediment metagenome which represents a new genus within the FCB (Fibrobacteres, Chlorobi, Bacteroidetes) superphylum. Consistent with the geochemical data, we

  3. The behavior of biologically important trace elements across the oxic/euxinic transition of meromictic Fayetteville Green Lake, New York, USA

    NASA Astrophysics Data System (ADS)

    Havig, Jeff R.; McCormick, Michael L.; Hamilton, Trinity L.; Kump, Lee R.

    2015-09-01

    Trace elements are central components of enzymes that catalyze many of the essential reactions mediated by life. The redox sensitive nature of trace elements also permits their use as a record of ancient ocean conditions preserved in the geologic record. Trace element geochemistry in modern stratified systems is often used as a proxy for the redox state of the ancient oceans, which are thought to have been largely anoxic. In the present study, we examined trace element behavior of simultaneously collected samples at a heretofore unprecedented depth resolution (1-0.25 m intervals) throughout the redox-stratified water column of Fayetteville Green Lake, N.Y. (FGL), a 53 m deep meromictic lake under euxinic conditions similar to those thought to have been prevalent in Proterozoic oceans. Among characterized Proterozoic ocean analogs, FGL represents an understudied proxy in terms of trace elements, with characteristics of low salinity and high sulfate. In the FGL water column, spikes in the concentration of dissolved Mn, Fe and Co are coincident with the transition from oxic to euxinic conditions, and are associated with a decrease in dissolved Mo concentration. In contrast, the concentration of dissolved Ni did not vary across this transition despite the dramatic shift in redox state. From these data we present a one dimensional model for element transport and cycling through the water column to the sediments. Collectively, this comprehensive analysis of water column geochemistry provides insight into the effects of biogeochemical cycling in stratified systems on dissolved trace element concentrations in the water column. This study, in concert with characterization of other early Earth analogs, will greatly enhance the use of trace elements in interpreting the geologic record.

  4. Thiocystis chemoclinalis sp. nov. and Thiocystis cadagnonensis sp. nov., motile purple sulfur bacteria isolated from the chemocline of a meromictic lake.

    PubMed

    Peduzzi, Sandro; Welsh, Allana; Demarta, Antonella; Decristophoris, Paola; Peduzzi, Raffaele; Hahn, Dittmar; Tonolla, Mauro

    2011-07-01

    Two isolates, designated CadH11(T) and Cad448(T), representing uncultured purple sulfur bacterial populations H and 448, respectively, in the chemocline of Lake Cadagno, a crenogenic meromictic lake in Switzerland, were obtained using enrichment and isolation conditions that resembled those used for cultured members of the genus Thiocystis. Phenotypic, genotypic and phylogenetic analyses of these isolates confirmed their assignment to the genus Thiocystis. However, 16S rRNA gene sequence similarities of 98.2 % between CadH11(T) and Cad448(T), and similarities of 97.7 and 98.5 %, respectively, with their closest cultured relative Thiocystis gelatinosa DSM 215(T), as well as differences in DNA G+C content and carbon source utilization suggested that the isolates belonged to two distinct species. DNA-DNA hybridization of CadH11(T) and Cad448(T) with T. gelatinosa DSM 215(T) showed relatedness values of 46.4 and 60.8 %, respectively; the relatedness value between CadH11(T) and Cad448(T) was 59.2 %. Based on this evidence, strains CadH11(T) and Cad448(T) represent two novel species within the genus Thiocystis, for which the names Thiocystis chemoclinalis sp. nov. and Thiocystis cadagnonensis sp. nov. are proposed, respectively. The type strains of T. chemoclinalis sp. nov. and T. cadagnonensis sp. nov. are CadH11(T) ( = JCM 15112(T)  = KCTC 5954(T)) and Cad448(T) ( = JCM 15111(T)  = KCTC 15001(T)), respectively.

  5. Isolation and characterization of aggregate-forming sulfate-reducing and purple sulfur bacteria from the chemocline of meromictic Lake Cadagno, Switzerland.

    PubMed

    Peduzzi, Sandro; Tonolla, Mauro; Hahn, Dittmar

    2003-07-01

    Abstract In situ hybridization with specific oligonucleotide probes was used to monitor enrichment cultures of yet uncultured populations of sulfate-reducing and small-celled purple sulfur bacteria found to associate into aggregates in the chemocline of meromictic Lake Cadagno, Switzerland, and to select potential isolates. Enrichment and isolation conditions resembled those of their nearest cultured relatives, the sulfate-reducing bacterium Desulfocapsa thiozymogenes and small-celled purple sulfur bacteria belonging to the genus Lamprocystis, respectively. Based on comparative 16S rRNA analysis and physiological characterization, isolate Cad626 was found to resemble D. thiozymogenes although it differed from the type strain by its ability to grow on lactate and pyruvate. Like D. thiozymogenes, isolate Cad626 was able to disproportionate inorganic sulfur compounds (sulfur, thiosulfate, sulfite) and to grow, although growth on sulfur required a sulfide scavenger (FeOOH). Isolate Cad16 represented small-celled purple sulfur bacteria that belonged to a previously detected, but uncultured population designated F and was related to Lamprocystis purpurea as evidenced by comparative 16S rRNA analysis and the presence of bacteriochlorophyll a and the carotenoid okenone. Mixed cultures of isolates Cad626 and Cad16 resulted in their association in aggregates similar to those observed in the chemocline of Lake Cadagno. Concomitant growth enhancement of both isolates in mixed culture suggested synergistic interactions that presumably resemble a source-sink relationship for sulfide between the sulfate-reducing bacterium growing by sulfur disproportionation and the purple sulfur bacteria acting as biotic scavenger.

  6. [Roseibacula alcaliphilum gen. nov. sp. nov., a new alkaliphilic aerobic anoxygenic phototrophic bacterium from a meromictic soda Lake Doroninskoe (East Siberia, Russia)].

    PubMed

    Nuianzina-Boldareva, E N; Gorlenko, V M

    2014-01-01

    A bacterial strain De was isolated from the surface water layer of the meromictic soda lake Doroninskoe. When grown in the dark, it formed-pink colonies on agar media. The cells were nonmotile, contained bacteriochlorophyll a and carotenoids. Stationary-phase cells contained intracellular vesicular membranes similar to the membranes of the photosynthetic apparatus of some ndnsulfur purple bacteria. Aerobic growth did not occur. Sucrose, citrate, mannitol, sorbitol, case in hydrolysate,and yeast extract were the preferable substrates for aerobic growth, Xylose, lactose, aspartate, benzoate, malate, malonate, succinate, tartrate, formate, fumarate, glycerol, methanol, and ethanol were not utilized; Growth occurred at up to 50.g/L NaCl (optimum at 5 g/L) and pH 9.8. According to the 16S rRNA gene sequencing, similarity between the isolate and the known alkaliphilic genera of nonsulfur purple bacteria (Rhodobaca) and of aerobic anoxygenic phototrophic bacteria (Roseinatronobacter) was 96%, which was sufficient for description ofa new genus of aerobic anoxygenic phototrophic bacteria. The name Roseibacula alcaliphiluin gen. nov., sp. nov. was, proposed for the isolate.

  7. Desulfoplanes formicivorans gen. nov., sp. nov., a novel sulfate-reducing bacterium isolated from a blackish meromictic lake, and emended description of the family Desulfomicrobiaceae.

    PubMed

    Watanabe, Miho; Kojima, Hisaya; Fukui, Manabu

    2015-06-01

    A novel sulfate-reducing bacterium, designated strain Pf12BT, was isolated from sediment of meromictic Lake Harutori in Japan. Cells were vibroid (1.0 × 3.0-4.0 μm), motile and Gram-stain-negative. For growth, the optimum pH was 7.0-7.5 and the optimum temperature was 42-45 °C. Strain Pf12BT used sulfate, thiosulfate and sulfite as electron acceptors. The G+C content of the genomic DNA was 55.4 mol%. Major cellular fatty acids were C16 : 0 and C18 : 0. The strain was desulfoviridin-positive. Phylogenetic analysis based on the 16S rRNA gene revealed that the novel strain belonged to the order Desulfovibrionales in the class Deltaproteobacteria. The closest relative was Desulfomicrobium baculatum DSM 4028T with which it shared 91 % 16S rRNA gene sequence similarity. On the basis of phylogenetic and phenotypic characterization, a novel species of a new genus belonging to the family Desulfomicrobiaceae is proposed, Desulfoplanes formicivorans gen. nov., sp. nov. The type strain of Desulfoplanes formicivorans is Pf12BT ( = NBRC 110391T = DSM 28890T).

  8. A comprehensive sulfur and oxygen isotope study of sulfur cycling in a shallow, hyper-euxinic meromictic lake

    NASA Astrophysics Data System (ADS)

    Gilhooly, William P.; Reinhard, Christopher T.; Lyons, Timothy W.

    2016-09-01

    Mahoney Lake is a permanently anoxic and sulfidic (euxinic) lake that has a dense plate of purple sulfur bacteria positioned at mid-water depth (∼7 m) where free sulfide intercepts the photic zone. We analyzed the isotopic composition of sulfate (δ34SSO4 and δ18OSO4), sulfide (δ34SH2S), and the water (δ18OH2O) to track the potentially coupled processes of dissimilatory sulfate reduction and phototrophic sulfide oxidation within an aquatic environment with extremely high sulfide concentrations (>30 mM). Large isotopic offsets observed between sulfate and sulfide within the monimolimnion (δ34SSO4-H2S = 51‰) and within pore waters along the oxic margin (δ34SSO4-H2S > 50‰) are consistent with sulfate reduction in both the sediments and the anoxic water column. Given the high sulfide concentrations of the lake, sulfur disproportionation is likely inoperable or limited to a very narrow zone in the chemocline, and therefore the large instantaneous fractionations are best explained by the microbial process of sulfate reduction. Pyrite extracted from the sediments reflects the isotopic composition of water column sulfide, suggesting that pyrite buried in the euxinic depocenter of the lake formed in the water column. The offset between sulfate and dissolved sulfide decreases at the chemocline (δ34SSO4-H2S = 37‰), a trend possibly explained by elevated sulfate reduction rates and inconsistent with appreciable disproportionation within this interval. Water column sulfate exhibits a linear response in δ18OSO4-δ34SSO4 and the slope of this relationship suggests relatively high sulfate reduction rates that appear to respond to seasonal changes in the productivity of purple sulfur bacteria. Although photosynthetic activity within the microbial plate influences the δ18OSO4-δ34SSO4 relationship, the biosignature for photosynthetic sulfur bacteria is restricted to the oxic/anoxic transition zone and is apparently minor relative to the more prevalent process of

  9. Unveiling fungal zooflagellates as members of freshwater picoeukaryotes: evidence from a molecular diversity study in a deep meromictic lake.

    PubMed

    Lefèvre, Emilie; Bardot, Corinne; Noël, Christophe; Carrias, Jean-François; Viscogliosi, Eric; Amblard, Christian; Sime-Ngando, Télesphore

    2007-01-01

    This study presents an original 18S rRNA PCR survey of the freshwater picoeukaryote community, and was designed to detect unidentified heterotrophic picoflagellates (size range 0.6-5 microm) which are prevalent throughout the year within the heterotrophic flagellate assemblage in Lake Pavin. Four clone libraries were constructed from samples collected in two contrasting zones in the lake. Computerized statistic tools have suggested that sequence retrieval was representative of the in situ picoplankton diversity. The two sampling zones exhibited similar diversity patterns but shared only about 5% of the operational taxonomic units (OTUs). Phylogenetic analysis clustered our sequences into three taxonomic groups: Alveolates (30% of OTUs), Fungi (23%) and Cercozoa (19%). Fungi thus substantially contributed to the detected diversity, as was additionally supported by direct microscopic observations of fungal zoospores and sporangia. A large fraction of the sequences belonged to parasites, including Alveolate sequences affiliated to the genus Perkinsus known as zooparasites, and chytrids that include host-specific parasitic fungi of various freshwater phytoplankton species, primarily diatoms. Phylogenetic analysis revealed five novel clades that probably include typical freshwater environmental sequences. Overall, from the unsuspected fungal diversity unveiled, we think that fungal zooflagellates have been misidentified as phagotrophic nanoflagellates in previous studies. This is in agreement with a recent experimental demonstration that zoospore-producing fungi and parasitic activity may play an important role in aquatic food webs.

  10. Spectroscopic study of the microbial community in chemocline zones of relic meromictic lakes separating from the White Sea

    NASA Astrophysics Data System (ADS)

    Kharcheva, Anastasia V.; Krasnova, Elena D.; Voronov, Dmitry A.; Patsaeva, Svetlana V.

    2015-03-01

    As a result of a recent years study on the Karelia shore of the White Sea more than ten relict lakes in different stages of separation from the sea have been discovered. Five of them are located close to the Nikolai Pertsov White Sea Biological Station of Moscow State University. Such separated lakes are interesting to explore for their firm vertical stratification. Water layers differ not only by temperature, salinity and other physic and chemical characteristics and optical properties, but also by ibhabiting microorganisms and by the quality of dissolved organic matter. To study phototropic organisms in water sampled from different depths we used spectroscopic techniques. Identification of the main bands in the absorption and fluorescence spectra showed that there are two main groups of photosynthetic organisms in the redox zone (chemocline): unicellular algae containing chlorophyll a and green sulfur bacteria with bacteriochlorophylls c, d, e. Spectral data were compared with physical and chemical characteristics of the water layer (temperature, salinity, pH, dissolved oxygen and sunlight illumination at certain depth). It gave an opportunity to compare vertical profiles of oxygen and hydrogen sulphide concentration with the number and distribution of oxygenic and anoxygenic phototrophic microorganisms. Maximum abundance of both algae and green sulfur bacteria were achieved within the redox zone. Typical thickness of the layer with the highest concentration of microorganisms did not exceed 10-20 cm.

  11. Tindallia Californiensis sp. nov.: A New Halo-Alkaliphilic Primary Anaerobe, Isolated from Meromictic soda Mono Lake in California and the Correction of Diagnosis for Genus Tindallia

    NASA Technical Reports Server (NTRS)

    Pikuta, Elena; Marsic, Damien; Hoover, Richard B.; Kevbrin, Vadim; Whitman, William B.; Krader, Paul; Cleland, Dave; Six, N. Frank (Technical Monitor)

    2002-01-01

    A novel extremely halo-alkaliphilic, bacterium strain APO (sup T) was isolated from sediments of the athalassic, meromictic, soda Mono Lake in California. Gram positive, spore-forming, slightly curved rods with sizes 0.6-0.7x 2.5-4.0 micrometers which occur singly, in pairs or short curved chains. Cells, are motile by singular subcentral flagellum. Strain APO (sup T) is mesophilic: growth was observed over the temperature range of +10 C to +48 C (optimum +37 C), NaCl concentration range 1-20 %, wt/vol (optimum 3-5%, wt/vol) and pH range 8.0-11.0 (optimum pH 9.5). The novel isolate is strictly halo-alkaliphilic, requires sodium chloride in medium, obligately anaerobic and catalase-negative. Strain APO (sup T) is organo-heterotroph with fermentative type of metabolism, and uses as substrates: peptone, badotryptone, casamino acids, yeast extract, L-serine, L-lysine, L-histidine, L-arginine, and pyruvate. The main end products of growth on peptone medium were: lactate, acetate, propionate, and ethanol. Strain APO (sup T) is resistant to kanamycin, but sensitive to chloramphenicol, tetracycline, and gentamycin. The sum of G+C in DNA is 44.4 mol% (by HPLC method). On the bait of physiological and molecular properties, the isolate was considered as novel species of genus Tindallia; and the name Tindallia californiensis sp. nov., is proposed for new isolate (type strain APO (sup T) - ATCC BAA_393(sup T) = DSMZ 14871 (sup T)).

  12. Microbial processes of the carbon and sulfur cycles in an ice-covered, iron-rich meromictic lake Svetloe (Arkhangelsk region, Russia).

    PubMed

    Savvichev, Alexander S; Kokryatskaya, Natalia M; Zabelina, Svetlana A; Rusanov, Igor I; Zakharova, Elena E; Veslopolova, Elena F; Lunina, Olga N; Patutina, Ekaterina O; Bumazhkin, Boris K; Gruzdev, Denis S; Sigalevich, Pavel A; Pimenov, Nikolay V; Kuznetsov, Boris B; Gorlenko, Vladimir M

    2017-02-01

    Biogeochemical, isotope geochemical and microbiological investigation of Lake Svetloe (White Sea basin), a meromictic freshwater was carried out in April 2014, when ice thickness was ∼0.5 m, and the ice-covered water column contained oxygen to 23 m depth. Below, the anoxic water column contained ferrous iron (up to 240 μμM), manganese (60 μM), sulfide (up to 2 μM) and dissolved methane (960 μM). The highest abundance of microbial cells revealed by epifluorescence microscopy was found in the chemocline (redox zone) at 23-24.5 m. Oxygenic photosynthesis exhibited two peaks: the major one (0.43 μmol C L(-1)  day(-1) ) below the ice and the minor one in the chemocline zone, where cyanobacteria related to Synechococcus rubescens were detected. The maximum of anoxygenic photosynthesis (0.69 μmol C L(-1)  day(-1) ) at the oxic/anoxic interface, for which green sulfur bacteria Chlorobium phaeoclathratiforme were probably responsible, exceeded the value for oxygenic photosynthesis. Bacterial sulfate reduction peaked (1.5 μmol S L(-1)  day(-1) ) below the chemocline zone. The rates of methane oxidation were as high as 1.8 μmol CH4  L(-1)  day(-1) at the oxi/anoxic interface and much lower in the oxic zone. Small phycoerythrin-containing Synechococcus-related cyanobacteria were probably involved in accumulation of metal oxides in the redox zone. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  13. Tindallia Californiensis sp. nov.: A New Halo-Alkaliphilic Primary Anaerobe, Isolated from Meromictic soda Mono Lake in California and the Correction of Diagnosis for Genus Tindallia

    NASA Technical Reports Server (NTRS)

    Pikuta, Elena; Marsic, Damien; Hoover, Richard B.; Kevbrin, Vadim; Whitman, William B.; Krader, Paul; Cleland, Dave; Six, N. Frank (Technical Monitor)

    2002-01-01

    A novel extremely halo-alkaliphilic, bacterium strain APO (sup T) was isolated from sediments of the athalassic, meromictic, soda Mono Lake in California. Gram positive, spore-forming, slightly curved rods with sizes 0.6-0.7x 2.5-4.0 micrometers which occur singly, in pairs or short curved chains. Cells, are motile by singular subcentral flagellum. Strain APO (sup T) is mesophilic: growth was observed over the temperature range of +10 C to +48 C (optimum +37 C), NaCl concentration range 1-20 %, wt/vol (optimum 3-5%, wt/vol) and pH range 8.0-11.0 (optimum pH 9.5). The novel isolate is strictly halo-alkaliphilic, requires sodium chloride in medium, obligately anaerobic and catalase-negative. Strain APO (sup T) is organo-heterotroph with fermentative type of metabolism, and uses as substrates: peptone, badotryptone, casamino acids, yeast extract, L-serine, L-lysine, L-histidine, L-arginine, and pyruvate. The main end products of growth on peptone medium were: lactate, acetate, propionate, and ethanol. Strain APO (sup T) is resistant to kanamycin, but sensitive to chloramphenicol, tetracycline, and gentamycin. The sum of G+C in DNA is 44.4 mol% (by HPLC method). On the bait of physiological and molecular properties, the isolate was considered as novel species of genus Tindallia; and the name Tindallia californiensis sp. nov., is proposed for new isolate (type strain APO (sup T) - ATCC BAA_393(sup T) = DSMZ 14871 (sup T)).

  14. Dominant microbial composition and its vertical distribution in saline meromictic Lake Kaiike (Japan) as revealed by quantitative oligonucleotide probe membrane hybridization.

    PubMed

    Koizumi, Yoshikazu; Kojima, Hisaya; Fukui, Manabu

    2004-08-01

    Vertical distributions of dominant bacterial populations in saline meromictic Lake Kaiike were investigated throughout the water column and sediment by quantitative oligonucleotide probe membrane hybridization. Three oligonucleotide probes specific for the small-subunit (SSU) rRNA of three groups of Chlorobiaceae were newly designed. In addition, three general domain (Bacteria, Archaea, and Eukarya)-specific probes, two delta-Proteobacteria-specific probes, a Chlorobiaceae-specific probe, and a Chloroflexi-specific probe were used after optimization of their washing conditions. The abundance of the sum of SSU rRNAs hybridizing with probes specific for three groups of Chlorobiaceae relative to total SSU rRNA peaked in the chemocline, accounting for up to 68%. The abundance of the delta-proteobacterial SSU rRNA relative to total SSU rRNA rapidly increased just below the chemocline up to 29% in anoxic water and peaked at the 2- to 3-cm sediment depth at ca. 34%. The abundance of SSU rRNAs hybridizing with the probe specific for the phylum Chloroflexi relative to total SSU rRNA was highest (31 to 54%) in the top of the sediment but then steeply declined with depth and became stable at 11 to 19%, indicating the robust coexistence of sulfate-reducing bacteria and Chloroflexi in the top of the sediment. Any SSU rRNA of Chloroflexi in the water column was under the detection limit. The summation of the signals of group-specific probes used in this study accounted for up to 89% of total SSU rRNA, suggesting that the DGGE-oligonucleotide probe hybridization approach, in contrast to conventional culture-dependent approaches, was very effective in covering dominant populations.

  15. Alkalitalea saponilacus gen. nov., sp. nov., an obligately anaerobic, alkaliphilic, xylanolytic bacterium from a meromictic soda lake.

    PubMed

    Zhao, Baisuo; Chen, Shulin

    2012-11-01

    A Gram-positive, obligately anaerobic, motile, slender, flexible rod, designated SC/BZ-SP2(T), was isolated from mixed alkaline water and sediment of Soap Lake, Washington State, USA. Strain SC/BZ-SP2(T) formed salmon to pink colonies and was alkaliphilic. The isolate grew at pH(35 °C) 7.5-10.5 (optimum pH(35 °C) 9.7), at 8-40 °C (optimum 35-37 °C) and with 0.35-1.38 M Na(+) (optimum 0.44-0.69 M Na(+)). The isolate utilized L-arabinose, D-ribose, D-xylose, D-fructose, D-mannose, D-galactose, cellobiose, maltose, sucrose, trehalose, sorbitol, xylan, malate and yeast extract as carbon and energy sources; best growth was observed with L-arabinose, cellobiose, maltose and trehalose. The major fermentation products from beechwood xylan were propionate and acetate. The dominant fatty acids were iso-C(15:0), anteiso-C(15:0), iso-C(17:0) 3-OH, C(17:0) 3-OH and C(15:0) 3-OH. The cell-wall sugars were ribose, xylose, galactose and glucose. Thiosulfate and sulfite could be reduced to sulfide. The genomic DNA G+C content was 39.5 ± 0.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SC/BZ-SP2(T) belonged to the family Marinilabiliaceae of the order Bacteroidales, class Bacteroidia. The most closely related strains were Alkaliflexus imshenetskii Z-7010(T) (91.8% 16S rRNA gene sequence similarity), Marinilabilia salmonicolor Cy s1(T) (91.0%) and Anaerophaga thermohalophila Fru22(T) (90.4%). On the basis of phenotypic, chemotaxonomic and phylogenetic features, strain SC/BZ-SP2(T) represents a novel species in a new genus of the family Marinilabiliaceae, for which the name Alkalitalea saponilacus gen. nov., sp. nov. is proposed. The type strain of Alkalitalea saponilacus is SC/BZ-SP2(T) (=ATCC BAA-2172(T) =DSM 24412(T)).

  16. Temperature Trends in Montane Lakes

    NASA Astrophysics Data System (ADS)

    Melack, J. M.; Sadro, S.; Jellison, R.

    2014-12-01

    Long-term temperature trends in lakes integrate hydrological and meteorological factors. We examine temperature trends in a small montane lake with prolonged ice-cover and large seasonal snowfall and in a large saline lake. Emerald Lake, located in the Sierra Nevada (California), is representative of high-elevation lakes throughout the region. No significant trend in outflow temperature was apparent from 1991to 2012. Snowfall in the watershed accounted for 93% of the variability in average summer lake temperatures. Mono Lake (California) lies in a closed, montane basin and is hypersaline and monomictic or meromictic. Temperature profiles have been collected from 1982 to 2010. In the upper water column, the July-August-September water temperatures increased 0.8-1.0°C over the 29 years. This rate of warming is less than published estimates based on satellite-derived skin temperatures and will discussed in the context of general limnological interpretation of temperature trends.

  17. Vertical and temporal shifts in microbial communities in the water column and sediment of saline meromictic Lake Kaiike (Japan), as determined by a 16S rDNA-based analysis, and related to physicochemical gradients.

    PubMed

    Koizumi, Yoshikazu; Kojima, Hisaya; Oguri, Kazumasa; Kitazato, Hiroshi; Fukui, Manabu

    2004-06-01

    The vertical and temporal changes in microbial communities were investigated throughout the water column and sediment of the saline meromictic Lake Kaiike by PCR-denaturing gradient gel electrophoresis (DGGE) of 16S rDNA. Marked depth-related changes in microbial communities were observed at the chemocline and the sediment-water interface. However, no major temporal changes in the microbial community below the chemocline were observed during the sampling period, suggesting that the ecosystem in the anoxic zone of Lake Kaiike was nearly stable. Although the sequence of the most conspicuous DGGE band throughout the anoxic water and in the top of the microbial mat was most similar to that of an anoxic, photosynthetic, green sulphur bacterium, Pelodyction luteolum DSM273 (97% similarity), it represented a new phylotype. A comparison of DGGE banding patterns of the water column and sediment samples demonstrated that specific bacteria accumulated on the bottom from the anoxic water layers, and that indigenous microbial populations were present in the sediment. The measurements of bicarbonate assimilation rates showed significant phototrophic assimilation in the chemocline and lithoautotrophic assimilation throughout the anoxic water, but were not clearly linked with net sulphide turnover rates, indicating that sulphur and carbon metabolisms were not directly correlated.

  18. Lake Life.

    ERIC Educational Resources Information Center

    Ohrn, Deborah Gore, Ed.

    1993-01-01

    This quarterly publication of the State Historical Society of Iowa features articles and activities for elementary school students. This summer issue focuses on the topic of lake life. The issue includes the following features: (1) "Where the Lakes Are Map"; (2) "Letter from the Lake"; (3) "Lake People"; (4)…

  19. Members of candidate divisions OP11, OD1 and SR1 are widespread along the water column of the meromictic Lake Pavin (France).

    PubMed

    Borrel, Guillaume; Lehours, Anne-Catherine; Bardot, Corinne; Bailly, Xavier; Fonty, Gérard

    2010-07-01

    The vertical distribution of OP11, OD1 and SR1 divisions in the oxycline and in the anoxic water column of Lake Pavin, a freshwater permanently stratified mountain lake in France, was determined by temporal temperature gel gradient electrophoresis and 16S rRNA clone libraries. Gradual changes in the community structure were noted in relation to environmental variables along the oxidized/reduced environment. In addition, a separate effort to identify members of these lineages in the oxic mixolimnion identified sequences affiliated to SR1 and OP11 divisions, indicating that they are more widespread than previously expected.

  20. Autumn snowfall and hydroclimatic variability during the past millennium inferred from the varved sediments of meromictic Lake A, northern Ellesmere Island, Canada

    NASA Astrophysics Data System (ADS)

    Tomkins, Jessica D.; Lamoureux, Scott F.; Antoniades, Dermot; Vincent, Warwick F.

    2010-09-01

    We examined the hydroclimatic signal in a record of annual lamina (varve) thickness from High Arctic Lake A, Ellesmere Island (83°00.00'N, 75°30.00'W). In this unglacierized catchment, nival melt is the dominant source for meltwater and transport of sediment to the lake, and autumn snowfall is highly influential on varve thickness through the amount of snow available for melt in the following year. For the period during which climatic data are available, varve thickness in Lake A was significantly correlated ( r = 0.50, p < 0.01) with the cumulative snowfall from August to October (ASO) during the previous year and, to a lesser extent, ASO mean daily temperature ( r = 0.39, p < 0.01) at Alert, Nunavut (175 km east). The varve thickness record, interpreted as a proxy record of ASO snowfall and, by extension, ASO temperature, indicated above-mean conditions during five periods of the past millennium, including most of the 20th century. These results corresponded well to other available high-resolution proxy climate records from the region, with some discrepancies prior to AD 1500 and during the period AD 1700-1900.

  1. Lake Tahoe

    EPA Pesticide Factsheets

    Information on the Lake Tahoe watershed, EPA's protection efforts, water quality issues, effects of climate change, Lake Tahoe Total Maximum Daily Load (TMDL), EPA-sponsored projects, list of partner agencies.

  2. Genetic Diversity of Microbial Eukaryotes in Anoxic Sediment of the Saline Meromictic Lake Namako-ike (Japan): On the Detection of Anaerobic or Anoxic-tolerant Lineages of Eukaryotes.

    PubMed

    Takishita, Kiyotaka; Tsuchiya, Masashi; Kawato, Masaru; Oguri, Kazumasa; Kitazato, Hiroshi; Maruyama, Tadashi

    2007-01-01

    Available sequence data on eukaryotic small-subunit ribosomal DNA (SSU rDNA) directly retrieved from various environments have increased recently, and the diversity of microbial eukaryotes (protists) has been shown to be much greater than previously expected. However, the molecular information accumulated to date does still not thoroughly reveal ecological distribution patterns of microbial eukaryotes. In the ongoing challenge to detect anaerobic or anoxic-tolerant lineages of eukaryotes, we directly extracted DNA from the anoxic sediment of a saline meromictic lake, constructed genetic libraries of PCR-amplified SSU rDNA, and performed phylogenetic analyses with the cloned SSU rDNA sequences. Although a few sequences could not be confidently assigned to any major eukaryotic groups in the analyses and are debatable regarding their taxonomic positions, most sequences obtained have affiliations with known major lineages of eukaryotes (Cercozoa, Alveolata, Stramenopiles, and Opisthokonta). Among these sequences, some branched with lineages predominantly composed of uncultured environmental clones retrieved from other anoxic environments, while others were closely related to those of eukaryotic parasites (e.g. Phytomyxea of Cercozoa, Gregarinea of Alveolata, and Ichthyosporea of Opisthokonta).

  3. Lake Powell

    Atmospheric Science Data Center

    2014-05-15

    article title:  Lake Powell     View Larger Image ... format (14.42 mb)   This true-color image over Lake Powell was acquired by Multi-angle Imaging SpectroRadiometer (MISR) in late March 2000. Lake Powell was formed with the construction of the Glen Canyon Dam in 1963, on ...

  4. Future volcanic lake research: revealing secrets from poorly studied lakes

    NASA Astrophysics Data System (ADS)

    Rouwet, D.; Tassi, F.; Mora-Amador, R. A.

    2012-04-01

    Volcanic lake research boosted after the 1986 Lake Nyos lethal gas burst, a limnic rather than volcanic event. This led to the formation of the IAVCEI-Commission on Volcanic Lakes, which grew out into a multi-disciplinary scientific community since the 1990's. At Lake Nyos, a degassing pipe is functional since 2001, and two additional pipes were added in 2011, aimed to prevent further limnic eruption events. There are between 150 and 200 volcanic lakes on Earth. Some acidic crater lakes topping active magmatic-hydrothermal systems are monitored continuously or discontinuously. Such detailed studies have shown their usefulness in volcanic surveillance (e.g. Ruapehu, Yugama-Kusatsu-Shiran, Poás). Others are "Nyos-type" lakes, with possible gas accumulation in bottom waters and thus potentially hazardous. "Nyos-type" lakes tend to remain stably stratified in tropical and sub-tropical climates (meromictic), leading to long-term gas build-up and thus higher potential risk. In temperate climates, such lakes tend to turn over in winter (monomictic), and thus liberating its gas charge yearly. We line out research strategies for the different types of lakes. We believe a complementary, multi-disciplinary approach (geochemistry, geophysics, limnology, biology, statistics, etc.) will lead to new insights and ideas, which can be the base for future following-up and monitoring. After 25 years of pioneering studies on rather few lakes, the scientific community should be challenged to study the many poorly studied volcanic lakes, in order to better constrain the related hazard, based on probabilistic approaches.

  5. Dynamics of CFCs in northern temperate lakes and adjacent groundwater

    NASA Astrophysics Data System (ADS)

    Walker, John F.; Saad, David A.; Hunt, Randall J.

    2007-04-01

    Three dimictic lakes and one meromictic lake in and near the Trout Lake, Wisconsin, watershed were sampled to determine the variation of chlorofluorocarbon (CFC) concentrations within the lakes. The lakes were sampled during stratified conditions, during fall turnover, and during ice cover. The results demonstrate a considerable variation in CFC concentrations and corresponding atmospheric mixing ratios in the lakes sampled, both with depth and season within a given lake, and across different lakes. CFC profiles and observed degradation were not related to the groundwater inflow rate and hence are likely the result of in-lake processes influenced by CFC degradation in the (lake) water column, CFC degradation in the lake-bed sediments, and gas exchange rates and the duration of turnover (turnover efficiency).

  6. Dynamics of CFCs in northern temperate lakes and adjacent groundwater

    USGS Publications Warehouse

    Walker, J.F.; Saad, D.A.; Hunt, R.J.

    2007-01-01

    [1] Three dimictic lakes and one meromictic lake in and near the Trout Lake, Wisconsin, watershed were sampled to determine the variation of chlorofluorocarbon (CFC) concentrations within the lakes. The lakes were sampled during stratified conditions, during fall turnover, and during ice cover. The results demonstrate a considerable variation in CFC concentrations and corresponding atmospheric mixing ratios in the lakes sampled, both with depth and season within a given lake, and across different lakes. CFC profiles and observed degradation were not related to the groundwater inflow rate and hence are likely the result of in-lake processes influenced by CFC degradation in the (lake) water column, CFC degradation in the lake-bed sediments, and gas exchange rates and the duration of turnover (turnover efficiency).

  7. Lake Constance

    Atmospheric Science Data Center

    2013-04-17

    ... Swiss shores of Lake Constance at the town of Rorschach. Eutrophication, or the process of nutrient enrichment, is rapidly accelerated ... of the value of Lake Constance, efforts to mitigate eutrophication were initiated in the 1970's. MISR was built and is managed ...

  8. Lake Powell

    NASA Image and Video Library

    2007-09-20

    The white ring around Lake Powell tells the story. The surface is down 98 feet. This is critical, because Powell, Lake Mead, and other lakes along the Colorado River provide water for millions of people in five states. We are in the eighth year of a drought on the Colorado River. This year was the driest year ever reported in Southern California, and there is a severe drought in Northern California, down to less than 30-percent of snow pack. This ASTER image of part of Lake Powell was acquired in 2001. The gray area depicts the shrunken, reduced 2007 lake extent compared to the extended, larger black area in 2001. The image covers an area of 24 x 30 km, and is centered near 37.1 degrees north latitude, 111.3 degrees west longitude. This image from NASA Terra satellite. http://photojournal.jpl.nasa.gov/catalog/PIA10614

  9. Methane efflux from the pelagic regions of four lakes

    SciTech Connect

    Miller, L.G.; Oremland, R.S. )

    1988-09-01

    Methane emission to the atmosphere was studied in the deepest, central (pelagic) regions of one freshwater and three meromictic, alkaline saline lakes. The range of methane emissions was 0.004 to 2.916 mmol/sq m/hr (n=41). Outward flux was dominated by bubble ebullition only in the freshwater lake. Diffusive gas exchange was the sole mechanism of transfer in the meromictic lakes, and flux from these lakes was equivalent to or lower than that from the freshwater lake during its periods of ebullition. A comparison of measured flux with flux calculated using a model of gas exchange in Mono Lake suggested that floating chambers provide reasonable estimates of the magnitude of methane emissions from diffusion-dominated systems. 43 refs., 4 figs., 2 tabs.

  10. Great Lakes

    NASA Image and Video Library

    2017-09-28

    Bands of lake effect snow drift eastward from the western Great Lakes in this true-color image captured by the NOAA/NASA Suomi NPP satellite's Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on January 5, 2017. National Weather Service forecasters expect light to moderate lake effect snow showers to continue throughout the day today and into Saturday (1/7). Lake-effect snow forms when cold air passes over the warmer waters of a lake. This causes some lake water to evaporate into the air and warm it. This warmer, wetter air rises and cools as it moves away from the lake. When it cools, it releases that moisture and, if it’s cold enough, that moisture turns into snow. Although true-color images like this may appear to be photographs of Earth, they aren't. They are created by combining data from the three color channels on the VIIRS instrument sensitive to the red, green and blue (or RGB) wavelengths of light into one composite image. In addition, data from several other channels are often also included to cancel out or correct atmospheric interference that may blur parts of the image. Credit: NOAA/NASA/Suomi NPP via NOAA's Environmental Visualization Laboratory

  11. White Lake AOC

    EPA Pesticide Factsheets

    White Lake is in Muskegon County along the eastern shore of Lake Michigan. It was named an Area of Concern on the Great Lakes under the Great Lakes Water Quality Agreement of 1987 and delisted in 2014.

  12. Principles of lake sedimentology

    SciTech Connect

    Janasson, L.

    1983-01-01

    This book presents a comprehensive outline on the basic sedimentological principles for lakes, and focuses on environmental aspects and matters related to lake management and control-on lake ecology rather than lake geology. This is a guide for those who plan, perform and evaluate lake sedimentological investigations. Contents abridged: Lake types and sediment types. Sedimentation in lakes and water dynamics. Lake bottom dynamics. Sediment dynamics and sediment age. Sediments in aquatic pollution control programmes. Subject index.

  13. Lake Powell

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The white ring around Lake Powell tells the story. The surface is down 98 feet. This is critical, because Powell, Lake Mead, and other lakes along the Colorado River provide water for millions of people in five states. We are in the eighth year of a drought on the Colorado River. This year was the driest year ever reported in Southern California, and there is a severe drought in Northern California, down to less than 30-percent of snow pack. This ASTER image of part of Lake Powell was acquired in 2001. The gray area depicts the shrunken, reduced 2007 lake extent compared to the extended, larger black area in 2001.

    The image covers an area of 24 x 30 km, and is centered near 37.1 degrees north latitude, 111.3 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  14. Great Lakes

    USGS Publications Warehouse

    Edsall, Thomas A.; Mac, Michael J.; Opler, Paul A.; Puckett Haecker, Catherine E.; Doran, Peter D.

    1998-01-01

    The Great Lakes region, as defined here, includes the Great Lakes and their drainage basins in Minnesota, Wisconsin, Illinois, Indiana, Ohio, Pennsylvania, and New York. The region also includes the portions of Minnesota, Wisconsin, and the 21 northernmost counties of Illinois that lie in the Mississippi River drainage basin, outside the floodplain of the river. The region spans about 9º of latitude and 20º of longitude and lies roughly halfway between the equator and the North Pole in a lowland corridor that extends from the Gulf of Mexico to the Arctic Ocean.The Great Lakes are the most prominent natural feature of the region (Fig. 1). They have a combined surface area of about 245,000 square kilometers and are among the largest, deepest lakes in the world. They are the largest single aggregation of fresh water on the planet (excluding the polar ice caps) and are the only glacial feature on Earth visible from the surface of the moon (The Nature Conservancy 1994a).The Great Lakes moderate the region’s climate, which presently ranges from subarctic in the north to humid continental warm in the south (Fig. 2), reflecting the movement of major weather masses from the north and south (U.S. Department of the Interior 1970; Eichenlaub 1979). The lakes act as heat sinks in summer and heat sources in winter and are major reservoirs that help humidify much of the region. They also create local precipitation belts in areas where air masses are pushed across the lakes by prevailing winds, pick up moisture from the lake surface, and then drop that moisture over land on the other side of the lake. The mean annual frost-free period—a general measure of the growing-season length for plants and some cold-blooded animals—varies from 60 days at higher elevations in the north to 160 days in lakeshore areas in the south. The climate influences the general distribution of wild plants and animals in the region and also influences the activities and distribution of the human

  15. Recent warming of lake Kivu.

    PubMed

    Katsev, Sergei; Aaberg, Arthur A; Crowe, Sean A; Hecky, Robert E

    2014-01-01

    Lake Kivu in East Africa has gained notoriety for its prodigious amounts of dissolved methane and dangers of limnic eruption. Being meromictic, it is also expected to accumulate heat due to rising regional air temperatures. To investigate the warming trend and distinguish between atmospheric and geothermal heating sources, we compiled historical temperature data, performed measurements with logging instruments, and simulated heat propagation. We also performed isotopic analyses of water from the lake's main basin and isolated Kabuno Bay. The results reveal that the lake surface is warming at the rate of 0.12°C per decade, which matches the warming rates in other East African lakes. Temperatures increase throughout the entire water column. Though warming is strongest near the surface, warming rates in the deep waters cannot be accounted for solely by propagation of atmospheric heat at presently assumed rates of vertical mixing. Unless the transport rates are significantly higher than presently believed, this indicates significant contributions from subterranean heat sources. Temperature time series in the deep monimolimnion suggest evidence of convection. The progressive deepening of the depth of temperature minimum in the water column is expected to accelerate the warming in deeper waters. The warming trend, however, is unlikely to strongly affect the physical stability of the lake, which depends primarily on salinity gradient.

  16. Recent Warming of Lake Kivu

    PubMed Central

    Katsev, Sergei; Aaberg, Arthur A.; Crowe, Sean A.; Hecky, Robert E.

    2014-01-01

    Lake Kivu in East Africa has gained notoriety for its prodigious amounts of dissolved methane and dangers of limnic eruption. Being meromictic, it is also expected to accumulate heat due to rising regional air temperatures. To investigate the warming trend and distinguish between atmospheric and geothermal heating sources, we compiled historical temperature data, performed measurements with logging instruments, and simulated heat propagation. We also performed isotopic analyses of water from the lake's main basin and isolated Kabuno Bay. The results reveal that the lake surface is warming at the rate of 0.12°C per decade, which matches the warming rates in other East African lakes. Temperatures increase throughout the entire water column. Though warming is strongest near the surface, warming rates in the deep waters cannot be accounted for solely by propagation of atmospheric heat at presently assumed rates of vertical mixing. Unless the transport rates are significantly higher than presently believed, this indicates significant contributions from subterranean heat sources. Temperature time series in the deep monimolimnion suggest evidence of convection. The progressive deepening of the depth of temperature minimum in the water column is expected to accelerate the warming in deeper waters. The warming trend, however, is unlikely to strongly affect the physical stability of the lake, which depends primarily on salinity gradient. PMID:25295730

  17. Lake Bonneville

    USGS Publications Warehouse

    Gilbert, Grove Karl

    1890-01-01

    This volume is a contribution to the later physical history of the Great Basin. As a geographic province the Great Basin is characterized by a dry climate, changes of drainage, volcanic eruption, and crustal displacement. Lake Bonneville, the special theme of the volume, was a phenomenon of climate and drainage, but its complete history includes an account of contemporaneous eruption and displacement.

  18. Diversity of extremophilic purple phototrophic bacteria in Soap Lake, a Central Washington (USA) Soda Lake.

    PubMed

    Asao, Marie; Pinkart, Holly C; Madigan, Michael T

    2011-08-01

    Culture-based and culture-independent methods were used to explore the diversity of phototrophic purple bacteria in Soap Lake, a small meromictic soda lake in the western USA. Among soda lakes, Soap Lake is unusual because it consists of distinct upper and lower water bodies of vastly different salinities, and its deep waters contain up to 175 mM sulfide. From Soap Lake water new alkaliphilic purple sulfur bacteria of the families Chromatiaceae and Ectothiorhodospiraceae were cultured, and one purple non-sulfur bacterium was isolated. Comparative sequence analysis of pufM, a gene that encodes a key photosynthetic reaction centre protein universally found in purple bacteria, was used to measure the diversity of purple bacteria in Soap Lake. Denaturing gradient gel electrophoresis and subsequent phylogenetic analyses of pufMs amplified from Soap Lake water revealed that a significant diversity of purple bacteria inhabit this soda lake. Although close relatives of several of the pufM phylotypes obtained from cultured species could also be detected in Soap Lake water, several other more divergent pufM phylotypes were also detected. It is possible that Soap Lake purple bacteria are major contributors of organic matter into the ecosystem of this lake, especially in its extensive anoxic and sulfidic deep waters. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  19. Lake Mackay, Australia

    NASA Image and Video Library

    2014-10-27

    This image from NASA Terra spacecraft shows Lake Mackay, the largest of hundreds of ephemeral lakes scattered throughout Western Australia and the Northern Territory, and is the second largest lake in Australia.

