An ostracod-based calibration function for electrical conductivity reconstruction in lacustrine environments in Patagonia, Southern South America

Mercau, Josefina Ramón; Laprida, Cecilia

doi:10.1016/j.ecolind.2016.05.026

Cited by 18 publications

(9 citation statements)

References 31 publications

(48 reference statements)

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“…Moreover, the strong dominance of the polyhaline L. rionegroensis along the entire core suggests the presence of a lake with saline waters through the last 3000 years (Whatley and Cusminsky, 1999). This species inhabits high evaporative environments, such as temporary lakes and ponds (Ramón-Mercau et al, 2012; Schwalb et al, 2002) and has been postulated as a possible indicator of saline waters and dry climatic conditions (Coviaga et al, 2017; Cusminsky et al, 2005; Ohlendorf et al, 2014; Ramón-Mercau and Laprida, 2016; Whatley and Cusminsky, 1999). Furthermore, the variety of species present also gives information about limnological conditions; the morphotype I of L. rionegroensis representing higher ionic concentrations than morphotype III (Ramos et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

“…Particularly, the presence of the oligohaline L. patagonica and A. argentinensis indicates a lake with low ionic concentrations with surrounding vegetation in the catchment (Coviaga et al, 2018a; Schwalb et al, 2002). Limnocythere patagonica is a Patagonian stenohaline taxa, characteristic of permanent ponds and lakes of moderate salinity (Coviaga et al, 2018a; Cusminsky et al, 2005; Ramón-Mercau and Laprida, 2016; Ramón Mercau et al, 2012; Schwalb et al, 2002). An elevated abundance of this species in Lake Cháltel, southeastern Patagonia, has been interpreted to reflect periods of low salinity (Ohlendorf et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

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Paleoenvironmental changes during the last 3000 years in Lake Cari-Laufquen (Northern Patagonia, Argentina), inferred from ostracod paleoecology, petrophysical, sedimentological and geochemical data

et al. 2018

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South American paleoreconstructions are of global interest because it is the only landmass extending from the tropics to the southern high latitudes and intersecting the entire southern westerly wind belt. In this context, endorheic environments, as Lake Cari-Laufquen Grande (LCLG; 41º35'S, 69º25'W) are excellent sites for paleoenvironmental studies, since they react rapidly to changes in the precipitation/evaporation ratio. In this study, the limnological conditions prevailing during the last 3000 years have been inferred based on a multiproxy analysis of the sedimentary sequence of LCLG (water depth 4 m, core length 505 cm). Today, this is one of the few lakes in Northern Patagonia, providing a unique paleoclimatic and paleoecological lacustrine record. The ostracod assemblages, along with sedimentological, petrophysical and geochemical data, show hydrological changes in Cari-Lauquen Grande basin during the studied period. Our results indicate the continuous presence of a saline to brackish lake. However, changes in ostracod assemblages and sedimentological features reveal variations in the relative salinity of the system. The lake paleosalinity was estimated based on ostracod salinity optima, using a calibration dataset of 29 species and 72 different environments. Intervals of high salinity (24-26 g L-1) were dominated by L. rionegroensis (morph.I) and organic-poor sediments. Periods of lower salinity (14-20 g L-1) favored the occurrence of oligo-mesohaline taxa, such as R. whatleyi, L. rionegroensis (morph.III), Cypridopsis sp., L. patagonica and I. ramirezi. The sediments further display higher values of both TOC and magnetic susceptibility. These salinity changes are interpreted as water level variations, associated in turn to cold-wet and warm-dry periods in northern Patagonia. Our results provide new insights into the late-Holocene environmental history of the region, characterized by a paucity of records. In addition, the ostracod paleoecology modeled using a WA approach allowed quantitative inferences of salinity changes, highlighting their potential in Quaternary paleoclimate research.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Paleoenvironmental changes during the last 3000 years in Lake Cari-Laufquen (Northern Patagonia, Argentina), inferred from ostracod paleoecology, petrophysical, sedimentological and geochemical data

et al. 2018

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“…; Ramón‐Mercau et al . ; Ramón‐Mercau & Laprida ; Ramos et al . ), denoting a period with elevated ionic concentrations (mesohaline range), probably associated with dry climatic conditions.…”

Section: Discussionmentioning

confidence: 99%

“…Limnocythere rionegroensis and L. patagonica are considered proxies for contrasting salinity conditionsm, unlike L. rionegroensis (species optimum = 24 861 μS cm −1 ), L. patagonica presents its optimum in oligohaline waters (species optimum = 1072 μS cm −1 ) (Ramón‐Mercau et al . ; Ramón‐Mercau & Laprida ; Coviaga et al . ).…”

