Lake In Argentina Research Articles

Detection of total water mass changes in the Patagonian glaciers area by satellite gravimetry

Despite present efforts to better understand glacier changes and their trends, the satellite gravimetry is a powerful tool still not applied in depth to study relatively large areas in the Andes of Argentina and Chile.
 In this work the mass variations of the Patagonian Icefield are analyzed together with the decrease trends of the ice layer in the region. The purpose of this study is to demonstrate the GRACE satellite mission (Gravity Recovery and Climate Experiment) ability to detect the water storage changes over the glaciers area. Furthermore, the variations of the hydrometric level of some Patagonian lakes were monitored by combining satellite altimetry data and in situ measurements with the observed water mass variations.
 Data from GRACE was used to estimate gravity trends, and high-resolution CSR GRACE RL05 mascon solutions were used to analyze the water storage change of the icefields in the region under study for the 2002-2017 period.
 Virtual stations from satellite altimetry obtained from a lake database and also hydrometric height data from in situ stations, located at Patagonian lakes in Argentina and Chile, were also used in order to compare the TWS from GRACE to the water level of the specific lakes. Additionally, correlation coefficients were determined at each station. 
 The results show a significant water storage decrease in the Icefield area, and they also demonstrate that the ice melt in southern Patagonia (of about 6 cm/year) tends to be more pronounced than in the northern region.

Covariation patterns of phytoplankton and bacterioplankton in hypertrophic shallow lakes.

The aim of this work was to assess the temporal patterns in the community composition of phytoplankton (PCC) and bacterioplankton (BCC) in two interconnected and hypertrophic Pampean shallow lakes in Argentina. Factors shaping their community dynamics and community temporal covariations were also analysed. We performed 4 years of seasonal samplings (2012-2016) and communities were studied by the Utermöhl approach (PCC) and Illumina MiSeq sequencing (BCC). We found marked seasonal variations in both communities and inter-annual variations with decreasing microbial community similarities during the study. We also observed covariation in community-level dynamics among PCC and BCC within and between shallow lakes. The within-lake covariations remained positive and significant, while controlling for the effects of intrinsic (environmental) and extrinsic (temporal and meteorological) factors, suggesting a community coupling mediated by intrinsic biotic interactions. Algal-bacterial associations between different taxa of phytoplankton and bacterioplankton within each lake were also found. PCC was mainly explained by pure regional extrinsic (17-21%) and intrinsic environmental (8-9%) factors, while BCC was explained by environmental (8-10%) and biotic interactions with phytoplankton (7-8%). Our results reveal that the influence of extrinsic regional factors can be channeled to bacterioplankton through both environmental (i.e. water temperature) and phytoplankton effects.

Novel Genes Involved in Resistance to Both Ultraviolet Radiation and Perchlorate From the Metagenomes of Hypersaline Environments.

Microorganisms that thrive in hypersaline environments on the surface of our planet are exposed to the harmful effects of ultraviolet radiation. Therefore, for their protection, they have sunscreen pigments and highly efficient DNA repair and protection systems. The present study aimed to identify new genes involved in UV radiation resistance from these microorganisms, many of which cannot be cultured in the laboratory. Thus, a functional metagenomic approach was used and for this, small-insert libraries were constructed with DNA isolated from microorganisms of high-altitude Andean hypersaline lakes in Argentina (Diamante and Ojo Seco lakes, 4,589 and 3,200 m, respectively) and from the Es Trenc solar saltern in Spain. The libraries were hosted in a UV radiation-sensitive strain of Escherichia coli (recA mutant) and they were exposed to UVB. The resistant colonies were analyzed and as a result, four clones were identified with environmental DNA fragments containing five genes that conferred resistance to UV radiation in E. coli. One gene encoded a RecA-like protein, complementing the mutation in recA that makes the E. coli host strain more sensitive to UV radiation. Two other genes from the same DNA fragment encoded a TATA-box binding protein and an unknown protein, both responsible for UV resistance. Interestingly, two other genes from different and remote environments, the Ojo Seco Andean lake and the Es Trenc saltern, encoded two hypothetical proteins that can be considered homologous based on their significant amino acid similarity (49%). All of these genes also conferred resistance to 4-nitroquinoline 1-oxide (4-NQO), a compound that mimics the effect of UV radiation on DNA, and also to perchlorate, a powerful oxidant that can induce DNA damage. Furthermore, the hypothetical protein from the Es Trenc salterns was localized as discrete foci possibly associated with damaged sites in the DNA in cells treated with 4-NQO, so it could be involved in the repair of damaged DNA. In summary, novel genes involved in resistance to UV radiation, 4-NQO and perchlorate have been identified in this work and two of them encoding hypothetical proteins that could be involved in DNA damage repair activities not previously described.