  20. Limnological investigation of six lakes in southeast Alaska

    USGS Publications Warehouse

    McCoy, George A.; Wiggins, William W.; Schmidt, Artwin E.

    1976-01-01

    Limnological data were collected from six lakes in southeast Alaska in 1974. The data include concentrations of major inorganic constituents, nutrients, selected trace metals, total organic carbon, and chlorophyll. Vertical profiles of specific conductance, temperature, dissolved-oxygen saturation, and pH were drawn. With the exception of Redoubt Lake, all of the lakes are very similar chemically. The small differences in chemical composition probably reflect variations in geology of the drainage basins, altitudes, and morphometric characteristics of the lakes. Productivity is so low in all the lakes that it was not possible to rank the lakes by relative productivity from the reconnaissance sampling. Redoubt Lake is meromictic, but the others are probably holomictic and dimictic. (Woodard-USGS)

  1. Okanagan Lake, British Columbia

    NASA Image and Video Library

    1994-10-01

    STS068-155-011 (30 September-11 October 1994) --- (Okanagan Lake, British Columbia) View southward down the lake; Vernon is in the foreground, Kelowna just before the bend in the lake, and Penticton at the far end of the lake. Green crops are still vigorous despite the season (early October); clear-cuts dot the forested hillsides.

  2. Rediscovery of lake balls in Lake Michigan

    USGS Publications Warehouse

    Schloesser, Donald W.; Hiltunen, Jarl K.; Owens, Randall W.

    1983-01-01

    For the first time in 70 years, the occurrence of a 'lake ball' in Lake Michigan is here reported in the literature. According to a published system of classification, the object we collected in 1978 was a 'false' lake ball. Dissection revealed that it was colonized by 5 chironomid larvae and 162 oligochaetes. The species and numerical proportions of the oligochaetes indicated that it was formed in or near the mouth of a eutrophic tributary rather than in the open waters of Lake Michigan where it was found. Because of their mobility, false lake balls may be ecologically important, serving as natural vehicles for the dispersal of invertebrates.

  3. Basic limnology of fifty-one lakes in Costa Rica.

    PubMed

    Haberyan, Kurt A; Horn, Sally P; Umaña, Gerardo

    2003-03-01

    We visited 51 lakes in Costa Rica as part of a broad-based survey to document their physical and chemical characteristics and how these relate to the mode of formation and geographical distribution of the lakes. The four oxbow lakes were low in elevation and tended to be turbid, high in conductivity and CO2, but low in dissolved O2; one of these, L. Gandoca, had a hypolimnion essentially composed of sea water. These were similar to the four wetland lakes, but the latter instead had low conductivities and pH, and turbidity was often due to tannins rather than suspended sediments. The thirteen artificial lakes formed a very heterogenous group, whose features varied depending on local factors. The thirteen lakes dammed by landslides, lava flows, or lahars occurred in areas with steep slopes, and were more likely to be stratified than most other types of lakes. The eight lakes that occupy volcanic craters tended to be deep, stratified, clear, and cool; two of these, L. Hule and L. Río Cuarto, appeared to be oligomictic (tending toward meromictic). The nine glacial lakes, all located above 3440 m elevation near Cerro Chirripó, were clear, cold, dilute, and are probably polymictic. Cluster analysis resulted in three significant groups of lakes. Cluster 1 included four calcium-rich lakes (average 48 mg l-1), Cluster 2 included fourteen lakes with more Si than Ca+2 and higher Cl- than the other clusters, and Cluster 3 included the remaining thirty-three lakes that were generally less concentrated. Each cluster included lakes of various origins located in different geographical regions; these data indicate that, apart from the high-altitude glacial lakes and lakes in the Miravalles area, similarity in lake chemistry is independent of lake distribution.

  4. Lake Volta, Ghana

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This true-color image of Lake Volta in Ghana was acquired March 31, 2002 by the Moderate Resolution Imaging Spectroradiometer (MODIS). Lake Volta is one of the world's largest artificially created lakes. Lake Volta is actually a reservoir formed from the damming of the Volta River, and extends 250 miles north of the Akosombo Dam. The lake covers an area of 8,482 square km. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  5. Lake Chad, Chad, Africa

    NASA Image and Video Library

    1990-04-29

    Africa's Lake Chad where the borders of Chad, Niger, Nigeria and Cameroon merge (13.0N, 14.0E) has been undergoing change for the past 25 to 30 years when it was first noticed that the lake is drying up. Since then, astronauts have been photographing it on a regular basis to record the diminishing lake bed. This lake was once the aproximate size of Lake Erie but is now only about half that size and is still receeding.

  6. Past and present mercury flux to a West African crater lake (Lake Bosomtwe/Bosumtwi, Ghana).

    PubMed

    Poste, Amanda E; Muir, Derek C G; Otu, Megan K; Hall, Roland I; Hecky, Robert E

    2012-03-15

    Lake sediment cores have been used to reconstruct mercury deposition patterns in many parts of the world; however, no studies to date have used these methods in West Africa, nor are there any published measurements of mercury deposition to this region. We measured mercury in a (210)Pb dated sediment core from a meromictic crater lake in West Africa (Lake Bosomtwe, Ghana). Lake Bosomtwe has a very small catchment area to lake area ratio (1.1) and the sediment mercury profile is expected to reflect past and present atmospheric mercury deposition to the lake. Mercury concentrations in sediments as well as mercury flux to the sediments increased from the mid-1800s to latter half of the 1900s, however there has been a sharp decline in mercury flux to Lake Bosomtwe in recent decades. The recent decline in mercury flux to Lake Bosomtwe's sediments does not appear to be consistent with trends in local, regional or global mercury emissions, and may instead reflect declining global atmospheric mercury concentrations or declining European emissions, highlighting the importance of long-range atmospheric transport of mercury. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Lake Nasser and Toshka Lakes, Egypt

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Lake Nasser (center) and the Toshka Lakes (center left) glow emerald green and black in this MODIS true-color image acquired March 8, 2002. Located on and near the border of Egypt and Norther Sudan, these lakes are an oasis of water in between the Nubian (lower right) and Libyan Deserts (upper left). Also visible are the Red Sea (in the upper right) and the Nile River (running north from Lake Nasser). Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  8. Lake Huron LAMPs

    EPA Pesticide Factsheets

    The approach in Lake Huron differs from the Lakewide Management Plans of the other Great Lakes: no formal binational designation of lakewide beneficial use impairments, nor extensive lakewide modeling of chemical loadings

  9. Lake Tahoe Projects

    EPA Pesticide Factsheets

    Information on the Lake Tahoe watershed, EPA's protection efforts, water quality issues, effects of climate, change, Lake Tahoe Total Maximum Daily Load TMDL), EPA-sponsored projects, list of partner agencies.

  10. The Great Lakes

    EPA Pesticide Factsheets

    The Great Lakes form the largest surface freshwater system on Earth. The U.S. and Canada work together to restore and protect the environment in the Great Lakes Basin. Top issues include contaminated sediments, water quality and invasive species.

  11. Lakes on Titan

    NASA Image and Video Library

    2006-07-24

    The Cassini spacecraft, using its radar system, has discovered very strong evidence for hydrocarbon lakes on Titan. Dark patches, which resemble terrestrial lakes, seem to be sprinkled all over the high latitudes surrounding Titan north pole

  12. Looking Down on Lakes

    NASA Image and Video Library

    2014-04-07

    NASA Cassini spacecraft peers down though layers of haze to glimpse the lakes of Titan northern regions. Titan has a hydrological cycle similar to Earth, but instead of water, Titan lakes and seas are filled with liquid methane and ethane.

  13. Lakes Ecosystem Services Online

    EPA Science Inventory

    Northeastern lakes provide valuable ecosystem services that benefit residents and visitors and are increasingly important for provisioning of recreational opportunities and amenities. Concurrently, however, population growth threatens lakes by, for instance, increasing nutrient ...

  14. National Lakes Assessment

    EPA Pesticide Factsheets

    The National Lakes Assessment is a collaborative, statistical survey of the nation's lakes. It is one of four national surveys that EPA and its partners conduct to assess the condition and health of the nation's water resources.

  15. About Lake Tahoe

    EPA Pesticide Factsheets

    Information on the Lake Tahoe watershed, EPA's protection efforts, water quality issues, effects of climate, change, Lake Tahoe Total Maximum Daily Load TMDL), EPA-sponsored projects, list of partner agencies.

  16. Lakes Ecosystem Services Online

    EPA Science Inventory

    Northeastern lakes provide valuable ecosystem services that benefit residents and visitors and are increasingly important for provisioning of recreational opportunities and amenities. Concurrently, however, population growth threatens lakes by, for instance, increasing nutrient ...

  17. Lake trout rehabilitation in Lake Ontario

    USGS Publications Warehouse

    Elrod, Joseph H.; O'Gorman, Robert; Schneider, Clifford P.; Eckert, Thomas H.; Schaner, Ted; Bowlby, James N.; Schleen, Larry P.

    1995-01-01

    Attempts to maintain the native lake trout (Salvelinus namaycush) population in Lake Ontario by stocking fry failed and the species was extirpated by the 1950s. Hatchery fish stocked in the 1960s did not live to maturity because of sea lamprey (Petromyzon marinus) predation and incidental commercial harvest. Suppression of sea lampreys began with larvicide treatments of Lake Ontario tributaries in 1971 and was enhanced when the tributaries of Oneida Lake and Lake Erie were treated in the 1980s. Annual stocking of hatchery fish was resumed with the 1972 year class and peaked at about 1.8 million yearlings and 0.3 million fingerlings from the 1985–1990 year classes. Survival of stocked yearlings declined over 50% in the 1980 s and was negatively correlated with the abundance of lake trout > 550 mm long (r = −0.91, P < 0.01, n = 12). A slot length limit imposed by the State of New York for the 1988 fishing season reduced angler harvest. Angler harvest in Canadian waters was 3 times higher in eastern Lake Ontario than in western Lake Ontario. For the 1977–1984 year classes, mean annual survival rate of lake trout age 6 and older was 0.45 (range: 0.35–0.56). In U.S. waters during 1985–1992, the total number of lake trout harvested by anglers was about 2.4 times greater than that killed by sea lampreys. The number of unmarked lake trout < 250 mm long in trawl catches in 1978–1992 was not different from that expected due to loss of marks and failure to apply marks at the hatchery, and suggested that recruitment of naturally-produced fish was nil. However, many of the obstacles which may have impeded lake trout rehabilitation in Lake Ontario during the 1980s are slowly being removed, and there are signs of a general ecosystem recovery. Significant recruitment of naturally produced lake trout by the year 2000, one interim objective of the rehabilitation plan for the Lake, may be achieved.

  18. Demonstration of antifreeze protein activity in Antarctic lake bacteria.

    PubMed

    Gilbert, Jack A; Hill, Philip J; Dodd, Christine E R; Laybourn-Parry, Johanna

    2004-01-01

    Antifreeze proteins (AFPs) are a structurally diverse group of proteins that have the ability to modify ice crystal structure and inhibit recrystallization of ice. AFPs are well characterized in fish and insects, but very few bacterial species have been shown to have AFP activity to date. Thirty eight freshwater to hypersaline lakes in the Vestfold Hills and Larsemann Hills of Eastern Antarctica were sampled for AFPs during 2000. Eight hundred and sixty six bacterial isolates were cultivated. A novel AFP assay, designed for high-throughput analysis in Antarctica, demonstrated putative activity in 187 of the cultures. Subsequent analysis of the putative positive isolates showed 19 isolates with significant recrystallization inhibition (RI) activity. The 19 RI active isolates were characterized using ARDRA (amplified rDNA restriction analysis) and 16S rDNA sequencing. They belong to genera from the alpha- and gamma-Proteobacteria, with genera from the gamma-subdivision being predominant. The 19 AFP-active isolates were isolated from four physico-chemically diverse lakes. Ace Lake and Oval Lake were both meromictic with correspondingly characteristic chemically stratified water columns. Pendant Lake was a saline holomictic lake with different chemical properties to the two meromictic lakes. Triple Lake was a hypersaline lake rich in dissolved organic carbon and inorganic nutrients. The environments from which the AFP-active isolates were isolated are remarkably diverse. It will be of interest, therefore, to elucidate the evolutionary forces that have led to the acquisition of functional AFP activity in microbes of the Vestfold Hills lakes and to discover the role the antifreezes play in these organisms.

  19. A Killer Lake

    ERIC Educational Resources Information Center

    Horvath, Thomas

    2005-01-01

    In 1986, Lake Nyos, a volcanic lake in Cameroon, released a huge amount of carbon dioxide gas, killing over 1,700 people in the surrounding area. This case study, developed for use in a limnology or aquatic biology course, explores that event, introducing students to concepts relating to lake formation, thermal stratification, and dissolved gases.…

  20. Lake Layers: Stratification.

    ERIC Educational Resources Information Center

    Brothers, Chris; And Others

    This teacher guide and student workbook set contains two learning activities, designed for fifth through ninth grade students, that concentrate on lake stratification and water quality. In the activities students model the seasonal temperature changes that occur in temperate lakes and observe the resulting stratification of lake waters. Students…

  1. Great Minds? Great Lakes!

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Chicago, IL. Great Lakes National Program Office.

    This book contains lesson plans that provide an integrated approach to incorporating Great Lakes environmental issues into elementary subjects. The book is divided into three subject areas: (1) History, which includes the origins of the Great Lakes, Great Lakes people, and shipwrecks; (2) Social Studies, which covers government, acid rain as a…

  2. Great Lakes: Chemical Monitoring

    ERIC Educational Resources Information Center

    Delfino, Joseph J.

    1976-01-01

    The Tenth Great Lakes Regional Meeting of the American Chemical Society met to assess current Chemical Research activity in the Great Lakes Basin, and addressed to the various aspects of the theme, Chemistry of the Great Lakes. Research areas reviewed included watershed studies, atmospheric and aquatic studies, and sediment studies. (BT)

  3. A Killer Lake

    ERIC Educational Resources Information Center

    Horvath, Thomas

    2005-01-01

    In 1986, Lake Nyos, a volcanic lake in Cameroon, released a huge amount of carbon dioxide gas, killing over 1,700 people in the surrounding area. This case study, developed for use in a limnology or aquatic biology course, explores that event, introducing students to concepts relating to lake formation, thermal stratification, and dissolved gases.…

  4. Great Lakes in January

    NASA Image and Video Library

    2017-09-28

    This image taken on January 13, 2015 from the Suomi NPP satellite's VIIRS instrument shows the Great Lakes and surrounding areas. The latest Great Lakes Surface Environmental Analysis (GLSEA) from the NOAA Great Lakes Environmental Research Laboratory shows total ice cover of 29.3% as of January 13th. Credit: NOAA/NASA/NPP Via NOAA Environmental Visualization Laboratory

  5. Great Lakes: Chemical Monitoring

    ERIC Educational Resources Information Center

    Delfino, Joseph J.

    1976-01-01

    The Tenth Great Lakes Regional Meeting of the American Chemical Society met to assess current Chemical Research activity in the Great Lakes Basin, and addressed to the various aspects of the theme, Chemistry of the Great Lakes. Research areas reviewed included watershed studies, atmospheric and aquatic studies, and sediment studies. (BT)

  6. Spatial structure and persistence of methanogen populations in humic bog lakes.

    PubMed

    Milferstedt, Kim; Youngblut, Nicholas D; Whitaker, Rachel J

    2010-06-01

    Patterns of diversity within methanogenic archaea in humic bog lakes are quantified over time and space to determine the roles that spatial isolation and seasonal mixing play in structuring microbial populations. The protein encoding gene mcrA is used as a molecular marker for the detection of fine-scale differences between methanogens in four dimictic bog lakes in which the water column is mixed twice a year and one meromictic lake that is permanently stratified. Although similar sequences are observed in each bog lake, each lake has its own characteristic set of persisting sequence types, indicating that methanogen populations are delimited either by low migration between the anaerobic hypolimnia or by lake-specific selection. The meromictic lake is differentiated from all other lakes and contains sequences with a higher degree of microdiversity than the dimictic lakes. By relating the structure of diversity to the depth of each bog lake, we propose the hypothesis that the deeper parts of the water column favor microdiversification of methanogens, whereas the periodically disturbed water column of shallower dimictic lakes promote genetically more diverse methanogen communities.

  7. Lake Effects: The Lake Superior Curriculum Guide.

    ERIC Educational Resources Information Center

    Beery, Tom; And Others

    This curriculum guide was launched in response to a need for Lake Superior-specific educational materials and contains lessons and activities that can be used to teach about Lake Superior. The lessons in this book are divided into four sections. Each of the first three sections has a background section that provides basic information about Lake…

  8. Lake Effects: The Lake Superior Curriculum Guide.

    ERIC Educational Resources Information Center

    Beery, Tom; And Others

    This curriculum guide was launched in response to a need for Lake Superior-specific educational materials and contains lessons and activities that can be used to teach about Lake Superior. The lessons in this book are divided into four sections. Each of the first three sections has a background section that provides basic information about Lake…

  9. Stream, Lake, and Reservoir Management.

    PubMed

    Dai, Jingjing; Mei, Ying; Chang, Chein-Chi

    2017-10-01

    This review on stream, lake, and reservoir management covers selected 2016 publications on the focus of the following sections: Stream, lake, and reservoir management • Water quality of stream, lake, and reservoir • Reservoir operations • Models of stream, lake, and reservoir • Remediation and restoration of stream, lake, and reservoir • Biota of stream, lake, and reservoir • Climate effect of stream, lake, and reservoir.

  10. Hazardous crater lakes studied

    NASA Astrophysics Data System (ADS)

    Kusakabe, Minoru

    Crater lakes usually sit on top of volcanic conduits and act as condensers of magmatic vapor. Studies of crater lakes can therefore provide information on both deep magmatic activity and variations in the degassing state of a shallow magmatic body. The Lake Nyos gas disaster of August 1986 and a similar event in August 1984 at Lake Monoun, both in Cameroon, resulted from the accumulation of magmatic CO2 in the bottom layers of the lakes. Geochemical monitoring of crater lakes is a promising tool for forecasting not only limnic but also volcanic eruptions. Acid-mineralized waters formed by condensation of hot magmatic volatiles in crater lakes are thought to bear some resemblance to hydrothermal fluids acting in the genesis of acid-sulfate alteration and Au-Cu-Ag mineralization of volcanic-hosted precious metal deposits.

  11. Water quality of Lake Austin and Town Lake, Austin, Texas

    SciTech Connect

    Andrews, F.L.; Wells, F.C.; Shelby, W.J.; McPherson, E.M.

    1988-01-01

    Lake Austin and Town Lake are impoundments on the Colorado River in Travis County, central Texas, and are a source of water for municipal industrial water supplies, electrical-power generation, and recreation for more than 500,000 people in the Austin metropolitan area. Small vertical temperature variations in both lakes were attributed to shallow depths in the lakes and short retention times of water in the lakes during the summer months. The largest areal variations in dissolved oxygen generally occur in Lake Austin during the summer as a result of releases of water from below the thermocline in Lake Travis. Except for iron, manganese, and mercury, dissolved concentrations of trace elements in water collected from Lake Austin and Town Lake did not exceed the primary or secondary drinking water standards set by the US Environmental Protection Agency. Little or no effect of stormwater runoff on temperature, dissolved oxygen, or minor elements could be detected in either Lake Austin or Town Lake. Little seasonal or areal variation was noted in nitrogen concentrations in Lake Austin or Town lake. Total phosphorus concentrations generally were small in both lakes. Increased concentrations of nitrogen and phosphorus were detected after storm runoff inflow in Town Lake, but not in Lake Austin; densities of fecal-coliform bacteria increased in Lake Austin and Town Lake, but were substantially greater in Town Lake than in Lake Austin. 18 refs., 38 figs., 59 tabs.

  12. Lake trout rehabilitation in Lake Huron

    USGS Publications Warehouse

    Eshenroder, Randy L.; Payne, N. Robert; Johnson, James E.; Bowen, Charles; Ebener, Mark P.

    1995-01-01

    Efforts to restore lake trout (Salvelinus namaycush) in Lake Huron after their collapse in the 1940s were underway in the early 1970s with completion of the first round of lampricide applications in tributary streams and the stocking of several genotypes. We assess results of rehabilitation and establish a historical basis for comparison by quantifying the catch of spawning lake trout from Michigan waters in 1929-1932. Sixty-eight percent of this catch occurred in northern waters (MH-1) and most of the rest (15%) was from remote reefs in the middle of the main basin. Sea lampreys (Petromyzon marinus) increased in the early 1980s in the main basin and depressed spawning populations of lake trout. This increase was especially severe in northern waters and appeared to be associated with untreated populations in the St. Marys River. Excessive commercial fishing stemming from unresolved treaty rights also contributed to loss of spawning fish in northern Michigan waters. Seneca-strain lake trout did not appear to be attacked by sea lampreys until they reached a size > 532 mm. At sizes > 632 mm, Seneca trout were 40-fold more abundant than the Marquette strain in matched-planting experiments. Natural reproduction past the fry stage has occurred in Thunder Bay and South Bay, but prospects for self-sustaining populations of lake trout in the main basin are poor because sea lampreys are too abundant, only one side of the basin is stocked, and stocking is deferred to allow commercial gillnetting in areas where most of the spawning occurred historically. Backcross lake trout, a lake trout x splake (s. Fontinalis x s. Namaycush) hybrid, did not reproduce in Georgian Bay, but this genotype is being replaced with pure-strain lake trout, whose early performance appears promising.

  13. Change in the wind flow regime in stratified lakes

    NASA Astrophysics Data System (ADS)

    Belolipetskii, V. M.; Belolipetskii, P. V.

    2016-01-01

    Wind flows in meromictic saline lakes in which the water column is not mixed to the bottom for at least one year are studied. This leads to the formation of upper and depth layers with small density gradients, between which there is a water layer with a large density gradient. It has been shown that, depending on the density stratification and the wind speed, wind flows (in the vertical plane) of two types are possible: with one or two circulation zones. For a two-layer lake model, a criterion for the change in the wind flow regime is proposed.

  14. Stage fluctuations of Wisconsin lakes

    USGS Publications Warehouse

    House, Leo B.

    1985-01-01

    This report describes lake-stage fluctuations of 83 gaged lakes in Wisconsin and presents techniques for estimating stage fluctuation at ungaged lakes. Included are stage information at 83 lakes and stage-frequency data for 32 of these lakes that had sufficient record for analysis. Lakes are classified by a hydrologic-topographic lake classification scheme as ground-water flowthrough (GWF) lakes, surface-water drainage (SWD) lakes, and surface-water flow-through (SWF) lakes. Lakes within the same class were found to have similar water-level fluctuations. The lake-stage records indicate that most annual maximums occur during the months of May and June for all three classes. Annual minimum lake levels generally occur in September for surface-water drainage lakes, in March for surface-water flowthrough lakes, and in November for ground-water flow-through lakes. Data for each lake include location, period of water-level record, hydrologic classification, drainage area, surface area, lake volume, maximum depth, long-term mean stage and its standard deviation, maximum and minimum observed lake stage, and the average annual lake-stage fluctuation.

  15. Past and future warming of a deep European lake (Lake Lugano): What are the climatic drivers?

    USGS Publications Warehouse

    Lepori, Fabio; Roberts, James J.

    2015-01-01

    We used four decades (1972–2013) of temperature data from Lake Lugano, Switzerland and Italy, to address the hypotheses that: [i] the lake has been warming; [ii] part of the warming reflects global trends and is independent from climatic oscillations and [iii] the lake will continue to warm until the end of the 21st century. During the time spanned by our data, the surface waters of the lake (0–5 m) warmed at rates of 0.2–0.9 °C per decade, depending on season. The temperature of the deep waters (50-m bottom) displayed a rising trend in a meromictic basin of the lake and a sawtooth pattern in the other basin, which is holomictic. Long-term variation in surfacewater temperature correlated to global warming and multidecadal variation in two climatic oscillations, the Atlantic Multidecadal Oscillation (AMO) and the East Atlantic Pattern (EA).However, we did not detect an influence of the EA on the lake's temperature (as separate from the effect of global warming). Moreover, the effect of the AMO, estimated to a maximum of +1 °C, was not sufficient to explain the observed temperature increase (+2–3 °C in summer). Based on regional climate projections, we predicted that the lake will continue to warm at least until the end of the 21st century. Our results strongly suggest that the warming of Lake Lugano is tied to globalclimate change. To sustain current ecosystem conditions in Lake Lugano, we suggest that manage- ment plans that curtail eutrophication and (or) mitigation of global warming be pursued.

  16. Salting our freshwater lakes.

    PubMed

    Dugan, Hilary A; Bartlett, Sarah L; Burke, Samantha M; Doubek, Jonathan P; Krivak-Tetley, Flora E; Skaff, Nicholas K; Summers, Jamie C; Farrell, Kaitlin J; McCullough, Ian M; Morales-Williams, Ana M; Roberts, Derek C; Ouyang, Zutao; Scordo, Facundo; Hanson, Paul C; Weathers, Kathleen C

    2017-04-10

    The highest densities of lakes on Earth are in north temperate ecosystems, where increasing urbanization and associated chloride runoff can salinize freshwaters and threaten lake water quality and the many ecosystem services lakes provide. However, the extent to which lake salinity may be changing at broad spatial scales remains unknown, leading us to first identify spatial patterns and then investigate the drivers of these patterns. Significant decadal trends in lake salinization were identified using a dataset of long-term chloride concentrations from 371 North American lakes. Landscape and climate metrics calculated for each site demonstrated that impervious land cover was a strong predictor of chloride trends in Northeast and Midwest North American lakes. As little as 1% impervious land cover surrounding a lake increased the likelihood of long-term salinization. Considering that 27% of large lakes in the United States have >1% impervious land cover around their perimeters, the potential for steady and long-term salinization of these aquatic systems is high. This study predicts that many lakes will exceed the aquatic life threshold criterion for chronic chloride exposure (230 mg L(-1)), stipulated by the US Environmental Protection Agency (EPA), in the next 50 y if current trends continue.

  17. Lake Balkhash, Kazakhstan

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image of crescent-shaped Lake Balkhash was taken by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) on April 27, 2000. Lake Balkhash is located in eastern Kazakhstan, north of the Tian-Shan mountains. The Ili River flows into the western end of the lake, filling it with bright sediment. This sediment highlights the difference between the freshwater western side of the lake and the saline eastern side. A sandbar prevents mixing between the lake's two sections.Other features in this image include Lake Sayram in the lower right (southeast) corner, which is surrounded by the Borohoro Shan mountain range. At center right, just north of the Borohoro Shan, are lakes Sasykkol (left) and Alakol (right). The Karatal River flows northward through an arid and sandy landscape into the center of Lake Balkhash. The full-size image compares the region on April 27th image with one from the 18th. In that time sediments in lakes Balkhash and Sasykol increased noticeably, probably due to snowmelt-note the decrease in snowcover on the region's mountains. Also, the ice on Lake Sayram melted. These images were retrieved by the SeaWiFS high-resolution ground station in Mongolia, which recently began sending data to Goddard Space Flight Center. Image provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  18. Salting our freshwater lakes

    PubMed Central

    Bartlett, Sarah L.; Burke, Samantha M.; Doubek, Jonathan P.; Krivak-Tetley, Flora E.; Skaff, Nicholas K.; Summers, Jamie C.; Farrell, Kaitlin J.; McCullough, Ian M.; Morales-Williams, Ana M.; Roberts, Derek C.; Ouyang, Zutao; Scordo, Facundo; Hanson, Paul C.; Weathers, Kathleen C.

    2017-01-01

    The highest densities of lakes on Earth are in north temperate ecosystems, where increasing urbanization and associated chloride runoff can salinize freshwaters and threaten lake water quality and the many ecosystem services lakes provide. However, the extent to which lake salinity may be changing at broad spatial scales remains unknown, leading us to first identify spatial patterns and then investigate the drivers of these patterns. Significant decadal trends in lake salinization were identified using a dataset of long-term chloride concentrations from 371 North American lakes. Landscape and climate metrics calculated for each site demonstrated that impervious land cover was a strong predictor of chloride trends in Northeast and Midwest North American lakes. As little as 1% impervious land cover surrounding a lake increased the likelihood of long-term salinization. Considering that 27% of large lakes in the United States have >1% impervious land cover around their perimeters, the potential for steady and long-term salinization of these aquatic systems is high. This study predicts that many lakes will exceed the aquatic life threshold criterion for chronic chloride exposure (230 mg L−1), stipulated by the US Environmental Protection Agency (EPA), in the next 50 y if current trends continue. PMID:28396392

  19. View of Lake Sabrina Dam and Lake Sabrina from east ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of Lake Sabrina Dam and Lake Sabrina from east ridge showing spillway at photo center, view southwest - Bishop Creek Hydroelectric System, Plant 2, Lake Sabrina Dam, Bishop Creek, Bishop, Inyo County, CA

  20. In-lake Modeling Recommendation Report for Lake Champlain TMDL

    EPA Pesticide Factsheets

    This report describes the recommended modeling approach for the in-lake modeling component of the Lake Champlain TMDL project. The report was prepared by Tetra Tech, with input from the Lake Champlain modeling workgroup. (TetraTech, 2012b)

  1. 9. GRANT LAKE AND MONO LAKE IN DISTANCE, LOOKING NORTHEAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. GRANT LAKE AND MONO LAKE IN DISTANCE, LOOKING NORTHEAST - Los Angeles Aqueduct, From Lee Vining Intake (Mammoth Lakes) to Van Norman Reservoir Complex (San Fernando Valley), Los Angeles, Los Angeles County, CA

  2. 2016 Lake Michigan Lake Trout Working Group Report

    USGS Publications Warehouse

    Madenjian, Charles P.; Breidert, Brian; Boyarski, David; Bronte, Charles R.; Dickinson, Ben; Donner, Kevin; Ebener, Mark P.; Gordon, Roger; Hanson, Dale; Holey, Mark; Janssen, John; Jonas, Jory; Kornis, Matthew; Olsen, Erik; Robillard, Steve; Treska, Ted; Weldon, Barry; Wright, Greg D.

    2017-01-01

    This report provides a review on the progression of lake trout rehabilitation towards meeting the Salmonine Fish Community Objectives (FCOs) for Lake Michigan (Eshenroder et. al. 1995) and the interim goal and evaluation objectives articulated in A Fisheries Management Implementation Strategy for the Rehabilitation of Lake Trout in Lake Michigan (Dexter et al. 2011); we also include data describing lake trout stocking and mortality to portray the present state of progress towards lake trout rehabilitation.

  3. Origins of rainbow smelt in Lake Ontario

    USGS Publications Warehouse

    Bergstedt, Roger A.

    1983-01-01

    The first rainbow smelt (Osmerus mordax) to enter Lake Ontario were probably migrants from an anadromous strain introduced into New York's Finger Lakes. Since the upper Great Lakes were originally stocked with a landlocked strain from Green Lake, Maine, subsequent migration to Lake Ontario from Lake Erie makes Lake Ontario unique among the Great Lakes in probably having received introductions from two distinct populations.

  4. Hydrology of Indiana lakes

    USGS Publications Warehouse

    Perrey, Joseph Irving; Corbett, Don Melvin

    1956-01-01

    The stabilization of lake levels often requires the construction of outlet control structures. A detailed study of past lake-level elevations and other hydologic date is necessary to establish a level that can be maintained and to determine the means necessary for maintaining the established level. Detailed lake-level records for 28 lakes are included in the report, and records for over 100 other lakes data are available in the U.S. Geological Survey Office, Indianapolis, Ind. Evaporation data from the four Class A evaporation station of the U. S. Weather Bureau have been compiled in this report. A table showing the established legal lake level and related data is included.

  5. Mono Lake, California

    NASA Image and Video Library

    2017-03-24

    In eastern California, along the western edge of the Great Basin, sits Mono Lake. This is a salty remnant of a wetter era. Estimates are that the lake existed for at least 760,000 years. Now surrounded by mountain ranges, however, Mono Lake has no outlet; water entering the lake can only evaporate away, so Mono Lake is saltier than the ocean. South of the lake appear some of the geologic features known as Mono Craters. Geologists estimate that the Mono Craters last erupted about 650 years ago. The image was acquired July 7, 2016, covers an area of 22.6 by 34 km, and is located at 37.9 degrees north, 119 degrees west. http://photojournal.jpl.nasa.gov/catalog/PIA21518

  6. Lake Enriquillo, Dominican Republic

    NASA Image and Video Library

    2017-08-15

    Lake Enriquillo is a hypersaline lake in the Dominican Republic. In 2004, the lake covered an area of 164 square kilometers; by 2011, it had doubled in size and grown to 350 km2, inundating farmland and homes. Various reasons for the flooding include increases in rainfall; increase of sediments going into the lake, raising the lakebed; and milder temperatures, reducing surface evaporation. The lake is home to the largest population of American crocodiles in the Caribbean. The images were acquired October 26, 2003 and June 10, 2017, cover an area of 22.7 by 45.4 km, and are located at 18.5 degrees north, 71.6 degrees west. An image of Lake Enriquillo taken in 2003 is available at https://photojournal.jpl.nasa.gov/catalog/PIA21815

  7. Speciation in ancient lakes.

    PubMed

    Martens, K

    1997-05-01

    About a dozen lakes in the world are up to three orders of magnitude older than most others. Lakes Tanganyika (East Africa) and Baikal (Siberia) have probably existed in some form for 12-20 million years, maybe more. Such lakes can have different origins, sizes, shapes, depths and limnologies, but, in contrast to short-lived (mostly post-glacial) lakes, they have exceptionally high faunal diversity and levels of endemicity. A multitude of and processes accounting for these explosive radiations have recently been documented, most of them based on particular groups in certain lakes, but comparative research can detect repeated patterns. No special speciafion mechanism, exclusive to ancient lakes has been demonstrated, although cases of ultra-rapid speciation have been documented. Extant diversity results not by simple accumulation, but by a complex process of immigration, speciation and extinction.

  8. David Morrison on Lake Vostok

    NASA Image and Video Library

    Dr. David Morrison discusses the implications of research possibilities at Lake Vostok, one of the largest subglacial lakes located over two miles beneath the ice in Antarctica. The lake has been c...

  9. Aquatic biogeochemistry: Cleaner Chinese lakes

    NASA Astrophysics Data System (ADS)

    Corman, Jessica

    2017-07-01

    Phosphorus loading can cause eutrophication of lakes. Analyses of lake chemistry in China reveal that policies have led to lower phosphorus levels overall, but increasing trends in some lakes suggest that expanded policies may be needed.

  10. Lake Mead, NV

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Lake Mead, Nevada, (36.0N, 114.5E) where the water from the Colorado River empties after it's 273 mile journey through the Grand Canyon of Arizona is the subject of this photo. Other features of interest are Hoover Dam on the south shore of Lake Mead where cheap hydroelectric power is secondary to the water resources made available in this northern desert region and the resort city of Las Vegas, just to the west of Lake Mead.

  11. Great Lakes Literacy Principles

    NASA Astrophysics Data System (ADS)

    Fortner, Rosanne W.; Manzo, Lyndsey

    2011-03-01

    Lakes Superior, Huron, Michigan, Ontario, and Erie together form North America's Great Lakes, a region that contains 20% of the world's fresh surface water and is home to roughly one quarter of the U.S. population (Figure 1). Supporting a $4 billion sport fishing industry, plus $16 billion annually in boating, 1.5 million U.S. jobs, and $62 billion in annual wages directly, the Great Lakes form the backbone of a regional economy that is vital to the United States as a whole (see http://www.miseagrant.umich.edu/downloads/economy/11-708-Great-Lakes-Jobs.pdf). Yet the grandeur and importance of this freshwater resource are little understood, not only by people in the rest of the country but also by many in the region itself. To help address this lack of knowledge, the Centers for Ocean Sciences Education Excellence (COSEE) Great Lakes, supported by the U.S. National Science Foundation and the National Oceanic and Atmospheric Administration, developed literacy principles for the Great Lakes to serve as a guide for education of students and the public. These “Great Lakes Literacy Principles” represent an understanding of the Great Lakes' influences on society and society's influences on the Great Lakes.

  12. Lakes, Lagerstaetten, and Evolution

    NASA Astrophysics Data System (ADS)

    Kordesch, E. G.; Park, L. E.

    2001-12-01

    The diversity of terrestrial systems is estimated to be greater than in the marine realm. However no hard data yet exists to substantiate this claim. Ancient lacustrine deposits may preserve an exceptionally diverse fossil fauna and aid in determining continental faunal diversities. Fossils preserved in lake deposits, especially those with exceptional preservation (i.e. Konservat Lagerstaetten), may represent a dependable method for determining species diversity changes in the terrestrial environment because of their faunal completeness. Important Konservat Lagerstaetten, such as the Green River Formation (US) and Messel (Germany), both Eocene in age, are found in lake sediments and show a remarkable faunal diversity for both vertebrates and invertebrates. To date information from nearly 25 lake lagerstaetten derived from different types of lake basins from the Carboniferous to the Miocene have been collected and described. Carboniferous sites derive from the cyclothems of Midcontinent of the US while many Cenozoic sites have been described from North and South America as well as Europe and Australia. Asian sites contain fossils from the Mesozoic and Cenozoic. With this data, insight into the evolutionary processes associated with lake systems can be examined. Do lakes act as unique evolutionary crucibles in contrast to marine systems? The speciation of cichlid fishes in present-day African lakes appears to be very high and is attributed to the diversity of environments found in large rift lakes. Is this true of all ancient lakes or just large rift lakes? The longevity of a lake system may be an important factor in allowing speciation and evolutionary processes to occur; marine systems are limited only in the existence of environments as controlled by tectonics and sea level changes, on the order of tens of millions of years. Rift lakes are normally the longest lived in the millions of years. Perhaps there are only certain types of lakes in which speciation of

  13. Great Lakes: Great Gardening.

    ERIC Educational Resources Information Center

    New York Sea Grant Inst., Albany, NY.

    This folder contains 12 fact sheets designed to improve the quality of gardens near the Great Lakes. The titles are: (1) "Your Garden and the Great Lakes"; (2) "Organic Gardening"; (3) "Fruit and Vegetable Gardening"; (4) "Composting Yard Wastes"; (5) "Herbicides and Water Quality"; (6)…

  14. Utah: Salt Lake Region

    Atmospheric Science Data Center

    2014-05-15

    ... mountains including the Wasatch Range to the east, and the temperature difference between the Great Salt Lake and the overlying atmosphere ... snow cover between the winter and summer views, water color changes in parts of the Great Salt Lake are apparent in these images. The ...

  15. Lessons from a Lake.

    ERIC Educational Resources Information Center

    Goethals, Susan

    1997-01-01

    Describes a study that included classroom lessons on hydroelectric power, the history and construction of a nearby lake, data recording, the use of field guides, and methods of counting natural populations. The study culminated in a field trip to the lake. (JRH)

  16. Great Lakes Teacher's Guide.

    ERIC Educational Resources Information Center

    Reid, Ron

    The Great Lakes are one of the world's greatest reservoirs of fresh water, the foundation of Ontario's economic development, a primary force in ecological systems, and a base for pleasure and recreation. They are also a magnificent resource for the teachers of Ontario. Study of the Great Lakes can bring to life the factors that shape the ecology…

  17. The Great Lakes.

    ERIC Educational Resources Information Center

    Seasons, 1987

    1987-01-01

    The Great Lakes are one of the world's greatest reserviors of fresh water, the foundation of Ontario's economic development, a primary force in ecological systems, and a base for pleasure and recreation. These lakes and their relationship with people of Canada and the United States can be useful as a subject for teaching the impact of human…

  18. The lakes of Titan.

    PubMed

    Stofan, E R; Elachi, C; Lunine, J I; Lorenz, R D; Stiles, B; Mitchell, K L; Ostro, S; Soderblom, L; Wood, C; Zebker, H; Wall, S; Janssen, M; Kirk, R; Lopes, R; Paganelli, F; Radebaugh, J; Wye, L; Anderson, Y; Allison, M; Boehmer, R; Callahan, P; Encrenaz, P; Flamini, E; Francescetti, G; Gim, Y; Hamilton, G; Hensley, S; Johnson, W T K; Kelleher, K; Muhleman, D; Paillou, P; Picardi, G; Posa, F; Roth, L; Seu, R; Shaffer, S; Vetrella, S; West, R

    2007-01-04

    The surface of Saturn's haze-shrouded moon Titan has long been proposed to have oceans or lakes, on the basis of the stability of liquid methane at the surface. Initial visible and radar imaging failed to find any evidence of an ocean, although abundant evidence was found that flowing liquids have existed on the surface. Here we provide definitive evidence for the presence of lakes on the surface of Titan, obtained during the Cassini Radar flyby of Titan on 22 July 2006 (T16). The radar imaging polewards of 70 degrees north shows more than 75 circular to irregular radar-dark patches, in a region where liquid methane and ethane are expected to be abundant and stable on the surface. The radar-dark patches are interpreted as lakes on the basis of their very low radar reflectivity and morphological similarities to lakes, including associated channels and location in topographic depressions. Some of the lakes do not completely fill the depressions in which they lie, and apparently dry depressions are present. We interpret this to indicate that lakes are present in a number of states, including partly dry and liquid-filled. These northern-hemisphere lakes constitute the strongest evidence yet that a condensable-liquid hydrological cycle is active in Titan's surface and atmosphere, in which the lakes are filled through rainfall and/or intersection with the subsurface 'liquid methane' table.

  19. The lakes of Titan

    USGS Publications Warehouse

    Stofan, E.R.; Elachi, C.; Lunine, J.I.; Lorenz, R.D.; Stiles, B.; Mitchell, K.L.; Ostro, S.; Soderblom, L.; Wood, C.; Zebker, H.; Wall, S.; Janssen, M.; Kirk, R.; Lopes, R.; Paganelli, F.; Radebaugh, J.; Wye, L.; Anderson, Y.; Allison, M.; Boehmer, R.; Callahan, P.; Encrenaz, P.; Flamini, E.; Francescetti, G.; Gim, Y.; Hamilton, G.; Hensley, S.; Johnson, W.T.K.; Kelleher, K.; Muhleman, D.; Paillou, P.; Picardi, G.; Posa, F.; Roth, L.; Seu, R.; Shaffer, S.; Vetrella, S.; West, R.

    2007-01-01

    The surface of Saturn's haze-shrouded moon Titan has long been proposed to have oceans or lakes, on the basis of the stability of liquid methane at the surface. Initial visible and radar imaging failed to find any evidence of an ocean, although abundant evidence was found that flowing liquids have existed on the surface. Here we provide definitive evidence for the presence of lakes on the surface of Titan, obtained during the Cassini Radar flyby of Titan on 22 July 2006 (T16). The radar imaging polewards of 70?? north shows more than 75 circular to irregular radar-dark patches, in a region where liquid methane and ethane are expected to be abundant and stable on the surface. The radar-dark patches are interpreted as lakes on the basis of their very low radar reflectivity and morphological similarities to lakes, including associated channels and location in topographic depressions. Some of the lakes do not completely fill the depressions in which they lie, and apparently dry depressions are present. We interpret this to indicate that lakes are present in a number of states, including partly dry and liquid-filled. These northern-hemisphere lakes constitute the strongest evidence yet that a condensable-liquid hydrological cycle is active in Titan's surface and atmosphere, in which the lakes are filled through rainfall and/or intersection with the subsurface 'liquid methane' table. ??2007 Nature Publishing Group.