Section: Discussionmentioning

confidence: 99%

“…However, this species has also been recorded in extant limnic to oligohaline environments and in Holocene sediments from Laguna Chaltel (50°S) during a period characterized by a lake‐level rise (Ohlendorf et al . ; Ramón‐Mercau & Laprida ). Thus, the presence of both L. patagonica and K. megapodus in Lago Cardiel sediments indicates waters substantially more dilute than in older biozones (limnetic to oligohaline conditions) and a positive hydrological balance (Fig.…”

Section: Discussionmentioning

confidence: 99%

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Changes in ostracod assemblages and morphologies during lake‐level variations of Lago Cardiel (49°S), Patagonia, Argentina, over the last 15.6 ka

Ramos

Alperín

Schwalb

et al. 2019

Boreas

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Changes in the ostracod assemblages from two sediment cores collected from Lago Cardiel in southeastern Patagonia (49°S) reflect the main regional abrupt climatic changes over the last 15.6 cal. ka BP. Shifts in species abundance and switches in dominances suggest that these were mainly driven by variable salinity. During the Late Pleistocene, Limnocythere rionegroensis was abundant and dominant, indicating waters with high salinity and prevalence of evaporative processes. Between 12.6 and 10.8 cal. ka BP, Lago Cardiel expanded markedly and reached an Early Holocene highstand of +55 m above present lake level. A major change in ostracod assemblage in which Limnocythere patagonica appears as the dominant species in parallel with the disappearance of L. rionegroensis and Eucypris aff. cecryphalium mirrored this transitional period between the cold and dry Late Pleistocene and the humid and warm Early Holocene. Over the last 4 cal. ka BP, L. rionegroensis returned to the species assemblage and Riocypris whatleyi increased its abundance pointing towards increasing salinities. The variations in size, shape and ornamentation of L. rionegroensis and R. whatleyi fossil valves were examined using geometric morphometric techniques and further compared to those of modern Patagonian sites. Limnocythere rionegroensis specimens displayed high morphological variability during the evolution of Lago Cardiel. More specifically, the switch in reproductive mode – from sexual to parthenogenetic– and the increase in valve ornamentation around 12.7 cal. ka BP suggest that these changes were promoted by the hydrological alteration that occurred in the Late Pleistocene. This exercise provides a robust range of morphological variation for these proxies, which will be useful in further taxonomic and palaeoenvironmental studies adding more information about different factors influencing the observed morphological trends.

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Diatom-based inference model for conductivity reconstructions in dryland river systems from north Patagonia, Argentina

2021

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Dryland river systems support a diverse aquatic biota in semi-arid and arid landscapes, but they are increasingly vulnerable to natural and human impacts. This study provides the first modern diatom training set (n = 38) from three dryland rivers in northern Patagonia, Argentina. The relationship between surface-sediment diatoms and contemporary environmental variables was explored using multivariate analyses. The results showed that surface-water chemistry varies among rivers in accordance with local-scale factors such hydro-climatic variability and anthropic activities. A total of 378 diatom taxa were identified but only 45 taxa occurred with relative abundances higher than 2% in at least one sediment sample. The Colorado and Negro rivers were characterized by high abundances of small tychoplanktic fragilarioids whereas the Chubut River was dominated by epiphytic and planktic taxa. The canonical correspondence analyses (CCA) showed that conductivity, pH and HCO 3 − were the main environmental variables governing diatoms distributions. A transfer function was developed for water conductivity using unimodal methods because of partial CCA and λ 1 /λ 2 ratio revealed that this variable had the largest unique effect on diatom variance. A weighted averaging (WA) model with tolerance downweighting and classic deshrinking provided a reasonably robust model (r 2 jack = 0.94 and RMSEP = 0.249 log 10 μS cm −1 ). However, the diatom-inferred conductivity values should be carefully interpreted because of the uneven distribution of sampling sites and the dominance of small araphid diatoms belonging to the genera Staurosira, Pseudostaurosira and Punctastriata. By their benthic habitat, the distribution of these taxa could be influenced by other factors as light and substrate in addition to water chemistry. The autoecological information achieved through this study will provide the basis for a better insight into the hydrological responses of the dryland rivers in northern Patagonia to climate and environmental changes.

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An ostracod-based calibration function for electrical conductivity reconstruction in lacustrine environments in Patagonia, Southern South America

Cited by 18 publications

References 31 publications

Paleoenvironmental changes during the last 3000 years in Lake Cari-Laufquen (Northern Patagonia, Argentina), inferred from ostracod paleoecology, petrophysical, sedimentological and geochemical data

Paleoenvironmental changes during the last 3000 years in Lake Cari-Laufquen (Northern Patagonia, Argentina), inferred from ostracod paleoecology, petrophysical, sedimentological and geochemical data

Changes in ostracod assemblages and morphologies during lake‐level variations of Lago Cardiel (49°S), Patagonia, Argentina, over the last 15.6 ka

Diatom-based inference model for conductivity reconstructions in dryland river systems from north Patagonia, Argentina

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