Differentiation of Diatom Guilds in Extreme Environments in the Andean Altiplano

The Andean Altiplano is characterized by its isolation, high altitude (>3,600 m a.s.l.), and a unique biodiversity, containing water systems such as lakes, rivers, wetlands, and salt flats. Near the southernmost area of the Andean Altiplano are two salt flats, Carcote and Ascotán, the former almost undisturbed by human intervention and the latter historically intervened with by brine mining. These mining activities deplete, pollute, and alter water flow, suggesting a significant threat to ecosystem functions. With regard to identifying the main factors promoting biotic community differentiation in these salt flats at different levels of human intervention, the aim of this study was to compare diatom community indices by guild (high-profile, low-profile, and motile) between these systems with a functional perspective, their relationship to environmental conditions, and the potential anthropic impact on their community structures. Diatom guilds were compared between salt flats based on their diversity, species richness, and abundance relative to ionic concentrations and granulometry. Beta diversity and the percentages of nestedness and turnover for each guild were also estimated. Results showed significant differences in ecological variables between the two salt flats. The largest values of species abundance, richness, and diatom diversity were measured in Carcote, suggesting greater primary productivity and diversity. The results also showed that the species composition of the motile guild was more differentiated between salt flats than those of other guilds (with the greatest diversity and richness), suggesting that motile diatoms are a key guild in maintaining the diatom community and that species from this guild are more sensitive to local conditions from each salt flat. Additionally, beta diversity in all guilds was mainly explained by turnover rather than nestedness, and the turnover was the highest for the motile and low-profile guilds. A more heterogeneous community was observed in Ascotán, showing that the mechanisms of diversity maintenance, such as dispersion abilities, were salt flat dependent. This suggests that the highest diversity could be related to human use, which challenges us to reexamine the effectiveness of past conservation activities in the area and to develop future strategies including both connected basins.

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Spring-flowering herbaceous plant species of the deciduous forests of eastern Canada and 20th century climate warming

Canadian Journal of Forest Research ◽

10.1139/x06-239 ◽

2007 ◽

Vol 37 (2) ◽

pp. 505-512 ◽

Cited By ~ 21

Author(s):

Gilles Houle

Keyword(s):

20Th Century ◽

Plant Species ◽

Climate Warming ◽

Plant Phenology ◽

Deciduous Forests ◽

Metropolitan Region ◽

Ecosystem Functions ◽

Herbaceous Plant ◽

Eastern Canada ◽

Local Conditions

Increases in the emission of greenhouse gases, particularly during the second half of the 20th century, have been associated with climate warming at the global scale. High latitude areas have been reported to be particularly sensitive to such changes, with significant impacts on plant phenology. The objectives of the present study were to (i) estimate changes in the flowering dates of 18 spring-flowering herbaceous plant species typical of the deciduous forests of eastern North America in three areas of eastern Canada (Gatineau–Ottawa, Montréal, and Québec) from 1900 to 2000 and (ii) associate these changes with those of annual and spring local temperatures. My results show a 2–6 days advance in flowering date over 100 years, depending on the region considered (corresponding to a ~2–3 days advance per 1 °C); these values are somewhat lower than those published in other studies, but still support the increasing body of literature on the effects of climate warming on plant phenology. Shifts in flowering phenology were particularly evident for Montréal, a large metropolitan region; this suggests that global climate warming, and its effects on plant phenology, may be exacerbated by local conditions, particularly those associated with large urban areas. Furthermore, species-specific responses to climate warming, as those presented here, might lead to significant changes in community composition and ecosystem functions.

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A hydro-thermo-haline numerical approach of the groundwater flow to explain the extreme Li-enrichment in the Salar de Atacama (NE Chile)

10.5194/egusphere-egu2020-9524 ◽

2020 ◽

Author(s):

Miguel Angel Marazuela ◽

Carlos Ayora ◽

Enric Vázquez Suñé ◽

Sebastià Olivella Pastallé ◽

Alejandro García Gil

Keyword(s):