  20. Great Lakes Teacher's Guide.

    ERIC Educational Resources Information Center

    Reid, Ron

    The Great Lakes are one of the world's greatest reservoirs of fresh water, the foundation of Ontario's economic development, a primary force in ecological systems, and a base for pleasure and recreation. They are also a magnificent resource for the teachers of Ontario. Study of the Great Lakes can bring to life the factors that shape the ecology…

  1. Lessons from a Lake.

    ERIC Educational Resources Information Center

    Goethals, Susan

    1997-01-01

    Describes a study that included classroom lessons on hydroelectric power, the history and construction of a nearby lake, data recording, the use of field guides, and methods of counting natural populations. The study culminated in a field trip to the lake. (JRH)

  2. Lake Wobegon Dice

    ERIC Educational Resources Information Center

    Moraleda, Jorge; Stork, David G.

    2012-01-01

    We introduce Lake Wobegon dice, where each die is "better than the set average." Specifically, these dice have the paradoxical property that on every roll, each die is more likely to roll greater than the set average on the roll, than less than this set average. We also show how to construct minimal optimal Lake Wobegon sets for all "n" [greater…

  3. Lake Wobegon Dice

    ERIC Educational Resources Information Center

    Moraleda, Jorge; Stork, David G.

    2012-01-01

    We introduce Lake Wobegon dice, where each die is "better than the set average." Specifically, these dice have the paradoxical property that on every roll, each die is more likely to roll greater than the set average on the roll, than less than this set average. We also show how to construct minimal optimal Lake Wobegon sets for all "n" [greater…

  4. Great Salt Lake, Utah

    USGS Publications Warehouse

    Stephens, Doyle W.; Gardner, Joe F.

    1999-01-01

    This document is intended as a source of general information and facts about Great Salt Lake, Utah. This U.S. Geological Survey information sheet answers frequently asked questions about Great Salt Lake. Topics include: History, salinity, brine shrimp, brine flies, migratory birds, and recreation. Great Salt Lake, the shrunken remnant of prehistoric Lake Bonneville, has no outlet. Dissolved salts accumulate in the lake by evaporation. Salinity south of the causeway has ranged from 6 percent to 27 percent over a period of 22 years (2 to 7 times saltier than the ocean). The high salinity supports a mineral industry that extracts about 2 million tons of salt from the lake each year. The aquatic ecosystem consists of more than 30 species of organisms. Harvest of its best-known species, the brine shrimp, annually supplies millions of pounds of food for the aquaculture industry worldwide. The lake is used extensively by millions of migratory and nesting birds and is a place of solitude for people. All this occurs in a lake that is located at the bottom of a 35,000-square-mile drainage basin that has a human population of more than 1.5 million.

  5. Evaporation From Lake Superior

    NASA Astrophysics Data System (ADS)

    Spence, C.; Blanken, P.; Hedstrom, N.; Leshkevich, G.; Fortin, V.; Charpentier, D.; Haywood, H.

    2009-05-01

    Evaporation is a critical component of the water balance of each of the Laurentian Great Lakes, and understanding the magnitude and physical controls of evaporative water losses are important for several reasons. Recently, low water levels in Lakes Superior and Michigan/Huron have had socioeconomic, ecological, and even meteorological impacts (e.g. water quality and quantity, transportation, invasive species, recreation, etc.). The recent low water levels may be due to increased evaporation, but this is not known as operational evaporation estimates are currently calculated as the residual of water or heat budgets. Perhaps surprisingly, almost nothing is known about evaporation dynamics from Lake Superior and few direct measurements of evaporation have been made from any of the Laurentian Great Lakes. This research is the first to attempt to directly measure evaporation from Lake Superior by deploying eddy covariance instrumentation. Results of evaporation rates, their patterns and controlling mechanisms will be presented. The direct measurements of evaporation are used with concurrent satellite and climate model data to extrapolate evaporation measurements across the entire lake. This knowledge could improve predictions of how climate change may impact the lake's water budget and subsequently how the water in the lake is managed.

  6. The Great Lakes.

    ERIC Educational Resources Information Center

    Seasons, 1987

    1987-01-01

    The Great Lakes are one of the world's greatest reserviors of fresh water, the foundation of Ontario's economic development, a primary force in ecological systems, and a base for pleasure and recreation. These lakes and their relationship with people of Canada and the United States can be useful as a subject for teaching the impact of human…

  7. LakeMIP Kivu: Evaluating the representation of a large, deep tropical lake by a set of 1-dimensional lake models

    NASA Astrophysics Data System (ADS)

    Thiery, Wim; Stepanenko, Viktor; Darchambeau, François; Joehnk, Klaus; Martynov, Andrey; Mironov, Dmitrii; Perroud, Marjorie; van Lipzig, Nicole

    2013-04-01

    The African great lakes are of utmost importance for the local economy (fishing), as well as being essential to the survival of the local people. During the last decades, these lakes experienced fast changes in ecosystem structure and functioning and their future evolution is a major concern. In this study, for the first time a set of one-dimensional lake models are evaluated over East-Africa, in particular over Lake Kivu (2.28 °S; 28.98 °E). The unique limnology of meromictic Lake Kivu, with the importance of salinity and geothermal springs in a tropical high-altitude climate, presents a worthy challenge to the 1D-lake models currently involved in the Lake Model Intercomparison Project (LakeMIP). Furthermore, this experiment will serve as the basis for a future, more complex intercomparison, coupling lake models with atmospheric circulation models to analyse climate change effects on the lake. Meteorological observations from two automatic weather stations, one at Kamembe airport (Rwanda, 2003-2008), the other at ISP Bukavu (DRC, 2003-2011), are used to drive each of these models. For the evaluation, a unique dataset is used which contains over 150 temperature profiles recorded since 2002. The standard LakeMIP protocol is adapted to mirror the limnological conditions in Lake Kivu and to unify model parameters as far as possible. Since some lake models do not account for salinity and its effect upon lake stratification, two sets of simulations are performed with each model: one for the freshwater layer only (60 m) and one for the average lake depth (240 m) including salinity. Therewith, on the one hand it is investigated whether each model is able to reproduce the correct mixing regime in Lake Kivu and captures the controlling of this seasonality by the relative humidity, which constrains evaporation except during summer (JJA). On the other hand, the ability of different models to simulate salinity- and geothermal-induced effects upon deep water stratification is

  8. Water quality of Lake Austin and Town Lake, Austin, Texas

    USGS Publications Warehouse

    Andrews, Freeman L.; Wells, Frank C.; Shelby, Wanda J.; McPherson, Emma

    1988-01-01

    Water-quality data collected from Lake Austin and Town Lake, following runoff, generally were not adequate to fully determine the effects of runoff on the lakes. Data collection should not to be limited to fixed-station sampling following runoff, and both lakes need to be sampled simultaneously as soon as possible following significant precipitation.

  9. Lake trout in northern Lake Huron spawn on submerged drumlins

    USGS Publications Warehouse

    Riley, Stephen C.; Binder, Thomas; Wattrus, Nigel J.; Faust, Matthew D.; Janssen, John; Menzies, John; Marsden, J. Ellen; Ebener, Mark P.; Bronte, Charles R.; He, Ji X.; Tucker, Taaja R.; Hansen, Michael J.; Thompson, Henry T.; Muir, Andrew M.; Krueger, Charles C.

    2014-01-01

    Recent observations of spawning lake trout Salvelinus namaycush near Drummond Island in northern Lake Huron indicate that lake trout use drumlins, landforms created in subglacial environments by the action of ice sheets, as a primary spawning habitat. From these observations, we generated a hypothesis that may in part explain locations chosen by lake trout for spawning. Most salmonines spawn in streams where they rely on streamflows to sort and clean sediments to create good spawning habitat. Flows sufficient to sort larger sediment sizes are generally lacking in lakes, but some glacial bedforms contain large pockets of sorted sediments that can provide the interstitial spaces necessary for lake trout egg incubation, particularly if these bedforms are situated such that lake currents can penetrate these sediments. We hypothesize that sediment inclusions from glacial scavenging and sediment sorting that occurred during the creation of bedforms such as drumlins, end moraines, and eskers create suitable conditions for lake trout egg incubation, particularly where these bedforms interact with lake currents to remove fine sediments. Further, these bedforms may provide high-quality lake trout spawning habitat at many locations in the Great Lakes and may be especially important along the southern edge of the range of the species. A better understanding of the role of glacially-derived bedforms in the creation of lake trout spawning habitat may help develop powerful predictors of lake trout spawning locations, provide insight into the evolution of unique spawning behaviors by lake trout, and aid in lake trout restoration in the Great Lakes.

  10. Lake Superior revisited 1984

    USGS Publications Warehouse

    MacCallum, Wayne R.; Selgeby, James H.

    1987-01-01

    The Lake Superior fish community has changed substantially since the early 1960s, when control of the sea lamprey (Petromyzon marinus) became effective. Self-reproducing stocks of lake trout (Salvelinus namaycush) have been reestablished in many inshore areas, although they have not yet reached pre-sea lamprey abundance; offshore lake trout are probably at or near pre-sea lamprey abundance. Stocks of lake whitefish (Coregonus clupeaformis) appear to have fully recovered; commercial catches are at or above historical levels. Lake herring (Coregonus artedii) are recovering rapidly in U.S. waters and are abundant in western Canadian waters. The population of rainbow smelt (Osmerus mordax), which declined in the 1970s, is recovering. Pacific salmon (Oncorhynchus) are becoming more abundant as a result of increased stocking in U.S. waters and are reproducing in most suitable tributaries; they have become significant in anglers' creels.

  11. Lake Morphometry for NHD Lakes in California Region 18 HUC

    EPA Pesticide Factsheets

    Lake morphometry metrics are known to influence productivity in lakes and are important for building various types of ecological and environmental models of lentic systems. The lake morphometry dataset included here contains estimates of Surface Area, Shoreline Length, Shoreline Development, Maximum Depth, Mean Depth, Lake Volume, Maximum Lake Length, Mean Lake Width, Maximum Lake Width, and Fetch for each of the ??lakepond?? waterbodies in the NHDPlus V2. The current release of the datasets is version 0.1 and future refinements to the data are expected.

  12. Lake Morphometry for NHD Lakes in Tennessee Region 6 HUC

    EPA Pesticide Factsheets

    Lake morphometry metrics are known to influence productivity in lakes and are important for building various types of ecological and environmental models of lentic systems. The lake morphometry dataset included here contains estimates of Surface Area, Shoreline Length, Shoreline Development, Maximum Depth, Mean Depth, Lake Volume, Maximum Lake Length, Mean Lake Width, Maximum Lake Width, and Fetch for each of the ??lakepond?? waterbodies in the NHDPlus V2. The current release of the datasets is version 0.1 and future refinements to the data are expected.

  13. Lake Morphometry for NHD Lakes in Ohio Region 5 HUC

    EPA Pesticide Factsheets

    Lake morphometry metrics are known to influence productivity in lakes and are important for building various types of ecological and environmental models of lentic systems. The lake morphometry dataset included here contains estimates of Surface Area, Shoreline Length, Shoreline Development, Maximum Depth, Mean Depth, Lake Volume, Maximum Lake Length, Mean Lake Width, Maximum Lake Width, and Fetch for each of the ??lakepond?? waterbodies in the NHDPlus V2. The current release of the datasets is version 0.1 and future refinements to the data are expected.

  14. Evidence of offshore lake trout reproduction in Lake Huron

    USGS Publications Warehouse

    DeSorcie, Timothy J.; Bowen, Charles A.

    2003-01-01

    Six Fathom Bank-Yankee Reef, an offshore reef complex, was an historically important spawning area believed to represent some of the best habitat for the rehabilitation of lake trout Salvelinus namaycush in Lake Huron. Since 1986, lake trout have been stocked on these offshore reefs to reestablish self-sustaining populations. We sampled with beam trawls to determine the abundance of naturally reproduced age-0 lake trout on these offshore reefs during May-July in 1994-1998 and 2000-2002. In total, 123 naturally reproduced lake trout fry were caught at Six Fathom Bank, and 2 naturally reproduced lake trout fry were caught at nearby Yankee Reef. Our findings suggest that this region of Lake Huron contains suitable habitat for lake trout spawning and offers hope that lake trout rehabilitation can be achieved in the main basin of Lake Huron.

  15. Lake whitefish and lake herring population structure and niche in ten south-central Ontario lakes

    USGS Publications Warehouse

    Carl, Leon M.; McGuiness, Fiona

    2006-01-01

    This study compares simple fish communities of ten oligotrophic lakes in south-central Ontario. Species densities and population size structure vary significantly among these lake communities depending on fish species present beyond the littoral zone. Lake whitefish are fewer and larger in the presence of lake herring than in their absence. Diet analysis indicates that lake whitefish shift from feeding on both plankton and benthic prey when lake herring are absent to a primarily benthic feeding niche in the presence of lake herring. When benthic round whitefish are present, lake whitefish size and density decline and they move lower in the lake compared to round whitefish. Burbot are also fewer and larger in lakes with lake herring than in lakes without herring. Burbot, in turn, appear to influence the population structure of benthic coregonine species. Lower densities of benthic lake whitefish and round whitefish are found in lakes containing large benthic burbot than in lakes with either small burbot or where burbot are absent. Predation on the pelagic larvae of burbot and lake whitefish by planktivorous lake herring alters the size and age structure of these populations. As life history theory predicts, those species with poor larval survival appear to adopt a bet-hedging life history strategy of long-lived individuals as a reproductive reserve.

  16. Past, present and future of volcanic lake monitoring

    NASA Astrophysics Data System (ADS)

    Rouwet, Dmitri; Tassi, Franco; Mora-Amador, Raúl; Sandri, Laura; Chiarini, Veronica

    2014-02-01

    Volcanic lake research boosted after lethal gas burst occurred at Lake Nyos (Cameroon) in 1986, a limnic rather than a volcanic event. This led to the foundation of the IAVCEI-Commission on Volcanic Lakes, which grew out into a multi-disciplinary scientific community since the 1990s. We here introduce the first data base of volcanic lakes VOLADA, containing 474 lakes, a number that, in our opinion, is surprisingly high. VOLADA could become an interactive, open-access working tool where our community can rely on in the future. Many of the compiled lakes were almost unknown, or at least unstudied to date, whereas there are acidic crater lakes topping active magmatic-hydrothermal systems that are continuously or discontinuously monitored, providing useful information for volcanic surveillance (e.g., Ruapehu, Yugama, Poás). Nyos-type lakes, i.e. those hosted in quiescent volcanoes and characterized by significant gas accumulation in bottom waters, are potentially hazardous. These lakes tend to remain stably stratified in tropical and sub-tropical climates (meromictic), leading to long-term build-up of gas, which can be released after a trigger. Some of the unstudied lakes are possibly in the latter situation. Acidic crater lakes are easily recognized as active, whereas Nyos-type lakes can only be recognized as potentially hazardous if bottom waters are investigated, a less obvious operation. In this review, research strategies are lined out, especially for the “active crater lakes”. We make suggestions for monitoring frequency based on the principle of the “residence time dependent monitoring time window”. A complementary, multi-disciplinary (geochemistry, geophysics, limnology, statistics) approach is considered to provide new ideas, which can be the bases for future volcanic lake monitoring. More profound deterministic knowledge (e.g., precursory signals for phreatic eruptions, or lake roll-over events) should not only serve to enhance conceptual models of

  17. Carbon cycling in the mixolimnion of Lake Kivu (East Africa)

    NASA Astrophysics Data System (ADS)

    Borges, A. V.; Descy, J.-P.; Delille, B.; Lepoint, G.; Servais, P.; Abril, G.; Bouillon, S.; Schmid, M.; Pasche, N.; Darchambeau, F.

    2009-04-01

    Lake Kivu is situated in the Western Rift Valley, and has unique limnological characteristics, as temperature and salinity increase with depth, due to bottom geothermal inputs. Due to its permanent meromictic nature, CO2 concentrations are extremely high in Lake Kivu's bottom waters, similar to other "killer lakes" such lake Nyos in Cameroon. We obtained a data-set of inorganic carbon (pCO2, pH, TA, DIC, DIC stable isotopes), CH4, inorganic nutrients, organic carbon, bacterial production, and primary production in the mixolimnion of lake Kivu during the rainy season (March 2007), the late dry season (September 2007) and the mid dry season (June 2008). We show that the surface waters of lake Kivu were a source of CO2 and CH4 to the atmosphere albeit that the mixolimnion was net autotrophic at the community level, based on DIC mass balance budgets, sediment trap data and measurements of bacterial production and primary production. This rather unique situation is related to the important magmatic sources of CO2 in the bottom of the lake.

  18. Lake sturgeon population characteristics in Rainy Lake, Minnesota and Ontario

    USGS Publications Warehouse

    Adams, W.E.; Kallemeyn, L.W.; Willis, D.W.

    2006-01-01

    Rainy Lake contains a native population of lake sturgeon Acipenser fulvescens that has been largely unstudied. The aims of this study were to document the population characteristics of lake sturgeon in Rainy Lake and to relate environmental factors to year-class strength for this population. Gill-netting efforts throughout the study resulted in the capture of 322 lake sturgeon, including 50 recaptures. Lake sturgeon in Rainy Lake was relatively plump and fast growing compared with a 32-population summary. Population samples were dominated by lake sturgeon between 110 and 150 cm total length. Age–structure analysis of the samples indicated few younger (<10 years) lake sturgeon, but the smallest gill net mesh size used for sampling was 102 mm (bar measure) and would not retain small sturgeon. Few lake sturgeon older than age 50 years were captured, and maximum age of sampled fish was 59 years. Few correlations existed between lake sturgeon year-class indices and both annual and monthly climate variables, except that mean June air temperature was positively correlated with year-class strength. Analysis of Rainy Lake water elevation and resulting lake sturgeon year-class strength indices across years yielded consistent but weak negative correlations between late April and early June, when spawning of lake sturgeon occurs. The baseline data collected in this study should allow Rainy Lake biologists to establish more specific research questions in the future.

  19. Lake sturgeon population characteristics in Rainy Lake, Minnesota and Ontario

    USGS Publications Warehouse

    Adams, W.E.; Kallemeyn, L.W.; Willis, D.W.

    2006-01-01

    Rainy Lake contains a native population of lake sturgeon Acipenser fulvescens that has been largely unstudied. The aims of this study were to document the population characteristics of lake sturgeon in Rainy Lake and to relate environmental factors to year-class strength for this population. Gill-netting efforts throughout the study resulted in the capture of 322 lake sturgeon, including 50 recaptures. Lake sturgeon in Rainy Lake was relatively plump and fast growing compared with a 32-population summary. Population samples were dominated by lake sturgeon between 110 and 150 cm total length. Age–structure analysis of the samples indicated few younger (<10 years) lake sturgeon, but the smallest gill net mesh size used for sampling was 102 mm (bar measure) and would not retain small sturgeon. Few lake sturgeon older than age 50 years were captured, and maximum age of sampled fish was 59 years. Few correlations existed between lake sturgeon year-class indices and both annual and monthly climate variables, except that mean June air temperature was positively correlated with year-class strength. Analysis of Rainy Lake water elevation and resulting lake sturgeon year-class strength indices across years yielded consistent but weak negative correlations between late April and early June, when spawning of lake sturgeon occurs. The baseline data collected in this study should allow Rainy Lake biologists to establish more specific research questions in the future.

  20. Lake sediment records of industrialization in the Sudbury area of Ontario, Canada

    SciTech Connect

    Huhn, F.J.

    1985-01-01

    The smelting of nickel and copper sulfide ores has drastically modified the original landscape around Sudbury, Ontario. A record of this impact exists in the sediments of local lakes. Changes in the annual fallout of heavy metals, identifiable smoke particulates, and pollen grains reflect the changes that occurred in the sedimentation rate and the vegetation. A year by year chronology for the last 300 years was provided by meromictic lake sediments containing countable seasonal laminations, obtained by a freezing technique that kept the sediments and sediment/water interface undisturbed. Results indicate that: correspondences of vegetation changes, and sedimentation rates with metal residues and smoke particulates in the sediments, and with published smelter records are good; annual laminations in meromictic lakes provided an excellent chronology, as checked against known dates for settlement and the onset of smelting; identifiable smoke particulates provided a good record of smelter activity, and were also a check on metal residue mobility in the sediments.

  1. Whiting in Lake Michigan

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Satellites provide a view from space of changes on the Earth's surface. This series of images from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) aboard the Orbview-2 satellite shows the dramatic change in the color of Lake Michigan during the summer. The bright color that appears in late summer is probably caused by calcium carbonate-chalk-in the water. Lake Michigan always has a lot of calcium carbonate in it because the floor of the lake is limestone. During most of the year the calcium carbonate remains dissolved in the cold water, but at the end of summer the lake warms up, lowering the solubility of calcium carbonate. As a result, the calcium carbonate precipitates out of the water, forming clouds of very small solid particles that appear as bright swirls from above. The phenomenon is appropriately called a whiting event. A similar event occured in 1999, but appears to have started later and subsided earlier. It is also possible that a bloom of the algae Microcystis is responsible for the color change, but unlikely because of Lake Michigan's depth and size. Microcystis blooms have occured in other lakes in the region, however. On the shore of the lake it is possible to see the cities of Chicago, Illinois, and Milwaukee, Wisconsin. Both appear as clusters of gray-brown pixels. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  2. Yellowstone lake nanoarchaeota.

    PubMed

    Clingenpeel, Scott; Kan, Jinjun; Macur, Richard E; Woyke, Tanja; Lovalvo, Dave; Varley, John; Inskeep, William P; Nealson, Kenneth; McDermott, Timothy R

    2013-01-01

    Considerable Nanoarchaeota novelty and diversity were encountered in Yellowstone Lake, Yellowstone National Park (YNP), where sampling targeted lake floor hydrothermal vent fluids, streamers and sediments associated with these vents, and in planktonic photic zones in three different regions of the lake. Significant homonucleotide repeats (HR) were observed in pyrosequence reads and in near full-length Sanger sequences, averaging 112 HR per 1349 bp clone and could confound diversity estimates derived from pyrosequencing, resulting in false nucleotide insertions or deletions (indels). However, Sanger sequencing of two different sets of PCR clones (110 bp, 1349 bp) demonstrated that at least some of these indels are real. The majority of the Nanoarchaeota PCR amplicons were vent associated; however, curiously, one relatively small Nanoarchaeota OTU (71 pyrosequencing reads) was only found in photic zone water samples obtained from a region of the lake furthest removed from the hydrothermal regions of the lake. Extensive pyrosequencing failed to demonstrate the presence of an Ignicoccus lineage in this lake, suggesting the Nanoarchaeota in this environment are associated with novel Archaea hosts. Defined phylogroups based on near full-length PCR clones document the significant Nanoarchaeota 16S rRNA gene diversity in this lake and firmly establish a terrestrial clade distinct from the marine Nanoarcheota as well as from other geographical locations.

  3. Yellowstone Lake Nanoarchaeota

    PubMed Central

    Clingenpeel, Scott; Kan, Jinjun; Macur, Richard E.; Woyke, Tanja; Lovalvo, Dave; Varley, John; Inskeep, William P.; Nealson, Kenneth; McDermott, Timothy R.

    2013-01-01

    Considerable Nanoarchaeota novelty and diversity were encountered in Yellowstone Lake, Yellowstone National Park (YNP), where sampling targeted lake floor hydrothermal vent fluids, streamers and sediments associated with these vents, and in planktonic photic zones in three different regions of the lake. Significant homonucleotide repeats (HR) were observed in pyrosequence reads and in near full-length Sanger sequences, averaging 112 HR per 1349 bp clone and could confound diversity estimates derived from pyrosequencing, resulting in false nucleotide insertions or deletions (indels). However, Sanger sequencing of two different sets of PCR clones (110 bp, 1349 bp) demonstrated that at least some of these indels are real. The majority of the Nanoarchaeota PCR amplicons were vent associated; however, curiously, one relatively small Nanoarchaeota OTU (71 pyrosequencing reads) was only found in photic zone water samples obtained from a region of the lake furthest removed from the hydrothermal regions of the lake. Extensive pyrosequencing failed to demonstrate the presence of an Ignicoccus lineage in this lake, suggesting the Nanoarchaeota in this environment are associated with novel Archaea hosts. Defined phylogroups based on near full-length PCR clones document the significant Nanoarchaeota 16S rRNA gene diversity in this lake and firmly establish a terrestrial clade distinct from the marine Nanoarcheota as well as from other geographical locations. PMID:24062731

  4. Ecology under lake ice.

    PubMed

    Hampton, Stephanie E; Galloway, Aaron W E; Powers, Stephen M; Ozersky, Ted; Woo, Kara H; Batt, Ryan D; Labou, Stephanie G; O'Reilly, Catherine M; Sharma, Sapna; Lottig, Noah R; Stanley, Emily H; North, Rebecca L; Stockwell, Jason D; Adrian, Rita; Weyhenmeyer, Gesa A; Arvola, Lauri; Baulch, Helen M; Bertani, Isabella; Bowman, Larry L; Carey, Cayelan C; Catalan, Jordi; Colom-Montero, William; Domine, Leah M; Felip, Marisol; Granados, Ignacio; Gries, Corinna; Grossart, Hans-Peter; Haberman, Juta; Haldna, Marina; Hayden, Brian; Higgins, Scott N; Jolley, Jeff C; Kahilainen, Kimmo K; Kaup, Enn; Kehoe, Michael J; MacIntyre, Sally; Mackay, Anson W; Mariash, Heather L; McKay, Robert M; Nixdorf, Brigitte; Nõges, Peeter; Nõges, Tiina; Palmer, Michelle; Pierson, Don C; Post, David M; Pruett, Matthew J; Rautio, Milla; Read, Jordan S; Roberts, Sarah L; Rücker, Jacqueline; Sadro, Steven; Silow, Eugene A; Smith, Derek E; Sterner, Robert W; Swann, George E A; Timofeyev, Maxim A; Toro, Manuel; Twiss, Michael R; Vogt, Richard J; Watson, Susan B; Whiteford, Erika J; Xenopoulos, Marguerite A

    2017-01-01

    Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer 'growing seasons'. We executed the first global quantitative synthesis on under-ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors. Plankton were more abundant under ice than expected; mean winter values were 43.2% of summer values for chlorophyll a, 15.8% of summer phytoplankton biovolume and 25.3% of summer zooplankton density. Dissolved nitrogen concentrations were typically higher during winter, and these differences were exaggerated in smaller lakes. Lake size also influenced winter-summer patterns for dissolved organic carbon (DOC), with higher winter DOC in smaller lakes. At coarse levels of taxonomic aggregation, phytoplankton and zooplankton community composition showed few systematic differences between seasons, although literature suggests that seasonal differences are frequently lake-specific, species-specific, or occur at the level of functional group. Within the subset of lakes that had longer time series, winter influenced the subsequent summer for some nutrient variables and zooplankton biomass.

  5. Whiting in Lake Michigan

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Satellites provide a view from space of changes on the Earth's surface. This series of images from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) aboard the Orbview-2 satellite shows the dramatic change in the color of Lake Michigan during the summer. The bright color that appears in late summer is probably caused by calcium carbonate-chalk-in the water. Lake Michigan always has a lot of calcium carbonate in it because the floor of the lake is limestone. During most of the year the calcium carbonate remains dissolved in the cold water, but at the end of summer the lake warms up, lowering the solubility of calcium carbonate. As a result, the calcium carbonate precipitates out of the water, forming clouds of very small solid particles that appear as bright swirls from above. The phenomenon is appropriately called a whiting event. A similar event occured in 1999, but appears to have started later and subsided earlier. It is also possible that a bloom of the algae Microcystis is responsible for the color change, but unlikely because of Lake Michigan's depth and size. Microcystis blooms have occured in other lakes in the region, however. On the shore of the lake it is possible to see the cities of Chicago, Illinois, and Milwaukee, Wisconsin. Both appear as clusters of gray-brown pixels. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  6. Ecology of playa lakes

    USGS Publications Warehouse

    Haukos, David A.; Smith, Loren M.

    1992-01-01

    Between 25,000 and 30,000 playa lakes are in the playa lakes region of the southern high plains (Fig. 1). Most playas are in west Texas (about 20,000), and fewer, in New Mexico, Oklahoma, Kansas, and Colorado. The playa lakes region is one of the most intensively cultivated areas of North America. Dominant crops range from cotton in southern areas to cereal grains in the north. Therefore, most of the native short-grass prairie is gone, replaced by crops and, recently, grasses of the Conservation Reserve Program. Playas are the predominant wetlands and major wildlife habitat of the region.More than 115 bird species, including 20 species of waterfowl, and 10 mammal species have been documented in playas. Waterfowl nest in the area, producing up to 250,000 ducklings in wetter years. Dominant breeding and nesting species are mallards and blue-winged teals. During the very protracted breeding season, birds hatch from April through August. Several million shorebirds and waterfowl migrate through the area each spring and fall. More than 400,000 sandhill cranes migrate through and winter in the region, concentrating primarily on the larger saline lakes in the southern portion of the playa lakes region.The primary importance of the playa lakes region to waterfowl is as a wintering area. Wintering waterfowl populations in the playa lakes region range from 1 to 3 million birds, depending on fall precipitation patterns that determine the number of flooded playas. The most common wintering ducks are mallards, northern pintails, green-winged teals, and American wigeons. About 500,000 Canada geese and 100,000 lesser snow geese winter in the playa lakes region, and numbers of geese have increased annually since the early 1980’s. This chapter describes the physiography and ecology of playa lakes and their attributes that benefit waterfowl.

  7. Magnetic properties of bottom sediments from Meromectic Shira Lake (Siberia, Russia)

    NASA Astrophysics Data System (ADS)

    Rogozin, D. Yu.; Balaev, D. A.; Semenov, S. V.; Shaikhutdinov, K. A.; Bayukov, O. A.

    2016-08-01

    Magnetic properties were studied in bottom sediments of saline meromictic Shira Lake by the methods of static magnetometry and resonance Mössbauer spectroscopy for the first time. All layers of bottom sediments contain nanosized single-domain magnetite particles produced by magnetotactic bacteria. The concentration of magnetite in bottom sediments decreased with depth, reaching a local minimum in the layer corresponding to the minimal level of the lake observed in 1910-1930. It is demonstrated that biogenic magnetite may indicate climate-related changes in the level of Shira Lake, in addition to the other biological and geochemical characteristics.

  8. Lake Tengiz from space

    NASA Image and Video Library

    2017-09-28

    In orbit above the semi-desert grasslands in Kazakhstan, an astronaut aboard the International Space Station spotted one of the few features that stand out. Lake Tengiz is the only large lake (1590 square kilometers, 615 square miles) in northern Kazakhstan. Through white wisps of cloud, the crew member photographed the 50 kilometer-long eastern shore of the lake, with its thin, winding islands and white beaches. The islands and intervening waterways make a rich habitat for birds in this part of Asia. At least 318 species of birds have been identified at the lake; 22 of them are endangered. It is the northernmost habitat of the pink flamingo. The lake system is Kazakhstan’s first UNESCO World Heritage Site, and it has been declared a RAMSAR wetland site of international importance. Part of the richness of area is its complex hydrology. Fresh water enters the system via the Kulanutpes River, so there are small lakes (lower right) full of fresh water. But in this closed basin, the water in the main lake (top) slowly evaporates, becoming salty. Winds stir up bigger waves on the main lake, dispersing sediment and salt and making the water a cloudier and lighter blue-green. (Another astronaut photograph shows the entire lake system, while this story provides more information.) The strange shape of the islands is not easy to interpret. They may be drowned remnants of delta distributaries of the Kulanutpes River. Westerly winds probably have had a smoothing effect on the shorelines, especially in a shallow lake like Tengiz, which is only about 6 meters (20 feet) deep. The lake has an exciting history for people who follow space exploration. In 1976, a Soyuz spacecraft landed in the lake near the north shore (top right). The capsule crashed through the ice and sank during an October snowstorm when temperatures were -22°C (-8°F). Because of low power, the capsule was unheated and the crew was feared lost. It was many hours before the airtight capsule was located and

  9. Lake Mead, NV

    NASA Image and Video Library

    1973-06-22

    SL2-03-192 (22 June 1973) --- Lake Mead, Nevada, (36.0N, 114.5E) where the water from the Colorado River empties after it's 273 mile journey through the Grand Canyon of Arizona is the subject of this photo. Other features of interest are Hoover Dam on the south shore of Lake Mead where cheap hydroelectric power is secondary to the water resources made available in this northern desert region and the resort city of Las Vegas, just to the west of Lake Mead. In this harsh desert environment, color infrared photography readily penetrates haze, detects and portrays vegetation as shades of red. Photo credit: NASA

  10. Lake Mead, NV

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Lake Mead, Nevada, (36.0N, 114.5E) where the water from the Colorado River empties after it's 273 mile journey through the Grand Canyon of Arizona is the subject of this photo. Other features of interest are Hoover Dam on the south shore of Lake Mead where cheap hydroelectric power is secondary to the water resources made available in this northern desert region and the resort city of Las Vegas, just to the west of Lake Mead. In this harsh desert environment, color infrared photography readily penetrates haze, detects and portrays vegetation as shades of red.

  11. Yamzho Yumco Lake, Tibet

    NASA Image and Video Library

    2017-02-01

    Yamzho Yumco (Sacred Swan) Lake in Tibet is surrounded by snow-capped mountains and is one of the three largest sacred lakes. It is highly crenellated with many bays and inlets. The lake is home to Samding Monastery, headed by a female re-incarnation (Wikipedia). The image was acquired March 6, 2014, covers an area of 49.8 by 60 km, and is centered at 28.9 degrees north, 90.6 degrees east. http://photojournal.jpl.nasa.gov/catalog/PIA21304

  12. Lake Poopo, Bolivia

    NASA Image and Video Library

    2017-04-28

    In the high plains of the Andes in Bolivia, Lake Poopo has virtually vanished, as shown in this image from NASA Terra spacecraft. Once covering over 3,000 square kilometers, the lake essentially dried up in 2015. What led to Lake Poopo's demise? Water diversions upstream, weather extremes and recurrent droughts are thought to blame. The images cover an area of 48.9 by 55.1 km, were acquired February 14, 2001 and November 6, 2016, and are located near 18.7 degrees south, 67.1 degrees west. https://photojournal.jpl.nasa.gov/catalog/PIA21546

  13. National Lakes Assessment Data

    EPA Pesticide Factsheets

    The National Lakes Assessment (NLA) is a first-ever statistically-valid survey of the biological condition of lakes and reservoirs throughout the U.S. The U.S. Environmental Protection Agency (EPA) worked with states and tribes to conduct the assessment in 2007. Data for each parameter sampled in the National Lakes Assessment (NLA) are available for downloading in a series of files as comma separated values (*.csv). Each *.csv data file has a companion text file (*.txt) that lists a dataset label and individual descriptions for each variable. Users should view the *.txt files first to help guide their understanding and use of the data.

  14. Lake Morphometry for NHD Lakes in Great Lakes Region 4 HUC

    EPA Pesticide Factsheets

    Lake morphometry metrics are known to influence productivity in lakes and are important for building various types of ecological and environmental models of lentic systems. The lake morphometry dataset included here contains estimates of Surface Area, Shoreline Length, Shoreline Development, Maximum Depth, Mean Depth, Lake Volume, Maximum Lake Length, Mean Lake Width, Maximum Lake Width, and Fetch for each of the ??lakepond?? waterbodies in the NHDPlus V2. The current release of the datasets is version 0.1 and future refinements to the data are expected.

  15. Can lake sensitivity to desiccation be predicted from lake geometry?

    NASA Astrophysics Data System (ADS)

    Torabi Haghighi, Ali; Menberu, Meseret Walle; Aminnezhad, Mousa; Marttila, Hannu; Kløve, Bjørn

    2016-08-01

    Declining lake levels (Aral Sea syndrome) can be caused by changes in climate, increased water use or changed regulation patterns. This paper introduces a novel lake geometry index (LGI) to quantify lake hydrological characteristics. The index was developed using a large representative dataset of lake hypsographic characteristics from 152 lakes and man-made reservoirs. Using the LGI index, lakes can be classified into five groups: groups 1-4 when LGI is 0.5-2.5, 2.5-4.5, 4.5-6.5 and 6.5-8.5, respectively, and group 5 when LGI is >8.5. Naturally shallow and vast lakes and wetlands fall into the first group and deep man-made reservoirs in narrow valleys are in group 5. The response of three different lake systems (LGI 0.75, 2.75 and 6.5) to different water flow scenarios was then simulated using the water balance equation. From this, the index 'potential lake area' (Apot) was developed to show lake responses to changed hydro-climatological conditions. Apot and LGI can be used to classify lakes into open or closed systems. Simulations showed that lakes with low LGI have a shorter response time to flow and climate changes. As a result, the impact of water balance restoration is faster for lakes with low LGI than for lakes with high LGI. The latter are also more vulnerable to climate variation and change.

  16. Lake Ilopango, El Salvador

    NASA Image and Video Library

    2015-03-10

    Lake Ilopango is a crater lake which fills a volcanic caldera in central El Salvador, immediately east of the capital city San Salvador. The caldera collapsed most recently in about 500 AD, producing 20 times as much ash as the Mount St. Helens eruption, and blanketing an area of at least 10,000 square kilometers waist-deep in ash. The only historical eruption occurred in 1879, forming lava domes, now islets in the lake. Quetzaltepec is the stratovolcano just west of the city. Its last eruption in 1917 produced lavas flowing down the northwest flank, and evaporated the crater lake. The image was acquired March 5, 2006, covers an area of 27 by 42 km, and is located at 13.7 degrees north, 89.1 degrees west. http://photojournal.jpl.nasa.gov/catalog/PIA19237

  17. Challenges to the Lake

    EPA Science Inventory

    During the past decade we have extensively studied coastal ecosystems in the Great Lakes. Some research efforts have linked coastal receiving systems to conditions in their contributing watersheds; others have focused on developing invasive species detection and monitoring strat...

  18. About Deer Lake AOC

    EPA Pesticide Factsheets

    Named an Area of Concern under the Great Lakes Water Quality Agreement of 1987, due to beneficial use impairments caused by mercury contamination: consumption restrictions, deformities or reproductive problems, eutrophication.

  19. Pompton Lakes Photo Gallery

    EPA Pesticide Factsheets

    This gallery provides representative photographs of the soil removal and dredging operations within the Pompton Lake Study Area (PLSA) performed starting in 2016 through the present. It will be periodically updated in conjunction with the progress of the

  20. Lake Sharpe, South Dakota

    NASA Image and Video Library

    2014-03-26

    NASA Terra spacecraft views central South Dakota, where the Missouri River forms a meander bend, creating Lake Sharpe. Eventually, the Missouri River will cut through the skinny peninsula, creating a shorter path.

  1. Challenges to the Lake

    EPA Science Inventory

    During the past decade we have extensively studied coastal ecosystems in the Great Lakes. Some research efforts have linked coastal receiving systems to conditions in their contributing watersheds; others have focused on developing invasive species detection and monitoring strat...

  2. Is Lake Tahoe Terminal?

    NASA Astrophysics Data System (ADS)

    Coats, R. N.; Reuter, J.; Heyvaert, A.; Lewis, J.; Sahoo, G. B.; Schladow, G.; Thorne, J. H.

    2014-12-01

    Lake Tahoe, an iconic ultra-oligotrophic lake in the central Sierra Nevada, has been studied intensively since 1968, with the goal of understanding and ultimately controlling its eutrophication and loss of clarity. Research on the lake has included a) periodic profiles of primary productivity, nutrients, temperature, and plankton; b) Secchi depth; c) nutrient limitation experiments; d) analysis of sediment cores; e) radiocarbon dating of underwater in-place tree stumps; g) analysis of long-term temperature trends. Work in its watershed has included a) monitoring of stream discharge, sediment and nutrients at up to 20 stream gaging stations; b) monitoring of urban runoff water quality at selected sites; c) development of a GIS data base, including soils, vegetation, and land use. Based on these studies, we know that a) primary productivity in the lake is limited by phosphorus, and continues to increase; b) the loss of clarity continues, but at a declining rate; c) the lake has been warming since 1970, and its resistance to deep mixing is increasing; d) historically the lake level drops below the outlet elevation about one year in seven; e) 6300 to 4300 yrs BP lake level was below the present outlet elevation long enough for large trees to grow; f) the date of the peak snowmelt runoff is shifting toward earlier dates; g) after accounting for annual runoff, loads of nutrients and suspended sediment have declined significantly in some basin streams since 1980. Downscaled outputs from GCM climatic models have recently been used to drive hydrologic models and a lake clarity model, projecting future trends in the lake and watersheds. Results show a) the temperature and thermal stability will likely continue to increase, with deep mixing shutting down in the latter half of this century; b) the lake may drop below the outlet for an extended period beginning about 2085; c) the annual snowpack will continue to decline, with earlier snowmelt and shift from snowfall to rain; d

  3. Antarctic subglacial lake discharges

    NASA Astrophysics Data System (ADS)

    Pattyn, Frank

    Antarctic subglacial lakes were long time supposed to be relatively closed and stable environments with long residence times and slow circulations. This view has recently been challenged with evidence of active subglacial lake discharge underneath the Antarctic ice sheet. Satellite altimetry observations witnessed rapid changes in surface elevation across subglacial lakes over periods ranging from several months to more than a year, which were interpreted as subglacial lake discharge and subsequent lake filling, and which seem to be a common and widespread feature. Such discharges are comparable to jökulhlaups and can be modeled that way using the Nye-Röthlisberger theory. Considering the ice at the base of the ice sheet at pressure melting point, subglacial conduits are sustainable over periods of more than a year and over distances of several hundreds of kilometers. Coupling of an ice sheet model to a subglacial lake system demonstrated that small changes in surface slope are sufficient to start and sustain episodic subglacial drainage events on decadal time scales. Therefore, lake discharge may well be a common feature of the subglacial hydrological system, influencing the behavior of large ice sheets, especially when subglacial lakes are perched at or near the onset of large outlet glaciers and ice streams. While most of the observed discharge events are relatively small (101-102 m3 s-1), evidence for larger subglacial discharges is found in ice free areas bordering Antarctica, and witnessing subglacial floods of more than 106 m3 s-1 that occurred during the middle Miocene.

  4. Lake Superior, Duluth, MN

    NASA Technical Reports Server (NTRS)

    1973-01-01

    This view shows the west end of Lake Superior and Duluth, MN (47.0N, 91.0W). Portions of Minnesota, Michigan and Ontario, Canada are in the scene. The Duluth metropolitan area is at the west end of the lake. The discoloration plume in the water at Duluth is the result of tailings from the iron ore smelters that process the iron ore from the nearby open pit mines seen near the upper left corner of the photo.

  5. Dragon Lake, Siberia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Nicknamed 'Dragon Lake,' this body of water is formed by the Bratskove Reservoir, built along the Angara river in southern Siberia, near the city of Bratsk. This image was acquired in winter, when the lake is frozen. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on December 19, 1999. This is a natural color composite image made using blue, green, and red wavelengths. Image provided by the USGS EROS Data Center Satellite Systems Branch

  6. Lake Chad, Chad, Africa

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The fluctuating water levels of Lake Chad, (13.0N, 15.0E) at the intersection of the borders of Chad, Niger and Cameroon in the Sahara Desert, is an index of the drought in Africa. The lake level continues to decrease as indicated by the growing number and extent of emerging islands as previously submerged ancient sand dunes become visible. The water impounded between the dunes is probably because of local rainfall rather than a reversal of desertification.

  7. Lake Chad, Chad, Africa

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The fluctuating water levels of Lake Chad, (13.0N, 15.0E) at the intersection of the borders of Chad, Niger and Cameroon in the Sahara Desert, is an index of the drought in Africa. The lake level continues to decrease as indicated by the growing number and extent of emerging islands as previously submerged ancient sand dunes become visible. The water impounded between the dunes is probably because of local rainfall rather than a reversal of desertification.

  8. Lake Chad, Chad, Africa

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Once a great inland lake, Lake Chad (13.0N, 14.0E) in the Sahara Desert at the intersection of the African nations of Chad, Niger, Nigeria and Cameroon, is now in decline. The larger northern lobe is almost totally dry and slowly filling in with encroaching sand dunes. The southern lobe, still retains some water in the lower center but the water surface area is less than 2000 square kilometers and sand dunes are filling in the north end.

