La Brava Research Articles

Compositional Changes in Sediment Microbiota Are Associated with Seasonal Variation of the Water Column in High-Altitude Hyperarid Andean Lake Systems.

The lacustrine systems of La Brava and La Punta, located in the Tilopozo sector in the extreme south of Salar de Atacama, are pristine high-altitude Andean lakes found along the central Andes of South America. This shallow ecosystem suffers from permanent evaporation, leading to falling water levels, causing it to recede or disappear during the dry season. This dynamic causes physicochemical changes in lakes, such as low nutrient availability, pH change, and dissolved metals, which can influence the composition of the microbial community. In this study, we used a metataxonomic approach (16S rRNA hypervariable regions V3 to V4) to characterize the sedimentary microbiota of these lakes. To understand how the water column affects and is structured in the microbiota of these lakes, we combined the analysis of the persistence of the water column through satellite images and physicochemical characterization. Our results show a significant difference in abiotic factors and microbiota composition between La Punta and La Brava lakes. In addition, microbiota analysis revealed compositional changes in the ecological disaggregation (main and isolated bodies) and antagonistic changes in the abundance of certain taxa between lakes. These findings are an invaluable resource for understanding the microbiological diversity of high Andean lakes using a multidisciplinary approach that evaluates the microbiota behavior in response to abiotic factors. IMPORTANCE In this study, we analyzed the persistence of the water column through satellite images and physicochemical characterization to investigate the composition and diversity in High Andean Lake Systems in a hyperarid environment. In addition to the persistence of the water column, this approach can be used to analyze changes in the morphology of saline accumulations and persistence of snow or ice; for example, for establishing variable plant cover over time and evaluating the microbiota associated with soils with seasonal changes in plants. This makes it an ideal approach to search for novel extremophilic microorganisms with unique properties. In our case, it was used to study microorganisms capable of resisting desiccation and water restriction for a considerable period and adapting to survive in ecological niches, such as those with high UV irradiation, extreme drought, and high salt concentration.

Tolerancia salina y rendimiento pesquero del pejerrey Odontesthes bonariensis (Actinopterygii; Atherinopsidae) en un lago somero de la Argentina

The silverside (Odontesthes bonariensis) is the most important species in Argentine fisheries due to its wide distribution, great demand and supply of fish protein. This species shows a great ecological plasticity; however, there is little research describing its tolerance to salinity in natural conditions. Dam constructions for irrigation, hydroelectric generation and human consumption, in synergy with glacial retraction, cause great instability in certain wetlands located downstream. In Curacó chained lakes, in the Desaguadero basin (La Pampa, Argentina), the environments reach high salinity and can even dry out entirely. During the period 2004-2008, a significant increase in water flows in this region modified its chemical characteristics and favored the development of silverside. In October 2009, water stopped entering into the system and, in 2011, many lakes disappeared. The objective of this work was to analyze the survival and fishing yield of O. bonariensis in a context of environmental tolerance due to the gradual surface decrease and the increase of salts concentration in La Brava shallow lake (37°55’24’’ S - 65°55’18’’ W). Water salinity increased progressively from 7.05 to 59.3 g/L and O. bonariensis was present up to a concentration of 49.9 g/L. Fish size evidenced a virgin population with specimens up to 482 mm of LEst and 7 years of age. High catches per unit of effort (CPUE) in number and biomass were observed, with maximums of 375 fish and 204. 6 kg/night, but these did not exhibit a strong linear correlation with saline concentration. The salinity tolerance observed in O. bonariensis is higher than that reported by other authors and places this freshwater fish among the most euryhaline in the world.

Physicochemical Parameters Affecting the Distribution and Diversity of the Water Column Microbial Community in the High-Altitude Andean Lake System of La Brava and La Punta.

Due to the low incidence of precipitation attributed to climate change, many high-altitude Andean lakes (HAALs) and lagoons distributed along the central Andes in South America may soon disappear. This includes La Brava–La Punta, a brackish lake system located south of the Salar de Atacama within a hyper-arid and halophytic biome in the Atacama Desert. Variations in the physicochemical parameters of the water column can induce changes in microbial community composition, which we aimed to determine. Sixteen sampling points across La Brava–La Punta were studied to assess the influence of water physicochemical properties on the aquatic microbial community, determined via 16S rRNA gene analysis. Parameters such as pH and the concentrations of silica, magnesium, calcium, salinity, and dissolved oxygen showed a more homogenous pattern in La Punta samples, whereas those from La Brava had greater variability; pH and total silica were significantly different between La Brava and La Punta. The predominant phyla were Proteobacteria, Bacteroidetes, Actinobacteria, and Verrucomicrobia. The genera Psychroflexus (36.85%), Thiomicrospira (12.48%), and Pseudomonas (7.81%) were more abundant in La Brava, while Pseudospirillum (20.73%) and Roseovarius (17.20%) were more abundant in La Punta. Among the parameters, pH was the only statistically significant factor influencing the diversity within La Brava lake. These results complement the known microbial diversity and composition in the HAALs of the Atacama Desert.