Land Surface ◽

Volcanic Rocks ◽

Numerical Approach ◽

Origin And Evolution ◽

Rare Elements ◽

Salt Flat ◽

Major Cations ◽

Salt Flats ◽

Strong Evaporation ◽

Hydrogeological Systems

Salt flats (salars) are endorheic hydrogeological systems associated with arid to hyperarid climates. The brines of salt flats account the 80 % of the world&#8217;s reserves of Li highly demanded by modern industry. About 40 % of the worldwide Li is extracted from the brine that fills the pores and cavities of the Salar de Atacama. However, the origin of the extreme Li-enrichment of these brines is still unknown.The thick accumulation of salts and brines in salt flats results from the groundwater discharge (phreatic evaporation) near the land surface for thousands to millions of years. The strong evaporation contributes the enrichment in major cations and anions as well as other rare elements (e.g. Li, B, Ba, Sr, Br, I and F) which are very attractive for mining exploitation. However, only evaporation cannot explain by itself the extreme concentrations of some of these elements and the strong decoupling between the most evaporated brines and the most Li-enriched brines in the Salar de Atacama. Several hypotheses have been proposed to explain the extreme Li-enrichment of the salt flat brines: (a) concentrated brines leaking down from salt flats located in the Andean Plateau, (b) leaching of hypothetical ancient salt flats buried among volcanic rocks, and (c) rising of hydrothermal brines from deep reservoirs through faults. However, none of them has been able probed neither validated by a numerical model till the date.The objective of this work is to discuss the feasibility of the different hypotheses proposed until now to explain the formation of the world's largest lithium reserve. To achieve this objective, two sets of numerical simulations of a 2D vertical cross-section of the entire Salar de Atacama basin are carried out to define (1) the origin and evolution of a salt flat and how climate cycles can affect the location of the most Li-concentrated brines by evaporation and (2) the establishment of the hydro-thermo-haline circulation of a mature salt flat basin.

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Ascotán and Carcote salt flats as sensors of humidity fluctuations and anthropic impacts in the transition zone of the Andean Altiplano

Journal of South American Earth Sciences ◽

10.1016/j.jsames.2020.102934 ◽

2021 ◽

Vol 105 ◽

pp. 102934

Author(s):

Abraham Flores-Varas ◽

Inger Heine-Fuster ◽

Camila López-Allendes ◽

Héctor Pizarro ◽

Daniela Castro ◽

...

Keyword(s):

Transition Zone ◽

Salt Flats ◽

Andean Altiplano

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On the origin of saline compounds in acidic salt flats (Central Andean Altiplano)

Chemical Geology ◽

10.1016/j.chemgeo.2021.120155 ◽

2021 ◽

pp. 120155

Author(s):

JuanJosé Pueyo ◽

Cecilia Demergasso ◽

Lorena Escudero ◽

Guillermo Chong ◽

Paulina Cortéz-Rivera ◽

...

Keyword(s):

Salt Flats ◽

Andean Altiplano ◽

Acidic Salt

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BETA DIVERSITY OF BIRDS (Passeriformes, Linnaeus, 1758) IN SOUTHERN AMAZON

Ciência Animal Brasileira ◽

10.1590/1089-6891v18e-40703 ◽

2017 ◽

Vol 18 (0) ◽

Author(s):

Welvis Felipe Fernandes Castilheiro ◽

Manoel do Santos-Filho ◽

Robson Flores de Oliveira

Keyword(s):

At Risk ◽

Beta Diversity ◽

Biological Diversity ◽

Environmental Changes ◽

Selective Logging ◽

Dry Forest ◽

Spatial Distance ◽

Local Conditions ◽

Flooded Forest ◽

High Beta

Abstract The importance of estimating the biological diversity and understanding how ecological specialization of species changes with spatially-organized habitats in undeniable. High beta diversity between neighboring places means an elevated number of species living within small distances, which usually are adapted to local conditions and highly vulnerable to anthropogenic actions as deforestation and burning. We investigated beta diversity of birds from the order Passeriformes in Southern Amazon, within landscapes with a large heterogeneous vegetation cover (habitats with flooded forest, dry forest, and marsh palm) through sound, observational, and photographic censuses. We marked 126 points in equidistant transects. A total of 148 species of birds were identified, distributed in 27 families. We found that 97% of the species foraged in flooded forest, 77% in dry forest and 19% in marsh palms, and only 18% foraged in the three habitats. An ordination analyses revealed which species showed the strongest preference to each habitat. The analysis for the Global beta diversity showed that this value is high (Whittaker: 7.7405), and the same pattern was obtained with the measure of pairwise dissimilarity. An influence of spatial distance was clearly observed in the cluster analysis and confirmed with a partial Mantel analysis; however, this was not observed at points that coincided with the transition and substitution of species. The influence of spatial distance in the dissimilarity index (beta diversity) was significant (r: 0.0608, p: 0.0049). The assemblage of species in small local populations with high beta diversity may be at risk if deforestation, selective logging, and poaching continue. In summary, this study provides important information on specific habitats with high beta diversity that may be at risk of destabilization of its populations due to continuing environmental changes imposed by humans.

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Neoglacial trends in diatom dynamics from a small alpine lake in the Qinling Mountains of central China

10.5194/cp-2019-85 ◽

2019 ◽

Author(s):

Bo Cheng ◽

Jennifer Adams ◽

Jianhui Chen ◽

Aifeng Zhou ◽

Qing Zhang ◽

...