  9. Dragon Lake, Siberia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Nicknamed 'Dragon Lake,' this body of water is formed by the Bratskove Reservoir, built along the Angara river in southern Siberia, near the city of Bratsk. This image was acquired in winter, when the lake is frozen. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on December 19, 1999. This is a natural color composite image made using blue, green, and red wavelengths. Image provided by the USGS EROS Data Center Satellite Systems Branch

  10. Lake retention of manufactured nanoparticles.

    PubMed

    Koelmans, A A; Quik, J T K; Velzeboer, I

    2015-01-01

    For twenty-five world lakes and three engineered nanoparticles (ENP), lake retention was calculated using a uniformly mixed lake mass balance model. This follows similar approaches traditionally used in water quality management. Lakes were selected such that lake residence times, depths and areal hydraulic loadings covered the widest possible range among existing lakes. Sedimentation accounted for natural colloid as well as suspended solid settling regimes. An ENP-specific mixed sedimentation regime is proposed. This regime combines ENP sedimentation through slow settling with natural colloids from the water column, with faster settling with suspended solids from a selected part of the water column. Although sedimentation data and hydrodynamic concepts as such were not new, their first time combination or application to ENPs shows in which cases lake retention is important for these particles. In combination with ENP emission data, lake retention translates directly into potential risks of ENPs for lake benthic communities.

  11. Lake Garda, Italy

    NASA Image and Video Library

    2001-07-21

    This ASTER image was acquired on July 29, 2000 and covers an area of 30 by 57 km in northern Italy. Lake Garda was formed by glaciers during the last Ice Age, and is Italy's largest lake. Lago di Garda lies in the provinces of Verona, Brescia, and Trento, and is 51 kilometers (32 miles) long and from 3 to 18 kilometers (2 to 11 miles) wide. The Sarca is its chief affluent, and the lake is drained southward by the Mincio, which discharges into the Po River. Many villas are situated on its shores. On the peninsula of Sirmione, at the southern end of the lake, are the ruins of a Roman villa and a castle of the Scaligers, an Italian family of the 16th century. The RIGHT image has the land area masked out, and a harsh stretch was applied to the lake values to display variations in sediment load. Also visible are hundreds of boats and their wakes, criss-crossing the lake. The image is centered at 45.6 degrees north latitude, 10.6 degrees east longitude. http://photojournal.jpl.nasa.gov/catalog/PIA02671

  12. Schistosomiasis in Lake Malawi.

    PubMed

    Cetron, M S; Chitsulo, L; Sullivan, J J; Pilcher, J; Wilson, M; Noh, J; Tsang, V C; Hightower, A W; Addiss, D G

    1996-11-09

    Schistosomiasis is a parasitic infection caused by trematodes. Humans are infected through skin contact with free-swimming cercariae which develop in freshwater snails. Schistosomiasis has been endemic to Malawi for several decades, but the open waters and shores of Lake Malawi have long been thought to be risk-free with regard to schistosomiasis transmission. However, in 1992, two US Peace Corps volunteers developed central nervous system schistosomiasis due to infection with Schistosoma haematobium following recreational water exposure at Cape Maclear on Lake Malawi. In light of these infections, a cross-sectional survey of resident expatriates and visitors to Malawi was subsequently conducted during March-April 1993 to determine the transmission potential and risk for acquiring schistosomiasis in the lake. 305 US citizens and 650 non-US foreign nationals participated in the study. Serological evidence of current or past schistosome infection was identified in 303 subjects. Indeed, seroprevalence was 32% among expatriates whose freshwater exposure was limited to Lake Malawi; S. haematobium antibodies were found in 135 of 141 seropositive specimens. The risk of seropositivity increased with the number of freshwater exposures at Lake Malawi resorts. While many resort areas in the southwestern lake region posed a significant risk, Cape Maclear was the location most strongly associated with seropositivity. Schistosome-infected Bulinus globosus, the snail vector of S. haematobium in Malawi, were found at Cape Maclear and other locations along the lakeshore.

  13. Salt Lake City, Utah

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Salt Lake City, Utah, will host the 2002 Winter Olympic Games. The city is located on the southeastern shore of the Great Salt Lake and sits to the west of the Wasatch Mountains, which rise more than 3,500 meters (10,000 feet) above sea level. The city was first settled in 1847 by pioneers seeking relief from religious persecution. Today Salt Lake City, the capital of Utah, is home to more than 170,000 residents. This true-color image of Salt Lake City was acquired by the Enhanced Thematic Mapper Plus (ETM+), flying aboard Landsat 7, on May 26, 2000. The southeastern tip of the Great Salt Lake is visible in the upper left of the image. The furrowed green and brown landscape running north-south is a portion of the Wasatch Mountains, some of which are snow-capped (white pixels). The greyish pixels in the center of the image show the developed areas of the city. A number of water reservoirs can be seen east of the mountain range. Salt Lake City International Airport is visible on the northwestern edge of the city. About 20 miles south of the airport is the Bingham Canyon Copper Mine (tan pixels), the world's largest open pit excavation. See also this MODIS image of Utah. Image courtesy NASA Landsat7 Science Team and USGS Eros Data Center

  14. Overview: Ancient Lake Creede

    USGS Publications Warehouse

    Bethke, Philip M.; Hay, Richard L.

    2000-01-01

    Lake Creede was moderately saline closed-basin lake that developed in the 26.9 Ma Creede caldera in the San Juan Mountains in the southwest Colorado. The volcaniclastic sediments deposited within the late Oligocene lake were first described and named as the Creede Formation by Emmons and Larsen (1923). The lake and its sedimentary fill are of interest first as representatives of a caldera-hosted lake in a silicic volcanic terrane, and second because of the likely involvement of lake fluids or related pore waters in the deposition of the 25 Ma silver and base-metal ores of the Creede mining district north of the Creede caldera (Fig. 1), as proposed Bethke and Rye (1979). Much of the material presented in this volume is based on observation of core samples and on downhole geophysical measurements obtained as part of a U.S. Continental Scientific Drilling Program in the moat of the Creede caldera. These core and downhole studies are supplemented by outcrop studies, some initiated in support of the drilling program (Bethke and Lipman, 1987), and by conceptual studies of the evolution of the Creede caldera and its surrounding landscape. Not surprisingly, not all authors agree on all interpretation. Most disagreements are pointed out in this overview chapter, and may present opportunities for future study.

  15. Salt Lake City, Utah

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Salt Lake City, Utah, will host the 2002 Winter Olympic Games. The city is located on the southeastern shore of the Great Salt Lake and sits to the west of the Wasatch Mountains, which rise more than 3,500 meters (10,000 feet) above sea level. The city was first settled in 1847 by pioneers seeking relief from religious persecution. Today Salt Lake City, the capital of Utah, is home to more than 170,000 residents. This true-color image of Salt Lake City was acquired by the Enhanced Thematic Mapper Plus (ETM+), flying aboard Landsat 7, on May 26, 2000. The southeastern tip of the Great Salt Lake is visible in the upper left of the image. The furrowed green and brown landscape running north-south is a portion of the Wasatch Mountains, some of which are snow-capped (white pixels). The greyish pixels in the center of the image show the developed areas of the city. A number of water reservoirs can be seen east of the mountain range. Salt Lake City International Airport is visible on the northwestern edge of the city. About 20 miles south of the airport is the Bingham Canyon Copper Mine (tan pixels), the world's largest open pit excavation. See also this MODIS image of Utah. Image courtesy NASA Landsat7 Science Team and USGS Eros Data Center

  16. Is Lake Chabot Eutrophic?

    NASA Astrophysics Data System (ADS)

    Pellegrini, K.; Logan, J.; Esterlis, P.; Lew, A.; Nguyen, M.

    2013-12-01

    Introduction/Abstract: Lake Chabot is an integral part of the East Bay watershed that provides habitats for animals and recreation for humans year-round. Lake Chabot has been in danger of eutrophication due to excessive dumping of phosphorous and nitrogen into the water from the fertilizers of nearby golf courses and neighboring houses. If the lake turned out to be eutrophified, it could seriously impact what is currently the standby emergency water supply for many Castro Valley residents. Eutrophication is the excessive richness of nutrients such as nitrogen and phosphorus in a lake, usually as a result of runoff. This buildup of nutrients causes algal blooms. The algae uses up most of the oxygen in the water, and when it dies, it causes the lake to hypoxify. The fish in the lake can't breathe, and consequently suffocate. Other oxygen-dependant aquatic creatures die off as well. Needless to say, the eutrophication of a lake is bad news for the wildlife that lives in or around it. The level of eutrophication in our area in Northern California tends to increase during the late spring/early summer months, so our crew went out and took samples of Lake Chabot on June 2. We focused on the area of the lake where the water enters, known on the map as Honker Bay. We also took readings a ways down in deeper water for comparison's sake. Visually, the lake looked in bad shape. The water was a murky green that glimmered with particulate matter that swirled around the boat as we went by. In the Honker Bay region where we focused our testing, there were reeds bathed in algae that coated the surface of the lake in thick, swirling patterns. Surprisingly enough, however, our test results didn't reveal any extreme levels of phosphorous or nitrogen. They were slightly higher than usual, but not by any significant amount. The levels we found were high enough to stimulate plant and algae growth and promote eutrophication, but not enough to do any severe damage. After a briefing with a

  17. TOXAPHENE STUDY OF GREAT LAKES TRIBUTARY SEDIMENTS

    EPA Science Inventory

    The Product is the paper "Pulp and Paper Mills as Sources of Toxaphene to Lake Superior and Northern Lake Michigan" published in the Journal of Great Lakes Research, 25(2):383-394 International Association of Great Lakes 1999.

  18. TOXAPHENE STUDY OF GREAT LAKES TRIBUTARY SEDIMENTS

    EPA Science Inventory

    The Product is the paper "Pulp and Paper Mills as Sources of Toxaphene to Lake Superior and Northern Lake Michigan" published in the Journal of Great Lakes Research, 25(2):383-394 International Association of Great Lakes 1999.

  19. Glacial lake inventory and lake outburst potential in Uzbekistan.

    PubMed

    Petrov, Maxim A; Sabitov, Timur Y; Tomashevskaya, Irina G; Glazirin, Gleb E; Chernomorets, Sergey S; Savernyuk, Elena A; Tutubalina, Olga V; Petrakov, Dmitriy A; Sokolov, Leonid S; Dokukin, Mikhail D; Mountrakis, Giorgos; Ruiz-Villanueva, Virginia; Stoffel, Markus

    2017-03-16

    Climate change has been shown to increase the number of mountain lakes across various mountain ranges in the World. In Central Asia, and in particular on the territory of Uzbekistan, a detailed assessment of glacier lakes and their evolution over time is, however lacking. For this reason we created the first detailed inventory of mountain lakes of Uzbekistan based on recent (2002-2014) satellite observations using WorldView-2, SPOT5, and IKONOS imagery with a spatial resolution from 2 to 10m. This record was complemented with data from field studies of the last 50years. The previous data were mostly in the form of inventories of lakes, available in Soviet archives, and primarily included localized in-situ data. The inventory of mountain lakes presented here, by contrast, includes an overview of all lakes of the territory of Uzbekistan. Lakes were considered if they were located at altitudes above 1500m and if lakes had an area exceeding 100m(2). As in other mountain regions of the World, the ongoing increase of air temperatures has led to an increase in lake number and area. Moreover, the frequency and overall number of lake outburst events have been on the rise as well. Therefore, we also present the first outburst assessment with an updated version of well-known approaches considering local climate features and event histories. As a result, out of the 242 lakes identified on the territory of Uzbekistan, 15% are considered prone to outburst, 10% of these lakes have been assigned low outburst potential and the remainder of the lakes have an average level of outburst potential. We conclude that the distribution of lakes by elevation shows a significant influence on lake area and hazard potential. No significant differences, by contrast, exist between the distribution of lake area, outburst potential, and lake location with respect to glaciers by regions.

  20. Will hypolimnetic waters become anoxic in all deep tropical lakes?

    NASA Astrophysics Data System (ADS)

    Fukushima, Takehiko; Matsushita, Bunkei; Subehi, Luki; Setiawan, Fajar; Wibowo, Hendro

    2017-03-01

    To elucidate trends of hypolimnetic oxygen concentrations, vertical distributions of dissolved oxygen were measured in eight deep tropical bodies of water (one natural lake with two basins, five natural lakes, and one reservoir) in Indonesia. A comparison of those concentrations with previously reported data revealed that shoaling of hypolimnetic oxygen-deficient (around a few decimeters to a few meter per year) water had occurred in all of the lakes. Calculated areal hypolimnetic oxygen depletion rates were 0.046-5.9 g m-2 y-1. The oligomictic or meromictic characteristics of the bodies of water suppressed circulation and mixing in the hypolimnions and thus resulted in continuous shoaling of the uppermost oxygen-deficient layers. In some lakes, millions of fish sometimes died suddenly, probably owing to upward movement of oxygen-deficient water to near the surface during periods of strong winds. In the future, the rate of shoaling will be accelerated by human impacts in the basins and by climate warming, the influence of which has already been manifested by rising water temperatures in these lakes. Appropriate monitoring and discussions of future restoration challenges are urgently needed to prevent the hypolimnions of the lakes from becoming completely anoxic.

  1. Molecular and isotopic insights into methane oxidation in Lake Kivu

    NASA Astrophysics Data System (ADS)

    Zigah, P. K.; Wehrli, B.; Schubert, C. J.

    2013-12-01

    Lake Kivu is a meromictic lake in the East African Rift Valley, located between the Republic of Rwanda and the Democratic Republic of Congo. The hypolimnion is permanently stratified and contain an unusually high amount of dissolved methane (CH4; ~ 60 km3) and carbon dioxide (CO2; ~300 km3) at standard temperature and pressure. While microbial-mediated methane oxidation is an important sink of methane in the lake, little is known about the distribution of microbes involved in the methane oxidation. To provide insights into methanotrophy in the lake, we analyzed depth profile of CH4, δ13C-CH4 and δ13C-DIC, δ13C-POC and the biomarkers of methanotrophic archaea and bacteria and their stable carbon isotopic composition from suspended particulate matter isolated from the lake water column. Our preliminary data show enhanced methane oxidation in oxic-anoxic transition zone in the water column. Depth distribution of diagnostic methanotrophic archaeal biomarkers such as archaeol and hydroxyarchaeol suggest archaea might be involved in anaerobic methane oxidation. Phospholipid fatty acids and diplopterol distribution and carbon isotopic signatures indicate bacteria-mediated anaerobic (and aerobic) methane oxidation in the lake.

  2. Will hypolimnetic waters become anoxic in all deep tropical lakes?

    PubMed Central

    Fukushima, Takehiko; Matsushita, Bunkei; Subehi, Luki; Setiawan, Fajar; Wibowo, Hendro

    2017-01-01

    To elucidate trends of hypolimnetic oxygen concentrations, vertical distributions of dissolved oxygen were measured in eight deep tropical bodies of water (one natural lake with two basins, five natural lakes, and one reservoir) in Indonesia. A comparison of those concentrations with previously reported data revealed that shoaling of hypolimnetic oxygen-deficient (around a few decimeters to a few meter per year) water had occurred in all of the lakes. Calculated areal hypolimnetic oxygen depletion rates were 0.046–5.9 g m−2 y−1. The oligomictic or meromictic characteristics of the bodies of water suppressed circulation and mixing in the hypolimnions and thus resulted in continuous shoaling of the uppermost oxygen-deficient layers. In some lakes, millions of fish sometimes died suddenly, probably owing to upward movement of oxygen-deficient water to near the surface during periods of strong winds. In the future, the rate of shoaling will be accelerated by human impacts in the basins and by climate warming, the influence of which has already been manifested by rising water temperatures in these lakes. Appropriate monitoring and discussions of future restoration challenges are urgently needed to prevent the hypolimnions of the lakes from becoming completely anoxic.

  3. Great Lakes, No Clouds

    NASA Image and Video Library

    2017-09-28

    NASA image acquired August 28, 2010 Late August 2010 provided a rare satellite view of a cloudless summer day over the entire Great Lakes region. North Americans trying to sneak in a Labor Day weekend getaway on the lakes were hoping for more of the same. The Great Lakes comprise the largest collective body of fresh water on the planet, containing roughly 18 percent of Earth's supply. Only the polar ice caps contain more fresh water. The region around the Great Lakes basin is home to more than 10 percent of the population of the United States and 25 percent of the population of Canada. Many of those people have tried to escape record heat this summer by visiting the lakes. What they found, according to The Hamilton Spectator, was record-breaking water temperatures fueled by record-breaking air temperatures in the spring and summer. By mid-August, the waters of Lake Superior were 6 to 8°C (11 to 14°F) above normal. Lake Michigan set records at about 4°C (7°F) above normal. The other three Great Lakes – Huron, Erie, and Ontario -- were above normal temperatures, though no records were set. The image was gathered by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite at 1:30 p.m. Central Daylight Time (18:30 UTC) on August 28. Open water appears blue or nearly black. The pale blue and green swirls near the coasts are likely caused by algae or phytoplankton blooms, or by calcium carbonate (chalk) from the lake floor. The sweltering summer temperatures have produced an unprecedented bloom of toxic blue-green algae in western Lake Erie, according to the Cleveland Plain Dealer. NASA image by Jeff Schmaltz, MODIS Rapid Response Team, Goddard Space Flight Center. Caption by Mike Carlowicz. Instrument: Aqua - MODIS Click here to see more images from NASA Goddard’s Earth Observatory NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft

  4. Contaminants in American alligator eggs from Lake Apopka, Lake Griffin, and Lake Okeechobee, Florida

    USGS Publications Warehouse

    Heinz, G.H.; Percival, H.F.; Jennings, Michael L.

    1991-01-01

    Residues of organochlorine pesticides, polychlorinated biphenyls (PCBs), and 16 elements were measured in American alligator (Alligator mississippiensis) eggs collected in 1984 from Lakes Apopka, Griffin, and Okeechobee in central and south Florida. Organochlorine pesticides were highest in eggs from Lake Apopka. None of the elements appeared to be present at harmful concentrations in eggs from any of the lakes. A larger sample of eggs was collected in 1985, but only from Lakes Griffin, a lake where eggs were relatively clean, and Apopka, where eggs were most contaminated. In 1985, hatching success of artificially incubated eggs was lower for Lake Apopka, and several organochlorine pesticides were higher than in eggs from Lake Griffin. However, within Lake Apopka, higher levels of pesticides in chemically analyzed eggs were not associated with reduced hatching success of the remaining eggs in the clutch. Therefore, it did not appear that any of the pesticides we measured were responsible for the reduced hatching of Lake Apopka eggs.

  5. Evidence of Lake Trout reproduction at Lake Michigan's mid-lake reef complex

    USGS Publications Warehouse

    Janssen, J.; Jude, D.J.; Edsall, T.A.; Paddock, R.W.; Wattrus, N.; Toneys, M.; McKee, P.

    2006-01-01

    The Mid-Lake Reef Complex (MLRC), a large area of deep (> 40 m) reefs, was a major site where indigenous lake trout (Salvelinus namaycush) in Lake Michigan aggregated during spawning. As part of an effort to restore Lake Michigan's lake trout, which were extirpated in the 1950s, yearling lake trout have been released over the MLRC since the mid-1980s and fall gill net censuses began to show large numbers of lake trout in spawning condition beginning about 1999. We report the first evidence of viable egg deposition and successful lake trout fry production at these deep reefs. Because the area's existing bathymetry and habitat were too poorly known for a priori selection of sampling sites, we used hydroacoustics to locate concentrations of large fish in the fall; fish were congregating around slopes and ridges. Subsequent observations via unmanned submersible confirmed the large fish to be lake trout. Our technological objectives were driven by biological objectives of locating where lake trout spawn, where lake trout fry were produced, and what fishes ate lake trout eggs and fry. The unmanned submersibles were equipped with a suction sampler and electroshocker to sample eggs deposited on the reef, draw out and occasionally catch emergent fry, and collect egg predators (slimy sculpin Cottus cognatus). We observed slimy sculpin to eat unusually high numbers of lake trout eggs. Our qualitative approaches are a first step toward quantitative assessments of the importance of lake trout spawning on the MLRC.

  6. Big lake records preserved in a little lake's sediment: An example from Silver Lake, Michigan, USA

    USGS Publications Warehouse

    Fisher, T.G.; Loope, W.L.; Pierce, W.; Jol, H.M.

    2007-01-01

    We reconstruct postglacial lake-level history within the Lake Michigan basin using soil stratigraphy, ground-penetrating radar (GPR), sedimentology and 14C data from the Silver Lake basin, which lies adjacent to Lake Michigan. Stratigraphy in nine vibracores recovered from the floor of Silver Lake appears to reflect fluctuation of water levels in the Lake Michigan basin. Aeolian activity within the study area from 3,000 years (cal yr. B.P.) to the present was inferred from analysis of buried soils, an aerial photograph sequence, and GPR. Sediments in and around Silver Lake appear to contain a paleoenvironmental record that spans the entire post-glacial history of the Lake Michigan basin. We suggest that (1) a pre-Nipissing rather than a Nipissing barrier separated Silver Lake basin from the Lake Michigan basin, (2) that the Nipissing transgression elevated the water table in the Silver Lake basin about 6,500 cal yr. B.P., resulting in reestablishment of a lake within the basin, and (3) that recent dune migration into Silver Lake is associated with levels of Lake Michigan.

  7. Winter Lake Breezes near the Great Salt Lake

    NASA Astrophysics Data System (ADS)

    Crosman, Erik T.; Horel, John D.

    2016-05-01

    Case studies of lake breezes during wintertime cold air pools in Utah's Salt Lake Valley are examined. While summer breezes originating from the Great Salt Lake are typically deeper, of longer duration, and have higher wind speeds than winter breezes, the rate of inland penetration and cross-frontal temperature differences can be higher during the winter. The characteristics of winter breezes and the forcing mechanisms controlling them (e.g., snow cover, background flow, vertical stability profile, clouds, lake temperature, lake sheltering, and drainage pooling) are more complex and variable than those evident in summer. During the afternoon in the Salt Lake Valley, these lake breezes can lead to elevated pollution levels due to the transport of fine particle pollutants from over the Great Salt Lake, decreased vertical mixing depth, and increased vertical stability.

  8. Multidisciplinary characterisation of sedimentary processes in a recent maar lake (Lake Pavin, French Massif Central) and implication for natural hazards

    NASA Astrophysics Data System (ADS)

    Chapron, E.; Albéric, P.; Jézéquel, D.; Versteeg, W.; Bourdier, J.-L.; Sitbon, J.

    2010-09-01

    Sedimentation processes occurring in the most recent maar lake of the French Massif Central (Lake Pavin) are documented for the first time based on high resolution seismic reflection and multibeam bathymetric surveys and by piston coring and radiocarbon dating on a sediment depocentre developed on a narrow sub aquatic plateau. This new data set confirms the mid Holocene age of maar lake Pavin formation at 6970±60 yrs cal BP and highlights a wide range of gravity reworking phenomena affecting the basin. In particular, a slump deposit dated between AD 580-640 remoulded both mid-Holocene lacustrine sediments, terrestrial plant debris and some volcanic material from the northern crater inner walls. Between AD 1200 and AD 1300, a large slide scar mapped at 50 m depth also affected the southern edge of the sub aquatic plateau, suggesting that these gas-rich biogenic sediments (laminated diatomite) are poorly stable. Although several triggering mechanisms can be proposed for these prehistoric sub-aquatic mass wasting deposits in Lake Pavin, we argue that such large remobilisation of gas-rich sediments may affect the gas stability in deep waters of meromictic maar lakes. This study highlights the need to further document mass wasting processes in maar lakes and their impacts on the generation of waves, favouring the development of dangerous (and potentially deadly) limnic eruptions.

  9. Crater Lake revealed

    USGS Publications Warehouse

    Ramsey, David W.; Dartnell, Peter; Bacon, Charles R.; Robinson, Joel E.; Gardner, James V.

    2003-01-01

    Around 500,000 people each year visit Crater Lake National Park in the Cascade Range of southern Oregon. Volcanic peaks, evergreen forests, and Crater Lake’s incredibly blue water are the park’s main attractions. Crater Lake partially fills the caldera that formed approximately 7,700 years ago by the eruption and subsequent collapse of a 12,000-foot volcano called Mount Mazama. The caldera-forming or climactic eruption of Mount Mazama drastically changed the landscape all around the volcano and spread a blanket of volcanic ash at least as far away as southern Canada. Prior to the climactic event, Mount Mazama had a 400,000 year history of cone building activity like that of other Cascade volcanoes such as Mount Shasta. Since the climactic eruption, there have been several less violent, smaller postcaldera eruptions within the caldera itself. However, relatively little was known about the specifics of these eruptions because their products were obscured beneath Crater Lake’s surface. As the Crater Lake region is still potentially volcanically active, understanding past eruptive events is important to understanding future eruptions, which could threaten facilities and people at Crater Lake National Park and the major transportation corridor east of the Cascades. Recently, the lake bottom was mapped with a high-resolution multibeam echo sounder. The new bathymetric survey provides a 2m/pixel view of the lake floor from its deepest basins virtually to the shoreline. Using Geographic Information Systems (GIS) applications, the bathymetry data can be visualized and analyzed to shed light on the geology, geomorphology, and geologic history of Crater Lake.

  10. Lake Sarez, Tajikistan

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Lake Sarez (top), deep in the Pamir mountains of Tajikistan, was created 90 years ago when a strong earthquake triggered a massive landslide that, in turn, became a huge dam along the Murghob River, now called the Usoi Dam. The resulting lake is perched above surrounding drainages at an elevation greater than 3000m, and is part of the watershed that drains the towering Akademi Nauk Range (see the regional image, lower). The lake is 61 km long and as deep as 500 m, and holds an estimated 17 cubic km of water. The area experiences considerable seismic activity, and scientists fear that part of the right bank may slump into the lake, creating a huge wave that will top over and possibly breach the natural dam. Such a wave would create a catastrophic flood downstream along the Bartang, Panj and Amu Darya Rivers, perhaps reaching all the way to the Aral Sea. Currently, central Asian governments, as well as the World Bank and the UN are monitoring the dam closely, and have proposed gradually lowering the lake level as a preventive measure. More information about the lake is available at the following web sites: Lake Sarez Study group, UN Report, Reliefweb Digital photograph numbers ISS002-E-7771 and ISS002-E-7479 were taken in the spring of 2001 from Space Station Alpha and are provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

  11. The Wandering Lake

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In the area at the very far eastern corner of China's Taklimakan Desert, Lop Nor Lake was located up until some years ago. Lop Nor, also called the 'the heart of the heart' of Asia, was the place where the waters of the largest inner basin (i.e., not flowing into the sea) of the world-including the Tarim and Kum-daria Rivers-were collected. Depending on the balance between rainfall water yield and evaporation, both position and size of the lake were strongly variable, thus giving rise to the legend of the Wandering Lake. 'Lop City' was the place where Marco Polo took his last rest before facing the one-year long crossing of the Gobi Desert. Starting from the end of the 19th century, several explorers tried to find the legendary place. One such explorer was Sven Hedin, who was commissioned by the Governor of Nanjing to lead an expedition to find the lake. In 1937, the Swedish explorer published his book entitled The Wandering Lake. Comparing this very precise map from Sven Hedin's book with the above Moderate-resolution Imaging Spectroradiometer (MODIS) false-color image (acquired on October 28, 2001), one can find a faint sign on the soil where the Lop Nor was located. This image, derived using a combination of MODIS' near-infrared and red channels (vegetation in red), shows where the Tarim River waters currently end their flow. The Wandering Lake does not exist anymore. The combination of climate change and human exploitation of water resources for agriculture caused the disappearance of the lake. This image was processed by Telespazio, Earth Observation division, new products development facility in Rome, Italy. The MODIS sensor flies aboard NASA's Terra spacecraft, launched in December 1999. Caption and image courtesy Luca Pietranera, Telespazio, Rome, Italy, based on data from the MODIS Science Team

  12. The Wandering Lake

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In the area at the very far eastern corner of China's Taklimakan Desert, Lop Nor Lake was located up until some years ago. Lop Nor, also called the 'the heart of the heart' of Asia, was the place where the waters of the largest inner basin (i.e., not flowing into the sea) of the world-including the Tarim and Kum-daria Rivers-were collected. Depending on the balance between rainfall water yield and evaporation, both position and size of the lake were strongly variable, thus giving rise to the legend of the Wandering Lake. 'Lop City' was the place where Marco Polo took his last rest before facing the one-year long crossing of the Gobi Desert. Starting from the end of the 19th century, several explorers tried to find the legendary place. One such explorer was Sven Hedin, who was commissioned by the Governor of Nanjing to lead an expedition to find the lake. In 1937, the Swedish explorer published his book entitled The Wandering Lake. Comparing this very precise map from Sven Hedin's book with the above Moderate-resolution Imaging Spectroradiometer (MODIS) false-color image (acquired on October 28, 2001), one can find a faint sign on the soil where the Lop Nor was located. This image, derived using a combination of MODIS' near-infrared and red channels (vegetation in red), shows where the Tarim River waters currently end their flow. The Wandering Lake does not exist anymore. The combination of climate change and human exploitation of water resources for agriculture caused the disappearance of the lake. This image was processed by Telespazio, Earth Observation division, new products development facility in Rome, Italy. The MODIS sensor flies aboard NASA's Terra spacecraft, launched in December 1999. Caption and image courtesy Luca Pietranera, Telespazio, Rome, Italy, based on data from the MODIS Science Team

  13. Lake Sarez, Tajikistan

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Lake Sarez (top), deep in the Pamir mountains of Tajikistan, was created 90 years ago when a strong earthquake triggered a massive landslide that, in turn, became a huge dam along the Murghob River, now called the Usoi Dam. The resulting lake is perched above surrounding drainages at an elevation greater than 3000m, and is part of the watershed that drains the towering Akademi Nauk Range (see the regional image, lower). The lake is 61 km long and as deep as 500 m, and holds an estimated 17 cubic km of water. The area experiences considerable seismic activity, and scientists fear that part of the right bank may slump into the lake, creating a huge wave that will top over and possibly breach the natural dam. Such a wave would create a catastrophic flood downstream along the Bartang, Panj and Amu Darya Rivers, perhaps reaching all the way to the Aral Sea. Currently, central Asian governments, as well as the World Bank and the UN are monitoring the dam closely, and have proposed gradually lowering the lake level as a preventive measure. More information about the lake is available at the following web sites: Lake Sarez Study group, UN Report, Reliefweb Digital photograph numbers ISS002-E-7771 and ISS002-E-7479 were taken in the spring of 2001 from Space Station Alpha and are provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

  14. Vertical distribution of microbial communities in a perennially stratified Arctic lake with saline, anoxic bottom waters

    PubMed Central

    Comeau, André M.; Harding, Tommy; Galand, Pierre E.; Vincent, Warwick F.; Lovejoy, Connie

    2012-01-01

    Meromictic lakes are useful biogeochemical models because of their stratified chemical gradients and separation of redox reactions down the water column. Perennially ice-covered meromictic lakes are particularly stable, with long term constancy in their density profiles. Here we sampled Lake A, a deep meromictic lake at latitude 83°N in High Arctic Canada. Sampling was before (May) and after (August) an unusual ice-out event during the warm 2008 summer. We determined the bacterial and archaeal community composition by high-throughput 16S rRNA gene tag-pyrosequencing. Both prokaryote communities were stratified by depth and the Bacteria differed between dates, indicating locally driven selection processes. We matched taxa to known taxon-specific biogeochemical functions and found a close correspondence between the depth of functional specialists and chemical gradients. These results indicate a rich microbial diversity despite the extreme location, with pronounced vertical structure in taxonomic and potential functional composition, and with community shifts during ice-out. PMID:22930670

  15. Vertical distribution of microbial communities in a perennially stratified Arctic lake with saline, anoxic bottom waters.

    PubMed

    Comeau, André M; Harding, Tommy; Galand, Pierre E; Vincent, Warwick F; Lovejoy, Connie

    2012-01-01

    Meromictic lakes are useful biogeochemical models because of their stratified chemical gradients and separation of redox reactions down the water column. Perennially ice-covered meromictic lakes are particularly stable, with long term constancy in their density profiles. Here we sampled Lake A, a deep meromictic lake at latitude 83°N in High Arctic Canada. Sampling was before (May) and after (August) an unusual ice-out event during the warm 2008 summer. We determined the bacterial and archaeal community composition by high-throughput 16S rRNA gene tag-pyrosequencing. Both prokaryote communities were stratified by depth and the Bacteria differed between dates, indicating locally driven selection processes. We matched taxa to known taxon-specific biogeochemical functions and found a close correspondence between the depth of functional specialists and chemical gradients. These results indicate a rich microbial diversity despite the extreme location, with pronounced vertical structure in taxonomic and potential functional composition, and with community shifts during ice-out.

  16. Examining indirect effects of lake trout recovery

    EPA Science Inventory

    With the recovery of lake trout populations in Lake Superior, there are indications of decreased forage fish abundance and density-dependence in lake trout. In Lake Superior, lean lake trout historically occupied depths < 60 m, and siscowet lake trout occupied depths > 60 m...

  17. Examining indirect effects of lake trout recovery

    EPA Science Inventory

    With the recovery of lake trout populations in Lake Superior, there are indications of decreased forage fish abundance and density-dependence in lake trout. In Lake Superior, lean lake trout historically occupied depths < 60 m, and siscowet lake trout occupied depths > 60 m...

  18. Microbial and biogeochernical processes Soda Lake, Nevada

    USGS Publications Warehouse

    Oremland, R.S.; Cloern, J.E.; Sofer, Z.; Smith, R.L.; Culbertson, C.W.; Zehr, J.; Miller, L.; Cole, B.; Harvey, R.; Iversen, N.; Klug, M.; Des Marais, D J; Rau, G.

    1988-01-01

    Meromictic, alkaline lakes represent modern-day analogues of lacustrine source rock depositional environments. In order to further our understanding of how these lakes function in terms of limnological and biogeochemical processes, we have conducted an interdisciplinary study of Big Soda Lake. Annual mixolimnion productivity (ca. 500 g m-2) is dominated by a winter diatom bloom (60% of annual) caused by upward transport of ammonia to the epilimnion. The remainder of productivity is attributable to chemoautotrophs (30%) and photosynthetic bacteria (10%) present at the oxic -anoxic interface from May to November. Studies of bacterial heterotrophy and particulate fluxes in the water column indicate that about 90% of annual productivity is remineralized in the mixolimnion, primarily by fermentative bacteria. However, high rates of sulphate reduction (9-29 mmol m-2 yr-1) occur in the monimolimnion waters, which could remineralize most (if not all) of the primary productivity. This discrepancy has not as yet been fully explained. Low rates of methanogenesis also occur in the monimolimnion waters and sediments. Most of the methane is consumed by anaerobic methane oxidation occurring in the monimolimnion water column. Other bacterial processes occurring in the lake are also discussed. Preliminary studies have been made on the organic geochemistry of the monimolimnion sediments. Carbon-14-dating indicates a lower depositional rate prior to meromixis and a downcore enrichment in 13C of organic carbon and chlorophyll derivatives. Hydrous pyrolysis experiments indicate that the sediment organic matter is almost entirely derived from the water column with little or no contribution from terrestrial sources. The significance of the organics released by hydrous pyrolysis is discussed.

  19. Hydrogeologic Controls on Lake Level at Mountain Lake, Virginia

    NASA Astrophysics Data System (ADS)

    Roningen, J. M.; Burbey, T. J.

    2011-12-01

    Mountain Lake in Giles County, Virginia has a documented history of severe natural lake-level changes involving groundwater seepage that extend over the past 4200 years. Featured in the 1986 movie Dirty Dancing, the natural lake dried up completely in September 2008 and levels have not yet recovered. A hydrogeologic investigation was undertaken in an effort to determine the factors influencing lake level changes. A daily water balance, dipole-dipole electrical resistivity surveying, well logging and chemical sampling have shed light on: 1) the influence of a fault not previously discussed in literature regarding the lake, 2) the seasonal response to precipitation of a forested first-order drainage system in fractured rock, and 3) the possibility of flow pathways related to karst features. Geologic controls on lake level were investigated using several techniques. Geophysical surveys using dipole-dipole resistivity located possible subsurface flowpaths both to and from the lake. Well logs, lineament analysis, and joint sampling were used to assess structural controls on lake hydrology. Major ions were sampled at wells, springs, streams, and the lake to evaluate possible mixing of different sources of water in the lake. Groundwater levels were monitored for correlation to lake levels, rainfall events, and possible seismic effects. The hydrology of the lake was quantified with a water balance on a daily time step. Results from the water balance indicate steady net drainage and significant recharge when vegetation is dormant, particularly during rain-on-snow melt events. The resistivity survey reveals discrete areas that represent flow pathways from the lake, as well as flowpaths to springs upgradient of the lake located in the vicinity of the fault. The survey also suggests that some flowpaths may originate outside of the topographic watershed of the lake. Chemical evidence indicates karst may underlie the lakebed. Historical data suggest that artificial intervention

  20. Chemours Pompton Lakes Works Site, Pompton Lakes, NJ

    EPA Pesticide Factsheets

    E.I. DuPont De Nemours & Company is located at 2000 Cannonball Road, Pompton Lakes, New Jersey. The DuPont Pompton Lakes Works site (DuPont) occupies approximately 570 acres of land in Pompton Lakes and Wanaque.

  1. National Lakes Assessment: A Collaborative Survey of the Nation's Lakes

    EPA Science Inventory

    The National Lakes Assessment A Collaborative Survey of the Nation's Lakes presents the results of an unprecedented assessment of the nation’s lakes. This report is part of the National Aquatic Resource Surveys, a series of statistically based surveys designed to provide the pub...

  2. View of Lake Sabrina Dam and dry Lake Sabrina Basin ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of Lake Sabrina Dam and dry Lake Sabrina Basin with the upstream side of the outlet structure visible at photo center, view to north-northwest - Bishop Creek Hydroelectric System, Plant 2, Lake Sabrina Dam, Bishop Creek, Bishop, Inyo County, CA

  3. National Lakes Assessment: A Collaborative Survey of the Nation's Lakes

    EPA Science Inventory

    The National Lakes Assessment A Collaborative Survey of the Nation's Lakes presents the results of an unprecedented assessment of the nation’s lakes. This report is part of the National Aquatic Resource Surveys, a series of statistically based surveys designed to provide the pub...

  4. Predicting Lake Depths from Topography to Map Global Lake Volume

    NASA Astrophysics Data System (ADS)

    Holtzman, N.; Pavelsky, T.

    2016-12-01

    The depth of a lake affects its role in climate and biogeochemical cycling. There is a lack of lake depth data due to the difficulty of measuring bathymetry, which impedes the accurate inclusion of lakes in climate models and the assessment of global water resources and carbon storage. However, lake depths can be estimated from land topography, for which remotely-sensed DEM data is available. We develop a simple statistical model to predict lake depth from two explanatory variables: the mean relief above the lake surface of a buffer surrounding the lake, and whether the lake's location was glaciated in the last ice age. The model is based on 328 lakes with known depths, located on all continents but Antarctica, and has an r2 of 0.57. We then apply this model to a set of over 200,000 lakes from the Global Lakes and Wetlands Database to produce global gridded maps of predicted total lake volume and average depth. The realistic depth estimates provided by our model may improve the accuracy of future studies of climate and water resources.

  5. Lake Michigan lake trout PCB model forecast post audit

    EPA Science Inventory

    Scenario forecasts for total PCBs in Lake Michigan (LM) lake trout were conducted using the linked LM2-Toxics and LM Food Chain models, supported by a suite of additional LM models. Efforts were conducted under the Lake Michigan Mass Balance Study and the post audit represents th...

  6. Lake Michigan lake trout PCB model forecast post audit

    EPA Science Inventory

    Scenario forecasts for total PCBs in Lake Michigan (LM) lake trout were conducted using the linked LM2-Toxics and LM Food Chain models, supported by a suite of additional LM models. Efforts were conducted under the Lake Michigan Mass Balance Study and the post audit represents th...

  7. 42. Peaks of Otter, Abbott Lake. View across lake to ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    42. Peaks of Otter, Abbott Lake. View across lake to peaks of Outter Lodge, completed in 1964. Construction of the lake got underway in 1964. Looking east-northeast. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  8. [Fractionation of stable sulfur isotopes during microbiological processes in Slavyansk lakes].

    PubMed

    Chebotarev, E N; Matrosov, A G; Kudriavtseva, A I; Ziakun, A M; Ivanov, M V

    1975-01-01

    The isotopic content of sulphur in sulphates increases with depth in waters containing hydrogen sulphide of the meromictic lakes Repnoe and Veisovo as a result of microbiological reduction of sulphates. At the same time, hydrogen sulphide enrichments 19 to 25% of the light isotope 32S in the lake Veisovo, and 24 to 32% in the lake Repnoe. The fractionation of sulphur isotopes, manifested in the enrichment of sulphides with lighter isotopes, and that of sulphates with heavier isotopes, was found also in the bottom deposits of the lake Repnoe. The isotope and microbiological data suggest that, in the zone of mass growth of the phototrophic sulphur bacteria in the lake Repnoe, there are two processes of fractionation: (a) due to the bacterial reduction of sulphates; and (b) due to anaerobic oxidation of hydrogen sulphide, resulting in the enrichment of hydrogen sulphide with the light isotope 32S by 5 to 7 promille.

  9. Real-estate lakes

    USGS Publications Warehouse

    Rickert, David A.; Spieker, Andrew Maute

    1971-01-01

    Since the dawn of civilization waterfront land has been an irresistible attraction to man. Throughout history he has sought out locations fronting on oceans, rivers, and lakes. Originally sought for proximity .to water supply and transportation, such locations are now sought more for their esthetic qualities and for recreation. Usable natural waterfront property is limited, however, and the more desirable sites in many of our urban areas have already been taken. The lack of available waterfront sites has led to the creation of many artificial bodies of water. The rapid suburbanization that has characterized urban growth in America since the end of World War II, together with increasing affluence and le-isure time, has created a ready market for waterfront property. Accordingly, lake-centered subdivisions and developments dot the suburban landscape in many of our major urban areas. Literally thousands of lakes surrounded by homes have materialized during this period of rapid growth. Recently, several "new town" communities have been planned around this lake-centered concept. A lake can be either an asset or a liaoility to a community. A clean, clear, attractively landscaped lake is a definite asset, whereas a weed-choked, foul-smelling mudhole is a distinct liability. The urban environment poses both problems and imaginative opportunities in the development of lakes. Creation of a lake causes changes in all aspects of the environment. Hydrologic systems and ecological patterns are usually most severely altered. The developer should be aware of the potential changes; it is not sufficient merely to build a dam across a stream or to dig a hole in the ground. Development of Gl a successful lake requires careful planning for site selection and design, followed by thorough and cc ntinual management. The purpose of this report is to describe the characteristics of real-estate lakes, to pinpoint potential pmblems, and to suggest possible planning and management guidelines

  10. Great Lakes Initiative (GLI) Clearinghouse

    EPA Pesticide Factsheets

    The Great Lakes Initiative Toxicity Clearinghouse is a central location for information on criteria, toxicity data, exposure parameters and other supporting documents used in developing water quality standards in the Great Lakes watershed.

  11. National Lakes Assessment 2007 Results

    EPA Pesticide Factsheets

    The National Lakes Assessment samples over 1,000 lakes, ponds and reservoirs across the country. Key findings from this assessment in 2007 include the biological condition and most widespread stressors of these waterbodies.

  12. Different Looks for Titan Lakes

    NASA Image and Video Library

    2013-01-08

    Lakes on Saturn moon Titan reflect radio waves in varying ways in this image from NASA Cassini spacecraft. If a lake is fully liquid, it looks dark, but if it is only partially liquid, it looks brighter.

