scholarly journals Diatom Assemblages in Lacustrine Sediments of Lake Shibu-ike, L. Misumi-ike, L. Naga-ike, L. Kido-ike in Shiga Highland and a New Biotic Index based on the Diatom Assemblage for the Acidity of Lake Water.

1982 ◽  
Vol 43 (4) ◽  
pp. 237-245 ◽  
Author(s):  
Toshiharu WATANABE ◽  
Ikuko YASUDA
Keyword(s):  
Lake Water ◽  
Lacustrine Sediments ◽  
Diatom Assemblage ◽  
Biotic Index ◽  
Diatom Assemblages

Varved lacustrine sediments and diatom assemblages of Lake Fukami, central Japan

2003 ◽  
Vol 105 (1) ◽  
pp. 21-24 ◽  
Author(s):  
Sonoko Ishihara ◽  
Megumi Kato ◽  
Yoshihiro Tanimura ◽  
Hitoshi Fukusawa
Keyword(s):  
Lacustrine Sediments ◽  
Diatom Assemblages ◽  
Central Japan

Effects of Didymosphenia geminata blooms on benthic diatom assemblages in the Restigouche River Watershed, eastern Canada

Botany ◽  
2015 ◽  
Vol 93 (5) ◽  
pp. 317-323 ◽  
Author(s):  
Branaavan Sivarajah ◽  
Joshua Kurek ◽  
Kathleen M. Rühland ◽  
John P. Smol
Keyword(s):  
Benthic Diatom ◽  
Diatom Assemblage ◽  
Diatom Assemblages ◽  
Eastern Canada ◽  
Didymosphenia Geminata ◽  
Assemblage Composition ◽  
River Watershed ◽  
And Function ◽  
Riverine Systems ◽  
The Impact

Nuisance Didymosphenia geminata (Lyngbye) M. Schmidt (didymo) blooms were first reported in 2006 from the Restigouche River Watershed (RRW), eastern Canada. Although government agencies and recreational users are concerned about these blooms, little is known about the impact on biota and (or) the structure and function of the relatively pristine riverine systems of the RRW. Here, we assess whether didymo blooms affect overall benthic diatom assemblage composition by examining epilithic samples from middle stretches of the Patapedia and Upsalquitch rivers. Significant (albeit minor) differences (P < 0.05) in diatom assemblage composition between sites, with and without didymo blooms, were only observed from the Patapedia River. Rarefied diatom species diversity (Hill’s N2) and rarefied richness did not differ significantly among sites, regardless of the presence or absence of blooms. Our data show that didymo blooms have minimal effect on benthic diatom assemblage composition in the RRW.

How do abiotic environmental variables shape benthic diatom assemblages in subtropical streams?

2017 ◽  
Vol 68 (5) ◽  
pp. 863 ◽  
Author(s):  
Wing Ying Tsoi ◽  
Wade L. Hadwen ◽  
F. Sheldon
Keyword(s):  
Environmental Gradients ◽  
Critical Role ◽  
Benthic Diatom ◽  
Base Flow ◽  
Diatom Assemblage ◽  
Environmental Drivers ◽  
Diatom Assemblages ◽  
Physical And Chemical Variables ◽  
Ecological Importance ◽  
Physical And Chemical

Diatoms (Division Bacillariophyta) commonly dominate benthic algal communities in upland streams and are the major primary producers that sit at the base of food webs. Given their ecological importance, the aim of the present study was to investigate the spatial patterns of freshwater biofilm biomass and diatom assemblage composition in response to differences in physical and chemical variables in the Bremer, Logan and Albert catchments in south-east Queensland. Patterns in benthic diatom assemblage structure were examined during base flow conditions and the focus was on relating the spatial hierarchical interrelationships among ultimate (i.e. catchments and geology) and proximate (i.e. flow, nutrients, light, conductivity, pH and turbidity) environmental drivers. The spatial difference observed in the benthic diatom assemblages was predominantly driven by proximate environmental drivers, which, in turn, were affected by ultimate drivers. Flow played a critical role in controlling both biofilm biomass and affecting the occurrence of diatom taxa. Nutrients and light also played roles as limiting resources structuring biofilm biomass and the relative abundance of diatoms. Diatom growth form, cell size and attachment mode can be used to create a more quantitative and predictive approach to establishing relationships between diatoms and environmental gradients.