Keyword(s):

Beta Diversity ◽

Asian Summer Monsoon ◽

Alpine Lake ◽

Central China ◽

Ice Age ◽

Qinling Mountains ◽

Diatom Community ◽

And Shifts ◽

The Impact

Abstract. During the latter stages of the Holocene, and prior to anthropogenic global warming, the Earth underwent a period of cooling called the neoglacial. The neoglacial was associated with declining summer insolation and changes to Earth surface albedo. Although impacts varied globally, in China the neoglacial was generally associated with cooler, more arid climate, which led to renewed permafrost formation, and shifts in vegetation composition. Few studies in central China, however, have explored the impact of neoglacial cooling on freshwater diversity, especially in remote alpine regions. Here we take a palaeolimnological approach to characterise multidecadal variability in diatom community composition, beta-diversity, and flux-inferred productivity over the past 3,500 years in the Qinling Mountains, biodiversity hotspot. We investigate the impact of long-term cooling on primary producers in an alpine lake, which are fundamental to overall aquatic ecosystem function. We show that trends in beta-diversity and shifts in ecological guilds likely reflect changing lake-catchment resource availability, linked to both long-term attenuation of the Asian summer monsoon, and abrupt cool events, linked to a strengthened Siberian High. Important diatom community and productivity responses to the Medieval Climatic Optimum and the Little Ice Age are all apparent in our record, although impact from previous centennial-scale, cool-events are less evident.

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Metabolic Potential of Microbial Communities in the Hypersaline Sediments of the Bonneville Salt Flats

10.1101/2021.10.18.464844 ◽

2021 ◽

Author(s):

Julia M McGonigle ◽

Jeremiah A Bernau ◽

Brenda B Bowen ◽

William J Brazelton

Keyword(s):

Microbial Communities ◽

Metabolic Pathways ◽

Carbon Fixation ◽

Sulfide Oxidation ◽

Anaerobic Respiration ◽

Ecosystem Functions ◽

Metabolic Potential ◽

Shallow Subsurface ◽

Microbial Ecosystems ◽

Salt Flats

The Bonneville Salt Flats (BSF) appear to be entirely desolate when viewed from above, but in reality they host rich microbial communities just below the surface salt crust. In this study, we investigate the metabolic potential of the BSF microbial ecosystem. The predicted and measured metabolic activities provide new insights into the ecosystem functions of evaporite landscapes and are an important analog for potential subsurface microbial ecosystems on ancient and modern Mars. Hypersaline and evaporite systems have been investigated previously as astrobiological analogs for Mars and other salty celestial bodies. Still, these studies have generally focused on aquatic systems and cultivation-dependent approaches. Here, we present an ecosystem-level examination of metabolic pathways within the shallow subsurface of evaporites. We detected aerobic and anaerobic respiration as well as methanogenesis in BSF sediments. Metagenome-assembled genomes (MAGs) of diverse bacteria and archaea encoded a remarkable diversity of metabolic pathways, including those associated with carbon fixation, carbon monoxide oxidation, acetogenesis, methanogenesis, sulfide oxidation, denitrification, and nitrogen fixation. These results demonstrate the potential for multiple energy sources and metabolic pathways in BSF and highlight the possibility for vibrant microbial ecosystems in the shallow subsurface of evaporites.

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Mangrove forests associated with salt flats: a case study from southeast Brazil

Brazilian Journal of Oceanography ◽

10.1590/s1679-87592017083006502 ◽

2017 ◽

Vol 65 (2) ◽

pp. 102-115 ◽

Cited By ~ 5

Author(s):

Mario Luiz Gomes Soares ◽

Filipe de Oliveira Chaves ◽

Gustavo Calderucio Duque Estrada ◽

Viviane Fernandez

Keyword(s):

Forest Structure ◽

Interstitial Water ◽

Structural Characteristics ◽

Water Salinity ◽

Structural Development ◽

Mangrove Forests ◽

Species Dominance ◽

Salt Flat ◽

Salt Flats ◽

Se Brazil

Abstract In this study, forest structure variability of a mangrove associated to a salt flat in Sepetiba Bay (SE-Brazil) was assessed. Forest structure and interstitial water salinity were measured in 32 plots established along three transects ranging from the margin of the estuary to the transition with the salt flat. Structural development was shown to be highly variable, with mean height ranging from 0.54 m to 7.96 m, mean diameter ranging from 1.58 cm to 9.46 cm and trunk density ranging from 2,733 live trunks.ha-1 to 106,667 live trunks.ha-1. Forest structure variability responded to the gradient of increasing interstitial water salinity towards the salt flat, with mean height and diameter decreasing and trunks density increasing progressively in the same direction. The following pattern of species dominance was observed: Rhizophora mangle near the estuary margin; Laguncularia racemosa at the transition with the salt flat; and Avicennia schaueriana on intermediate zones. The assessment of structural characteristics of mangrove forests and their relationships with natural stressors (e.g., salinity) contribute to better understand the dynamics of the species along coastal plains associated with preserved salt flats, such as the one found in Guaratiba.

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