  13. Regional Lake quality patterns: Their relationship to lake conservation and management decisions

    SciTech Connect

    Peterson, S.A.; Hughes, R.M.; Larsen, D.P.; Paulsen, S.G.; Omernik, J.M.

    1996-05-01

    Understanding regional lake quality patterns is important to lake restoration. It puts specific lake conditions into perspective, provides a basis for establishing lake quality goals, identifies lakes most likely to benefit from restoration and forms a framework for assessing restoration success. Two techniques used to characterize regional lake quality patterns are discussed. Combining the two approaches provides an effective means to describe lake regions management goals and restoration success. Case examples illustrate the significant of regional lake quality to specific lake restoration projects.

  14. Microplastic pollution in lakes and lake shoreline sediments - A case study on Lake Bolsena and Lake Chiusi (central Italy).

    PubMed

    Fischer, Elke Kerstin; Paglialonga, Lisa; Czech, Elisa; Tamminga, Matthias

    2016-06-01

    Rivers and effluents have been identified as major pathways for microplastics of terrestrial sources. Moreover, lakes of different dimensions and even in remote locations contain microplastics in striking abundances. This study investigates concentrations of microplastic particles at two lakes in central Italy (Lake Bolsena, Lake Chiusi). A total number of six Manta Trawls have been carried out, two of them one day after heavy winds occurred on Lake Bolsena showing effects on particle distribution of fragments and fibers of varying size categories. Additionally, 36 sediment samples from lakeshores were analyzed for microplastic content. In the surface waters 2.68 to 3.36 particles/m(3) (Lake Chiusi) and 0.82 to 4.42 particles/m(3) (Lake Bolsena) were detected, respectively. Main differences between the lakes are attributed to lake characteristics such as surface and catchment area, depth and the presence of local wind patterns and tide range at Lake Bolsena. An event of heavy winds and moderate rainfall prior to one sampling led to an increase of concentrations at Lake Bolsena which is most probable related to lateral land-based and sewage effluent inputs. The abundances of microplastic particles in sediments vary from mean values of 112 (Lake Bolsena) to 234 particles/kg dry weight (Lake Chiusi). Lake Chiusi results reveal elevated fiber concentrations compared to those of Lake Bolsena what might be a result of higher organic content and a shift in grain size distribution towards the silt and clay fraction at the shallow and highly eutrophic Lake Chiusi. The distribution of particles along different beach levels revealed no significant differences. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Sanctuaries for lake trout in the Great Lakes

    USGS Publications Warehouse

    Stanley, Jon G.; Eshenroder, Randy L.; Hartman, Wilbur L.

    1987-01-01

    Populations of lake trout, severely depleted in Lake Superior and virtually extirpated from the other Great Lakes because of sea lamprey predation and intense fishing, are now maintained by annual plantings of hatchery-reared fish in Lakes Michigan, Huron, and Ontario and parts of Lake Superior. The extensive coastal areas of the Great Lakes and proximity to large populations resulted in fishing pressure on planted lake trout heavy enough to push annual mortality associated with sport and commercial fisheries well above the critical level needed to reestablish self-sustaining stocks. The interagency, international program for rehabilitating lake trout includes controlling sea lamprey abundance, stocking hatchery-reared lake trout, managing the catch, and establishing sanctuaries where harvest is prohibited. Three lake trout sanctuaries have been established in Lake Michigan: the Fox Island Sanctuary of 121, 500 ha, in the Chippewa-Ottawa Treaty fishing zone in the northern region of the lake; the Milwaukee Reef Sanctuary of 160, 000 ha in midlake, in boundary waters of Michigan and Wisconsin; and Julian's Reef Sanctuary of 6, 500 ha, in Illinois waters. In northern Lake Huron, Drummond Island Sanctuary of 55, 000 ha is two thirds in Indian treaty-ceded waters in Michigan and one third in Ontario waters of Canada. A second sanctuary, Six Fathom Bank-Yankee Reef Sanctuary, in central Lake Huron contains 168, 000 ha. Sanctuary status for the Canadian areas remains to be approved by the Provincial government. In Lake Superior, sanctuaries protect the spawning grounds of Gull Island Shoal (70, 000 ha) and Devils Island Shoal (44, 000 ha) in Wisconsin's Apostle Island area. These seven sanctuaries, established by the several States and agreed upon by the States, Indian tribes, the U.S. Department of the Interior, and the Province of Ontario, contribute toward solving an interjurisdictional fishery problem.

  16. Michigan: The Great Lakes State

    ERIC Educational Resources Information Center

    McKay, Sandra Lee; La Luzerne-Oi, Sally

    2009-01-01

    Although Michigan is often called the "Wolverine State," its more common nickname is the "Great Lakes State." This name comes from the fact that Michigan is the only state in the United States that borders four of the five Great Lakes. Also referred to as the "Water Wonderland," Michigan has 11,000 additional lakes,…

  17. AirMISR Rogers Lake

    Atmospheric Science Data Center

    2014-04-25

    AirMISR ROGERS LAKE 2001 Project Title:  AirMISR Discipline:  ... ER-2 Spatial Coverage:  Rogers Lake, California (34.75, 35.33)(-118.06, -117.51) Spatial ... Data Readme Files:  Readme Rogers Lake Read Software Files :  IDL Code ...

  18. Red Lake Forestry Greenhouse Program

    Treesearch

    Gloria Whitefeather-Spears

    2002-01-01

    In 1916, The Red Lake Indian Forest Act was created. The Red Lake Band of Chippewa in Minnesota stood alone and refused to consent to allotment. Consequently, The Red Lake Band is the only tribe in Minnesota for which a congressional act was passed to secure a permanent economic foundation for the band and its future.

  19. Viruses in Antarctic lakes

    NASA Technical Reports Server (NTRS)

    Kepner, R. L. Jr; Wharton, R. A. Jr; Suttle, C. A.; Wharton RA, J. r. (Principal Investigator)

    1998-01-01

    Water samples collected from four perennially ice-covered Antarctic lakes during the austral summer of 1996-1997 contained high densities of extracellular viruses. Many of these viruses were found to be morphologically similar to double-stranded DNA viruses that are known to infect algae and protozoa. These constitute the first observations of viruses in perennially ice-covered polar lakes. The abundance of planktonic viruses and data suggesting substantial production potential (relative to bacteria] secondary and photosynthetic primary production) indicate that viral lysis may be a major factor in the regulation of microbial populations in these extreme environments. Furthermore, we suggest that Antarctic lakes may be a reservoir of previously undescribed viruses that possess novel biological and biochemical characteristics.

  20. Viruses in Antarctic lakes

    NASA Technical Reports Server (NTRS)

    Kepner, R. L. Jr; Wharton, R. A. Jr; Suttle, C. A.; Wharton RA, J. r. (Principal Investigator)

    1998-01-01

    Water samples collected from four perennially ice-covered Antarctic lakes during the austral summer of 1996-1997 contained high densities of extracellular viruses. Many of these viruses were found to be morphologically similar to double-stranded DNA viruses that are known to infect algae and protozoa. These constitute the first observations of viruses in perennially ice-covered polar lakes. The abundance of planktonic viruses and data suggesting substantial production potential (relative to bacteria] secondary and photosynthetic primary production) indicate that viral lysis may be a major factor in the regulation of microbial populations in these extreme environments. Furthermore, we suggest that Antarctic lakes may be a reservoir of previously undescribed viruses that possess novel biological and biochemical characteristics.

  1. Dating problems with selected mining lakes and the adjacent groundwater body in Lusatia, Germany.

    PubMed

    Seebach, Anne; von Rohden, Christoph; Ilmberger, Johann; Weise, Stephan M; Knoller, Kay

    2010-09-01

    This study presents selected results, applying environmental tracers to investigate lake water-groundwater interactions at two study sites located in Lusatia, Germany. The focus of the investigations were two meromictic pit lakes and their adjacent aquifers. In order to follow hydrodynamic processes between lake and groundwater, mixing patterns within the lakes as well as ages of lake and groundwater, water samples of ground- and lake water were collected at three occasions, representing summer and winter conditions in the aquatic systems. The water samples were analysed for stable isotopes (deuterium, oxygen-18) and tritium and sulphurhexafluoride (SF(6) concentration). Lake water profiles of conductivity and (18)O could validate the permanent stratification pattern of both the lakes. Groundwater data sets showed a heterogeneous local distribution in stable isotope values between rain and lake water. A two-component mixing model had been adopted only from (18)O data to determine lake water proportions in the surrounding groundwater wells in order to correct measured tritium and SF(6) concentrations in groundwater samples. This procedure had been hampered by upstream-located wells indicating strong (18)O enrichment in groundwater samples. However, rough groundwater ages were estimated. For both study sites, Piston flow ages between 12.9 and 27.7 years were calculated. The investigations showed the good agreement between two different environmental dating tools, considering the marginal data sets.

  2. Lake-level frequency analysis for Devils Lake, North Dakota

    USGS Publications Warehouse

    Wiche, Gregg J.; Vecchia, Aldo V.

    1996-01-01

    An annual lake-volume model and a statistical water mass-balance model were used to estimate future lake-level probabilities for Devils Lake. Comparison of the models indicates upper exceedance levels of the water mass-balance model increase much more rapidly than those of the annual lake-volume model. For simulation year 5, the 99-percent exceedance is 1,417.6 feet above sea level for the annual lake-volume model and 1,423.2 feet above sea level for the water mass-balance model.

  3. Lake Superior, Deluth, MN

    NASA Image and Video Library

    1973-06-22

    SL2-05-454 (22 June 1973) --- This view shows the west end of Lake Superior and Duluth, MN (47.0N, 91.0W). Portions of Minnesota, Michigan and Ontario, Canada are in the scene. The Duluth metropolitan area is at the west end of the lake. The discoloration plume in the water at Duluth is the result of tailings from the iron ore smelters that process the iron ore from the nearby open pit mines seen near the upper left corner of the photo. Photo credit: NASA

  4. The Great Lakes whitefish

    USGS Publications Warehouse

    Van Oosten, John; Elliot, Charles

    1942-01-01

    In every one of the Great Lakes- Ontario, Erie, Huron, Michigan, and Superior- the most valuable fishes are declining, and there is no evidence that this trend will be reversed. Under existing conditions of a diversity of regulations that vary between states and between the two countries, and with the present methods of fishing, the Great Lakes fisheries are doomed. This chapter deals with the common whitefish, a valuable species which many believe to be the next that will go unless positive action is forthcoming soon.

  5. Transient Tsunamis in Lakes

    NASA Astrophysics Data System (ADS)

    Couston, L.; Mei, C.; Alam, M.

    2013-12-01

    A large number of lakes are surrounded by steep and unstable mountains with slopes prone to failure. As a result, landslides are likely to occur and impact water sitting in closed reservoirs. These rare geological phenomena pose serious threats to dam reservoirs and nearshore facilities because they can generate unexpectedly large tsunami waves. In fact, the tallest wave experienced by contemporary humans occurred because of a landslide in the narrow bay of Lituya in 1958, and five years later, a deadly landslide tsunami overtopped Lake Vajont's dam, flooding and damaging villages along the lakefront and in the Piave valley. If unstable slopes and potential slides are detected ahead of time, inundation maps can be drawn to help people know the risks, and mitigate the destructive power of the ensuing waves. These maps give the maximum wave runup height along the lake's vertical and sloping boundaries, and can be obtained by numerical simulations. Keeping track of the moving shorelines along beaches is challenging in classical Eulerian formulations because the horizontal extent of the fluid domain can change over time. As a result, assuming a solid slide and nonbreaking waves, here we develop a nonlinear shallow-water model equation in the Lagrangian framework to address the problem of transient landslide-tsunamis. In this manner, the shorelines' three-dimensional motion is part of the solution. The model equation is hyperbolic and can be solved numerically by finite differences. Here, a 4th order Runge-Kutta method and a compact finite-difference scheme are implemented to integrate in time and spatially discretize the forced shallow-water equation in Lagrangian coordinates. The formulation is applied to different lake and slide geometries to better understand the effects of the lake's finite lengths and slide's forcing mechanism on the generated wavefield. Specifically, for a slide moving down a plane beach, we show that edge-waves trapped by the shoreline and free

  6. Megasplash at Lake Tahoe

    NASA Astrophysics Data System (ADS)

    Moore, J. G.; Schweickert, R. A.

    2013-12-01

    Backwash from a major ~10 km3 landslide in Lake Tahoe washed away Tioga age (21 ka) moraines (Schweickert, et al 2000; Howle, 2012). Coring in the lake demonstrates a 7700-8000 yr Mt. Mazama ash is widely distributed in lake sediments that overlie the landslide blocks. Moreover, core stratigraphy and radiocarbon ages indicate that all of the sediments cored (to about 3 m depth reaching back 12 ka) were deposited after the landslide (Smith et al., 2013). The age of the landslide is hence constrained at 12-21 ka. Fifteen major subaqueous sand wave channels 2.5 to 10.2 km in length originate from subaqueous delta-terraces at depths of 5-28 m on the margins of the lake. The channels, apparently formed by turbidity currents, are distinctly erosional in their upper part, and transform to deposition aprons in their lower part as they approach the flat lake floor at 500 m depth. The channels contain wave forms (giant ripple marks) convex upstream with maximum wavelengths of 450 m. The lower depositional aprons are surfaced by sand waves convex downstream with maximum wavelengths of 100-300 m. Sand wave convexity mimics the contour of the substrate. The sand wave channel systems are mantled by the post-slide 12 ka sediments and hence have been inactive since that time. These channel-fan structures were apparently produced by backwash from the giant Tahoe landslide, which splashed ~5 km3 of water onto the surrounding countryside thereby lowering lake level by ~10 m. The sediment-charged backwash first deposited the delta-terraces at the lowered lake level and then partly eroded them to generate the sand wave channels, within minutes or hours, while seiche activity resurfaced the delta-terraces. A remarkably similar, though smaller, presently-forming system of turbidity sand wave channels has been imaged at the mouth of the Squamish River in British Columbia (Hughes Clark et al., 2012). The Tahoe splash-induced backwash was briefly equivalent to more than fifteen Squamish

  7. Extreme events in the sedimentary record of maar Lake Pavin: Implications for natural hazards assessment in the French Massif Central

    NASA Astrophysics Data System (ADS)

    Chassiot, Léo; Chapron, Emmanuel; Di Giovanni, Christian; Albéric, Patrick; Lajeunesse, Patrick; Lehours, Anne-Catherine; Meybeck, Michel

    2016-06-01

    A set of sedimentary cores, high resolution swath bathymetry and subbottom profiler data provides new insights on sedimentary processes in meromictic maar Lake Pavin, France. Three sedimentary environments (i.e., littoral, plateau and basin) have been identified in the lake from sediment composition using bulk organic geochemistry and the analysis of hydroacoustic images. Various forms of rapidly deposited layers (RDLs) have been identified and radiocarbon dated. An up to date stratigraphy of sedimentary events matching coeval RDLs across the lake is presented and illustrates a wide range of natural hazards linked to Lake Pavin during the last 2000 years. In AD 600, a sudden lake outburst triggered a slump deposit along with a 9 m lake-level drop that drove shifts in sedimentary organic matter composition. Outside the lake, outburst flood deposits have been described downstream and provide sedimentary evidence for this event. The lake-level drop also favored the generation of gravity reworking processes, as shown by (1) a regional earthquake-triggered large slope failure on the plateau connected to a mass-wasting deposit in the basin dated to AD 1300, and (2) a succession of turbidites in AD 1825 and AD 1860 contemporaneous to two historic earthquakes, suggesting that this lake is sensitive to earthquakes with a minimum epicentral intensity of V. Finally, past observations of lake water color changes in AD 1783 and AD 1936, similar to reports in other meromictic lakes, match iron-rich deposits identified in maar lake sediments and suggest that Lake Pavin could have undergone limnic eruptions.

  8. Reevaluation of lake trout and lake whitefish bioenergetics models

    USGS Publications Warehouse

    Madenjian, Charles P.; Pothoven, Steve A.; Kao, Yu-Chun

    2013-01-01

    Using a corrected algorithm for balancing the energy budget, we reevaluated the Wisconsin bioenergetics model for lake trout (Salvelinus namaycush) in the laboratory and for lake whitefish (Coregonus clupeaformis) in the laboratory and in the field. For lake trout, results showed that the bioenergetics model slightly overestimated food consumption by the lake trout when they were fed low and intermediate rations, whereas the model predicted food consumption by lake trout fed ad libitum without any detectable bias. The slight bias in model predictions for lake trout on restricted rations may have been an artifact of the feeding schedule for these fish, and we would therefore recommend application of the Wisconsin lake trout bioenergetics model to lake trout populations in the field without any revisions to the model. Use of the Wisconsin bioenergetics model for coregonids resulted in overestimation of food consumption by lake whitefish both in the laboratory and in the field by between 20 and 30%, on average. This overestimation of food consumption was most likely due to overestimation of respiration rate. We therefore adjusted the respiration component of the bioenergetics model to obtain a good fit to the observed consumption in our laboratory tanks. The adjusted model predicted the consumption in the laboratory and the field without any detectable bias. Until a detailed lake whitefish respiration study can be conducted, we recommend application of our adjusted version of the Wisconsin generalized coregonid bioenergetics model to lake whitefish populations in the field.

  9. Maturity schedules of lake trout in Lake Michigan

    USGS Publications Warehouse

    Madenjian, Charles P.; DeSorcie, Timothy J.; Stedman, Ralph M.

    1998-01-01

    We determined maturity schedules of male and female lake trout (Salvelinus namaycush) in Lake Michigan from nearshore populations and from an offshore population on Sheboygan Reef, which is located in midlake. Gill nets and bottom trawls were used to catch lake trout in fall 1994 and 1995 from two nearshore sites and Sheboygan Reef. Each lake trout was judged immature or mature, based on visual examination of gonads. Probit analysis, coupled with relative potency testing, revealed that age-at-maturity and length-at-maturity were similar at the two nearshore sites, but that lake trout from the nearshore sites matured at a significantly earlier age than lake trout from Sheboygan Reef. However, length at maturity for the nearshore populations was nearly identical to that for the offshore population, suggesting that rate of lake trout maturation in Lake Michigan was governed by growth rather than age. Half of the lake trout males reached maturity at a total length of 580 mm, whereas half of the females were mature at a length of 640 mm. Over half of nearshore males were mature by age 5, and over half the nearshore females matured by age 6. Due to a slower growth rate, maturity was delayed by 2 years on Sheboygan Reef compared with the nearshore populations. Documentation of this delay in maturation may be useful in deciding stocking allocations for lake trout rehabilitation in Lake Michigan.

  10. Gas exchange on Mono Lake and Crowley Lake, California

    NASA Technical Reports Server (NTRS)

    Wanninkhof, Rik; Ledwell, James R.; Broecker, Wallace S.

    1987-01-01

    Gas exchange coefficients (k) have been determined for freshwater Crowley Lake and saline Mono Lake through the use of a man-made purposefully injected gas, SF6. The concentration decreased from an initial value of 40 to 4 pmol/L for Mono Lake and from 20 to 1 pmol/L for Crowley lake over a period of 6 wks. Wind-speed (u) records from anemometers on the shore of each lake made it possible to determine the relationship between k and u. The average u and k values for the experiment were identical for the two lakes, despite the large chemical differences. It is estimated that, for the u values observed over Mono Lake from July to December 1984, the exchange of CO2 occurred 2.5 times faster than without chemical enhancement. This is a factor of 4 lower than needed to explain the high invasion rate of C-14 produced by nuclear bomb tests.

  11. Gas exchange on Mono Lake and Crowley Lake, California

    NASA Technical Reports Server (NTRS)

    Wanninkhof, Rik; Ledwell, James R.; Broecker, Wallace S.

    1987-01-01

    Gas exchange coefficients (k) have been determined for freshwater Crowley Lake and saline Mono Lake through the use of a man-made purposefully injected gas, SF6. The concentration decreased from an initial value of 40 to 4 pmol/L for Mono Lake and from 20 to 1 pmol/L for Crowley lake over a period of 6 wks. Wind-speed (u) records from anemometers on the shore of each lake made it possible to determine the relationship between k and u. The average u and k values for the experiment were identical for the two lakes, despite the large chemical differences. It is estimated that, for the u values observed over Mono Lake from July to December 1984, the exchange of CO2 occurred 2.5 times faster than without chemical enhancement. This is a factor of 4 lower than needed to explain the high invasion rate of C-14 produced by nuclear bomb tests.

  12. Variability of methane in the epilimnion of Lake Kivu

    NASA Astrophysics Data System (ADS)

    Borges, A. V.; Abril, G.; Morana, C.; Bouillon, S.; Darchambeau, F.

    2012-04-01

    We report a data-set of methane (CH4) concentrations in the surface waters of Lake Kivu obtained during four cruises (March 2007, September 2007, June 2008, April 2009) covering the two main seasons, rainy (October to May) and dry (June to September). Spatial gradients of CH4 concentrations were modest in the surface waters of the main basin. In Kabuno Bay (a small sub-basin), CH4 concentrations in surface waters were significantly higher than in the main basin. Seasonal variations of CH4 in the main basin were strongly driven by deepening of the mixolimnion and mixing of surface waters with deeper waters rich in CH4. On an annual basis, both Kabuno Bay and the main basin of Lake Kivu were over-saturated in CH4 with respect to atmospheric equilibrium (7330% and 2510%, respectively), and emitted CH4 to the atmosphere (39 mmol m-2 yr-1 and 13 mmol m-2 yr-1, respectively). The source of CH4 to atmosphere was two orders of magnitude lower than the CH4 upward flux. The source of CH4 to the atmosphere from Lake Kivu corresponded to ~60% of the terrestrial sink of atmospheric CH4 over the lake's catchment. A global cross-system comparison of CH4 in surface waters of lakes shows that both Kabuno Bay and the main basin are at the lower end of values in lakes globally, despite the huge amounts of CH4 in the deeper layers of the lake. This is related to the strongly meromictic nature of the lake that promotes an intense removal of CH4 by bacterial oxidation.

  13. 3D Thermal Stratification of Koycegiz Lake, Turkey.

    NASA Astrophysics Data System (ADS)

    Gurcan, Tugba; Kurtulus, Bedri; Avsar, Ozgur; Avsar, Ulas

    2017-04-01

    Water temperature in lakes, streams and coastal areas is an important indicator for several purposes (water quality, aquatic organism, land use, etc..). There are over a hundred lakes in Turkey. Most of them locates in the area known as the Lake District in southwestern Turkey. The Study area is located at the south and southwest part of Turkey in Muǧla region. The present study focuses on determining possible thermocline changes in Lake Koyceǧiz by in-situ measurements. The measurement were done by two snapshot campaign at July and August 2013. Using Mugla Sıtkı Kocman University geological engineering floating platform, temperature, specific conductance, salinity and depth values were measured with the YSI 6600 and Horiba U2 devices in surface and depth of Lake Köyceǧiz at specific grid. When the depth of the water and the coordinates were measured by GPS. Scattered data interpolation is used to perform interpolation on a scattered dataset that resides in 3D space. The 3D temperature color mesh grid were generated by using Delaunay triangulation and Natural neighbor interpolation methodology. At the end of the study a 3D conceptual lake temperature dynamics model was reconstructed using MATLAB functions. The results show that Koycegiz Lake is a meromictic lake and has a significance decrease of Temperature at 7m of depth.In this regard, we would like also to thank TUBITAK project (112Y137), French Embassy in Turkey and Sıtkı Kocman Foundation for their financial support.

  14. Predictability of Permanent Stratification In Opencast Mining Lakes

    NASA Astrophysics Data System (ADS)

    Boehrer, B.

    Residual voids from exploited or abandoned opencasts are increasingly becoming a world-wide environmental and landscape disruption. As soon as groundwater pump- ing ceases, some of the pits fill naturally from groundwater sources, others are flooded for several reasons from external sources, e.g. from near-by rivers. Especially in east- ern Germany, a large number of opencast lignite mines were abandonend within only few years, after the political wende of 1989 changed energy policy fundamentally. 490 lakes in opencast mines can be listed for Germany, many of which lie in the densely populated area of Central Germany. In many cases, the future shorelines are in imme- diate proximity of residential areas. As a consequence, public pressure is high for the utilisation of those lakes. Many mining lakes tend to be meromictic. To prognosticate water quality and biolog- ical evoloution, knowledge about the permanent stratification is essential. Due to their specific chemistry and temporal evolution, mining lakes pose a number of unsolved questions concerning the density structure. A number of approaches to those problems are discussed. In this context, we refer to four mining complexes where an intensive investigation has taken place on the development of the stratification in the new lakes.

  15. Lake whitefish diet, condition, and energy density in Lake Champlain and the lower four Great Lakes following dreissenid invasions

    USGS Publications Warehouse

    Herbst, Seth J.; Marsden, J. Ellen; Lantry, Brian F.

    2013-01-01

    Lake Whitefish Coregonus clupeaformis support some of the most valuable commercial freshwater fisheries in North America. Recent growth and condition decreases in Lake Whitefish populations in the Great Lakes have been attributed to the invasion of the dreissenid mussels, zebra mussels Dreissena polymorpha and quagga mussels D. bugensis, and the subsequent collapse of the amphipod, Diporeia, a once-abundant high energy prey source. Since 1993, Lake Champlain has also experienced the invasion and proliferation of zebra mussels, but in contrast to the Great Lakes, Diporeia were not historically abundant. We compared the diet, condition, and energy density of Lake Whitefish from Lake Champlain after the dreissenid mussel invasion to values for those of Lake Whitefish from Lakes Michigan, Huron, Erie, and Ontario. Lake Whitefish were collected using gill nets and bottom trawls, and their diets were quantified seasonally. Condition was estimated using Fulton's condition factor (K) and by determining energy density. In contrast to Lake Whitefish from some of the Great Lakes, those from Lake Champlain Lake Whitefish did not show a dietary shift towards dreissenid mussels, but instead fed primarily on fish eggs in spring, Mysis diluviana in summer, and gastropods and sphaeriids in fall and winter. Along with these dietary differences, the condition and energy density of Lake Whitefish from Lake Champlain were high compared with those of Lake Whitefish from Lakes Michigan, Huron, and Ontario after the dreissenid invasion, and were similar to Lake Whitefish from Lake Erie; fish from Lakes Michigan, Huron, and Ontario consumed dreissenids, whereas fish from Lake Erie did not. Our comparisons of Lake Whitefish populations in Lake Champlain to those in the Great Lakes indicate that diet and condition of Lake Champlain Lake Whitefish were not negatively affected by the dreissenid mussel invasion.

  16. The Mack Lake fire.

    Treesearch

    Albert J. Simard; Donald A. Haines; Richard W. Blank; John S. Frost

    1983-01-01

    Describes the Mack Lake Fire near Mio, Michigan. Few documented wildfires have exceeded its average spread rate (2 mi/h) and energy release rate (8,800 Btu/ft/sec). The extreme behavior resulted from high winds, low humidity, low fuel moisture and jack pine fuels. Horizontal roll vortices may have contributed to the death of one firefighter.

  17. The People's Lake

    ERIC Educational Resources Information Center

    Carlson, Karen Townsend

    1975-01-01

    Citizen action to stop the disposal of taconite tailings into Lake Superior was unsuccessful when the courts settled in the favor of industry. Although citizen research revealed a form of asbestos, as well as other toxic chemicals in the discharged wastes, company representatives stated that there were no health hazards. (MA)

  18. Great Minds? Great Lakes!

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Chicago, IL. Great Lakes National Program Office.

    This booklet introduces an environmental curriculum for use in a variety of elementary subjects. The lesson plans provide an integrated approach to incorporating Great Lakes environmental issues into the subjects of history, social studies, and environmental sciences. Each of these sections contains background information, discussion points, and a…

  19. Finger Lakes LPG

    EPA Pesticide Factsheets

    Finger Lakes LPG Storage, LLC; Two Brush Creek Blvd, Suite 200; Kansas City; Missouri 64112 (Applicant) has applied to the U.S. Environmental Protection Agency (EPA) under the provisions of the Safe Drinking Water Act, 42 U.S.C. 300f et. seq (the Act), for

  20. Lake Ontario: Nearshore Variability

    EPA Science Inventory

    We conducted a high-resolution survey with towed electronic instrumentation along the Lake Ontario nearshore (720 km) at a 20 meter contour. The survey was conducted September 6-10, 2008 with a shorter 300 km survey conducted August 14-15 for comparing of temporal variability. ...

  1. Lake Michigan: Nearshore Variability

    EPA Science Inventory

    We conducted a high-resolution survey in the nearshore of Lake Michigan at a 20 meter contour using towed electronic instrumentation. The nearly 1200 km survey was conducted Sep 8-15, 2010. We also conducted six cross-contour tows. Along the survey tracks we sampled fixed stat...

  2. Lake Naivasha, Kenya

    NASA Image and Video Library

    2008-02-29

    If you live in Europe and buy roses, the chance is good that they were grown in Kenya -- specifically, in one of the colossal greenhouses that blot out the once wild shores of Lake Naivasha, 90km north-west of Nairobi. Image from NASA Terra satellite.

  3. Utah: Salt Lake City

    Atmospheric Science Data Center

    2014-05-15

    ... mountains surrounding Salt Lake City are renowned for the dry, powdery snow that results from the arid climate and location at the ... should be used with the red filter placed over your left eye. The canyons and peaks of the Uinta and Wasatch Mountains are ...

  4. Quebec: Lake Manicouagan

    Atmospheric Science Data Center

    2013-04-17

    ... kilometers in diameter and is composed of impact-brecciated rock. Glaciation and other erosional processes have reduced the extent of the ... about 5 kilometers. The lake is bounded by erosion-resistant metamorphic and igneous rocks, and shock metamorphic effects are abundant in ...

  5. Lake classification in Vermont

    NASA Technical Reports Server (NTRS)

    Garrison, V.; Bryant, N.

    1981-01-01

    In order to comply with the Federal Clean Water Act and, in so doing, develop a procedure to periodically update the classification, the State of Vermont evaluated the ability of LANDSAT to detect general water quality and specific water quality parameters in Vermont lakes. Unsupervised and supervised classifications as well as regression analyses were used to examine LANDSAT data from Lake Champlain and from four small nearby lakes. Unsupervised and supervised classifications were found to be of somewhat limited value. Regression analyses revealed a good correlation between depth-integrated total phosphorus concentrations and LANDSAT band 4 data (r2= 0.92) and between Secchi disk transparencies and LANDSAT band 4 data (r2 - 0.85). No correlation was found between depth-integrated chlorophyll-a samples and LANDSAT data. Vermont is expanding this LANDSAT evaluation to include the remaining lakes in the state greater than twenty acres and steps are being taken to incorporate LANDSAT into the state's ongoing water quality monitoring programs.

  6. The Great Lakes

    NASA Image and Video Library

    2017-09-27

    NASA image captured March 28, 2011 The Great Lakes Satellite: Terra NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook

  7. The People's Lake

    ERIC Educational Resources Information Center

    Carlson, Karen Townsend

    1975-01-01

    Citizen action to stop the disposal of taconite tailings into Lake Superior was unsuccessful when the courts settled in the favor of industry. Although citizen research revealed a form of asbestos, as well as other toxic chemicals in the discharged wastes, company representatives stated that there were no health hazards. (MA)

  8. Mono Lake, California

    NASA Image and Video Library

    1994-10-01

    STS068-150-020 (30 September-11 October 1994) --- An exceptionally clear, high-contrast view of the desert basins east and south of Mono Lake, California. Light clouds dot the mountain ranges; the clouds were transparent to radar beams from the Space Radar Laboratory 2 (SRL-2) payload.

  9. Poet Lake Crystal Approval

    EPA Pesticide Factsheets

    This September 19, 2016 letter from EPA approves the petition from Poet Biorefining-Lake Crystal, regarding non-grandfathered ethanol produced through a dry mill process, qualifying under the Clean Air Act for renewable fuel (D-code 6) RINs under the RFS

  10. Autotrophic processes in meromictic Big Soda Lake, Nevada.

    USGS Publications Warehouse

    Cloern, J.E.; Cole, B.E.; Oremland, R.S.

    1983-01-01

    Daily rates of oxygenic photosynthesis (OP) by phytoplankton, anoxygenic photosynthesis (AP) by purple sulfur bacteria, and chemoautotrophic productivity (CP = dark CO2 assimilation) were measured once each season. Total daily productivity and the relative importance of each autotrophic process varied with seasonal changes in vertical mixing, light availability, and the biomass of phototrophs. Daily productivity was highest (2830 mg C.m-2) and was dominated by OP in winter when the mixolimnion was isothermal, the biomass of phytoplankton was high, and the biomass of purple sulfur bacteria was low. During the summer-fall period of thermal stratification, phytoplankton biomass decreased, a plate of purple sulfur bacteria formed below the oxycline, and daily rates of dark CO2 assimilation (CP = 390-680 mg C.m-2) exceeded phototrophic productivity (OP + AP = 200-370 mg C.m-2). Total annual productivity was approx 500 g C.m-2, of which 60% was produced by phytoplankton (mostly in winter), 30% by chemoautotrophs (nitrifying and sulfur-oxidizing bacteria), and only 10% by photosynthetic bacteria. -Authors

  11. Temperate Lakes Discovered on Titan

    NASA Astrophysics Data System (ADS)

    Vixie, Graham; Barnes, Jason W.; Jackson, Brian; Wilson, Paul

    2012-04-01

    We have discovered two temperate lakes on Titan using Cassini's Visual and Infrared Mapping Spectrometer (VIMS). Three key features help to identify these surface features as lakes: morphology, albedo, and specular reflection. The presence of lakes at the mid-latitudes mean liquid can accumulate and remain stable outside of the poles. We first identify a lake surface by looking for possible shorelines with a lacustrine morphology. Then, we apply a simple atmospheric correction that produces an approximate surface albedo. Next, we prepare cylindrical projection maps of the brightness of the sky as seen from any points on the surface to identify specular reflections. Our techniques can then be applied to other areas, such as Arrakis Planitia, to test for liquid. Currently, all the known lakes on Titan are concentrated at the poles. Lakes have been suggested in the tropic zone by Griffith et al. Our discovery of non-transient, temperate lakes has important implications for Titan's hydrologic cycle. Clouds have been recorded accumulating in the mid-latitudes and areas have been darkened by rainfall but later brightened after evaporation (Turtle et al. 2011). Stable temperate lakes would affect total rainfall, liquid accumulation, evaporation rates, and infiltration. Polaznik Macula (Figure 1) is a great candidate for lake filling, evaporation rates, and stability. References: Griffith, C., et al.: "Evidence for Lakes on Titan's Tropical Surface". AAS/Division for Planetary Sciences Meeting Abstracts #42, Vol. 42, pp. 1077, 2010. Turtle, E. P., et al.: "Rapid and Extensive Surface Changes Near Titan's Equator: Evidence of April Showers". Science, Vol. 331, pp. 1414-, 2011. Figure 1: Polaznik Macula is the large, dark area central to the figure. The encircled dark blue areas represent positively identified lake regions in the T66 flyby. The light blue areas represent lake candidates still under analysis. The green circle marks a non-lake surface feature enclosed by a

  12. The sources and evolution of sulfur in the hypersaline Lake Lisan (paleo-Dead Sea)

    NASA Astrophysics Data System (ADS)

    Torfstein, Adi; Gavrieli, Ittai; Stein, Mordechai

    2005-07-01

    δ34S values in gypsum are used to evaluate the fate of sulfur in the hypersaline Lake Lisan, the late Pleistocene precursor of the Dead Sea (70-14 ka BP), and applied as a paleo-limnological tracer. The Ca-chloride Lake Lisan evolved through meromictic periods characterized by precipitation of authigenic aragonite and holomictic episodes characterized by enhanced gypsum precipitation. The lake deposited two major gypsum units: the "Lower Gypsum unit" (deposited at ˜56 ka) showing δ34S values of 18-20‰, and the "Upper Gypsum unit" (deposited at 17 ka) displaying significantly higher δ34S values of 26-28‰. Laminated and disseminated gypsum, residing within the aragonite, exhibit δ34S values in the range of - 26‰ to 1‰. The isotopic composition of the gypsum was dictated by freshwater sulfate input that replenished the upper layer of the lake (the mixolimnion), bacterial sulfate reduction (BSR) that occurred under the anoxic conditions of the lower brine (the monimolimnion), and mixing between these two layers. During meromictic periods, the sulfate reservoir in the lower brine was replenished by precipitation of gypsum from the upper layer, and its subsequent dissolution due to sulfate deficiency induced by BSR activity. This process describes a "sulfur pump" mechanism and its effect on δ34S in the water can be modeled by a modified Rayleigh distillation equation. Steady state δ34S values (˜40‰) were reached in the lower brine after long meromictic periods. Following overturn episodes, induced by diminishing freshwater input and lake level decline, large quantities of δ34S enriched gypsum precipitated. The negative δ34S values in laminated and disseminated gypsum provide evidence for BSR activity in the lower brine that removed isotopically depleted sulfides from the water column, causing significant isotopic enrichment of remaining sulfate. Following the lake desiccation, the sediments were exposed and the latter sulfides oxidized and re

  13. Microbiology of Lonar Lake and other soda lakes.

    PubMed

    Antony, Chakkiath Paul; Kumaresan, Deepak; Hunger, Sindy; Drake, Harold L; Murrell, J Colin; Shouche, Yogesh S

    2013-03-01

    Soda lakes are saline and alkaline ecosystems that are believed to have existed throughout the geological record of Earth. They are widely distributed across the globe, but are highly abundant in terrestrial biomes such as deserts and steppes and in geologically interesting regions such as the East African Rift valley. The unusual geochemistry of these lakes supports the growth of an impressive array of microorganisms that are of ecological and economic importance. Haloalkaliphilic Bacteria and Archaea belonging to all major trophic groups have been described from many soda lakes, including lakes with exceptionally high levels of heavy metals. Lonar Lake is a soda lake that is centered at an unusual meteorite impact structure in the Deccan basalts in India and its key physicochemical and microbiological characteristics are highlighted in this article. The occurrence of diverse functional groups of microbes, such as methanogens, methanotrophs, phototrophs, denitrifiers, sulfur oxidizers, sulfate reducers and syntrophs in soda lakes, suggests that these habitats harbor complex microbial food webs that (a) interconnect various biological cycles via redox coupling and (b) impact on the production and consumption of greenhouse gases. Soda lake microorganisms harbor several biotechnologically relevant enzymes and biomolecules (for example, cellulases, amylases, ectoine) and there is the need to augment bioprospecting efforts in soda lake environments with new integrated approaches. Importantly, some saline and alkaline lake ecosystems around the world need to be protected from anthropogenic pressures that threaten their long-term existence.

  14. Microbiology of Lonar Lake and other soda lakes

    PubMed Central

    Paul Antony, Chakkiath; Kumaresan, Deepak; Hunger, Sindy; Drake, Harold L; Murrell, J Colin; Shouche, Yogesh S

    2013-01-01

    Soda lakes are saline and alkaline ecosystems that are believed to have existed throughout the geological record of Earth. They are widely distributed across the globe, but are highly abundant in terrestrial biomes such as deserts and steppes and in geologically interesting regions such as the East African Rift valley. The unusual geochemistry of these lakes supports the growth of an impressive array of microorganisms that are of ecological and economic importance. Haloalkaliphilic Bacteria and Archaea belonging to all major trophic groups have been described from many soda lakes, including lakes with exceptionally high levels of heavy metals. Lonar Lake is a soda lake that is centered at an unusual meteorite impact structure in the Deccan basalts in India and its key physicochemical and microbiological characteristics are highlighted in this article. The occurrence of diverse functional groups of microbes, such as methanogens, methanotrophs, phototrophs, denitrifiers, sulfur oxidizers, sulfate reducers and syntrophs in soda lakes, suggests that these habitats harbor complex microbial food webs that (a) interconnect various biological cycles via redox coupling and (b) impact on the production and consumption of greenhouse gases. Soda lake microorganisms harbor several biotechnologically relevant enzymes and biomolecules (for example, cellulases, amylases, ectoine) and there is the need to augment bioprospecting efforts in soda lake environments with new integrated approaches. Importantly, some saline and alkaline lake ecosystems around the world need to be protected from anthropogenic pressures that threaten their long-term existence. PMID:23178675

  15. Movements of hatchery-reared lake trout in Lake Superior

    USGS Publications Warehouse

    Pycha, Richard L.; Dryer, William R.; King, George R.

    1965-01-01

    The history of stocking of lake trout (Salvelinus namaycush) in the Great Lakes is reviewed. The study of movements is based on capture of 24,275 fin-clipped lake trout taken in experimental gill nets and trawls and commercial gill nets. Yearling lake trout planted from shore dispersed to 15-fath (27-m) depths in 3A? hr. Most fish remained within 2 miles (3.2 km) of the planting site 2 months, but within 4 months some fish had moved as much as 17 miles (27 km). The highest abundance of planted lake trout was in areas 2-4 miles (3.2-6.4 km) from the planting site even 3 years after release. Distance moved and size of fish were not correlated. Dispersal of lake trout begins at planting and probably continues until the fish are mature. Most movement was eastward in southern Lake Superior and followed the counterclockwise surface currents. Movement is most rapid in areas of strong currents and slowest in areas of weak currents or eddies. Movement to areas west of the Keweenaw Peninsula was insignificant from plantings in Keweenaw Bay and nil from other plantings farther east. Lake trout planted in the eastern third of the lake dispersed more randomly than those planted farther west. Few fish moved farther offshore than the 50-fath (91-m) contour. Lake trout planted in Canadian waters made insignificant contributions to populations in US waters.

  16. Lake trout rehabilitation in Lake Erie: a case history

    USGS Publications Warehouse

    Cornelius, Floyd C.; Muth, Kenneth M.; Kenyon, Roger

    1995-01-01

    Native lake trout (Salvelinus namaycush) once thrived in the deep waters of eastern Lake Erie. The impact of nearly 70 years of unregulated exploitation and over 100 years of progressively severe cultural eutrophication resulted in the elimination of lake trout stocks by 1950. Early attempts to restore lake trout by stocking were unsuccessful in establishing a self-sustaining population. In the early 1980s, New York's Department of Environmental Conservation, Pennsylvania's Fish and Boat Commission, and the U.S. Fish and Wildlife Service entered into a cooperative program to rehabilitate lake trout in the eastern basin of Lake Erie. After 11 years of stocking selected strains of lake trout in U.S. waters, followed by effective sea lamprey control, lake trout appear to be successfully recolonizing their native habitat. Adult stocks have built up significantly and are expanding their range in the lake. Preliminary investigations suggest that lake trout reproductive habitat is still adequate for natural reproduction, but natural recruitment has not been documented. Future assessments will be directed toward evaluation of spawning success and tracking age-class cohorts as they move through the fishery.

  17. Change in the circulation regime in the stratified saline Lake Shira (Siberia, Republic of Khakassia)

    NASA Astrophysics Data System (ADS)

    Belolipetskii, V. M.; Degermendzhi, A. G.; Genova, S. N.; Rogozin, D. Y.

    2017-06-01

    The in-situ data on the vertical structure and stability of the vertical stratification of saline Lake Shira over the past decade (2007-2015) are analyzed. Simplified mathematical models have shown that strong wind in the autumn of 2014 together with rather thick ice in the winter of 2015 caused a change in the circulation regime of this water reservoir from meromictic (incomplete mixing) to holomictic (compete mixing). Based on the results obtained, a circulation regime for deep saline lakes located in the continental climate zone, in particular, in the arid zones of Southern Siberia (Khakassia, Transbaikal, and Altai) can be predicted under various climate scenarios of the future.