Observations on crustacean zooplankton in two connected north Patagonian lakes (Calafquén-Pellaifa, 39°S, Chile)

Abstract The northern Patagonian lakes (38-41°S), are characterized by their location in catchment basins that have been markedly altered through human intervention. In those basins, the original native, perennial forest has been replaced by towns, villages and agricultural zones. The present study was done in two interconnected north Patagonian lakes (the lakes Calafquén and Pellaifa), where the species composition of the crustacean zooplankton community was compared, using a biodiversity index and size-structure null models. The results denoted the presence of marked differences between both sites, Calafquén lake being inhabited by less species and in general showing lower abundances of individuals in comparison to Pellaifa lake. The results of size-structure null models revealed the absence of interspecific competition for both sites. The obtained results would agree with similar observations for other northern Patagonian lakes in Argentina and Chile.

Watanabea acidotolerans: A new trebouxiophyte lineage (Chlorophyta) inhabiting low pH environments from Europe to South America

SUMMARYHere we studied a new Watanabea strain CAUP H 8901‐CRYO isolated from an extremely acidic (pH 2.6) pit lake in Czechia. We used morphological, ultrastructural and molecular data to ascertain its taxonomic position and phylogenetic relationships within the genus Watanabea. The morphology of the studied strain matched the formal Watanabea description, including its most characteristic feature, the production of two types of autospores. The new isolate morphologically and ultrastructurally resembled the Watanabea type species, W. reniformis. However, it differed from W. borysthenica by having a pyrenoid not surrounded by starch grains. Molecular phylogenetic analyses of nuclear 18S rDNA and plastid rbcL showed that the strain CAUP H 8901‐CRYO formed an independent lineage within the genus Watanabea. Furthermore, analyses of nuclear ITS2 secondary structure demonstrated an additional side loop coiling from the helix III, the unique feature of CAUP H 8901‐CRYO, not present in the authentic strain of W. reniformis SAG 211‐9b. The ITS2 secondary structures of the two strains also differed by one compensatory base change (CBC) and a number of additional nucleotide substitutions. The new acidotolerant strain and another Watanabea isolate from a naturally acidic lake in Argentina were identical in their plastid rbcL sequence. Consequently, here we proposed a new species, Watanabea acidotolerans, to accommodate a lineage of microalgae with a possible worldwide distribution and tolerance to low pH habitats.

Complete Genome Sequences of pLMA1 and pLMA7, Two Large Linear Plasmids of Micrococcus Strains Isolated from a High-Altitude Lake in Argentina

ABSTRACTThe two linear plasmids pLMA1 (109,112 bp) and pLMA7 (82,075 bp) from Micrococcus strains were isolated from a high-altitude lake in the Argentinean Puna, sequenced, and annotated. These extrachromosomal elements are probably conjugative and harbor genes potentially involved in coping with the harsh conditions in such extreme environments.

A new species of Hedruris Nitzsch, 1821 (Nematoda: Hedruridae) parasitic in the freshwater fish Oligosarcus jenynsii (Günther, 1864) (Characidae) from Argentina.

Nematodes belonging to genus Hedruris Nitzsch, 1821 (Nematoda: Hedruridae) were found in the stomach of the freshwater fish Oligosarcus jenynsii (Günther, 1864) (Characidae) from a shallow eutrophic lake in Argentina. Morphological comparisons with congeneric relatives showed that these nematodes belong to a new species, for which H. bifida n. sp. is proposed. Hedruris bifida n. sp. can be distinguished from its congeners by the following combination of characters: bifid deirids, absence of precloacal papillae and nine pairs of postcloacal papillae and non-mammillated eggs. The new species closely resembles Hedruris suttonae Brugni & Viozzi, 2010¸ the only known species from Argentina; however, the bifid deirids in the new species and the distribution pattern of perianal spines in females clearly distinguish both species. Hedruris bifida n. sp. represents the second nominal species of the genus in Argentina and the eighth species described in the Neotropical region.

Complete Genome Sequence of the Linear Plasmid pJD12 Hosted by Micrococcus sp. D12, Isolated from a High-Altitude Volcanic Lake in Argentina.

The linear plasmid pDJ12 from Micrococcus D12, isolated from the high-altitude volcanic Diamante Lake in the northwest of Argentina, was completely sequenced and annotated. It is noteworthy that the element is probably conjugative and harbors genes potentially instrumental in coping with stress conditions that prevail in such an extreme environment.

