0000000000563628
AUTHOR
Juan Antonio Villaescusa
Vertical structure of bi-layered microbial mats from Byers Peninsula, Maritime Antarctica
AbstractA summer study of the vertical structure of bi-layered microbial mats was carried out on Byers Peninsula (Livingston Island, South Shetland Islands). These benthic communities had a common basic structure that consisted of two distinct layers differing in composition, morphology and colour. Our sampling focused on mats showing more layering, which thrived over moist soils and at the bottom of ponds. The photosynthetic pigments analysis performed by high-performance liquid chromatography demonstrated a major occurrence of cyanobacteria and diatoms on these mats, the former being more abundant in relative terms on the surface and composed by morphospecies grouping into orders Oscillat…
Functional Metabolic Diversity of Bacterioplankton in Maritime Antarctic Lakes
A summer survey was conducted on the bacterioplankton communities of seven lakes from Byers Peninsula (Maritime Antarctica), differing in trophic and morphological characteristics. Predictions of the metabolic capabilities of these communities were performed with FAPROTAX using 16S rRNA sequencing data. The versatility for metabolizing carbon sources was also assessed in three of the lakes using Biolog Ecoplates. Relevant differences among lakes and within lake depths were observed. A total of 23 metabolic activities associated to the main biogeochemical cycles were foreseen, namely, carbon (11), nitrogen (4), sulfur (5), iron (2), and hydrogen (1). The aerobic metabolisms dominated, althou…
Bacterioplankton Community Composition Along Environmental Gradients in Lakes From Byers Peninsula (Maritime Antarctica) as Determined by Next-Generation Sequencing
This study comprises the first attempt to describe the planktonic bacterial communities of lakes from Byers Peninsula, one of the most significant limnological districts in the Maritime Antarctica, leveraging next-generation sequencing (NGS) technologies. For the survey, we selected 7 lakes covering the environmental gradient from inland to coastal lakes, some of them sampled both in surface and deep waters. Analysis provided just over 85,000 high quality sequences that were clustered into 864 unique Zero-radius Operational Taxonomic Units (ZOTUs) (i.e., 100% sequence similarity). Yet, several taxonomic uncertainties remained in the analysis likely suggesting the occurrence of local bacteri…
Heterogeneous vertical structure of the bacterioplankton community in a non-stratified Antarctic lake
10 páginas, 4 figuras, 2 tablas.
Modeling the Response of the Planktonic Microbial Community to Warming Effects in Maritime Antarctic Lakes
Abstract In this chapter, we describe the design and prognoses given by the simulation of an ecological model dealing with the functioning of the microbial community of a maritime Antarctic lake, whose main ecological features are also reported. The model is based on carbon fluxes through the planktonic community and the carbon subsides from the benthic mosses covering the lake bottom and microbial mats spread over the lake’s catchment. It describes the dynamics of the bacterioplankton, phytoplankton, and organic matter, both particulate and dissolved, during the austral summer, with temperature and solar radiation as the main forcing functions driving the response of the modeled state vari…
Stability and endemicity of benthic diatom assemblages from different substrates in a maritime stream on Byers Peninsula, Livingston Island, Antarctica: the role of climate variability
16 páginas, 3 tablas, 9 figuras.
Carbon dynamics modelization and biological community sensitivity to temperature in an oligotrophic freshwater Antarctic lake
Lake Limnopolar, located in one of the areas on Earth experiencing the strongest local warming, has been studied as a maritime Antarctic lake model by the Limnopolar Research Team during the last decade. Data collected during this period revealed the existence of an important meteorological interannual variability in the area of Byers Peninsula. With the aim of increasing the knowledge of this ecosystem and its sensibility to climate change as a model ecosystem, as well as to calibrate the extent of the interannual variability, a carbon flow model was developed partly describing its microbial food web. This preliminary model aims to describe part of the carbon dynamics, especially for bacte…
Structure of planktonic microbial communities along a trophic gradient in lakes of Byers Peninsula, South Shetland Islands
AbstractA systematic limnological survey of water bodies of Byers Peninsula (Livingston Island, South Shetland Islands) was carried out during the summer of 2001/02. Abundances of microbial plankton were determined which allowed a delineation of the pelagic food web structure. We also report the nutrient status of these lakes. We demonstrate the occurrence of a trophic gradient that extended from upland lakes (oligotrophic) to the coastal ones (eutrophic). The study shows that a lake's morphology regulates the relative importance of the pelagic and benthic habitats, whereas nutrient loads mainly determine its trophic status. Yet, some of the variability observed could be also a legacy of th…
Maritime antarctic lakes as sentinels of climate change
Remote lakes, such as lakes from the Maritime Antarctica, can be used as sentinels of climate change, because they are mostly free of direct anthropogenic pressures, and they experience climate change as a main stressor capable of modifying the ecosystem structure and function. In this paper, the content of a lecture that has been presented at the First Conference of Lake Sustainability, which has been centred in our studies on lakes from Byers Peninsula (Maritime Antarctica), are summarized. These included physical, chemical and biological studies of these lakes and other freshwater ecosystems, which highlighted the relevance of biotic interactions for these ecosystems and its sensibility …