  18. Evolution of alkaline lakes - Lake Van case study

    NASA Astrophysics Data System (ADS)

    Tillman Meyer, Felix; Viehberg, Finn; Bahroun, Sonya; Wolf, Annabel; Immenhauser, Adrian; Kwiecien, Ola

    2017-04-01

    Lake Van in Eastern Anatolia (Turkey) is the largest terminal soda lake on Earth. The lake sedimentary profile covers ca. 600 ka (Stockhecke et al. 2014) Based on lithological changes, the presence of freshwater microfossils and close-to-freshwater pH value in the pore water, members of ICDP PALEOVAN concluded that Lake Van might have started as an open lake. Here we show paleontological and geochemical evidence in favour of this idea and constrain the time, when Lake Van likely transformed into a closed lake. Additionally we provide the first conceptual model of how this closure may have happened. Our archives of choice are inorganic and biogenic carbonates, separated by wet sieving. We identified microfossil assemblages (fraction > 125 µm) and performed high-resolution oxygen isotope (delta18O) and elemental (Mg/Ca, Sr/Ca) analyses of the fraction < 63 µm assuming that it represents only carbonates precipitating in the water column. Microfossil assemblage consists of three different species of ostracods (Candona spp, Loxoconcha sp, Amnicythere spp.), diatoms, gastropods and bivalves. Brakish-water ostracods, Loxoconcha sp and Amnicythere sp occur more often after 530 ka. Additionaly, Loxoconcha sp is a shallow-water species relaying on plants growing in the photic zone as food supply. These two aspects point to an increasing salinity in a shallowing lake. The delta18O values of inorganic carbonates are relatively low during the initial phase of Lake Van and increase abruptly (ca. 7‰) after 530 ka BP. At approximately the same time combination of Sr/Ca and Mg/Ca data suggest first occurrence of aragonite. Again, these findings suggest geochemical changes of the lake water concurrent with transition documented by microfossils. Comparison between Lake Van and Lake Ohrid (Lacey et al. 2016) delta18O data, precludes regional climate change (e.g.: increased evaporation) as the main driver of observed changes. With no evidence for increased volcanic or tectonic

  19. Anaerobic halo- alkaliphilic bacterial community of athalassic, hypersaline Mono lake and Owens Lake in California

    NASA Astrophysics Data System (ADS)

    Pikuta, Elena V.; Detkova, Ekaterina N.; Bej, Asim K.; Marsic, Damien; Hoover, Richard B.

    2003-02-01

    The bacterial diversity of microbial extremophiles from the meromictic, hypersaline Mono Lake and a small evaporite pool in Owens Lake of California was studied. In spite of these regions had differing mineral background and different concentrations of NaCl in water they contain the same halo- alkaliphiles anaerobic bacterial community. Three new species of bacteria were detected in this community: primary anaerobe, dissipotrophic saccharolytic spirochete Spirochaeta americana strain AspG1T, primary anaerobe which is proteolytic Tindallia californiensis strain APOT, and secondary anaerobe, hydrogen using Desulfonatronum thiodismutans strain MLF1T, which is sulfate- reducer with chemo-litho-autotrophic metabolism. All of these bacteria are obligate alkaliphiles and dependent upon Na+ ions and CO32- ions in growth mediums. It is interesting that closest relationships for two of these species were isolates from samples of equatorial African soda Magadi lake: Spirochaeta americana AspG1T has 99.4% similarity on 16S rDNA- analyses with Spirochaeta alkalica Z- 7491T, and Tindallia californiensis APOT has 99.1% similarity with Tindallia magadiensis Z-7934T. But result of DNA-DNA- hybridization demonstrated less then 50% similarity between Spirochaeta americana AspG1T and Spirochaeta alkalica Z-7491T. Percent of homology between Tindallia californiensis APOT and Tindallia magadiensis Z-7934T is only 55%. The sulfate-reducer from the alkalic anaerobic community of Magadi lake Desulfonatronovibrio hydrogenovorans Z-7935T was phylogenetically distant from this sulfate-reducer in Mono lake, but genetically closer (99.7% similarity) to the sulfate-reducer, isolated from Central Asian alkalic lake Khadyn in Siberia Desulfonatronum lacustre Z-7951T. The study of key enzymes (hydrogenase and CO- hydrogenase) in Tindallia californiensis APOT and Desulfonatronum thiodismutans MLF1T showed the presence of high activity of both the enzymes in first and only hydrogenase in second

  20. Potential strategies for recovery of lake whitefish and lake herring stocks in eastern Lake Erie

    USGS Publications Warehouse

    Oldenburg, K.; Stapanian, M.A.; Ryan, P.A.; Holm, E.

    2007-01-01

    Lake Erie sustained large populations of ciscoes (Salmonidae: Coregoninae) 120 years ago. By the end of the 19th century, abundance of lake whitefish (Coregonus clupeaformis) had declined drastically. By 1925, the lake herring (a cisco) population (Coregonus artedii) had collapsed, although a limited lake herring fishery persisted in the eastern basin until the 1950s. In the latter part of the 20th century, the composition of the fish community changed as oligotrophication proceeded. Since 1984, a limited recovery of lake whitefish has occurred, however no recovery was evident for lake herring. Current ecological conditions in Lake Erie probably will not inhibit recovery of the coregonine species. Recovery of walleye (Sander vitreus) and efforts to rehabilitate the native lake trout (Salvelinus namaycush) in Lake Erie will probably assist recovery because these piscivores reduce populations of alewife (Alosa psuedoharengus) and rainbow smelt (Osmerus mordax), which inhibit reproductive success of coregonines. Although there are considerable spawning substrates available to coregonine species in eastern Lake Erie, eggs and fry would probably be displaced by storm surge from most shoals. Site selection for stocking or seeding of eggs should consider the reproductive life cycle of the stocked fish and suitable protection from storm events. Two potential sites in the eastern basin have been identified. Recommended management procedures, including commercial fisheries, are suggested to assist in recovery. Stocking in the eastern basin of Lake Erie is recommended for both species, as conditions are adequate and the native spawning population in the eastern basin is low. For lake herring, consideration should be given to match ecophenotypes as much as possible. Egg seeding is recommended. Egg seeding of lake whitefish should be considered initially, with fingerling or yearling stocking suggested if unsuccessful. Spawning stocks of whitefish in the western basin of Lake

  1. Predicting Maximum Lake Depth from Surrounding Topography

    EPA Science Inventory

    Lake volume aids understanding of the physical and ecological dynamics of lakes, yet is often not readily available. The data needed to calculate lake volume (i.e. bathymetry) are usually only collected on a lake by lake basis and are difficult to obtain across broad regions. ...

  2. Predicting Maximum Lake Depth from Surrounding Topography

    EPA Science Inventory

    Lake volume aids understanding of the physical and ecological dynamics of lakes, yet is often not readily available. The data needed to calculate lake volume (i.e. bathymetry) are usually only collected on a lake by lake basis and are difficult to obtain across broad regions. ...

  3. Lake Erie...Take a Bow.

    ERIC Educational Resources Information Center

    Canning, Maureen; Dunlevy, Margie

    This elementary school teaching unit was developed as a part of a series of teaching units that deal with Lake Erie. This unit was developed to enable children to: (1) identify the Great Lakes and pick out Lake Erie on a map; (2) demonstrate knowledge of Lake Erie's origin and geography; (3) list some uses of Lake Erie; and (4) give examples of…

  4. Lake Mead--clear and vital

    USGS Publications Warehouse

    Wessells, Stephen M.; Rosen, Michael

    2013-01-01

    Lake Mead – Clear and Vital” is a 13 minute documentary relating the crucial role of science in maintaining high water quality in Lake Mead. The program was produced coincident with release of the Lakes Mead and Mohave Circular a USGS publication covering past and on-going research in the lakes and tributaries of the Lake Mead National Recreation Area.

  5. Lake Garda, Italy

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This ASTER image was acquired on July 29, 2000 and covers an area of 30 by 57 km in northern Italy. Lake Garda was formed by glaciers during the last Ice Age, and is Italy's largest lake. Lago di Garda lies in the provinces of Verona, Brescia, and Trento, and is 51 kilometers (32 miles) long and from 3 to 18 kilometers (2 to 11 miles) wide. The Sarca is its chief affluent, and the lake is drained southward by the Mincio, which discharges into the Po River. Many villas are situated on its shores. On the peninsula of Sirmione, at the southern end of the lake, are the ruins of a Roman villa and a castle of the Scaligers, an Italian family of the 16th century. The RIGHT image has the land area masked out, and a harsh stretch was applied to the lake values to display variations in sediment load. Also visible are hundreds of boats and their wakes, criss-crossing the lake.

    The image is centered at 45.6 degrees north latitude, 10.6 degrees east longitude.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for

  6. Sediment Transforms Lake Michigan

    NASA Image and Video Library

    2017-09-27

    NASA image acquired December 17, 2010 In mid-December 2010, suspended sediments transformed the southern end of Lake Michigan. Ranging in color from brown to green, the sediment filled the surface waters along the southern coastline and formed a long, curving tendril extending toward the middle of the lake. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured these natural-color images on December 17, 2010 (top), and December 10, 2010 (bottom). Such sediment clouds are not uncommon in Lake Michigan, where winds influence lake circulation patterns. A scientificpaper published in 2007 described a model of the circulation, noting that while the suspended particles mostly arise from lake-bottom sediments along the western shoreline, they tend to accumulate on the eastern side. When northerly winds blow, two circulation gyres, rotating in opposite directions, transport sediment along the southern shoreline. As the northerly winds die down, the counterclockwise gyre predominates, and the smaller, clockwise gyre dissipates. Clear water—an apparent remnant of the small clockwise gyre—continues to interrupt the sediment plume. George Leshkevich, a researcher with the U.S. National Oceanic and Atmospheric Administration, explains that the wind-driven gyres erode lacustrine clay (very fine lakebed sediment) on the western shore before transporting it, along with re-suspended lake sediments, to the eastern shore. On the eastern side, the gyre encounters a shoreline bulge that pushes it toward the lake’s central southern basin, where it deposits the sediments. The sediment plume on December 17 followed a windy weather front in the region on December 16. NASA image courtesy MODIS Rapid Response Team at NASA GSFC. Caption by Michon Scott. Instrument: Aqua - MODIS NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard

  7. Lake Garda, Italy

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This ASTER image was acquired on July 29, 2000 and covers an area of 30 by 57 km in northern Italy. Lake Garda was formed by glaciers during the last Ice Age, and is Italy's largest lake. Lago di Garda lies in the provinces of Verona, Brescia, and Trento, and is 51 kilometers (32 miles) long and from 3 to 18 kilometers (2 to 11 miles) wide. The Sarca is its chief affluent, and the lake is drained southward by the Mincio, which discharges into the Po River. Many villas are situated on its shores. On the peninsula of Sirmione, at the southern end of the lake, are the ruins of a Roman villa and a castle of the Scaligers, an Italian family of the 16th century. The RIGHT image has the land area masked out, and a harsh stretch was applied to the lake values to display variations in sediment load. Also visible are hundreds of boats and their wakes, criss-crossing the lake.

    The image is centered at 45.6 degrees north latitude, 10.6 degrees east longitude.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for

  8. Long Term Deep Mixing Changes in Lakes to Climate Change. The Question of When and How?

    NASA Astrophysics Data System (ADS)

    Sahoo, G. B.; Schladow, S. G.; Reuter, J.

    2009-12-01

    Lake Tahoe (California-Nevada), an ice free warm-monomictic lake, has been warmed up over the last 35 years due to climate change. Lake Tahoe strongly stratifies during summer and its water body mixes well during winter. The last 35 years records indicate that complete lake turn over takes place once or twice in 3 to 4 years. If the lake warming trend continues, its deep mixing might be stopped at some point in the future. Since deep mixing supplies dissolved oxygen from surface to bottom, reduced mixing may result in evolution of anoxic condition near the sediment-water interface. The Intergovernmental Panel on Climate Change report (IPCC 2007) indicates continued warming over the next few decades. It is therefore important to assess mixing dynamics of the lake using predictions of the global circulation models (GCMs). The dynamic lake model (DLM), developed by University of California Davis researcher was used to estimate the mixing dynamics of the lake. The GCM-predicted trends in meteorological variables for the grid cell that includes Lake Tahoe were obtained from GCMs: (1) Model for Interdisciplinary Research on Climate V. 3.2 High Resolution (MIROC-HIRES) Japan, (2) National Center for Atmospheric Research, Community Climate Model (NCAR CCM V. 3.0), and (3) National Oceanic and Atmospheric Administration (NOAA) - Geophysical Fluid Dynamics Laboratory V CM2.1 (NOAA GFDL CM2.1). Sensitivity analysis results demonstrates that a change in longwave radiations has pronounced effect on lake warming. Results of 40-year simulations show that the lake continues to become warmer at the rate of approximately 0.013 oC per year and more stable. With continued climate change, deep mixing (full or greater than 300m) will cease after one-two decades. This indicates that Lake Tahoe is likely to transition to meromictic lake because of reduced mixing and increasing stability. This may result in major water quality problems and ecological changes over time.

  9. Genetic diversity of Diporeia in the Great Lakes: comparison of Lake Superior to the other Great Lakes

    EPA Science Inventory

    Abundances of Diporeia have dropped drastically in the Great Lakes, except in Lake Superior, where data suggest that population counts actually have risen. Various ecological, environmental, or geographic hypotheses have been proposed to explain the greater abundance of Lake Supe...

  10. Genetic diversity of Diporeia in the Great Lakes: comparison of Lake Superior to the other Great Lakes

    EPA Science Inventory

    Abundances of Diporeia have dropped drastically in the Great Lakes, except in Lake Superior, where data suggest that population counts actually have risen. Various ecological, environmental, or geographic hypotheses have been proposed to explain the greater abundance of Lake Supe...

  11. Evidence of spring spawning lake trout in Lake Superior

    USGS Publications Warehouse

    Bronte, Charles R.

    1993-01-01

    In 1992, the U. S. Fish and Wildlife Service began research on the life history, population dynamics, and stock delineation of siscowet lake trout Salvelinus namaycush siscowet in Lake Superior. Siscowet were captured with gill nets in 80-150 m of water on 23-26 April 1992 north of the Apostle Islands in western Lake Superior. Of 91 captured siscowets, one male had fully developed testes in nearly ripe condition and one female had eggs running from the vent. This observation represents the earliest dates that lake trout of any morphotype have been found in spawning or near-spawning condition.

  12. Human Impact on Biogeochemical Cycles and Deposition Dynamics in Karstic Lakes: El Tobar Lake Record (Central Iberian Range, Spain)

    NASA Astrophysics Data System (ADS)

    Barreiro-Lostres, F.; Moreno-Caballud, A.; Giralt, S.; Hillman, A. L.; Brown, E. T.; Abbott, M. B.; Valero-Garces, B. L.

    2014-12-01

    Karstic lakes in the Iberian Range (Central Spain) provide a unique opportunity to test the human impact in the watersheds and the aquatic environments during historical times. We reconstruct the depositional evolution and the changes in biogeochemical cycles of El Tobar karstic lake, evaluating the response and the resilience of this Mediterranean ecosystem to both anthropogenic impacts and climate forcing during the last 1000 years. Lake El Tobar (40°32'N, 3°56'W; 1200 m a.s.l.; see Figure), 16 ha surface area, 20 m max. depth and permanent meromictic conditions, has a relatively large watershed (1080 ha). Five 8 m long sediment cores and short gravity cores where recovered, imaged, logged with a Geotek, described and sampled for geochemical analyses (elemental TOC, TIC, TN, TS), XRF scanner and ICP-MS, and dated (137Cs and 10 14C assays). The record is a combination of: i) laminated dark silts with terrestrial remains and diatoms and ii) massive to banded light silts (mm to cm -thick layers) interpreted as flood deposits. Sediments, TOC, and Br/Ti and Sr/Ca ratios identify four periods of increased sediment delivery occurred about 1500, 1800, 1850 and 1900 AD, coinciding with large land uses changes of regional relevance such as land clearing and increased population. Two main hydrological changes are clearly recorded in El Tobar sequence. The first one, marked by a sharp decrease in Mg, Ca and Si concentrations, took place about 1200 AD, and during a period of increasing lake level, which shifted from shallower to deeper facies and from carbonatic to clastic and organic-rich deposition. This change was likely related to increased water availability synchronous to the transition from the Medieval Climate Anomaly to the Little Ice Age. The second one was a canal construction in 1967 AD when a nearby reservoir provided fresh water influx to the lake, and resulted in stronger meromictic conditions in the system after canal construction, which is marked by lower

  13. Salt Lake City, Utah

    NASA Image and Video Library

    2002-02-07

    The 2002 Winter Olympics are hosted by Salt Lake City at several venues within the city, in nearby cities, and within the adjacent Wasatch Mountains. This simulated natural color image presents a late spring view of north central Utah that includes all of the Olympic sites. The image extends from Ogden in the north, to Provo in the south; and includes the snow-capped Wasatch Mountains and the eastern part of the Great Salt Lake. This image was acquired on May 28, 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet. http://photojournal.jpl.nasa.gov/catalog/PIA03464

  14. Dongting Lake, China

    NASA Image and Video Library

    2002-09-15

    These images show dramatic change in the water at Dongting Lake in Hunan province, China. A flood crest surged down the Yangtze River in late August of this year, but the embankments made by residents there held. The left image was acquired on September 2, 2002 and shows the extent of the lake. The right image was obtained March 19, 2002 before the flooding began. These images were acquired on September 2, 2002 and March 19, 2002 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet. http://photojournal.jpl.nasa.gov/catalog/PIA03858

  15. Lake Mead and Drought

    NASA Image and Video Library

    2015-07-20

    Lake Mead supplies water for Arizona, California, Mexico, and other western states. On June 23, the water level fell to 1075 feet, a record low. In 2000, for comparison, the water level was at 1214 feet. A 15-year drought and increased demands for water are to blame for the critical status of the water supply. The difference in 15 years is seen in this pair of images of the western part of Lake Mead, acquired June 21, 2000 by Landsat 7, and June 21, 2015 by ASTER. The images cover an area of 22.5 x 28.5 km, and are located at 36.1 degrees north, 114.7 degrees west. http://photojournal.jpl.nasa.gov/catalog/PIA19731

  16. Hydrology of Lake County, Florida

    USGS Publications Warehouse

    Knochenmus, Darwin D.; Hughes, G.H.

    1976-01-01

    Lake County includes a 1,150 square-mile area consisting of ridges, uplands, and valleys in central-peninsular Florida. About 32 percent of the county is covered by lakes, swamps, and marshes. Water requirements in 1970 averaged about 54 million gallons per day. About 85 percent of the water was obtained from wells; about 15 percent from lakes. The Floridan aquifer supplies almost all the ground water used in Lake County. Annual recharge to the Floridan aquifer averages about 7 inches over the county; runoff average 8.5 inches. The quality of ground and surface water in Lake County is in general good enough for most uses; however, the poor quality of Floridan-aquifer water in the St. John River Valley probably results from the upward movement of saline water along a fault zone. Surface water in Lake County is usually less mineralized than ground water but is more turbid and colored. (Woodard-USGS)

  17. Great Lakes Demonstration 2

    DTIC Science & Technology

    2012-06-01

    Representatives from CG Districts 1, 5 , 13, and 17  Enbridge Pipeline, Co.  EPA  National Oceanic and Atmospheric Administration (NOAA)  Observers (CG...distances from the vessel‟s hull. (Figure 5 ) In that configuration, the recovery hose and hydraulic lines dragged across the surface of the nearby...No. CG-D-08-12 2. Government Accession Number 3. Recipient’s Catalog No. 4. Title and Subtitle Great Lakes Demonstration 2 Final Report 5

  18. Angora Fire, Lake Tahoe

    NASA Technical Reports Server (NTRS)

    2007-01-01

    On the weekend of June 23, 2007, a wildfire broke out south of Lake Tahoe, which stretches across the California-Nevada border. By June 28, the Angora Fire had burned more than 200 homes and forced some 2,000 residents to evacuate, according to The Seattle Times and the Central Valley Business Times. On June 27, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the burn scar left by the Angora fire. The burn scar is dark gray, or charcoal. Water bodies, including the southern tip of Lake Tahoe and Fallen Leaf Lake, are pale silvery blue, the silver color a result of sunlight reflecting off the surface of the water. Vegetation ranges in color from dark to bright green. Streets are light gray, and the customary pattern of meandering residential streets and cul-de-sacs appears throughout the image, including the area that burned. The burn scar shows where the fire obliterated some of the residential areas just east of Fallen Leaf Lake. According to news reports, the U.S. Forest Service had expressed optimism about containing the fire within a week of the outbreak, but a few days after the fire started, it jumped a defense, forcing the evacuation of hundreds more residents. Strong winds that had been forecast for June 27, however, did not materialize, allowing firefighters to regain ground in controlling the blaze. On June 27, authorities hoped that the fire would be completely contained by July 3. According to estimates provided in the daily report from the National Interagency Fire Center, the fire had burned 3,100 acres (about 12.5 square kilometers) and was about 55 percent contained as of June 28. Some mandatory evacuations remained in effect. NASA image by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

  19. Method for lake restoration

    DOEpatents

    Dawson, Gaynor W.; Mercer, Basil W.

    1979-01-01

    A process for removing pollutants or minerals from lake, river or ocean sediments or from mine tailings is disclosed. Magnetically attractable collection units containing an ion exchange or sorbent media with an affinity for a chosen target substance are distributed in the sediments or tailings. After a period of time has passed sufficient for the particles to bind up the target substances, a magnet drawn through the sediments or across the tailings retrieves the units along with the target substance.

  20. Great Lakes Energy Institute

    SciTech Connect

    Alexander, J. Iwan

    2012-11-18

    The vision of the Great Lakes Energy Institute is to enable the transition to advanced, sustainable energy generation, storage, distribution and utilization through coordinated research, development, and education. The Institute will place emphasis on translating leading edge research into next generation energy technology. The Institute’s research thrusts focus on coordinated research in decentralized power generation devices (e.g. fuel cells, wind turbines, solar photovoltaic devices), management of electrical power transmission and distribution, energy storage, and energy efficiency.

  1. Archaea in Yellowstone Lake.

    PubMed

    Kan, Jinjun; Clingenpeel, Scott; Macur, Richard E; Inskeep, William P; Lovalvo, Dave; Varley, John; Gorby, Yuri; McDermott, Timothy R; Nealson, Kenneth

    2011-11-01

    The Yellowstone geothermal complex has yielded foundational discoveries that have significantly enhanced our understanding of the Archaea. This study continues on this theme, examining Yellowstone Lake and its lake floor hydrothermal vents. Significant Archaea novelty and diversity were found associated with two near-surface photic zone environments and two vents that varied in their depth, temperature and geochemical profile. Phylogenetic diversity was assessed using 454-FLX sequencing (~51,000 pyrosequencing reads; V1 and V2 regions) and Sanger sequencing of 200 near-full-length polymerase chain reaction (PCR) clones. Automated classifiers (Ribosomal Database Project (RDP) and Greengenes) were problematic for the 454-FLX reads (wrong domain or phylum), although BLAST analysis of the 454-FLX reads against the phylogenetically placed full-length Sanger sequenced PCR clones proved reliable. Most of the archaeal diversity was associated with vents, and as expected there were differences between the vents and the near-surface photic zone samples. Thaumarchaeota dominated all samples: vent-associated organisms corresponded to the largely uncharacterized Marine Group I, and in surface waters, ~69-84% of the 454-FLX reads matched archaeal clones representing organisms that are Nitrosopumilus maritimus-like (96-97% identity). Importance of the lake nitrogen cycling was also suggested by >5% of the alkaline vent phylotypes being closely related to the nitrifier Candidatus Nitrosocaldus yellowstonii. The Euryarchaeota were primarily related to the uncharacterized environmental clones that make up the Deep Sea Euryarchaeal Group or Deep Sea Hydrothermal Vent Group-6. The phylogenetic parallels of Yellowstone Lake archaea to marine microorganisms provide opportunities to examine interesting evolutionary tracks between freshwater and marine lineages.

  2. Archaea in Yellowstone Lake

    PubMed Central

    Kan, Jinjun; Clingenpeel, Scott; Macur, Richard E; Inskeep, William P; Lovalvo, Dave; Varley, John; Gorby, Yuri; McDermott, Timothy R; Nealson, Kenneth

    2011-01-01

    The Yellowstone geothermal complex has yielded foundational discoveries that have significantly enhanced our understanding of the Archaea. This study continues on this theme, examining Yellowstone Lake and its lake floor hydrothermal vents. Significant Archaea novelty and diversity were found associated with two near-surface photic zone environments and two vents that varied in their depth, temperature and geochemical profile. Phylogenetic diversity was assessed using 454-FLX sequencing (∼51 000 pyrosequencing reads; V1 and V2 regions) and Sanger sequencing of 200 near-full-length polymerase chain reaction (PCR) clones. Automated classifiers (Ribosomal Database Project (RDP) and Greengenes) were problematic for the 454-FLX reads (wrong domain or phylum), although BLAST analysis of the 454-FLX reads against the phylogenetically placed full-length Sanger sequenced PCR clones proved reliable. Most of the archaeal diversity was associated with vents, and as expected there were differences between the vents and the near-surface photic zone samples. Thaumarchaeota dominated all samples: vent-associated organisms corresponded to the largely uncharacterized Marine Group I, and in surface waters, ∼69–84% of the 454-FLX reads matched archaeal clones representing organisms that are Nitrosopumilus maritimus-like (96–97% identity). Importance of the lake nitrogen cycling was also suggested by >5% of the alkaline vent phylotypes being closely related to the nitrifier Candidatus Nitrosocaldus yellowstonii. The Euryarchaeota were primarily related to the uncharacterized environmental clones that make up the Deep Sea Euryarchaeal Group or Deep Sea Hydrothermal Vent Group-6. The phylogenetic parallels of Yellowstone Lake archaea to marine microorganisms provide opportunities to examine interesting evolutionary tracks between freshwater and marine lineages. PMID:21544103

  3. Not so Great Lakes?

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    In 1965, Frank Sinatra won the Grammy Award for his album, “September of My Years” “Early Bird,” the first commercial communications satellite, was launched; and Dr. Martin Luther King, Jr. was arrested in Selma, Alabama, during demonstrations against voter-registration rules.The year 1965 was also the last time water levels in the U.S. Great Lakes were as low as they are now.

  4. Not so Great Lakes?

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    In 1965, Frank Sinatra won the Grammy Award for his album, "September of My Years;" "Early Bird," the first commercial communications satellite, was launched; and Dr. Martin Luther King, Jr. was arrested in Selma, Alabama, during demonstrations against voter-registration rules.The year 1965 was also the last time water levels in the U.S. Great Lakes were as low as they are now.

  5. Angora Fire, Lake Tahoe

    NASA Technical Reports Server (NTRS)

    2007-01-01

    On the weekend of June 23, 2007, a wildfire broke out south of Lake Tahoe, which stretches across the California-Nevada border. By June 28, the Angora Fire had burned more than 200 homes and forced some 2,000 residents to evacuate, according to The Seattle Times and the Central Valley Business Times. On June 27, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the burn scar left by the Angora fire. The burn scar is dark gray, or charcoal. Water bodies, including the southern tip of Lake Tahoe and Fallen Leaf Lake, are pale silvery blue, the silver color a result of sunlight reflecting off the surface of the water. Vegetation ranges in color from dark to bright green. Streets are light gray, and the customary pattern of meandering residential streets and cul-de-sacs appears throughout the image, including the area that burned. The burn scar shows where the fire obliterated some of the residential areas just east of Fallen Leaf Lake. According to news reports, the U.S. Forest Service had expressed optimism about containing the fire within a week of the outbreak, but a few days after the fire started, it jumped a defense, forcing the evacuation of hundreds more residents. Strong winds that had been forecast for June 27, however, did not materialize, allowing firefighters to regain ground in controlling the blaze. On June 27, authorities hoped that the fire would be completely contained by July 3. According to estimates provided in the daily report from the National Interagency Fire Center, the fire had burned 3,100 acres (about 12.5 square kilometers) and was about 55 percent contained as of June 28. Some mandatory evacuations remained in effect. NASA image by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

  6. THOUSAND LAKES WILDERNESS, CALIFORNIA.

    USGS Publications Warehouse

    Till, Alison B.; McHugh, Edward L.

    1984-01-01

    A mineral survey of the Thousand Lakes Wilderness in northern California indicated little promise for the occurrence of mineral resources. Volcanic stone and cinders occur, but similar materials are found in abundance outside the wilderness. The wilderness is in the Cascade Volcanic Province, a setting locally favorable for geothermal resource potential. No geothermal potential was identified in the wilderness; subsurface potential cannot be evaluated without regional studies and drilling.

  7. Where This Occurs: Lakes and Rivers

    EPA Pesticide Factsheets

    Nutrient pollution builds up in our nation's lakes, ponds, and streams. EPA's 2010 National Lakes Assessment found that almost 20 percent of the 50,000 lakes surveyed had been impacted by nitrogen and phosphorus pollution.

  8. Mariano Lake Mine: Legal Documents and Settlements

    EPA Pesticide Factsheets

    Mariano Lake Mine Administrative Order on Consent (AOC) with Statement of Work (SOW) and Mariano Lake Mine Site Settlement Agreement for Engineering Evaluation/Cost Analysis and Statement of Work (SOW) for the Mariano Lake Mine Site.

  9. Landsat analysis of lake quality

    NASA Technical Reports Server (NTRS)

    Scarpace, F. L.; Fisher, L. T.; Holmquist, K. W.

    1979-01-01

    The trophic status of a number of inland lakes in Wisconsin has been assessed. The feasibility of using both photographic and digital representations of Landsat imagery was investigated during the lake classification project. The result of the investigation has been a semi-automatic data acquisition and handling system which, in conjunction with an analytical categorization scheme, can be used to classify all the significant lakes in the state.

  10. Lake Erie Wastewater Management Study.

    DTIC Science & Technology

    1983-06-01

    Lake Erie water quality problem which It has been recognized for many years, dating back this program focused on may be succinctly described Ito...mechanisms fo’ detachment and less. As will be discussed , the costs of achieving fur- transport of sediment and phosphorus to the lake. Fur- ther...WETLANDS FOREST MIXED URBAN OTHER WATER TRANSPORTATION I UTILITIES MISSING are extensively grown in the Lake Erie Basin, especial- measurement by U.S

  11. Limited Regulation of Lake Erie.

    DTIC Science & Technology

    1983-11-01

    Ontario,, Cedar Point in Ohio, Presque Isle in Pennsylvania and Hamlin in New York. Recreational boating is a significant activity on Lake Erie . Along...RD-Al47 936 LIMITED REGULATION OF LAKE ERIE (U) INTERNATIONAL LAKE i/i ERIE REGULATION STUDY BOARD NOV 83 UNCLASSIFIED F/G 13/2 N lhhhhh..hEmhhI...o lake Erie ’Governmen of 4,- % * L CTE " 84100400 .- Canad Unite Stte INTRNAIONL OIN COMISIO 4WD’ This document hais been ow for public rleoe and so

  12. Great Lakes' regional climate regimes

    NASA Astrophysics Data System (ADS)

    Kravtsov, Sergey; Sugiyama, Noriyuki; Roebber, Paul

    2016-04-01

    We simulate the seasonal cycle of the Great Lakes' water temperature and lake ice using an idealized coupled lake-atmosphere-ice model. Under identical seasonally varying boundary conditions, this model exhibits more than one seasonally varying equilibrium solutions, which we associate with distinct regional climate regimes. Colder/warmer regimes are characterized by abundant/scarce amounts of wintertime ice and cooler/warmer summer temperatures, respectively. These regimes are also evident in the observations of the Great Lakes' climate variability over recent few decades, and are found to be most pronounced for Lake Superior, the deepest of the Great Lakes, consistent with model predictions. Multiple climate regimes of the Great Lakes also play a crucial role in the accelerated warming of the lakes relative to the surrounding land regions in response to larger-scale global warming. We discuss the physical origin and characteristics of multiple climate regimes over the lakes, as well as their implications for a longer-term regional climate variability.

  13. Progress toward lake trout restoration in Lake Michigan

    USGS Publications Warehouse

    Holey, Mark E.; Rybicki, Ronald W.; Eck, Gary W.; Brown, Edward H.; Marsden, J. Ellen; Lavis, Dennis S.; Toneys, Michael L.; Trudeau, Tom N.; Horrall, Ross M.

    1995-01-01

    Progress toward lake trout restoration in Lake Michigan is described through 1993. Extinction of the native lake trout fishery by sea lamprey predation, augmented by exploitation and habitat destruction, resulted in an extensive stocking program of hatchery-reared lake trout that began in 1965. Sea lamprey abundance was effectively controlled using selective chemical toxicants. The initial stocking produced a measurable wild year class of lake trout by 1976 in Grand Traverse Bay, but failed to continue probably due to excessive exploitation. The overall lack of successful reproduction lakewide by the late 1970s led to the development and implementation in 1985 of a focused inter-agency lakewide restoration plan by a technical committee created through the Lake Committee structure of the Great Lakes Fishery Commission. Strategies implemented in 1985 by the plan included setting a 40% total mortality goal lakewide, creating two large refuges designed to encompass historically the most productive spawning habitat and protect trout stocked over their home range, evaluating several lake trout strains, and setting stocking priorities throughout the lake. Target levels for stocking in the 1985 Plan have never been reached, and are much less than the estimated lakewide recruitment of yearlings by the native lake trout stocks. Since 1985, over 90% of the available lake trout have been stocked over the best spawning habitat, and colonization of the historically productive offshore reefs has occurred. Concentrations of spawning lake trout large enough for successful reproduction, based on observations of successful hatchery and wild stocks, have developed at specific reefs. Continued lack of recruitment at these specific sites suggests that something other than stotk abundance has limited success. Poor survival of lake trout eggs, assumed to be related to contaminant burden, occurred in the late 1970s and early 1980s, but survival has since increased to equal survival in the

  14. Glacioisostasy and Lake-Level Change at Moosehead Lake, Maine

    USGS Publications Warehouse

    Balco, G.; Belknap, D.F.; Kelley, J.T.

    1998-01-01

    Reconstructions of glacioisostatic rebound based on relative sea level in Maine and adjacent Canada do not agree well with existing geophysical models. In order to understand these discrepancies better, we investigated the lake-level history of 40-km-long Moosehead Lake in northwestern Maine. Glacioisostasy has affected the level of Moosehead Lake since deglaciation ca. 12,500 14C yr B.P. Lowstand features at the southeastern end and an abandoned outlet at the northwestern end of the lake indicate that the lake basin was tilted down to the northwest, toward the retreating ice sheet, by 0.7 m/km at 10,000 14C yr B.P. Water level then rose rapidly in the southeastern end of the lake, and the northwestern outlet was abandoned, indicating rapid relaxation of landscape tilt. Lowstand features at the northwestern end of the lake suggest that the lake basin was tilted to the southeast at ca. 8750 14C yr B.P., possibly as the result of a migrating isostatic forebulge. After 8000 14C yr B.P., water level at the southeastern end was again below present lake level and rose gradually thereafter. We found no evidence suggesting that postglacial climate change significantly affected lake level. The rebound history inferred from lake-level data is consistent with previous interpretations of nearby relative sealevel data, which indicate a significantly steeper and faster-moving ice-proximal depression and ice-distal forebulge than geophysical models predict. ?? 1998 University of Washington.

  15. Lake Powell Half Empty

    NASA Image and Video Library

    2017-09-27

    After 14 years of drought, Lake Powell was at 42 percent of its capacity as of May 20, 2014. The low water levels are evident in these images, which were acquired by the Landsat 8 satellite on May 13, 2014. White bleached rock show where Lake Powell’s shore is when the reservoir is at capacity. It is normal for water levels to fluctuate in the reservoir depending on how much water flows in from snow and rain and how much flows out to meet needs. However, it has been dry in all but three of the past 14 years. At the beginning of 2000, Lake Powell was at 94 percent of capacity. By October 2013 (the beginning of the 2014 water year), water levels had dropped to a low of 50 percent capacity, according to the Bureau of Reclamation, the agency that manages the reservoir. The Earth Observatory’s World of Change shows this annual fluctuation and overall decline. With slightly above average snowpack in the basin that feeds the lake, water levels are expected to rebound to about 51 percent of capacity by October 2014, the end of the water year. While the drop in water levels are worrying for those who generate electricity or use the water for agriculture, the lower water levels may be a draw for recreation. Boaters coming to Lake Powell in the spring of 2014 will find beaches and rock formations that are usually underwater. Bullfrog Bay is the starting point for many boat rentals. The popularity of the spot is evident in the lower image: boats dot the surface of the water, just tiny white flecks at this scale. NASA Earth Observatory image by Robert Simmon, using Landsat data from the U.S. Geological Survey. Caption by Holli Riebeek. Instrument(s): Landsat 8 - OLI Read more: 1.usa.gov/1hck6NX Credit: NASA Earth Observatory NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by

  16. Lake Charles CCS Project

    SciTech Connect

    Leib, Thomas; Cole, Dan

    2015-06-30

    In late September 2014 development of the Lake Charles Clean Energy (LCCE) Plant was abandoned resulting in termination of Lake Charles Carbon Capture and Sequestration (CCS) Project which was a subset the LCCE Plant. As a result, the project was only funded through Phase 2A (Design) and did not enter Phase 2B (Construction) or Phase 2C (Operations). This report was prepared relying on information prepared and provided by engineering companies which were engaged by Leucadia Energy, LLC to prepare or review Front End Engineering and Design (FEED) for the Lake Charles Clean Energy Project, which includes the Carbon Capture and Sequestration (CCS) Project in Lake Charles, Louisiana. The Lake Charles Carbon Capture and Sequestration (CCS) Project was to be a large-scale industrial CCS project intended to demonstrate advanced technologies that capture and sequester carbon dioxide (CO2) emissions from industrial sources into underground formations. The Scope of work was divided into two discrete sections; 1) Capture and Compression prepared by the Recipient Leucadia Energy, LLC, and 2) Transport and Sequestration prepared by sub-Recipient Denbury Onshore, LLC. Capture and Compression-The Lake Charles CCS Project Final Technical Report describes the systems and equipment that would be necessary to capture CO2 generated in a large industrial gasification process and sequester the CO2 into underground formations. The purpose of each system is defined along with a description of its equipment and operation. Criteria for selection of major equipment are provided and ancillary utilities necessary for safe and reliable operation in compliance with environmental regulations are described. Construction considerations are described including a general arrangement of the CCS process units within the overall gasification project. A cost estimate is provided, delineated by system area with cost breakdown showing equipment, piping and materials

  17. Embryotoxicity of an extract from Great Lakes lake trout to rainbow trout and lake trout

    SciTech Connect

    Wright, P.J.; Tillitt, D.E.

    1995-12-31

    Aquatic ecosystems such as the Great Lakes are known to be contaminated with chemicals that are toxic to fish. However, the role of these contaminants in reproductive failures of fishes, such as lake trout recruitment, has remained controvertible. It was the objective to evaluate dioxin-like embryotoxicity of a complex mixture of chemicals and predict their potential to cause the lack of recruitment in Great Lakes lake trout. Graded doses of a complex environmental extract were injected into eggs of both rainbow trout and lake trout. The extract was obtained from whole adult lake trout collected from Lake Michigan in 1988. The extract was embryotoxic in rainbow trout, with LD50 values for Arlee strain and Erwin strain of 33 eggEQ and 14 eggEQ respectively. The LOAEL for hemorrhaging, yolk-sac edema, and craniofacial deformities in rainbow trout were 2, 2, and 4 eggEQ, respectively. Subsequent injections of the extract into lake trout eggs were likewise embryotoxic, with an LD50 value of 7 eggEQ. The LOAEL values for the extract in lake trout for hemorrhaging, yolk-sac edema, and craniofacial deformities were 0.1, 1, and 2 eggEQ, respectively. The current levels of contaminants in lake trout eggs are above the threshold for hemorrhaging and yolk-sac edema. The results also support the use of an additive model of toxicity to quantify PCDDs, PCDFs, Non-o-PCBs, and Mono-o-PCBs in relation to early life stage mortality in Lake Michigan lake trout.

  18. Grand Canyon, Lake Powell, and Lake Mead

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A snowfall in the American West provides contrast to the landscape's muted earth tones and indicates changes in topography and elevation across (clockwise from top left) Nevada, Utah, Colorado, New Mexico, Arizona, and California. In Utah, the southern ranges of the Wasatch Mountains are covered in snow, and the Colorado River etches a dark ribbon across the red rock of the Colorado Plateau. In the center of the image is the reservoir created by the Glen Canyon Dam. To the east are the gray-colored slopes of Navaho Mountain, and to the southeast, dusted with snow is the region called Black Mesa. Southwest of Glen Canyon, the Colorado enters the Grand Canyon, which cuts westward through Arizona. At a deep bend in the river, the higher elevations of the Keibab Plateau have held onto snow. At the end of the Grand Canyon lies another large reservoir, Lake Mead, which is formed by the Hoover Dam. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  19. Grand Canyon, Lake Powell, and Lake Mead

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A snowfall in the American West provides contrast to the landscape's muted earth tones and indicates changes in topography and elevation across (clockwise from top left) Nevada, Utah, Colorado, New Mexico, Arizona, and California. In Utah, the southern ranges of the Wasatch Mountains are covered in snow, and the Colorado River etches a dark ribbon across the red rock of the Colorado Plateau. In the center of the image is the reservoir created by the Glen Canyon Dam. To the east are the gray-colored slopes of Navaho Mountain, and to the southeast, dusted with snow is the region called Black Mesa. Southwest of Glen Canyon, the Colorado enters the Grand Canyon, which cuts westward through Arizona. At a deep bend in the river, the higher elevations of the Keibab Plateau have held onto snow. At the end of the Grand Canyon lies another large reservoir, Lake Mead, which is formed by the Hoover Dam. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  20. Depth evolution of the Meirama pit lake, A Coruña, NW Spain

    NASA Astrophysics Data System (ADS)

    Delgado, Jordi; Juncosa-Rivera, Ricardo; Cereijo-Arango, José Luis; García-Morrondo, David; Muñoz-Ibáñez, Andrea; Grande-García, Elisa; Rodríguez-Cedrún, Borja

    2016-04-01

    The Meirama pit lake is a water mass in the process of controlled flooding that, by the end of December 2015, can be described as a steadily stratified meromictic system. The deepest portion of the lake (monimolimnion) is isolated regarding the annual mixing dynamics (December/January) of the upper water body (mixolimnion), for which the depth of mixing is restricted to a water column of 35-40 m thick. Due to the contrasting flooding history (access of groundwater at the beginning and mixed access of stream/groundwater (being dominant the stream water) the deepest portion of the lake is separated from the upper, non-mixed layer by a marked chemocline. Strictly speaking, the monimolimnion of a meromictic lake extends to the waters located beneath the mixed lake layer. In the case of the Meirama Lake the monimolimnion is internally stratified and made of two major water bodies. From hereafter the deep and upper monimolimnion will be identified as bottom and middle sections of the lake while the mixolimnion is referred to as the surface layer. The general characteristics and evolution of the Meirama Lake have been reported elsewhere. In this work we focus on a summary description of the chemical evolution of the monimolimnion of the lake based on data gathered between 2009 and 2015 from the still on-going monitoring survey. The chemical evolution of the monimolimnion of the lake differs significantly from that of the mixolimnion. In general, surface water is sensible to seasonal fluctuations due to weather conditions, rainfall and biogeochemical processes. The middle and bottom sections are not sensible, in general, to this effects and their evolution obeys to a number of internal processes. In the case of temperature we observe a nearly constant gradient increase (0.001 °C/day) in the middle and deep lake waters up to the beginning of 2012, where it remains constant. The rise in temperature is likely due to the heat provided by groundwater seepage whose temperature

  1. Holocene lake-level fluctuations of Lake Aricota, Southern Peru

    USGS Publications Warehouse

    Placzek, C.; Quade, Jay; Betancourt, J.L.

    2001-01-01

    Lacustrine deposits exposed around Lake Aricota, Peru (17?? 22???S), a 7.5-km2 lake dammed by debris flows, provide a middle to late Holocene record of lake-level fluctuations. Chronological context for shoreline deposits was obtained from radiocarbon dating of vascular plant remains and other datable material with minimal 14C reservoir effects (<350 yr). Diatomites associated with highstands several meters above the modern lake level indicate wet episodes. Maximum Holocene lake level was attained before 6100 14C yr B.P. and ended ???2700 14C yr B.P. Moderately high lake levels occurred at 1700 and 1300 14C yr B.P. The highstand at Lake Aricota during the middle Holocene is coeval with a major lowstand at Lake Titicaca (16?? S), which is only 130 km to the northeast and shares a similar climatology. Comparisons with other marine and terrestrial records highlight emerging contradictions over the nature of mid-Holocene climate in the central Andes. ?? 2001 University of Washington.