Stable isotope and fatty acid markers in plankton assemblages of a saline lake: seasonal trends and future scenario

Plankton fractions from a saline lake in Argentina were studied using a combined trophic marker approach. A strong seasonality of biomarkers was characteristic for the different fractions, particularly the variations in the 18:4(n 2 3) and 20:4(n 2 3) fatty acids and the d13C values. The primary production in the lake was mainly driven by diatoms, reflected by the close relation of d13C, chlorophyll a and diatom fatty acid markers. The combined approach of d13C and 20:4(n 2 3) enabled processes in the lipid metabolism of the copepod Boeckella poopoensis to be inferred. The polyunsaturated fatty acid 22:6(n 2 3) and the d15N separated the trophic levels in this food web with copepods at higher trophic level. Nutritional stress and omnivory of B. poopoensis partially explained the d15N variations in mesozooplankton. The d15N signature was probably driven by cyanobacteria in the microplankton and by microbial processes in the nanoplankton fraction. Warmer temperatures may favour the saturation of microalgae fatty acids and the abundance of plankton groups richer in saturated fatty acids. The tendency to unsaturation in mesozooplankton at colder temperatures was probably influenced by diet and metabolic requirements. Future temperature increase and eutrophication-like processes may increase the importance of cyanobacterial and bacterial markers under climate change scenarios.

Complete Genome Sequence of pAP13, a Large Linear Plasmid of a Brevibacterium Strain Isolated from a Saline Lake at 4,200 Meters above Sea Level in Argentina

pAP13 is an 89-kb linear plasmid hosted by Brevibacterium sp. strain Ap13, an actinobacterium isolated from the feces of a flamingo from an extremely high-altitude lake in Argentina. Because of the ecological importance of the genus Brevibacterium, the absolute lack of information concerning Brevibacterium linear plasmids, and the possible ecological significance of this unusual plasmid, pAP13 was completely sequenced, including the inversely oriented termini.

Effects of stocking density and natural food availability on the extensive cage culture of pejerrey (Odontesthes bonariensis) in a shallow Pampean lake in Argentina

Fil: Garcia, Javier Ricardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - La Plata. Instituto de Limnologia Dr. Raul A. Ringuelet. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnologia; Argentina

129I Dispersion in Argentina: Concentrations in Fresh and Marine Water and Deposition Fluences in Patagonia

Measurements of total iodine (I) and iodine-129 ((129)I) concentrations in rivers and lakes of Argentina are presented. Their latitudinal distribution can be explained by taking into account their main sources (oceanic emissions and biomass burning for I, and atmospheric nuclear tests for (129)I), transport mechanisms, and fallout patterns. From the measured (129)I concentrations in the studied lakes, deposition fluences for their catchment areas were estimated. These results agree with a model of the global deposition pattern due to the (129)I released by atmospheric nuclear weapon tests and with other fluences reported for the southern hemisphere. In addition, the first measurements of (129)I in shallow seawater from the South Atlantic Ocean are presented and discussed.

Vertical distribution of epiphyton biomass and diversity in a shallow lake during contrasting ecosystem regimes

We investigated seasonal and depth variations in biomass and composition of bulrush-associated epiphyton in a shallow seepage lake in Argentina and examined whether differences existed in the vertical profiles between sites, whether the zonation with respect to depth changed according to different regimes of the ecosystem, and what conditions most greatly affected the epiphyton vertical distribution. We performed sample collection every 4 weeks for one year at both the centre and the periphery of the bulrush stand, sectioned the bulrush stems into segments to give a fixed 7-level vertical profile, and recorded the water physicochemical characteristics over the same profile. The epiphyton vertical variations were similar at both sampling locations.The epiphyton-biomass profiles underwent an abrupt change at a depth of 45–65cm during the clear-water period, while comparable values were recorded along the profiles during the turbid phase. The temperature had a positive effect during late spring–early summer that coincided with the transitional period and beginning of the clear period.The principal driver of the epiphyton-biomass vertical distribution is the light availability, followed by the exposure to water movements. The resident species with high contributions to the overall biovolume were related to the percentage of incident light, and particularly those community members that were predominant in the clear-water period.

Determination of total I and129I concentrations in freshwater of Argentina

Total iodine and129-iodine in rivers and lakes of Argentina were measured by means of inductively coupled plasma mass spectrometry and accelerator mass spectrometry respectively. The obtained isotopic ratios, higher than the natural level, are explained as the delayed signal from nuclear weapon atmospheric tests. Besides, deposition fluences in catchment areas of the lakes are analyzed. Their latitudinal dependence, similar to the dependence of annual precipitation rates, favours wet deposition as the main 129 I fallout mechanism for this region.