Freshwater Diatom Influx in Intertropical Atlantic: Relationships with Continental Records from Africa

1989 ◽  
Vol 32 (2) ◽  
pp. 229-243 ◽  
Author(s):  
Françoise Gasse ◽  
Bjørg Stabell ◽  
Elizabeth Fourtanier ◽  
Yolanda van Iperen
Keyword(s):  
Geographical Origin ◽  
Lacustrine Sediments ◽  
West African ◽  
Diatom Assemblages ◽  
Good Tool ◽  
Fine Sediments ◽  
Chloride Water ◽  
Winter Dust ◽  
Diatom Productivity ◽  
Freshwater Diatom

AbstractDiatom assemblages from modern West African rivers and from lacustrine sediments subjected to deflation represent the present-day sources of continental diatoms to the sea. Diatom productivity in large rivers is high, especially for the genus Melosira. Windblown diatoms derive mainly from the central and northern Sahara (summer dust plume) where saline chloride-water assemblages are widespread, or from the southern edge of the Sahara (winter dust plume) where Melosira-rich assemblages of dilute water predominate. Freshwater diatom peaks in Atlantic cores may reflect (1) phases of increased river influx, correlated with humid episodes on the continent or (2) phases of enhanced deflation and wind transport during arid episodes (the single hypothesis for fine sediments from mid-ocean sites). Genus Melosira dominates the freshwater assemblages of many modern and fossil marine samples, whatever the transport agent is. Therefore, it is not an accurate paleoclimate indicator by itself, but associated taxa may provide information on the environmental and geographical origin of the displaced diatoms. This tentative approach shows that freshwater diatoms in Atlantic cores may be a good tool for reconstructing paleoclimates and for establishing continent-ocean correlations if species analyses are made and if the continental distribution of the taxa encountered is considered.

scholarly journals Interactions between climate and landscape drive Holocene ecological change in a High Arctic lake on Somerset Island, Nunavut, Canada

2017 ◽  
Vol 3 (1) ◽  
pp. 17-38 ◽  
Author(s):  
Tara M. Paull ◽  
Sarah A. Finkelstein ◽  
Konrad Gajewski
Keyword(s):  
Environmental History ◽  
Lake Water ◽  
Sediment Accumulation ◽  
Base Cations ◽  
High Arctic ◽  
Ecological Change ◽  
Diatom Assemblages ◽  
Time Period ◽  
Water Ph ◽  
Somerset Island

This study presents a diatom-based analysis of the post-glacial Holocene environmental history at Lake RS29 on Somerset Island in the Canadian High Arctic. Earliest post-glacial diatom assemblages (10 200–10 000 cal yr BP) consisted mainly of small, benthic fragilarioid taxa. Poor diatom preservation in the early Holocene (~10 000–6200 cal yr BP) is associated with warm conditions, as determined by pollen data from the same core and other paleoclimate estimates from the region. Analysis of this and other sites from across the Canadian Arctic suggest that zones of poor diatom preservation or diatom absence in lake sediment records may be associated with warm conditions. After 6200 cal yr BP, acidophilic assemblages consisting of Aulacoseira spp. and a suite of periphytic taxa indicate acidification since the mid-Holocene. During this time period, cooling causing changes in lake ice phenology was likely a major driver of the reconstructed mid-Holocene pH decline. Watershed processes, including reduced fluxes of base cations as the rate of sediment accumulation slowed, may also be contributors to long-term shifts in lake water pH and associated changes in diatom assemblages. The uppermost sediments in the Lake RS29 record were characterized by abrupt declines in Aulacoseira alpigena and increases in benthic diatom taxa Cyclotella sensu lato, suggesting an increase in lake water pH and longer ice-free seasons.

scholarly journals Calibration of Lacustrine Sediment Ages Using the Relationship Between 14C Levels in Lake Waters and in the Atmosphere: The Case of Lake Kinneret

Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 821-830 ◽  
Author(s):  
Mariana Stiller ◽  
Aaron Kaufman ◽  
Israel Carmi ◽  
Genia Mintz
Keyword(s):  
Lake Water ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Lacustrine Sediments ◽  
Lacustrine Sediment ◽  
Lake Kinneret ◽  
The Past ◽  
Organic And Inorganic Carbon ◽  
Lake Waters ◽  
The Relationship

The source of endogenic organic and inorganic carbon in lacustrine sediments is the dissolved inorganic carbon (DIC) in the lake water. The relation between the radiocarbon levels of DIC in Lake Kinneret and of CO2 in the atmosphere has been investigated. The ratio of the former to the latter was found to be 0.814 ± 0.013. This ratio is used for calibrating the age of the sediment according to the natural fluctuations in the atmospheric levels of 14C that occurred during the past 10,000 years.