  2. Geographical distributions of lake trout strains stocked in Lake Ontario

    USGS Publications Warehouse

    Elrod, Joseph H.; O'Gorman, Robert; Schneider, Clifford P.; Schaner, Ted

    1996-01-01

    Geographical distributions of lake trout (Salvelinus namaycush) stocked at seven locations in U.S. waters and at four locations in Canadian waters of Lake Ontario were determined from fish caught with gill nets in September in 17 areas of U.S. waters and at 10 fixed locations in Canadian waters in 1986-95. For fish of a given strain stocked at a given location, geographical distributions were not different for immature males and immature females or for mature males and mature females. The proportion of total catch at the three locations nearest the stocking location was higher for mature fish than for immature fish in all 24 available comparisons (sexes combined) and was greater for fish stocked as yearlings than for those stocked as fingerlings in all eight comparisons. Mature fish were relatively widely dispersed from stocking locations indicating that their tendency to return to stocking locations for spawning was weak, and there was no appreciable difference in this tendency among strains. Mature lake trout were uniformly distributed among sampling locations, and the strain composition at stocking locations generally reflected the stocking history 5 to 6 years earlier. Few lake trout moved across Lake Ontario between the north and south shores or between the eastern outlet basin and the main lake basin. Limited dispersal from stocking sites supports the concept of stocking different genetic strains in various parts of the lake with the attributes of each strain selected to match environmental conditions in the portion of the lake where it is stocked.

  3. The near extinction of lake trout in Lake Michigan

    USGS Publications Warehouse

    Eschmeyer, Paul H.

    1957-01-01

    Comparisons in 1949 and 1950 of numbers of legal-sized lake trout caught in large-mesh nets with numbers of small fish taken in chub nets showed that both large and small lake trout declined over the same period, and that by these years the decline may have been greater among small than among legal-sized fish.

  4. HABITAT: LAKE SUPERIOR - STATE OF THE LAKE 2005

    EPA Science Inventory

    This presentation briefly describes the state of research and management in Lake Superior concerning fisheries and their association to habitat. It discusses a general habitat classification for the lake and an increasing interest in the nearshore, summarizing the status of cont...

  5. ARE LAKES GETTING WARMER? REMOTE SENSING OF LARGE LAKE TEMPERATURES

    EPA Science Inventory

    Recent studies (Levitus et al., 2000) suggest a warning of the world ocean over the past 50 years. Freshwater lakes could also be getting warmer but thermal measurements to determine this are lacking. Large lake temperatures are vertically and horizontally heterogeneous and vary ...

  6. Delineation of sympatric morphotypes of lake trout in Lake Superior

    USGS Publications Warehouse

    Moore, Seth A.; Bronte, Charles R.

    2001-01-01

    Three morphotypes of lake trout Salvelinus namaycush are recognized in Lake Superior: lean, siscowet, and humper. Absolute morphotype assignment can be difficult. We used a size-free, whole-body morphometric analysis (truss protocol) to determine whether differences in body shape existed among lake trout morphotypes. Our results showed discrimination where traditional morphometric characters and meristic measurements failed to detect differences. Principal components analysis revealed some separation of all three morphotypes based on head and caudal peduncle shape, but it also indicated considerable overlap in score values. Humper lake trout have smaller caudal peduncle widths to head length and depth characters than do lean or siscowet lake trout. Lean lake trout had larger head measures to caudal widths, whereas siscowet had higher caudal peduncle to head measures. Backward stepwise discriminant function analysis retained two head measures, three midbody measures, and four caudal peduncle measures; correct classification rates when using these variables were 83% for leans, 80% for siscowets, and 83% for humpers, which suggests the measures we used for initial classification were consistent. Although clear ecological reasons for these differences are not readily apparent, patterns in misclassification rates may be consistent with evolutionary hypotheses for lake trout within the Laurentian Great Lakes.

  7. ARE LAKES GETTING WARMER? REMOTE SENSING OF LARGE LAKE TEMPERATURES

    EPA Science Inventory

    Recent studies (Levitus et al., 2000) suggest a warning of the world ocean over the past 50 years. Freshwater lakes could also be getting warmer but thermal measurements to determine this are lacking. Large lake temperatures are vertically and horizontally heterogeneous and vary ...

  8. Porewater salinity reveals past lake-level changes in Lake Van, the Earth's largest soda lake.

    PubMed

    Tomonaga, Yama; Brennwald, Matthias S; Livingstone, David M; Kwiecien, Olga; Randlett, Marie-Ève; Stockhecke, Mona; Unwin, Katie; Anselmetti, Flavio S; Beer, Jürg; Haug, Gerald H; Schubert, Carsten J; Sturm, Mike; Kipfer, Rolf

    2017-03-22

    In closed-basin lakes, sediment porewater salinity can potentially be used as a conservative tracer to reconstruct past fluctuations in lake level. However, until now, porewater salinity profiles did not allow quantitative estimates of past lake-level changes because, in contrast to the oceans, significant salinity changes (e.g., local concentration minima and maxima) had never been observed in lacustrine sediments. Here we show that the salinity measured in the sediment pore water of Lake Van (Turkey) allows straightforward reconstruction of two major transgressions and a major regression that occurred during the last 250 ka. We observed strong changes in the vertical salinity profiles of the pore water of the uppermost 100 m of the sediments in Lake Van. As the salinity balance of Lake Van is almost at steady-state, these salinity changes indicate major lake-level changes in the past. In line with previous studies on lake terraces and with seismic and sedimentological surveys, we identify two major transgressions of up to +105 m with respect to the current lake level at about 135 ka BP and 248 ka BP starting at the onset of the two previous interglacials (MIS5e and MIS7), and a major regression of about -200 m at about 30 ka BP during the last ice age.

  9. Lake Evaporation: a Model Study

    NASA Astrophysics Data System (ADS)

    Amayreh, Jumah Ahmad

    1995-01-01

    Reliable evaporation data are an essential requirement in any water and/or energy budget studies. This includes operation and management of both urban and agricultural water resources. Evaporation from large, open water surfaces such as lakes and reservoirs may influence many agricultural and irrigation decisions. In this study evaporation from Bear Lake in the states of Idaho and Utah was measured using advanced research instruments (Bowen Ratio and Eddy Correlation). Actual over-lake evaporation and weather data measurements were used to understand the mechanism of evaporation in the lake, determine lake-related parameters (such as roughness lengths, heat storage, net radiation, etc.), and examine and evaluate existing lake evaporation methods. This enabled the development of a modified and flexible model incorporating the tested methods for hourly and daily best estimates of lake evaporation using nearby simple land-based weather data and, if available, remotely sensed data. Average evaporation from Bear Lake was about 2 mm/day during the summer season (March-October) of this two-year (1993-1994) study. This value reflects the large amount of energy consumed in heating the water body of the lake. Moreover, evaporation from the lake was not directly related to solar radiation. This observation was clear during night time when the evaporation continued with almost the same rate as daytime evaporation. This explains the vital role of heat storage in the lake as the main driving energy for evaporation during night time and day time cloudy sky conditions. When comparing over-lake and nearby land-based weather parameters, land-based wind speed was the only weather parameter that had a significant difference of about 50% lower than over-lake measurements. Other weather parameters were quite similar. The study showed that evaporation from the lake can be accurately estimated using Penman-type equations if related parameters such as net radiation, heat storage, and

  10. The Lake Ohrid SCOPSCO project

    NASA Astrophysics Data System (ADS)

    Wagner, Bernd; Wilke, Thomas; Krastel, Sebastian; Zanchetta, Giovanni; Sulpizio, Roberto; Leng, Melanie J.; Francke, Alexander; Baumgarten, Henrike; Cvetkoska, Aleksandra; Giacco, Biagio; Lacey, Jack H.; Leicher, Niklas; Levkov, Zlatko; Lindhorst, Katja; Reed, Jane M.; Zhang, Xiaosen; Sadori, Laura; Vogel, Hendrik; Wagner-Cremer, Friederike; Wonik, Thomas

    2015-04-01

    The ICDP SCOPSCO project at Lake Ohrid in Macedonia and Albania was one of the most successful lake drilling campaigns worldwide. Drilling took place from April to June 2013 and yielded more than 2000 m of sediments from four different sites in the lake. The maximum penetration was 569 m below lake floor and the overall recovery at all drill sites was > 95 %. Almost two years after the drilling operation, core opening and processing as well as biological and geological analyses are still ongoing. However, most of the cores from the main drill site, the so-called DEEP site in the centre of the lake, are meanwhile opened and reveal a unique record of lake history. The extraordinary quality of seismic, borehole logging and core data allows us to achieve the major goals of the SCOPSCO project. Seismic data, diatoms and coarse-grained sediments in the basal cores indicate that Lake Ohrid had no marine origin, as it was speculated in the past. The data show that Lake Ohrid established in a highly dynamic pull-apart basin with varying fluvial and shallow water conditions. On top of these basal sediments, borehole logging data, XRF scanning data, carbonate, and the amount of organic matter indicate a complete and high resolution succession of glacial / interglacial cycles and interspersed stadials and interstadials. This allows us to determine the establishment of Lake Ohrid by means of chronostratigraphic tuning to about 1.3 to 1.5 Ma ago. Additional, independent age control is given by paleomagnetic data and by numerous tephra layers, which can be correlated with well-dated proximal tephra deposits in Italy. The uppermost 350 m of the sediment record contain more than 30 tephras, which makes the Lake Ohrid record to the rosetta stone of distal Italian tephra deposits in the Balkan region. The unique sediment record of Lake Ohrid is fundamental to obtain crucial information on the overall goal of the SCOPSCO project, i.e. to clarify why Lake Ohrid has one of highest

  11. Methane oxidation in anoxic lake waters

    NASA Astrophysics Data System (ADS)

    Su, Guangyi; Zopfi, Jakob; Niemann, Helge; Lehmann, Moritz

    2017-04-01

    presence of members of the Methylomirabiliaceae family (NC10 phylum), known to perform AOM with nitrite as terminal electron acceptor. Interestingly, albeit the similarly favorable conditions in both basins, the South Basin showed nearly two-fold higher CH4 oxidation rates, but the Methylomirabiliaceae abundance appeared to be much higher in the meromictic North Basin. Ongoing work will attempt to verify whether the apparent difference in the abundance of Methylomirabiliaceae is a permanent feature. We will further seek to determine the relative contribution of bacterial nitrite-dependent AOM to total methane oxidation, as well as the environmental controls that may explain the differential importance of Methylomirabiliaceae in the two connected lake basins.

  12. Geo- and Biogeochemical Processes in a Heliothermal Hypersaline Lake

    SciTech Connect

    Zachara, John M.; Moran, James J.; Resch, Charles T.; Lindemann, Stephen R.; Felmy, Andrew R.; Bowden, Mark E.; Cory, Alexandra B.; Fredrickson, Jim K.

    2016-03-17

    Water chemical variations were investigated over three annual hydrologic cycles in hypersaline, heliothermal, meromictic Hot Lake in north-central Washington State, USA. The lake, originally studied by Anderson (1958), contains diverse biota with dramatic zonation related to salinity and redox state. Water samples were collected at 10 cm depth intervals through the shallow lake (2.4 m) at a consistent location during 2012-2014, with comprehensive monitoring performed in 2013. Inorganic salt species, total dissolved solids (TDS), dissolved carbon forms (DOC, DIC), oxygen, sulfide, and methane were analyzed in lake water samples. Depth sonde measurements of pH and temperature were also performed to track their seasonal variations. A bathymetric survey of the lake was conducted to enable lake water volume and solute inventory calculations. Sediment cores were collected at low water and analyzed by x-ray diffraction to investigate sediment mineralogy. The primary dissolved salt in Hot Lake water was Mg2+-SO42- while sediments were dominated by gypsum (CaSO4•2H2O). Lake water concentrations increased with depth to reach saturation with epsomite that was exposed at lake bottom. At maximum volume in spring, Hot Lake exhibited a relatively dilute mixolimnion containing phyto- and zooplankton; a lower saline metalimnion with stratified oxygenic and anoxygenic photosynthetic microbiologic communities; and a stable, hypersaline monimolimnion, separated from above layers by a chemocline, containing high levels of sulfide and methane. The thickness of the mixolimnion regulates a heliothermal effect which creates temperatures in excess of 60 oC in the underlying metalimnion and monimolimnion. The mixolimnion was dynamic and actively mixed. It displayed large pH variations, in-situ calcium carbonate precipitation, and large evaporative volume losses. The depletion of this ephemeral layer by fall allowed deeper mixing into the volume-stable lower mixolimnion, more rapid heat

  13. Profundal sideritic mudstone from an Eocene lake in Alaska

    SciTech Connect

    Dickinson, K.A.

    1987-08-01

    Sideritic lacustrine mudstone was found in drill core from a uranium deposit in the Death Valley area in the eastern part of the Seward Peninsula, Alaska. The precursor sediments for this rock were deposited in an unusual iron-meromictic Eocene lake, herein named Lake Tubutulik, which occupied part of the Boulder Creek basin, a graben that is probably a southern extension of the larger Death Valley basin. The Boulder Creek basin is bounded on the west by granite of the Upper Cretaceous Darby pluton and on the east by Precambrian to Paleozoic metasedimentary rocks. The lake basin was formed by basaltic flows that dammed the valley of the ancestral Tubutulik River in early Eocene time. The lake sediments included a nearshore facies of fine-grained organic mud and an offshore facies of laminated sideritic mud. The offshore (profundal) laminated mudstone consists of alternating layers of authigenic siderite and detrital grains, mostly quartz and clay minerals. Both lacustrine facies contain turbidites. The lacustrine rocks graded laterally into an onshore facies of colluvial and fluvial sandstone, paludal mudstone, and coal. The ancient lake occupied a small, deep basin in a tectonically active area of high relief. Meromixis was apparently stabilized by reduced iron and bicarbonate dissolved in the monimolimnion. The intensity of meromixis decreased as the lake became shallower from sediment filling. The source of the dissolved iron in the monoimolimnion was probably the Eocene basalt. Carbon isotope analysis of the siderite suggests that the dissolved bicarbonate in the profundal facies was largely inorganic. Sideritic carbon in one sample from the onshore paludal facies has an isotopic signature (delta/sup 13/C = +16.9) consistent with residual carbonate formed during methanogenic fermentation.

  14. Forecasting Lake-Effect Snow in the Great Lakes Using NASA Satllite Data

    NASA Technical Reports Server (NTRS)

    Cipullo, Michelle; Molthan, Andrew; Shafer, Jackie; Case, Jonathan; Jedlovec, Gary

    2011-01-01

    This slide presentation reviews the forecast of the lake effect snow in the Great Lakes region using models and infrared estimates of Great Lake Surface Temperatures (GLSTs) from the MModerate Resolution Imaging Spectroradiometer (MODIS) instrument on Terra and Aqua satellites, and other satellite data. This study analyzes Lake Erie and Lake Ontario which produce storm total snowfall ranged from 8-18 inches off of Lake Ontario and 10-12 inches off of Lake Erie for the areas downwind.

  15. Feeding competition between larval lake whitefish and lake herring

    USGS Publications Warehouse

    Savino, Jacqueline F.; Hudson, Patrick L.

    1995-01-01

    The potential for competition for food between larval lake whitefish (Coregonus clupeaformis) and lake herring (C. artedi) 1- to 8-wk of age was explored in a series of 1-h laboratory feeding studies. Feeding started at 2-wk post-hatch. Learning and fish size appear to be more important than prey density at the onset of feeding. Species differed in their feeding behavior and consumption noticeably by 5-wk and substantially by 8-wk. Lake whitefish generally were more aggressive foragers than lake herring, attacking and capturing more prey. At high plankton density at 8-wk, lake herring feeding was depressed in mixed-fish treatments. This difference in competitive food consumption between the two coregonids occurs at a critical life stage, and when combined with other biotic and abiotic factors, may have a significant impact on recruitment.

  16. PCB concentrations in lake trout (Salvelinus namaycush) are correlated to habitat use and lake characteristics.

    PubMed

    Guildford, S J; Muir, D C G; Houde, M; Evans, M S; Kidd, K A; Whittle, D M; Drouillard, K; Wang, X; Anderson, M R; Bronte, C R; Devault, D S; Haffner, D; Payne, J; Kling, H J

    2008-11-15

    This study considers the importance of lake trout habitat as a factor determining persistent organochlorine (OC) concentration. Lake trout is a stenothermal, cold water species and sensitive to hypoxia. Thus, factors such as lake depth, thermal stratification, and phosphorus enrichment may determine not only which lakes can support lake trout but may also influence among-lake variability in lake trout population characteristics including bioaccumulation of OCs. A survey of 23 lakes spanning much of the natural latitudinal distribution of lake trout provided a range of lake trout habitat to test the hypothesis that lake trout with greater access to littoral habitat for feeding will have lower concentrations of OCs than lake trout that are more restricted to pelagic habitat. Using the delta13C stable isotope signature in lake trout as an indicator of influence of benthic littoral feeding, we found a negative correlation between lipid-corrected delta13C and sigmaPCB concentrations supporting the hypothesis that increasing accessto littoral habitat results in lower OCs in lake trout. The prominence of mixotrophic phytoplankton in lakes with more contaminated lake trout indicated the pelagic microbial food web may exacerbate the biomagnification of OCs when lake trout are restricted to pelagic feeding. A model that predicted sigmaPCB in lake trout based on lake area and latitude (used as proximate variables for proportion of littoral versus pelagic habitat and accessibility to littoral habitat respectively) explained 73% of the variability in sigmaPCBs in lake trout in the 23 lakes surveyed.

  17. PYRAMID LAKE RENEWEABLE ENERGY PLAN

    SciTech Connect

    HIGH DESERT GEOCULTURE, LLC

    2009-06-06

    The Pyramid Lake Renewable Energy Plan covers these areas: energy potential (primarily focusing on geothermal resource potential, but also more generally addressing wind energy potential); renewable energy market potential; transmission system development; geothermal direct use potential; and business structures to accomplish the development objectives of the Pyramid Lake Paiute Tribe.

  18. Surface seiches in Flathead Lake

    NASA Astrophysics Data System (ADS)

    Kirillin, G.; Lorang, M. S.; Lippmann, T. C.; Gotschalk, C. C.; Schimmelpfennig, S.

    2014-12-01

    Standing surface waves or seiches are inherent hydrodynamic features of enclosed water bodies. Their two-dimensional structure is important for estimating flood risk, coastal erosion and bottom sediment transport and for understanding shoreline habitats and lake ecology in general. In this work, we present analysis of two-dimensional seiche characteristics in Flathead Lake, Montana, USA, a large intermountain lake known to have high seiche amplitudes. To examine spatial characteristics of different seiche modes we used the original procedure of determining the seiche frequencies from the primitive equation model output with subsequent derivation of the spatial seiche structure at fixed frequencies akin the tidal harmonic analysis. The proposed procedure revealed specific seiche oscillation features in Flathead Lake including maximum surface level amplitudes of the first fundamental mode in straights around the largest island; several higher modes appearing locally in the vicinity of the river inflow; the "Helmholtz" open harbor mode, with the period approximately twice that of the longest seiche mode, generated by a large shallow bay connected to the main lake basin; and several rotating seiche modes potentially affecting the lake-wide circulation. We discuss the lake management problems related to of the spatial seiche distribution, such as shoreline erosion, floods and transport of sediments and invasive species in Flathead Lake.

  19. Surface seiches in Flathead Lake

    NASA Astrophysics Data System (ADS)

    Kirillin, G.; Lorang, M. S.; Lippmann, T. C.; Gotschalk, C. C.; Schimmelpfennig, S.

    2015-06-01

    Standing surface waves or seiches are inherent hydrodynamic features of enclosed water bodies. Their two-dimensional structure is important for estimating flood risk, coastal erosion, and bottom sediment transport, and for understanding shoreline habitats and lake ecology in general. In this work, we present analysis of two-dimensional seiche characteristics in Flathead Lake, Montana, USA, a large intermountain lake known to have high seiche amplitudes. To examine spatial characteristics of different seiche modes, we used the original procedure of determining the seiche frequencies from the primitive equation model output with subsequent derivation of the spatial seiche structure at fixed frequencies akin to the tidal harmonic analysis. The proposed procedure revealed specific seiche oscillation features in Flathead Lake, including maximum surface level amplitudes of the first fundamental mode in straights around the largest island; several higher modes appearing locally in the vicinity of the river inflow; the "Helmholtz" open harbor mode, with the period approximately twice that of the longest seiche mode, generated by a large shallow bay connected to the main lake basin; and several rotating seiche modes potentially affecting the lake-wide circulation. We discuss lake management problems related to the spatial seiche distribution, such as shoreline erosion, floods, and transport of sediments and invasive species in Flathead Lake.

  20. The Great Lakes Food Web.

    ERIC Educational Resources Information Center

    Baker, Marjane L.

    1997-01-01

    Presents a play for students in grades four to nine that incorporates the scientific names, physical characteristics, feeding habits, interactions, and interdependence of the plants and animals that make up the Great Lakes food web to facilitate the learning of this complex system. Includes a Great Lakes food web chart. (AIM)

  1. The Great Lakes Food Web.

    ERIC Educational Resources Information Center

    Baker, Marjane L.

    1997-01-01

    Presents a play for students in grades four to nine that incorporates the scientific names, physical characteristics, feeding habits, interactions, and interdependence of the plants and animals that make up the Great Lakes food web to facilitate the learning of this complex system. Includes a Great Lakes food web chart. (AIM)

  2. An urban lake remediation experiment

    SciTech Connect

    Castelli, S.E.; Gardner, K.H.; Jennings, A.A.

    1998-07-01

    Circumstances provided the opportunity to study a small urban lake as the surrounding municipalities attempted to improve its aesthetic quality by dredging. This manuscript focuses primarily on the sediments in the system: accumulation rates, the expected dynamics of the lake bed drying process, and the influence of the sediments on water quality.

  3. Pyramid Lake Renewable Energy Project

    SciTech Connect

    John Jackson

    2008-03-14

    The Pyramid Lake Paiute Tribe is a federally recognized Tribe residing on the Pyramid Lake Reservation in western Nevada. The funding for this project was used to identify blind geothermal systems disconnected from geothermal sacred sites and develop a Tribal energy corporation for evaluating potential economic development for profit.

  4. NATIONAL LAKE ASSESSMENT MONITORING DESIGN

    EPA Science Inventory

    The USEPA designed the National Lake Assessment in 2005-6 with field sampling being completed in 2007. The objective of the assessment is to estimate the ecological condition of lakes and reservoirs nationally. The objective of this paper is to describe the national survey desi...

  5. "Lake Woebegone," Twenty Years Later

    ERIC Educational Resources Information Center

    Cannell, John Jacob

    2006-01-01

    Almost 20 years ago, the author wrote--and then privately published--the two "Lake Woebegone" reports, named after Garrison Keillor's mythical Minnesota town where "all the women are strong, all the men are good-looking, and all the children are above average." The first "Lake Woebegone" report documented that all 50 states were testing above the…

  6. NATIONAL LAKE ASSESSMENT MONITORING DESIGN

    EPA Science Inventory

    The USEPA designed the National Lake Assessment in 2005-6 with field sampling being completed in 2007. The objective of the assessment is to estimate the ecological condition of lakes and reservoirs nationally. The objective of this paper is to describe the national survey desi...

  7. Planktonic diatoms of Lake Ontario

    USGS Publications Warehouse

    Reinwand, Jerry F.

    1969-01-01

    The major species of diatoms in surface collections from Lake Ontario in September 1964 were Asterionella formosa, Fragilaria crotonensis, and Tabellaris fenestrata. Dominant species in the deep-water samples were Stephanodiscus astraea, S. astraea var. mintula, and F. crotonensis. The diatom flora in surface collections varied among several stations in the eastern end of the lake.

  8. Lake Mackay, Australia

    NASA Image and Video Library

    2017-09-27

    Lake Mackay is the largest of hundreds of ephemeral lakes scattered throughout Western Australia and the Northern Territory, and is the second largest lake in Australia. The darker areas indicate some form of desert vegetation or algae, moisture within the soils, and lowest elevations where water pools. The image was acquired on September 19, 2010 and covers an area of 27 x 41 km. With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on Terra. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance. The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate, Washington, D.C. More information about ASTER is available at asterweb.jpl.nasa.gov/. Image Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

  9. Lava Lakes on Io?

    NASA Astrophysics Data System (ADS)

    Lopes, R. M. C.; Kamp, L. W.; Smythe, W. D.; Howell, R.; Mouginis-Mark, P.; Kargel, J. S.; Radebaugh, J.; Turtle, E. P.; Perry, J.; Williams, D. A.; Carlson, R. W.; Doute, S.; Galileo NIMS Team

    2003-05-01

    At least 152 active volcanic centers have been identified on Jupiter's moon Io [Lopes et al., 2003, submitted to Icarus]. Eruptions at these centers include lava flows (``Promethean" type eruptions), explosive ``Pillanian" eruptions [Keszthelyi et al., 2001, JGR 106, 33,025-52] and volcanism confined within patera walls (``Lokian", Lopes et al., 2003). Understanding the Lokian eruption mechanism is particularly important because paterae are the most ubiquitous volcanic constructs on Io's surface [Radebaugh et al. 2001, JGR, 106, 33,005-33,020] and patera volcanism is the most common eruption type on Io. We use observations from Galileo's Near-Infrared Mapping Spectrometer (NIMS) and compare them with images from Galileo's Solid State Imaging system (SSI) to map the distribution of thermal emission at several Ionian paterae. This allows us to examine how thermal emission correlates with visible features, and to investigate how thermal emission varies with time. Galileo's close fly-bys of Io from 1999 to 2001 allowed NIMS to observe the volcanoes at relatively high spatial resolution (1-30 km pixel). At these scales, observations of the several paterae reveal that the greatest thermal emission occurs at the edges. This can be explained as the crust of a lava lake breaking up against the base of the patera (caldera) walls, similar to what has been observed at lava lakes on Earth. Comparison with terrestrial analogs shows that several Ionian active paterae, such as Loki, Tupan, and Emakong, have thermal properties consistent with relatively inactive lava lakes on Earth. We discuss these results and their implications for eruption styles and resurfacing on Io. This work was supported in part by NASA's Planetary Geology and Geophysics Program.

  10. Using radon-222 for tracing groundwater discharge into an open-pit lignite mining lake--a case study.

    PubMed

    Schmidt, Axel; Schubert, Michael

    2007-12-01

    Groundwater discharge into an open pit lignite mining lake was investigated using radon-222 as a naturally occurring environmental tracer. The chosen study site was a meromictic lake, i.e., a water body that is divided horizontally into two separate layers--the upper mixolimnion (with seasonal mixing) and the lower monimolimnion (without seasonal mixing). For the estimation of groundwater discharge rates into the lake, a simple box model including all radon sinks and sources related to each layer was applied. Two field investigations were performed. During the October campaign, the total groundwater discharge into the lake was found to be 18.9 and 0.7 m(3) d(-1) for the mixolimnion and monimolimnion, respectively. During the December campaign, the groundwater discharge into the mixolimnion was 15.0 m(3) d(-1), whereas no discharge at all was observed into the monimolimnion. Based on the given water volumes, the residence time of lake water was 5.3 years for the monimolimnion and varies between 0.9 and 1.1 years for the mixolimnion. The investigation confirmed radon to be a useful environmental tracer for groundwater and surface water interactions in meromictic lake environments.

  11. Lake-floor sediment texture and composition of a hydrothermally-active, volcanic lake, Lake Rotomahana

    NASA Astrophysics Data System (ADS)

    Pittari, A.; Muir, S. L.; Hendy, C. H.

    2016-03-01

    Young volcanic lakes undergo a transition from rapid, post-eruptive accumulation of volcaniclastic sediment to slower pelagic settling under stable lake conditions, and may also be influenced by sublacustrine hydrothermal systems. Lake Rotomahana is a young (129 year-old), hydrothermally-active, volcanic lake formed after the 1886 Tarawera eruption, and provides a unique insight into the early evolution of volcanic lake systems. Lake-bottom sediment cores, 20-46 cm in length, were taken along a transect across the lake and characterised with respect to stratigraphy, facies characteristics (i.e., grain size, componentry) and pore water silica concentrations. The sediments generally comprise two widespread facies: (i) a lower facies of light grey to grey, very fine lacustrine silt derived from the unconsolidated pyroclastic deposits that mantled the catchment area immediately after the eruption, which were rapidly reworked and redeposited into the lake basin; and (ii) an upper facies of dark, fine-sandy diatomaceous silt, that settled from the pelagic zone of the physically stable lake. Adjacent to sublacustrine hydrothermal vents, the upper dark facies is absent, and the upper part of the light grey to grey silt is replaced by a third localised facies comprised of hydrothermally altered pale yellow to yellowish brown, laminated silt with surface iron-rich encrustations. Microspheres, which are thought to be composed of amorphous silica, although some may be halloysite, have precipitated from pore water onto sediment grains, and are associated with a decrease in pore water silicon concentration. Lake Rotomahana is an example of a recently-stabilised volcanic lake, with respect to sedimentation, that shows signs of early sediment silicification in the presence of hydrothermal activity.

  12. Seasonal bathythermal distribution of juvenile lake trout in Lake Ontario

    USGS Publications Warehouse

    Elrod, Joseph H.; Schneider, Clifford P.

    1987-01-01

    Bathythermal distributions of hatchery-reared lake trout (Salvelinus namaycush) of three genetic strains (Lake Superior; Clearwater Lake, Manitoba; and Seneca Lake, New York) were described from catches with bottom trawls in Lake Ontario during April-May, June, July-August, and October, 1978–1984. This work was part of a program to evaluate post-stocking performance of hatchery-reared fish and identify strains for continued use in rehabilitation of lake trout in Lake Ontario. All age groups of Lake Superior fish were in deeper water in April-May than in June each year; mean depth of capture was greatest at age II and became progressively shallower at ages III and IV. Mean depth of capture in April-May was positively correlated with severity of the preceding winter as judged by heating degree days and average wind speed. During July-August, the fish were concentrated between the epilimnion and 50 m, with no consistent trend in depth by age; however, 92% were captured at water temperatures of 12°C or lower. Mean temperatures of capture for Lake Superior fish during the four respective sampling periods were 3.9, 7.5, 6.9, and 9.5° C for fish of age II and 3.9, 8.4, 6.9, and 8.7° C for fish of age III. The age-II Clearwater Lake fish were consistently at shallower depths than age-II Lake Superior fish. Mean temperatures of capture were 4.2, 9.7, 9.6, and 10.7° C during the four respective sampling periods; during July-August, 91% were taken in water of 12° C or lower. The distribution of Seneca Lake fish was similar to that of the Lake Superior strain. Mean temperatures at which the three strains were captured were well below published preferred temperatures of yearlings in the laboratory. Annual variations in depth distributions during a given season were probably due to differing thermal regimes resulting from annual variations in the weather.

  13. Phosphorous Loading in Lake Champlain

    NASA Astrophysics Data System (ADS)

    Hoffman, H.; Halliday, B.; Lane, T.

    2016-12-01

    Phosphate movement from different sources into Lake Champlain is a problem. Excess phosphate generates algae growth causing eutrophication. This excessive growth known as algae blooms leads to poor water quality (State of Lake Report, 2015). Phosphate moves primarily by attachment to soil particles (Busman, Lamb, 09). Historically its movement has been limited to spring, summer and fall. Spring runoff is thought to contribute the most phosphate to Lake Champlain (Jensen, Tiessen, 11). With changes in global and local temperatures effecting weather patterns and the winter season, does phosphate continue to move into Lake Champlain during the winter months? Water samples from two tributaries to Lake Champlain were collected biweekly year around for the past three years. These samples were then tested for total suspended solids and phosphate levels. The results indicate that phosphate loading occurs throughout the year even during the winter months.

  14. L-Lake macroinvertebrate community

    SciTech Connect

    Specht, W.L.

    1996-06-01

    To characterize the present benthic macroinvertebrate community of L-Lake, Regions 5 and 7 of the reservoir were sampled in September 1995 at the same locations sampled in 1988 and 1989 during the L-Lake monitoring program. The macroinvertebrate community of 1995 is compared to that of 1988 and 1989. The species composition of L-Lake`s macroinvertebrate community has changed considerably since 1988-1989, due primarily to maturation of the reservoir ecosystem. L-Lake contains a reasonably diverse macroinvertebrate community that is capable of supporting higher trophic levels, including a diverse assemblage of fish species. The L-Lake macroinvertebrate community is similar to those of many other southeastern reservoirs, and there is no indication that the macroinvertebrate community is perturbed by chemical or physical stressors.

  15. Choking Lake Winnipeg

    NASA Astrophysics Data System (ADS)

    Byrne, J. M.; Little, L. J.; Dodgson, K. A.; MacDonald, R. J.; Graham, J.

    2009-12-01

    The problems of waterway eutrophication and coastal zone hypoxia are reaching epidemic proportions. Fresh water and coastal marine environments around the world are suffering unprecedented pollution loadings. We are developing an education program to address the dramatic need for public, community and K-12 education about the harsh impacts of elevated nutrient loads on fresh and marine water environments. The Lake Winnipeg watershed is adopted as the poster child of fresh water eutrophication in western North America. The watershed, one of the largest on the continent, is in rapid decline due to pollution, population pressures and water diversion. A concerted education program is needed to change personal and society actions that negatively impact the Winnipeg watershed; and the confluence of the watershed - Lake Winnipeg. But the education program goes beyond Lake Winnipeg. Negative impacts of nutrient loads are adversely affecting environments right to the oceans. Major dead zones that are expanding on our continental shelves due to nutrient overloading threaten to coalesce into extensive regions of marine life die-off. This presentation outlines the documentary education production process under development. We are building a series of Public Service Announcements (PSAs) for national television networks. The PSAs will direct educators, stakeholders and citizens to an associated website with educational video clips detailing the issues of eutrophication and hypoxia. The video clips or webisodes, present interviews with leading scientists. The discussions address the causes of the problems, and presents workable solutions to nutrient overloads from a variety of sources. The webisodes are accompanied by notes and advice to teachers on ways and means to use the webisodes in classrooms. The project is fully funed by a group of Canadian Community Foundations, with the understanding the work wil be available free to educators anywhere in the world. Our education

  16. Lake Shasta, California

    NASA Image and Video Library

    2015-06-17

    This image from NASA Terra spacecraft shows Shasta Lake in northern California, which has an area of 12,000 ha, making it the state largest reservoir. Impacts of the continuing drought in the western US is evident in the two ASTER images acquired 9 years apart. The images were acquired September 9, 2005 and September 2, 2014. They cover an area of 27.6 x 40.4 km, and are located at 40.6 degrees north, 122.4 degrees west. http://photojournal.jpl.nasa.gov/catalog/PIA19492

  17. Great Lakes Harbors Study

    DTIC Science & Technology

    1966-11-01

    Locally.assigned Library of Congress number: HE396 S25 U55 Nj 19. KEY WORDS (Continue on reverse side if necessary and identify by block number) 1. HARBORS 2... WATER TRANSPORTATION 3. ECONOMIC ANALYSIS 4. GREAT LJAKES - 20. ABSTRACT (Continue on ie.er.se side It necesaty nd identify by blocA number) Harbor...Scope 2 DESCRIPTION AND ECONOMIC DEVELOPMENT 3 Great Lakes-St. Lawrence Navigation System 2 4 Navigation Season 3 5 Water Levels 4 6 Tributary Area 6

  18. Lake Carnegie, Western Australia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Ephemeral Lake Carnegie, in Western Australia, fills with water only during periods of significant rainfall. In dry years, it is reduced to a muddy marsh. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on May 19, 1999. This is a false-color composite image made using shortwave infrared, infrared, and red wavelengths. The image has also been sharpened using the sensor's panchromatic band. Image provided by the USGS EROS Data Center Satellite Systems Branch. This image is part of the ongoing Landsat Earth as Art series.

  19. 78 FR 53675 - Safety Zone; Lake Erie Heritage Foundation, Battle of Lake Erie Reenactment; Lake Erie, Put-in...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-30

    ... Lake Erie Reenactment; Lake Erie, Put-in-Bay, OH AGENCY: Coast Guard, DHS. ACTION: Temporary final rule... vicinity of Put-In-Bay, OH. This safety zone is intended to restrict vessels from a portion of Lake Erie during Battle of Lake Erie Reenactment near Put-In-Bay. This temporary safety zone is necessary...

  20. Geo- and biogeochemical processes in a heliothermal hypersaline lake

    NASA Astrophysics Data System (ADS)

    Zachara, John M.; Moran, James J.; Resch, Charles T.; Lindemann, Stephen R.; Felmy, Andrew R.; Bowden, Mark E.; Cory, Alexandra B.; Fredrickson, James K.

    2016-05-01

    Water chemical variations were investigated over three annual hydrologic cycles in hypersaline, heliothermal, meromictic Hot Lake in north-central Washington State, USA. The lake contains diverse biota with dramatic zonation related to salinity and redox state. Water samples were collected at 10-cm depth intervals through the shallow lake (2.4 m) during 2012-2014, with comprehensive monitoring performed in 2013. Inorganic salt species, dissolved carbon forms (DOC, DIC), oxygen, sulfide, and methane were analyzed in lake water samples. Depth sonde measurements of pH and temperature were also performed to track their seasonal variations. A bathymetric survey of the lake was conducted to enable lake water volume and solute inventory calculations. Sediment cores were collected at low water and analyzed by X-ray diffraction to investigate sediment mineralogy. The primary dissolved salt in Hot Lake water was Mg2+-SO42- whereas sediments were dominated by gypsum (CaSO4·2H2O). Lake water concentrations increased with depth, reaching saturation with epsomite (MgSO4·7H2O) that was exposed at lake bottom. At maximum volume in spring, Hot Lake exhibited a relatively dilute mixolimnion; a lower saline metalimnion with stratified oxygenic and anoxygenic photosynthetic microbiological communities; and a stable, hypersaline monimolimnion, separated from above layers by a chemocline, containing high levels of sulfide and methane. The thickness of the mixolimnion regulates a heliothermal effect that creates temperatures in excess of 60 °C in the underlying metalimnion and monimolimnion. The mixolimnion was dynamic in volume and actively mixed. It displayed large pH variations, in-situ calcium carbonate precipitation, and large evaporative volume losses. The depletion of this layer by fall allowed deeper mixing into the metalimnion, more rapid heat exchange, and lower winter lake temperatures. Solubility calculations indicate seasonal biogenic and thermogenic aragonite

  1. Sedimentary Bacteriopheophytin a as an indicator of meromixis in varved lake sediments of Lake Jaczno, north-east Poland, CE 1891-2010

    NASA Astrophysics Data System (ADS)

    Butz, Christoph; Grosjean, Martin; Poraj-Górska, Anna; Enters, Dirk; Tylmann, Wojciech

    2016-09-01

    Trends in eutrophication and meromixis pose serious threats to water quality and biodiversity in freshwater ecosystems around the world. Because long-term observational data rarely exist, it is very difficult to assess whether meromixis is the result of anthropogenic impacts, climate variability, natural ecosystem development or a combination of these factors. Lake sediment proxy-data may help understand how and why eutrophication and meromixis occurred and disappeared in the past. In this study, we present a novel method and proxy to investigate past episodes of meromixis and hypolimnetic anoxia recorded in lake sediments. We use high-resolution (70 × 70 μm/pixel) calibrated hyperspectral imaging of a varved lake sediment core from meromictic Lake Jaczno (north-east Poland), to quantitatively map the spatial distribution of Bacteriopheophytin a (Bphe a) at very high sub-varve (i.e. seasonal) resolution. Bphe a is a bacterial pigment and stable degradation product of Bacteriochlorophyll a (Bchl a), which is produced by anoxygenic phototrophic bacteria (APBs) at the chemocline of meromictic lakes. Using sedimentary Bphe a we infer episodes of meromixis (i.e. long-term hypolimnetic anoxia) and changing mixing conditions (i.e. seasonal temperature, event-based water mixing) for the past ca. 120 years. Absence of meromixis occurred on several occasions. From the beginning of our record in CE 1891 until ca. CE 1918, meromixis was not observed. During this time, green pigments (mainly chlorophyll a [Chl a] and diagenetic products) produced by phototrophic algae were deposited while Bphe a was absent. This suggests that regular lake overturning prevented the formation of a persistent chemocline. Bphe a was identified before CE 1890 (Butz et al. 2015), but over the studied period 1891-2011, meromixis was established in CE 1918 and generally persisted through modern times. However, short-term interruptions of the chemocline were observed following events of rapid

  2. Will Lake Michigan lake trout meet the Great Lakes Strategy 2002 PCB reduction goal?

    PubMed

    Stow, Craig A; Lamon, E Conrad; Qian, Song S; Schrank, Candy S

    2004-01-15

    The Great Lakes Strategy 2002 establishes the long-term goal that all Great Lakes fish should be safe to eat without restriction. As an indicator of progress toward that goal, the Strategy specifies that lake trout PCBs will decline 25% from 2000 to 2007. We estimated the plausibility of achieving this near-term goal by examining a time-series of Lake Michigan lake trout PCB concentrations from 1972 to 2000. We used two different Bayesian approaches, Bayesian model averaging (BMA) and dynamic linear models (DLM), to model the trajectory of these historical data and forecast concentrations through 2007. Both approaches indicate that the probability of a 25% reduction from 2000 to 2007 is negligible. The most likely lake trout PCB declines predicted by the BMA and DLM over this time period are 6.8% and 8.9%, respectively. Our results suggest that declines in lake trout PCBs will be in the range of 5-10% assuming conditions similar to recent years. This rate of decline will be difficult to discern without adequate data collection. If sufficient data are not gathered to document further declines, then the relaxation of lake trout consumption advisories is indeed a long-term prospect.

  3. 14 CFR 93.69 - Special requirements, Lake Campbell and Sixmile Lake Airports.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Special requirements, Lake Campbell and... Anchorage, Alaska, Terminal Area § 93.69 Special requirements, Lake Campbell and Sixmile Lake Airports. Each person operating an aircraft to or from Lake Campbell or Sixmile Lake Airport shall conform to the flow...

  4. PLAT X41601 EAST (SALT LAKE CITY CEMETERY LOCATER), SALT LAKE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PLAT X-4-160-1 EAST (SALT LAKE CITY CEMETERY LOCATER), SALT LAKE CITY, UT. VIEW LOOKING SOUTH AT CEMETERY BETWEEN OLIVE STREET (1020 EAST) AND 1000 EAST STREET, REPHOTOGRAPH OF HISTORIC SHIPLER PHOTO # 12049, UTAH STATE HISTORICAL SOCIETY COLLECTION. - Salt Lake City Cemetery, 200 N Street, Salt Lake City, Salt Lake County, UT

  5. 14 CFR 93.69 - Special requirements, Lake Campbell and Sixmile Lake Airports.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Sixmile Lake Airports. 93.69 Section 93.69 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... Anchorage, Alaska, Terminal Area § 93.69 Special requirements, Lake Campbell and Sixmile Lake Airports. Each person operating an aircraft to or from Lake Campbell or Sixmile Lake Airport shall conform to the...

  6. 77 FR 39638 - Safety Zone; Barbara Harder Wedding Fireworks, Lake Erie, Lake View, NY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-05

    ... No. USCG-2012-0568] RIN 1625-AA00 Safety Zone; Barbara Harder Wedding Fireworks, Lake Erie, Lake View... temporary safety zone on Lake Erie, Lake View, NY. This safety zone is intended to restrict vessels from a portion of Lake Erie during the Barbara Harder Wedding Fireworks. This temporary safety zone is necessary...