Selenium Species and Their Distribution in Freshwater Fish from Argentina

The distribution and speciation of selenium (Se) in freshwater fish (muscle and liver tissue) from lakes in Argentina was investigated. Three introduced species, brown trout (Salmo trutta), rainbow trout (Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis), and one native species, creole perch (Percichthys trucha), were investigated. Values for total selenium in muscle ranged from 0.66 to 1.61 μg/g, while in the liver, concentrations were much higher, from 4.46 to 73.71 μg/g on a dry matter basis. Separation of soluble Se species (SeCys(2), selenomethionine (SeMet), SeMeSeCys, selenite and selenate) was achieved by ion exchange chromatography and detection was performed by inductively coupled plasma-mass spectrometry. The results showed that in fish muscle, from 47 to 55 % of selenium was soluble and the only Se species identified was SeMet, which represented around 80 % of soluble Se, while in the liver, the amount of soluble Se ranged from 61 to 76 % and the percentage of species identified (SeMet and SeCys(2)) was much lower and ranged from 8 to 17 % of soluble Se.

Extensive cage culture of pejerrey (Odontesthes bonariensis) in a shallow pampean lake in Argentina

AbstractPejerreyisanimportantzooplanktivorousnative¢shof theArgentinean inland waters. It has been tradi-tionally propagated for stocking purposes by rela-tively costly semi-intensive and intensive methods.Inthis study, we evaluated the implementationof anextensiveculturemethodbyusing£oatingcagesinashallow pampean lake. Four cages were installed inthe Lacombe Lake and stocked with juveniles(16.24 1.69mmlength)at50¢shm 3 density forgrowing until the size of 150mm, which is consid-ered as a suitable size for stocking. Throughout theexperiment, thetemperaturerangedbetween10 and26 1C and the zooplankton biomass ranged between12 and 3269 mgdwL 1 . The growth patterns in thelengthwere similar inthefourcages anddirectly re-latedtothelakethermalconditionsandzooplanktonavailability. The average ¢nal length after 315 dayswas 154.4 8.8mm. The survival rates ranged be-tween 53.5% and 64.7% during the ¢rst 110 daysand 11.1^25.7% at termination. Growth rate for the¢rst2monthswasthehighestdocumentedforpejer-reyculture.This simple technique oiers the possibi-lity to produce juvenile pejerrey at a low cost andprovidesthealternativeofreinforcingthenaturalpo-pulationswith¢shalreadyadaptedtothenaturalen-vironmentalconditions.Keywords: Odontesthes bonariensis,cageculture,pampean lakes, ¢shgrowth, zooplanktivorous ¢shIntroductionThe pejerrey (Odontesthes bonariensis) is consideredas one of the most important commercial and sport¢sh species inhabiting the inland waters of Argenti-na (Bonetto & Castello1985; Grosman1995; Reartes1995; Somoza, Miranda, Berasain, Colautti, RemesLenicov & Strˇssmann 2008). Because of the highqualityof its £esh and sport ¢shing attractiveness, ithasbeenintroducedwitharelativelygoodsuccesstoother South American, European and Asian coun-tries (Loubens & Osorio1992;Toda,Tonami,Yasuda S Strˇssmann & Yasuda 2005).The inter-est in this species stimulated the ¢rst culture at-tempts for stocking at the beginning of the pastcentury. Since then, the techniques of pejerrey pro-ductionhaveimprovedprogressivelyanditispossibleat present to complete the production cycle in tanks(Miranda,Berasain,Velasco,ShirojoSRinguelet, Iriart & Escalante 1980). Because pam-pean lakesareusuallyeutrophic, zooplanktonrepre-sents an important and abundant community(Escalante 2001; Claps, Gabellone & Ben|¤tez 2004).This feature represents a unique opportunity fordeveloping pejerrey culture based on natural zoo-plankton as the source of food.The use of cages is awell-developedtechnologythathasbeenmostlyused

Microcystin–LR, –RR, –YR and –LA in water samples and fishes from a shallow lake in Argentina