The influence of water-table depth and pH on the spatial distribution of diatom species in peatlands of the Boreal Shield and Hudson Plains, Canada

Botany ◽  
2015 ◽  
Vol 93 (2) ◽  
pp. 57-74 ◽  
Author(s):  
Kathryn E. Hargan ◽  
Kathleen M. Rühland ◽  
Andrew M. Paterson ◽  
Sarah A. Finkelstein ◽  
James R. Holmquist ◽  
...  
Keyword(s):  
Environmental Change ◽  
Water Table ◽  
Vegetation Type ◽  
Diatom Assemblage ◽  
Diatom Species ◽  
Diatom Assemblages ◽  
Poor Fen ◽  
Influence Of Water ◽  
Boreal Shield ◽  
Northern Peatlands

Diatoms collected from 113 surface peat samples from the Boreal Shield and Hudson Plains show taxonomic distributions that are associated with macro-vegetation type, pH, and position relative to the water table, the main environmental variables measured in this study. The overall goal of our research was to determine the ecological distribution and response of diatoms to microhabitat conditions, and to assess the potential for diatoms to be applied as indicators of long-term environmental change in northern peatlands. Our results indicate that diatom assemblage composition was determined by both the broader peatland type (i.e., bog, rich and poor fens) and microhabitats within peatland formations (e.g., hummock, hollow). The diatom assemblages were primarily influenced by pH with the sites divided at a critical pH of 5.5, and secondarily by the depth to the water table. Acidic bog hollow and hummock microhabitats were species-poor and dominated almost exclusively by Eunotia paludosa A.Grunow and (or) Eunotia mucophila (H.Lange-Bertalot, M.Nörpel-Schempp & E.Alles) H.Lange-Bertalot. These acidophilic and aerophilic diatom species were associated with the narrow pH optima of the dominant Sphagnum L. species (e.g., Sphagnum fuscum (Schimp.) Klinggr., Sphagnum angustifolium (C.E.O.Jensen ex Russow) C.E.O.Jensen) found in these bog habitats. Rich and poor fen samples, which were less acidic, supported a more diverse diatom assemblage (>30 species) with greater variability in both diatom and bryophyte pH tolerances. The diatom assemblages recorded in the bogs and fens of our study are similar to those found in peatlands around the world, demonstrating that diatom species are very specialized to exist in these often harsh semi-aquatic environments. Diatoms from peatlands have great potential as biomonitors of environmental change in these important ecosystems.

Paleoenvironmental inference models from sediment diatom assemblages in Baffin Island lakes (Nunavut, Canada) and reconstruction of summer water temperature

2001 ◽  
Vol 58 (6) ◽  
pp. 1222-1243 ◽  
Author(s):  
Ernest H Joynt III ◽  
Alexander P Wolfe
Keyword(s):  
Water Temperature ◽  
Lake Water ◽  
Ice Age ◽  
Weighted Averaging ◽  
Baffin Island ◽  
Forward Selection ◽  
Diatom Assemblages ◽  
Inference Models ◽  
The Past ◽  
Environmental Controls

Diatoms from the surface sediments of 61 lakes on Baffin Island, Nunavut, were identified, enumerated, and interpreted quantitatively. The samples span a latitudinal transect from 62 to 74°N, reflecting climatic and vegetational gradients that range from low Arctic to transitional mid-Arctic to high Arctic. While the sampled lakes encompass both predominantly maritime and continental climatic regimes, sites have been deliberately restricted to basins in Precambrian crystalline terrain to mitigate the edaphic consequences of alkaline sedimentary bedrock. Canonical correspondence analysis, using forward selection and Monte Carlo permutation tests, identified pH, conductivity, summer lake water temperature, and mean annual air temperature as significant environmental controls over diatom assemblages. Using weighted-averaging regression and calibration, predictive models for these parameters have been developed. When applied to down-core assemblages, the summer lake water temperature model provides realistic reconstructions when compared with other paleoenvironmental records. Over the past 5000 years, the amplitude of reconstructed summer lake water temperature is on the order of 4.0°C, expressed primarily as progressive Neoglacial cooling culminating in the Little Ice Age. Diatom-inferred summer water temperatures have increased by 2.0°C in the past 150 years, again in agreement with independent paleoclimatic reconstructions.

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