  7. 75 FR 20920 - Safety Zone; Lake Havasu Grand Prix, Lake Havasu, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-22

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lake Havasu Grand Prix, Lake Havasu, AZ... temporary safety zone upon the navigable waters of Lake Havasu on the Colorado River in Lake Havasu City, Arizona for the Lake Havasu Grand Prix. This temporary safety zone is necessary to provide for the safety...

  8. 75 FR 13232 - Safety Zone; Lake Mead Intake Construction, Lake Mead, Boulder City, NV

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-19

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lake Mead Intake Construction, Lake Mead... establishing a safety zone on the navigable waters of Lake Mead in support of the construction project for Lake... Pipe from Lake Mead throughout 2010. This safety zone is necessary to ensure non-authorized personnel...

  9. 78 FR 17097 - Safety Zone; Lake Havasu Triathlon; Lake Havasu City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-20

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lake Havasu Triathlon; Lake Havasu City, AZ... temporary safety zone within the navigable waters of Lake Havasu and the London Bridge Channel for the Lake... Triathlon will consist of 600 participants. The waterside swim course consists of 1500 meters in Lake Havasu...

  10. 76 FR 2579 - Safety Zone; Lake Mead Intake Construction, Lake Mead, Boulder City, NV

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-14

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lake Mead Intake Construction, Lake Mead... establishing a safety zone on the navigable waters of Lake Mead in support of the construction project for Lake... blasting operations for the placement of a water intake pipe in Lake Mead during the first 6 months of 2011...

  11. Congener specific PCB distribution in lake trout/siscowets and walleye from the Great Lakes

    SciTech Connect

    Zabik, M.J.; Zabik, M.E.; Booren, A.M.; Daubenmire, S.; Pascall, M.; Dickmann, G.; Khedr, G.

    1995-12-31

    Lean lake trout (Salvelinus namaycush) from Lakes Huron, Michigan and Ontario and siscowets (fat lake trout) from Lake Superior as well as walleye (Stizotedium vitreum vitreum) from Lakes Erie, Huron and Michigan were analyzed for 53 PCB congeners commonly found in Aroclor 1254. The average PCB congener pattern is presented for a minimum of 12 fish from each species from each lake and the distribution of PCB congeners among species and lakes is compared. Greater differences were found for the lake source of the lake trout than for the walleye. Lake trout from Lake Ontario had high levels of congener 198. Lake trout from Lakes Huron and Superior also tended to have higher levels of higher chlorinated congeners while lake trout from Lake Michigan had the highest levels of the lower chlorinated congeners. Fewer lake effect differences were found for distribution of PCB congeners for the walleye. Walleye from Lake Huron had a greater percentage of the total PCB congeners with lower chlorination than did lake trout but the pattern of percent of total for lake trout and walleye from Lake Michigan was quite similar.

  12. NASA Satellite Scares Up An Eerie Image of Haunted Lakes and Ghost Ships

    NASA Image and Video Library

    2011-10-29

    NASA Terra satellite presents this false color view of portions of Wisconsin and Michigan, including Devil Lake, Druid Lake, Ghost Lake, Spider Lake, and Witches Lake in Wisconsin; and Bat Lake, Corpse Pond and Witch Lake in Michigan.

  13. Ecosystem Dynamics of the Microbial Mats in Lake Fryxell, Antarctica

    NASA Astrophysics Data System (ADS)

    Krusor, M.; Mackey, T. J.; Hawes, I.; Jungblut, A. D.; Eisen, J.; Sumner, D. Y.

    2016-12-01

    Microbial communities drive biogeochemical cycles on Earth at micron scales, at which microbial ecosystem networks are highly interconnected to each other and their local environment through trophic interactions and the availability of electron acceptors. Feedbacks among microorganisms and environmental conditions structure microbial communities and micron-scale geochemical gradients. We are exploring interactions among microbial community structure and local geochemistry in Lake Fryxell, a perennially ice-covered, meromictic lake in the McMurdo Dry Valleys, Antarctica. In Lake Fryxell, O2 concentration and photosynthetically active radiation (PAR) decline with depth and influence layered benthic mats, which consist of microorganisms from all three domains. These layered mats change pigmentation and morphology with depth in the lake. In 2012, samples were collected for 16S rRNA and metagenomic sequencing in collaboration with the McMurdo Dry Valleys Long Term Ecological Research program. Samples were collected at 9.0, 9.35, and 9.8 m depth with temperature, pressure, O2 concentration, conductivity, PAR, irradiance, and morphology. O2 microelectrode profiles were also collected. At 9.0 and 9.35 m depths, PAR was relatively high, and the water was supersaturated with O2. At 9.8 m depth, PAR was low and lake water was anoxic, but 50 µmol L-1 of O2 was produced by cyanobacteria, creating a mm-thick zone with free O2 in the mat under anoxic water. As in many microbial mats, community-O2 correlations are present in Lake Fryxell: diversity increases with increasing depth into the mat at all lake depths, and diversity decreases with increasing depth in the lake. Microbial communities are less diverse and the dominant phototrophs change at lower PAR and O2 concentrations. Further, O2 generated by cyanobacteria creates a habitat for aerobic and microaerophilic heterotrophs under an anoxic water column. Some lineages, particularly alpha- and gammaproteobacteria and the

  14. EPA Research Strengthens Great Lakes Restoration Initiative

    EPA Science Inventory

    As the largest group of freshwater lakes on Earth, the Great Lakes (Lakes Erie, Huron, Michigan, Ontario and Superior) are a source of economic prosperity, recreation and raw materials. Human activity, however, has resulted in pollution and other stressors. The Great Lakes curren...

  15. TOXAPHENE IN THE GREAT LAKES. (R825246)

    EPA Science Inventory

    This paper presents the most current data for toxaphene in the water, sediments, and biota of the Laurentian Great Lakes of North America. Concentrations in water range from 1.1 ng/L in Lake Superior to 0.17 ng/L in Lake Ontario. Lake Superior has the highest water concentrati...

  16. EPA Research Strengthens Great Lakes Restoration Initiative

    EPA Science Inventory

    As the largest group of freshwater lakes on Earth, the Great Lakes (Lakes Erie, Huron, Michigan, Ontario and Superior) are a source of economic prosperity, recreation and raw materials. Human activity, however, has resulted in pollution and other stressors. The Great Lakes curren...

  17. 27 CFR 9.177 - Alexandria Lakes.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...; then (3) Along the shoreline until the point where the Lake Carlos shoreline parallels an unlabeled... point at BM 1411; then (7) North from BM 1411 in a straight line to the south shoreline of Lake Miltona; then (8) Generally west along the south shoreline of Lake Miltona onto the Lake Miltona West, Minn....

  18. TOXAPHENE IN THE GREAT LAKES. (R825246)

    EPA Science Inventory

    This paper presents the most current data for toxaphene in the water, sediments, and biota of the Laurentian Great Lakes of North America. Concentrations in water range from 1.1 ng/L in Lake Superior to 0.17 ng/L in Lake Ontario. Lake Superior has the highest water concentrati...

  19. 27 CFR 9.127 - Cayuga Lake.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Cayuga Lake. 9.127 Section... Lake. (a) Name. The name of the viticultural area described in this section is “Cayuga Lake.” (b) Approved maps. The appropriate map for determining the boundaries of the Cayuga Lake viticultural area is...

  20. 27 CFR 9.34 - Finger Lakes.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Finger Lakes. 9.34 Section... Lakes. (a) Name. The name of the viticultural area described in this section is “Finger Lakes.” (b) Approved maps. The appropriate maps for determining the boundaries of the Finger Lakes viticultural area...

  1. 33 CFR 125.08 - Great Lakes.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Great Lakes. 125.08 Section 125... VESSELS § 125.08 Great Lakes. The term Great Lakes as used in the regulations in this subchapter shall include the Great Lakes and their connecting and tributary waters. ...

  2. 33 CFR 125.08 - Great Lakes.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Great Lakes. 125.08 Section 125... VESSELS § 125.08 Great Lakes. The term Great Lakes as used in the regulations in this subchapter shall include the Great Lakes and their connecting and tributary waters. ...

  3. 27 CFR 9.127 - Cayuga Lake.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Cayuga Lake. 9.127 Section... Lake. (a) Name. The name of the viticultural area described in this section is “Cayuga Lake.” (b) Approved maps. The appropriate map for determining the boundaries of the Cayuga Lake viticultural area is...

  4. 33 CFR 125.08 - Great Lakes.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Great Lakes. 125.08 Section 125... VESSELS § 125.08 Great Lakes. The term Great Lakes as used in the regulations in this subchapter shall include the Great Lakes and their connecting and tributary waters. ...

  5. 33 CFR 125.08 - Great Lakes.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Great Lakes. 125.08 Section 125... VESSELS § 125.08 Great Lakes. The term Great Lakes as used in the regulations in this subchapter shall include the Great Lakes and their connecting and tributary waters. ...

  6. 33 CFR 125.08 - Great Lakes.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Great Lakes. 125.08 Section 125... VESSELS § 125.08 Great Lakes. The term Great Lakes as used in the regulations in this subchapter shall include the Great Lakes and their connecting and tributary waters. ...

  7. 27 CFR 9.127 - Cayuga Lake.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Cayuga Lake. 9.127 Section... Lake. (a) Name. The name of the viticultural area described in this section is “Cayuga Lake.” (b) Approved maps. The appropriate map for determining the boundaries of the Cayuga Lake viticultural area is...

  8. Increased piscivory by lake whitefish in Lake Huron

    USGS Publications Warehouse

    Pothoven, Steven A.; Madenjian, Charles P.

    2013-01-01

    We evaluated the diet of Lake Whitefish Coregonus clupeaformis in Lake Huron during 2002–2011 to determine the importance of Round Goby Neogobius melanostomus and other fish as prey items. Lake Whitefish that had reached approximately 400 mm in length incorporated fish into their diets. The overall percentage of adult Lake Whitefish in Lake Huron that had eaten fish increased from 10% in 2002–2006 to 20% in 2007–2011, with a corresponding decrease in the frequency of Lake Whitefish that ate Dreissena spp. from 52% to 33%. During 2002–2006, Round Goby (wet mass, 38%), sculpins (Cottidae) (34%), and Ninespine Stickleback Pungitius pungitius (18%) were the primary fish eaten, whereas Round Goby accounted for 92% of the fish eaten in 2007–2011. Overall, Round Goby were found in the fewest Lake Whitefish stomachs in the north region of Lake Huron (6%) and in the most in the central (23%) and south (19%) regions of the lake. In the central region, Round Goby were eaten during all seasons that were sampled (spring through fall). In the south region, Round Goby were eaten only in the winter and spring but not in the summer when Dreissena spp. and spiny water flea Bythotrephes longimanus dominated the diet. Based on the 2007–2011 diet composition, an individual Lake Whitefish would need to have increased their consumption relative to that in 1983–1994 by 6% in the north region, 12% in the central region, and 41% in the southern region in order to achieve the same growth that was observed before dreissenid mussels arrived. However, Lake Whitefish weight adjusted for length only increased by 2% between 2002–2006 and 2007–2011 in the central region, decreased by 4% in the northern region, and remained constant in the southern region. This suggests that a shift toward more frequent piscivory does not necessarily improve the condition of a generalist feeder like Lake Whitefish.

  9. Temporal dynamics of active Archaea in oxygen-depleted zones of two deep lakes.

    PubMed

    Hugoni, Mylène; Domaizon, Isabelle; Taib, Najwa; Biderre-Petit, Corinne; Agogué, Hélène; Galand, Pierre E; Debroas, Didier; Mary, Isabelle

    2015-04-01

    Deep lakes are of specific interest in the study of archaeal assemblages as chemical stratification in the water column allows niche differentiation and distinct community structure. Active archaeal community and potential nitrifiers were investigated monthly over 1 year by pyrosequencing 16S rRNA transcripts and genes, and by quantification of archaeal amoA genes in two deep lakes. Our results showed that the active archaeal community patterns of spatial and temporal distribution were different between these lakes. The meromictic lake characterized by a stable redox gradient but variability in nutrient concentrations exhibited large temporal rearrangements of the dominant euryarchaeal phylotypes, suggesting a variety of ecological niches and dynamic archaeal communities in the hypolimnion of this lake. Conversely, Thaumarchaeota Marine Group I (MGI) largely dominated in the second lake where deeper water layers exhibited only short periods of complete anoxia and constant low ammonia concentrations. Investigations conducted on archaeal amoA transcripts abundance suggested that not all lacustrine Thaumarchaeota conduct the process of nitrification. A high number of 16S rRNA transcripts associated to crenarchaeal group C3 or the Miscellaneous Euryarchaeotic Group indicates the potential for these uncharacterized groups to contribute to nutrient cycling in lakes. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  10. The Great Lakes' regional climate regimes

    NASA Astrophysics Data System (ADS)

    Sugiyama, Noriyuki

    For the last couple of decades, the Great Lakes have undergone rapid surface warming. In particular, the magnitude of the summer surface-warming trends of the Great Lakes have been much greater than those of surrounding land (Austin and Colman, 2007). Among the Great Lakes, the deepest Lake Superior exhibited the strongest warming trend in its annual, as well as summer surface water temperature. We find that many aspects of this behavior can be explained in terms of the tendency of deep lakes to exhibit multiple regimes characterized, under the same seasonally varying forcing, by the warmer and colder seasonal cycles exhibiting different amounts of wintertime lake-ice cover and corresponding changes in the summertime lake-surface temperatures. In this thesis, we address the problem of the Great Lakes' warming using one-dimensional lake modeling to interpret diverse observations of the recent lake behavior. (Abstract shortened by ProQuest.).

  11. Persistent Ice on Lake Superior

    NASA Image and Video Library

    2017-09-27

    Though North America is a full month into astronomical spring, the Great Lakes have been slow to give up on winter. As of April 22, 2014, the Great Lakes were 33.9 percent ice covered. The lake they call Superior dominated the pack. In the early afternoon on April 20, 2014, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this natural-color image of Lake Superior, which straddles the United States–Canada border. At the time Aqua passed over, the lake was 63.5 percent ice covered, according to the NOAA Great Lakes Environmental Research Lab (GLERL). Averaged across Lake Superior, ice was 22.6 centimeters (8.9 inches) thick; it was as much as twice that thickness in some locations. GLERL researcher George Leshkevich affirmed that ice cover this spring is significantly above normal. For comparison, Lake Superior had 3.6 percent ice cover on April 20, 2013; in 2012, ice was completely gone by April 12. In the last winter that ice cover grew so thick on Lake Superior (2009), it reached 93.7 percent on March 2 but was down to 6.7 percent by April 21. Average water temperatures on all of the Great Lakes have been rising over the past 30 to 40 years and ice cover has generally been shrinking. (Lake Superior ice was down about 79 percent since the 1970s.) But chilled by persistent polar air masses throughout the 2013-14 winter, ice cover reached 88.4 percent on February 13 and 92.2 percent on March 6, 2014, the second highest level in four decades of record-keeping. Air temperatures in the Great Lakes region were well below normal for March, and the cool pattern is being reinforced along the coasts because the water is absorbing less sunlight and warming less than in typical spring conditions. The graph below, based on data from Environment Canada, shows the 2014 conditions for all of the Great Lakes in mid-April compared to the past 33 years. Lake Superior ice cover got as high as 95.3 percent on March 19. By April 22, it was

  12. Rehabilitation of Delavan Lake, Wisconsin

    USGS Publications Warehouse

    Robertson, Dale M.; Goddard, Gerald L.; Helsel, D.R.; MacKinnon, Kevin L.

    2009-01-01

    A comprehensive rehabilitation plan was developed and implemented to shift Delavan Lake, Wisconsin, from a hypereutrophic to a mesotrophic condition. The plan was threefold: (1) reduce external phosphorus (P) loading by applying Best Management Practices in the watershed, enhance an existing wetland, and short-circuit the inflows through the lake, (2) reduce internal P loading by treating the sediments with alum and removing carp, and (3) rehabilitate the fishery by removing carp and bigmouth buffalo and adding piscivores (biomanipulation). The first and second parts of the plan met with only limited success. With only minor reductions in internal and external P loading, P concentrations in the lake returned to near pre-treatment concentrations. The intensive biomanipulation and resulting trophic cascade (increased piscivores, decreased planktivores, increased large zooplankton populations, and reduced phytoplankton populations) eliminated most of the original problems in the lake (blue-green algal blooms and limited water clarity). However, now there is extensive macrophyte growth and abundant filamentous algae. Without significantly reducing the sources of the problems (high P loading) in Delavan Lake, the increased water clarity may not last. With an improved understanding of the individual components of this rehabilitation program, better future management plans can be developed for Delavan Lake and other lakes and reservoirs with similar eutrophication problems.

  13. Early Holocene Great Salt Lake

    USGS Publications Warehouse

    Oviatt, Charles G.; Madsen, David B.; Miller, David; Thompson, Robert S.; McGeehin, John P.

    2015-01-01

    Shorelines and surficial deposits (including buried forest-floor mats and organic-rich wetland sediments) show that Great Salt Lake did not rise higher than modern lake levels during the earliest Holocene (11.5–10.2 cal ka BP; 10–9 14C ka BP). During that period, finely laminated, organic-rich muds (sapropel) containing brine-shrimp cysts and pellets and interbedded sodium-sulfate salts were deposited on the lake floor. Sapropel deposition was probably caused by stratification of the water column — a freshwater cap possibly was formed by groundwater, which had been stored in upland aquifers during the immediately preceding late-Pleistocene deep-lake cycle (Lake Bonneville), and was actively discharging on the basin floor. A climate characterized by low precipitation and runoff, combined with local areas of groundwater discharge in piedmont settings, could explain the apparent conflict between evidence for a shallow lake (a dry climate) and previously published interpretations for a moist climate in the Great Salt Lake basin of the eastern Great Basin.

  14. Microplastics in Taihu Lake, China.

    PubMed

    Su, Lei; Xue, Yingang; Li, Lingyun; Yang, Dongqi; Kolandhasamy, Prabhu; Li, Daoji; Shi, Huahong

    2016-09-01

    In comparison with marine environments, the occurrence of microplastics in freshwater environments is less understood. In the present study, we investigated microplastic pollution levels during 2015 in Taihu Lake, the third largest Chinese lake located in one of the most developed areas of China. The abundance of microplastics reached 0.01 × 10(6)-6.8 × 10(6) items/km(2) in plankton net samples, 3.4-25.8 items/L in surface water, 11.0-234.6 items/kg dw in sediments and 0.2-12.5 items/g ww in Asian clams (Corbicula fluminea). The average abundance of microplastics was the highest in plankton net samples from the southeast area of the lake and in the sediments from the northwest area of the lake. The northwest area of the lake was the most heavily contaminated area of the lake, as indicated by chlorophyll-α and total phosphorus. The microplastics were dominated by fiber, 100-1000 μm in size and cellophane in composition. To our best knowledge, the microplastic levels measured in plankton net samples collected from Taihu Lake were the highest found in freshwater lakes worldwide. The ratio of the microplastics in clams to each sediment sample ranged from 38 to 3810 and was negatively correlated to the microplastic level in sediments. In brief, our results strongly suggest that high levels of microplastics occurred not only in water but also in organisms in Taihu Lake.

  15. Monitoring Change in Great Salt Lake

    NASA Astrophysics Data System (ADS)

    Naftz, David; Angeroth, Cory; Freeman, Michael; Rowland, Ryan; Carling, Gregory

    2013-08-01

    Great Salt Lake is the largest hypersaline lake in the Western Hemisphere and the fourth largest terminal lake in the world (Figure 1). The open water and adjacent wetlands of the Great Salt Lake ecosystem support millions of migratory waterfowl and shorebirds from throughout the Western Hemisphere [Aldrich and Paul, 2002]. In addition, the area is of important economic value: Brine shrimp (Artemia franciscana) residing in Great Salt Lake support an aquaculture shrimp cyst industry with annual revenues as high as $60 million.

  16. Hydrological investigation of a multi-stratified pit lake using radioactive and stable isotopes combined with hydrometric monitoring

    NASA Astrophysics Data System (ADS)

    Sánchez-España, Javier; Diez Ercilla, Marta; Pérez Cerdán, Fernando; Yusta, Iñaki; Boyce, Adrian J.

    2014-04-01

    The internal configuration and hydrological dynamics of meromictic pit lakes is often complex and needs to be studied by different tools including stable and radiogenic isotopes. This study combines a multi-isotopic approach (3Hw, δ2Hw, δ18Ow, δ34SSO4) with meteorological, hydrological and hydrochemical monitoring to deduce the flooding history and hydrological dynamics of a meromictic and deeply stratified pit lake (Cueva de la Mora mine, SW Spain). The mine system is complex and includes horizontal galleries, shafts and large rooms physically connected to the mine pit. Specific conductance and temperature profiles obtained in the pit lake draw a physical structure with four monimolimnetic sub-layers of increasing density with depth. This characteristic stratification with m-scale layers separated by sharp transitional zones is rather unusual in other pit lakes and in most natural lakes. Tritium abundance in the different layers indicates that the deep lake water entered the pit basin between 1971 and 1972 which is coincident with the dates of mine closure. The oxygen and deuterium isotope composition of the different layers describes a marked and stable stratification, with an increasing evaporative influence towards the lake surface and a minimal influence of groundwater flow on the structure and composition of the monimolimnion. This study reveals that the initial stages of flooding (via influx of metal- and sulfate-loaded mine drainage from underlying galleries at different depths) may be essential to imprint a layered physical structure to pit lakes which would be very difficult to explain merely by physical processes. After reaching its present water level and morphology, the monimolimnion of this pit lake seems to have remained essentially isolated and chemically unmodified during decades.

  17. Maintaining meromixis in Lake Pavin (Auvergne, France): The key role of a sublacustrine spring

    NASA Astrophysics Data System (ADS)

    Bonhomme, Céline; Poulin, Michel; Vinçon-Leite, Brigitte; Saad, Mohamed; Groleau, Alexis; Jézéquel, Didier; Tassin, Bruno

    2011-11-01

    Lake Pavin is a deep meromictic lake. Its water column is divided into two parts: the mixolimnion, which is subjected to mixing during seasonal overturns; and the monimolimnion which remains unmixed. Using high precision and high frequency temperature and conductivity profiles along with continuous temperature measurements, this study reveals the presence of a sublacustrine, intermittent cold spring at the bottom of the mixolimnion at a depth between 50 and 55 m. This cold-water input rises in the water column by saline convection. The use of a simple conceptual model, representing turbulent diapycnal diffusivity and convection correlated with the presence of the spring within the water column indicates its role in maintaining the meromixis characteristic of the lake on the intra-annual time scale. The spring also influences seasonal overturns and thus contributes to establish the depth of the mixolimnion-monimolimnion interface on the inter-annual time scale.

  18. Biogeochemistry of Kenyan Rift Valley Lake Sediments

    NASA Astrophysics Data System (ADS)

    Grewe, Sina; Kallmeyer, Jens

    2013-04-01

    The numerous lakes in the Kenyan Rift Valley show strong hydrochemical differences due to their varying geologic settings. There are freshwater lakes with a low alkalinity like Lake Naivasha on the one hand and very salt-rich lakes with high pH values like Lake Logipi on the other. It is known that the underlying lake sediments are influenced by the lake chemistry and by the microorganisms in the sediment. The aim of this work is to provide a biogeochemical characterization of the lake sediments and to use these data to identify the mechanisms that control lake chemistry and to reconstruct the biogeochemical evolution of each lake. The examined rift lakes were Lakes Logipi and Eight in the Suguta Valley, Lakes Baringo and Bogoria south of the valley, as well as Lakes Naivasha, Oloiden, and Sonachi on the Kenyan Dome. The porewater was analysed for different ions and hydrogen sulphide. Additionally, alkalinity and salinity of the lake water were determined as well as the cell numbers in the sediment, using fluorescent microscopy. The results of the porewater analysis show that the overall chemistry differs considerably between the lakes. In some lakes, concentrations of fluoride, chloride, sulphate, and/or hydrogen sulphide show strong concentration gradients with depth, whereas in other lakes the concentrations show only minor variations. Fluoride is present in all lakes; the lowest concentration is found in Lake Oloiden (60 - 90 mg/l), the highest one in Lake Bogoria (1,025 - 1,930 mg/l). The lakes show also large differences in sulphate concentrations. The values vary between 2 mg/l in Lake Baringo and 15,250 mg/l in Lake Eight. In all cores, sulphate concentration does not change significantly with depth; however, there is a distinct peak in each core, raising the question of synchronicity. As expected, chloride concentrations correlate with total salinity. There is no hydrogen sulphide present in the porewater of Lakes Naivasha, Baringo, and Oloiden, whereas in

  19. Great Salt Lake, Utah, USA

    NASA Technical Reports Server (NTRS)

    1990-01-01

    As seen from space, the Great Salt Lake, Utah, USA (41.5N, 112.5W) appears as two separate bodies of water with a narrow divider in the middle. At the turn of the century, a railroad bridge without culverts, was built across the lake and ever since, the water and salinity levels have been uneqal on either side. Fed by snowmelt from the nearby Wasatch Mountains, the lake in recent years has had record high water levels, threatening to flood the local areas.

  20. Great Salt Lake, Utah, USA

    NASA Image and Video Library

    1990-03-04

    As seen from space, the Great Salt Lake, Utah, USA (41.5N, 112.5W) appears as two separate bodies of water with a narrow divider in the middle. At the turn of the century, a railroad bridge without culverts, was built across the lake and ever since, the water and salinity levels have been uneqal on either side. Fed by snowmelt from the nearby Wasatch Mountains, the lake in recent years has had record high water levels, threatening to flood the local areas.

  1. RAINBOW LAKE WILDERNESS AND FLYNN LAKE WILDERNESS STUDY AREA, WISCONSIN.

    USGS Publications Warehouse

    Cannon, W.F.; Dunn, Maynard L.

    1984-01-01

    The Rainbow Lake Wilderness and Flynn Lake Wilderness study area in Wisconsin are contiguous and were studied as a unit. The rainbow Lake Wilderness contains a demonstrated resource of about 210,000 tons of commercial-quality peat in an area of substantiated peat resource potential. The Flynn Lake Wilderness study area contains a demonstrated resource of about 300,000 tons of commercial-quality peat in an area of substantiated peat resource potential. These deposits, however, are of limited importance because larger deposits of similar material are abundant outside the areas, closer to present markets. Rocks in the subsurface contain a low-grade copper resource identified by mining company exploration drilling. Although this is an area of substantiated copper resource potential, it is a low-grade resource, thin and generally at great depth.

  2. Physical, chemical and biological processes in Lake Vostok and other Antarctic subglacial lakes.

    PubMed

    Siegert, M J; Ellis-Evans, J C; Tranter, M; Mayer, C; Petit, J R; Salamatin, A; Priscu, J C

    2001-12-06

    Over 70 lakes have now been identified beneath the Antarctic ice sheet. Although water from none of the lakes has been sampled directly, analysis of lake ice frozen (accreted) to the underside of the ice sheet above Lake Vostok, the largest of these lakes, has allowed inferences to be made on lake water chemistry and has revealed small quantities of microbes. These findings suggest that Lake Vostok is an extreme, yet viable, environment for life. All subglacial lakes are subject to high pressure (approximately 350 atmospheres), low temperatures (about -3 degrees C) and permanent darkness. Any microbes present must therefore use chemical sources to power biological processes. Importantly, dissolved oxygen is available at least at the lake surface, from equilibration with air hydrates released from melting basal glacier ice. Microbes found in Lake Vostok's accreted ice are relatively modern, but the probability of ancient lake-floor sediments leads to a possibility of a very old biota at the base of subglacial lakes.

  3. Lake trout in the Great Lakes: Basin-wide stock collapse and binational restoration

    USGS Publications Warehouse

    Hansen, Michael J.; Taylor, William W.; Ferreri, C. Paola

    1999-01-01

    The lake trout (Salvelinus namaycush) was important to the human settlement of each of the Great Lakes, and underwent catastrophic collapses in each lake in the nineteenth and twentieth centuries. The timing of lake trout stock collapses were different in each lake, as were the causes of the collapses, and have been the subject of much scientific inquiry and debate. The purpose of this chapter is to summarize and review pertinent information relating historical changes in Great Lakes lake trout stocks, binational efforts to restore those stocks, and progress toward stock restoration. This presentation attempts to generalize patterns across the Great Lakes, rather than to focus within each lake. Lake specific analyses have been used to understand lake specific causes and effects, but there is continuing debate about some of these causes and effects. A basinwide review may suggest mechanisms for observed changes that are not evident by lake specific analysis.

  4. 11. GRANT LAKE AND MONO LAKE LOOKING NORTH/NORTHEAST Los ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. GRANT LAKE AND MONO LAKE LOOKING NORTH/NORTHEAST - Los Angeles Aqueduct, From Lee Vining Intake (Mammoth Lakes) to Van Norman Reservoir Complex (San Fernando Valley), Los Angeles, Los Angeles County, CA

  5. 10. GRANT LAKE AND MONO LAKE LOOKING EAST/NORTHEAST Los ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. GRANT LAKE AND MONO LAKE LOOKING EAST/NORTHEAST - Los Angeles Aqueduct, From Lee Vining Intake (Mammoth Lakes) to Van Norman Reservoir Complex (San Fernando Valley), Los Angeles, Los Angeles County, CA

  6. Morphological variation of siscowet lake trout in Lake Superior

    USGS Publications Warehouse

    Bronte, C.R.; Moore, S.A.

    2007-01-01

    Historically, Lake Superior has contained many morphologically distinct forms of the lake trout Salvelinus namaycush that have occupied specific depths and locations and spawned at specific times of the year. Today, as was probably the case historically, the siscowet morphotype is the most abundant. Recent interest in harvesting siscowets to extract oil containing omega-3 fatty acids will require additional knowledge of the biology and stock structure of these lightly exploited populations. The objective of this study was to determine whether shape differences exist among siscowet populations across Lake Superior and whether these shape differences can be used to infer stock structure. Morphometric analysis (truss protocol) was used to differentiate among siscowets sampled from 23 locations in Lake Superior. We analyzed 31 distance measurements among 14 anatomical landmarks taken from digital images of fish recorded in the field. Cluster analysis of size-corrected data separated fish into three geographic groups: The Isle Royale, eastern (Michigan), and western regions (Michigan). Finer scales of stock structure were also suggested. Discriminant function analysis demonstrated that head measurements contributed to most of the observed variation. Cross-validation classification rates indicated that 67–71% of individual fish were correctly classified to their region of capture. This is the first study to present shape differences associated with location within a lake trout morphotype in Lake Superior.

  7. Restoration in northern Lake Gehu, a eutrophic lake in China

    NASA Astrophysics Data System (ADS)

    Wu, Xiaodong; Li, Wenchao; Pan, Jizheng; Ma, Shuzhan; Chen, Bingfa; He, Shangwei

    2017-02-01

    Lake Gehu is a severely eutrophic lake in southeast China. A series of restoration measures have been implemented since 2009 in northern Lake Gehu. This study compared aquatic plants, water quality, sediment, and phytoplankton between restoration and control areas to investigate the effect of restoration measures. The results demonstrated that aquatic macrophyte coverage increased from 0% to 10.6%; mean TP, TN, and CODMn concentrations increased by 50.0%, 42.4%, and 40.8%, respectively, compared with those before the measures were carried out; the mean Secchi depth (SD) increased to 42.5 cm, which is 1.4 times higher than that before restoration; the mean euphotic depth (Zeu) in the summer increased from 91 to 130 cm; the mean chl a concentration decreased from 34.8 to 20.2 μg/L, compared with that before restoration; the Shannon-Wiener index of phytoplankton increased by 28.7%. The mean TP and TN concentrations in sediments decreased by 63.8% and 52.4%, respectively, compared with that before dredging. These results indicate that the restoration in northern Lake Gehu was effective. To complete the transformation from an algae- to a macrophyte-stable state within the region, further measures must be adopted. This restoration of a eutrophic lake can serve as a reference for similar eutrophic lakes.

  8. Lakes and lake-like waters of the Hawaiian Archipelago

    USGS Publications Warehouse

    Maciolek, J.A.

    1982-01-01

    This summary of Hawaiian lacustrine limnology is based on 12 years of field and literature surveys of archipelagic inland waters. Lakes here are distinguished from other standing waters by limits on surface oceanic area (> 0.1 ha) and depth (> 2 m), and by the absence of flatural surface oceanic connection. A variety of extinct and existing water bodies, sometimes referred to as lakes, are noted. Six lakes are described. Five of them are in crater basins, 3 are freshwater, and 2 are elevated (highest = 3969 m). The scarcity of elevated lakes results from general permeability of the substrata. Among the 6 lakes, surface areas range from 0.22 to 88 ha and maximum depths from 3 to 248 m. Naturally occurring aquatic biota generally is low in species diversity except for phytoplankton; fishes and submersed vascular plants are absent. Two lowland lakes, freshwater Green (Wai a Pele) and saline Kauhak6, are described for the first time. Profundal Kauhak6, 248 m deep, has a surface area of only 0.35 ha, which results in an extraordinary relative depth of 370%. It is permanently stratified, a condition apparently due primarily to the unique morphometry of its basin. 

  9. Characterization of Lake Michigan coastal lakes using zooplankton assemblages

    USGS Publications Warehouse

    Whitman, Richard L.; Nevers, Meredith B.; Goodrich, Maria L.; Murphy, Paul C.; Davis, Bruce M.

    2004-01-01

    Zooplankton assemblages and water quality were examined bi-weekly from 17 April to 19 October 1998 in 11 northeastern Lake Michigan coastal lakes of similar origin but varied in trophic status and limnological condition. All lakes were within or adjacent to Sleeping Bear Dunes National Lakeshore, Michigan. Zooplankton (principally microcrustaceans and rotifers) from triplicate Wisconsin net (80 I?m) vertical tows taken at each lake's deepest location were analyzed. Oxygen-temperature-pH-specific conductivity profiles and surface water quality were concurrently measured. Bray-Curtis similarity analysis showed small variations among sample replicates but large temporal differences. The potential use of zooplankton communities for environmental lake comparisons was evaluated by means of BIOENV (Primer 5.1) and principal component analyses. Zooplankton analyzed at the lowest identified taxonomic level yielded greatest sensitivity to limnological variation. Taxonomic and ecological aggregations of zooplankton data performed comparably, but less well than the finest taxonomic analysis. Secchi depth, chlorophyll a, and sulfate concentrations combined to give the best correlation with patterns of variation in the zooplankton data set. Principal component analysis of these variables revealed trophic status as the most influential major limnological gradient among the study lakes. Overall, zooplankton abundance was an excellent indicator of variation in trophic status.

  10. Faro Lake, a big picture from a small ecosystem

    NASA Astrophysics Data System (ADS)

    Saccà, Alessandro

    2017-04-01

    Faro Lake is a small coastal basin located by the Straits of Messina (Central Mediterranean Sea) and is the deepest basin in Sicily and one of the deepest coastal lakes in Italy. Considering the correspondence of the shorelines of the lake with half-graben faults, a tectonic event is the most likely explanation for its remarkable depth (30 m in the central region). Due to its funnel-shape bathymetry and its limited water exchanges with the nearby sea, Faro Lake shows the typical trait of a meromictic basin, that is a persistent physical and chemical stratification of the water column. While the upper water layer is well oxygenated, chiefly due to advection processes, the bottom layer is anoxic and characterized by a vertical gradient of hydrogen sulfide concentration, reaching a maximum at the water/sediment interface. A transition zone also exists between these two layers where oxygen concentration sharply decreases with depth. As a result of this environmental heterogeneity, a variety of ecological niches arise along the water column of Faro Lake, which are exploited by a host of prokaryote groups showing a multiplicity of metabolic pathways. These microbes, in turn, affect the chemical gradients of the water column in a complex interplay and also serve as a food source for microbial eukaryotes in the so-called microbial food web. In summer, thanks to enhanced light availability and higher water temperature, a bloom of brown-colored photosynthetic sulfur bacteria develops in the upper part of the anoxic zone, resulting in a distinct "red water layer", coupled with significantly high biomasses of ciliated protozoa. During my researches, I have documented and quantified the trophic interactions between phagotrophic protozoa and the prokaryotes thriving in the "red water layer". I have also found a peculiar photosynthetic sulfur bacterium and a unique bacteriochlorophyll homologue that have been retrieved, to date, only from Faro Lake and from the Black Sea. I have

  11. Elemental sulfur in the brine of Lake Doroninskoe (Eastern Transbaikalia)

    NASA Astrophysics Data System (ADS)

    Zamana, L. V.; Borzenko, S. V.

    2011-06-01

    The concentration of elemental sulfur (S0) in the upper oxic layer of the meromictic (stratified by water mineralization) soda Lake Doroninskoe (about 5.5 m depth) varied in the survey periods from the detection limit (0.002 mg/l) to the registered maximum of 0.444 mg/l, with an average value of 0.12 mg/l. In the lower hydrosulfide layer, these concentrations amounted to 0.012-1.88 mg/l. The results obtained point to the processes of sulfide sulfur oxidation under reductive conditions, and of sulfate reduction to form hydrogen sulfide in the oxic medium. The dynamics of the seasonal S0-thiosulfate ratio testifies to the dual (oxidative and reductive) nature of the latter.

  12. Water Level Fluctuations of Lake Enriquillo and Lake Saumatre in Response to Environmental Changes

    NASA Astrophysics Data System (ADS)

    Poteau, D.; Romero Luna, E. J.; Walter, M. T.; Steenhuis, T. S.

    2011-12-01

    The water levels of Lake Saumatre in Haiti and Lake Enriquillo in the Dominican Republic have been increasing continuously for the past 5-10 years. As result roads and lake shore agriculture are flooded and there is an interest in determining the causes of the continuous lake growth and finding solutions to reverse the trend Various theories haven proposed for growth of the lakes such as climate change and deforestation. Deforestation would affect the hydrological balance by means of changing infiltration rates. To examine the temporal variations in the lake, the lake surface areas during the past 30 years were obtained from available satellite data and converted into volumes. These lake surface areas showed a steady increase starting in 2003 for Lake Saumatre and in 2008 for Lake Enriquillo. Land cover change obtained by means of remote sensing for the years of 1986 and 2010 showed no significant change and could therefore be ruled out as a cause for the lake levels increases. A simple water balance model that had been validated for monsoon climates matched the lake level volumes fluctuations well for the last 30 years including the recent rise in lake levels. Thus the lake level increases could be directly related to the greater precipitation starting some 10 years ago. The difference in starting time of lake level rise between the two lakes could be explained by a larger storage capacity in the a Lake Enriquillo watershed compared to the Lake Saumatre watershed

  13. Spatial variation among lakes within landscapes: Ecological organization along lake chains

    USGS Publications Warehouse

    Soranno, Patricia A.; Webster, Katherine E.; Riera, Joan L.; Kratz, Timothy K.; Baron, Jill S.; Bukaveckas, Paul A.; Kling, George; White, David S.; Caine, Nel; Lathrop, Richard C; Leavitt, Peter R.

    1999-01-01

    Although limnologists have long been interested in regional patterns in lake attributes, only recently have they considered lakes connected and organized across the landscape, rather than as spatially independent entities. Here we explore the spatial organization of lake districts through the concept of landscape position, a concept that considers lakes longitudinally along gradients of geomorphology and hydrology. We analyzed long-term chemical and biological data from nine lake chains (lakes in a series connected through surface or groundwater flow) from seven lake districts of diverse hydrologic and geomorphic settings across North America. Spatial patterns in lake variables driven by landscape position were surprisingly common across lake districts and across a wide range of variables. On the other hand, temporal patterns of lake variables, quantified using synchrony, the degree to which pairs of lakes exhibit similar dynamics through time, related to landscape position only for lake chains with lake water residence times that spanned a wide range and were generally long (close to or greater than 1 year). Highest synchrony of lakes within a lake chain occurred when lakes had short water residence times. Our results from both the spatial and temporal analyses suggest that certain features of the landscape position concept are robust enough to span a wide range of seemingly disparate lake types. The strong spatial patterns observed in this analysis, and some unexplained patterns, suggest the need to further study these scales and to continue to view lake ecosystems spatially, longitudinally, and broadly across the landscape.

  14. Titan Extraterrestrial Land of Lakes

    NASA Image and Video Library

    2013-12-12

    A colorized flyover of Titan's hydrocarbon seas and lakes. Data was collected by the Cassini spacecraft radar instrument between 2004 and 2013 during several flybys of Titan. Heights of features are exaggerated 10 times.

  15. Star patterns on lake ice.

    PubMed

    Tsai, Victor C; Wettlaufer, J S

    2007-06-01

    Star patterns, reminiscent of a wide range of diffusively controlled growth forms from snowflakes to Saffman-Taylor fingers, are ubiquitous features of ice-covered lakes. Despite the commonality and beauty of these "lake stars," the underlying physical processes that produce them have not been explained in a coherent theoretical framework. Here we describe a simple mathematical model that captures the principal features of lake-star formation; radial fingers of (relatively warm) water-rich regions grow from a central source and evolve through a competition between thermal and porous media flow effects in a saturated snow layer covering the lake. The number of star arms emerges from a stability analysis of this competition and the qualitative features of this meter-scale natural phenomenon are captured in laboratory experiments.

  16. Star patterns on lake ice

    NASA Astrophysics Data System (ADS)

    Tsai, Victor C.; Wettlaufer, J. S.

    2007-06-01

    Star patterns, reminiscent of a wide range of diffusively controlled growth forms from snowflakes to Saffman-Taylor fingers, are ubiquitous features of ice-covered lakes. Despite the commonality and beauty of these “lake stars,” the underlying physical processes that produce them have not been explained in a coherent theoretical framework. Here we describe a simple mathematical model that captures the principal features of lake-star formation; radial fingers of (relatively warm) water-rich regions grow from a central source and evolve through a competition between thermal and porous media flow effects in a saturated snow layer covering the lake. The number of star arms emerges from a stability analysis of this competition and the qualitative features of this meter-scale natural phenomenon are captured in laboratory experiments.

  17. Functional microbiology of soda lakes.

    PubMed

    Sorokin, Dimitry Y; Banciu, Horia L; Muyzer, Gerard

    2015-06-01

    Soda lakes represent unique permanently haloalkaline system. Despite the harsh conditions, they are inhabited by abundant, mostly prokaryotic, microbial communities. This review summarizes results of studies of main functional groups of the soda lake prokaryotes responsible for carbon, nitrogen and sulfur cycling, including oxygenic and anoxygenic phototrophs, aerobic chemolithotrophs, fermenting and respiring anaerobes. The main conclusion from this work is that the soda lakes are very different from other high-salt systems in respect to microbial richness and activity. The reason for this difference is determined by the major physico-chemical features of two dominant salts - NaCl in neutral saline systems and sodium carbonates in soda lakes, that are influencing the amount of energy required for osmotic adaptation.

  18. Titan Northern Lakes: Salt Flats?

    NASA Image and Video Library

    2013-10-23

    This false-color mosaic, made from infrared data collected by NASA Cassini spacecraft, reveals the differences in the composition of surface materials around hydrocarbon lakes at Titan, Saturn largest moon.

  19. Lake restoration technology transfer assessment

    SciTech Connect

    Daschbach, M.H.; Roe, E.M.; Sharpe, W.E.

    1982-06-01

    Based upon a review of the eutrophication problem and its impact on lake restoration (LR) programs, treatment of the relatively new problem of acid deposition and its impact on LR activities, consideration of the LR programs of the Environmental Protection Agency and several states, and a review of individual LR technology transfer publications, it is recommended that new LR technology transfer programs be given a low priority until more new information is available on the restoration of acidified lakes. Both primary and secondary users of LR research, technology transfer documents, and public awareness documents were considered in this assessment. Primary users included the general public and recreationists, lakeshore property owners, lake/homeowner associations, lake/sanitary districts, and research and environmental organizations; secondary users included state/county/local officials who administer/manage water-related regulations/activities. 4 tables.

  20. Mariano Lake Mine: Technical Reports

    EPA Pesticide Factsheets

    This Final Removal Site Evaluation describes the objectives, work performed, and results of a Removal Site Evaluation (RSE) at the Mariano Lake Mine, which was performed by ARCADIS U.S., Inc. on behalf of Chevron Environmental Management Company.