We evaluated the presence of four common microcystins (MC–LR, –RR, –YR and –LA) in water samples and tissues (liver and muscle) of Odontesthes bonariensis collected in Los Padres Lake (Argentina). MCs were quantified by HPLC–ESI-MS/MS. The total content of MCs in water samples (2.8 ± 5.6 μg L −1) and in O. bonariensis muscle (3.9 ± 2.2 μg kg −1) never surpassed guidelines values recommended by WHO for either recreational use of water or fish consumption. The total content of MCs in O. bonariensis liver was 33.6 ± 37.2 μg kg −1. However, we observed both spatial and temporal changes in MC profile, suggesting the need of an intensive monitoring program at such lake to ensure the health of people living in its surrounding. We observed a significant correlation between the content of total and dissolved MC in water and the concentration of these toxins in liver, showing the probable uptake of dissolved MC by O. bonariensis. MC–RR was the dominant variant in water samples, followed by MC–LA and MC–LR. MC–YR was always present in water samples, but in the lowest concentrations of the congeners measured. MC content in liver in O. bonariensis was ten-fold higher than the corresponding content in fish muscle. However, MCs were present in muscle of O. bonariensis during both wet and dry season, while we could not detect MCs in liver during the dry season. These results demonstrate that MC accumulation in liver and muscle of O. bonariensis occurred with different profiles. Moreover, different uptake, tissue distribution and excretion pathways may occur between diverse MC variants. For instance, during the dry season, an increase in the relative percentage of MC–LR in water samples was accompanied with an augmentation in the relative percentage of this toxin in muscle of O. bonariensis. Conversely, a rise in the relative percentage of MC–LA in water samples during the dry season did not impact on the distribution of this toxin in fish muscle. These results suggest the need of further studies on dynamics of different variants of MC to pursuit a complete evaluation of human health risk associated to MC occurrence.

Microbial Biogeography of Six Salt Lakes in Inner Mongolia, China, and a Salt Lake in Argentina

We used cultivation-independent methods to investigate the prokaryotic biogeography of the water column in six salt lakes in Inner Mongolia, China, and a salt lake in Argentina. These lakes had different salt compositions and pH values and were at variable geographic distances, on both local and intercontinental scales, which allowed us to explore the microbial community composition within the context of both contemporary environmental conditions and geographic distance. Fourteen 16S rRNA gene clone libraries were constructed, and over 200 16S rRNA gene sequences were obtained. These sequences were used to construct biotic similarity matrices, which were used in combination with environmental similarity matrices and a distance matrix in the Mantel test to discover which factors significantly influenced biotic similarity. We showed that archaeal biogeography was influenced by contemporary environmental factors alone (Na+, CO3(2-), and HCO3(-) ion concentrations; pH; and temperature). Bacterial biogeography was influenced both by contemporary environmental factors (Na+, Mg2+, and HCO3(-) ion concentrations and pH) and by geographic distance.

A Reversed Pattern of Association Between Song Dialects and Habitat in the Rufous-Collared Sparrow

Abstract Abstract. We studied song dialects of the Rufous-collared Sparrow (Zonotrichia capensis) in espinal woodland and steppe surrounding Guatraché Lake in Argentina. We recorded 150 individuals and analyzed 14 quantitative song variables. There were significant differences between habitats in song temporal structure. In particular, the internote interval of trills was shorter in the closed compared to the open habitat. This pattern is the reverse of what is usually found in this species, although it has previously been detected in another area of the region in which this study was conducted. This region is characterized by strong winds, which could be related to the reversed pattern found. Song frequencies were lower in the closed woodland habitat than in the open steppe, which also contrasts with the pattern usually found in this species. We also recorded and analyzed the songs in a portion of the area in which the woodland was converted into grassland during the last century. The temporal structure of songs in the converted area was intermediate between song structures in the original habitats and frequencies were lower in the converted area than in both original habitats. Song structure appears to have changed after habitat conversion, but this cannot be confirmed with the data at hand because of the lack of recordings obtained before habitat change.

Relative paleointensity of the geomagnetic field over the last 21,000 years BP from sediment cores, Lake El Trébol (Patagonia, Argentina)

Abstract Four cores from Lake El Trébol (Patagonia, Argentina) have been used to estimate regional geomagnetic paleointensity. The rock magnetic studies indicate that the magnetic mineralogy of the clay-rich sediments is dominated by pseudo-single domain magnetite in a range of grain sizes and concentration which are suitable for paleointensity studies. The remanent magnetisation at 20 mT (NRM20 mT) has been normalised using the an-hysteric remanent magnetisation at 20 mT (ARM20 mT), the saturation of the isothermal remanent magnetisation at 20 mT (SIRM20 mT) and the low field magnetic susceptibility (k). Coherence function analysis indicates that the normalised records are free of environmental influences. Our paleointensity (NRM20 mT/ARM20 mT) versus age curve shows good agreement with published record from another lake in Argentina and with records from other parts of the world, suggesting that, in suitable sediments, paleointensity of the geomagnetic field can give a globally coherent, dominantly dipolar signal.