A biological and nitrate isotopic assessment framework to understand eutrophication in aquatic ecosystems.

Eutrophication is a globally significant challenge facing aquatic ecosystems, mostly associated with human induced enrichment of these ecosystems with nitrogen and phosphorus. Given the complexity of assigning eutrophication issues to local primary N sources in field-based studies, this paper proposes a multi-stable isotope and biological framework to track nitrogen biogeochemical transformations, inputs and fate of nitrate in groundwater-dependent shallow lakes. Three representative freshwater ecosystems from the Pampa Plain (Argentina), with different land uses and topographic features were selected. Groundwater (N=24), lake (N=29) and stream (N=20) samples were collected for isotope (δ15N-NO3- and δ18O-NO3-, δ18O-H2O) and hydrogeochemical (major ions and nutrients) determinations, and in the case of surface water, also for biological determinations (chlorophyll-a, fecal coliforms and nitrifying bacteria abundance). Both chemical and isotopic characteristics clearly indicated that denitrification was limited in lakes and streams, while evidence of assimilation in shallow lakes was confirmed. The results suggested that groundwater denitrification plays a role in the nitrate concentration pattern observed in the Pampeano Aquifer. The proportional contribution of nitrate sources to the inflow streams for all years were estimated by using Bayesian isotope mixing models, being ammonium nitrified in the system from soil and fertilizers ~50 - 75 %, sewage/manure ~20 - 40 % and atmospheric deposition ~5 - 15 %. In this sense, agricultural practices seem to have a relevant role in the eutrophication and water quality deterioration for these watersheds. However, limnological, bacterial and algal variables, assessed simultaneously with isotopic tracers, indicated spatio-temporal differences within and between these aquatic ecosystems. In the case of Nahuel Rucá Lake, animal manure was a significant source of nitrogen pollution, in contrast to La Brava Lake. In Los Padres Lake, agricultural practices were considered the main sources of nitrate input to the ecosystem.

La Brava creek: Water quality evaluation

The water quality of the “La Brava” creek, in Ocaña Norte de Santander, was analyzed using physicochemical and biological parameters to determine quality indices. Three sampling sections were established throughout the study area, taking samples in duplicate every four months for each point during a year; characterization of each sample was done following the protocols of standard methods. The information obtained was analyzed through water quality and contamination indices, determining that the water quality of the micro-basin is moderate, and its level of contamination is low; remaining in good homogeneous condition along the entire area. The utilization of a systems of indices allows for a good approach to assess the conditions of the basin, establishing that, currently, anthropic activities have minimal effect on the water resource in the study area. It is important to highlight that, although the level of contamination is low, it is necessary to generate strategies that guarantee the continuous quality and water supply in the area.

De don Álvaro de Luna a doña María la Brava: el fin de un ciclo

King Juan II of Castille’s court is a common topic in nineteenth-century literature, featured in novels, short stories, plays, and poems alike. When Eduardo Marquina’s Doña María la Brava (1909) was previewed in the early years of the twentieth century, critics objected to the blending of the legendary and the historical represented respectively by the characters of María de Monroy and Álvaro de Luna since they evaluated Marquina’s play according to nineteenth-century interpretations of the role of the constable Luna. Yet, as this article argues, Doña María la Brava appropriates the characters of King Juan’s court (Luna, the poets, and the noblemen) with the new objective of showing the decadence of Castille. Thus, Marquina’s play stages Castille’s crisis shortly after the political disaster of 98 and the significant historical events of the African war and “The Tragic Week.” I claim that this play inaugurates a new form of reading the fifteenth century which strongly differs from previous readings and necessarily means the end of the nineteenth-century literary cycle of King Juan II.

Temporal variations of larval digenean assemblages parasitizing Heleobia parchappii (Mollusca: Cochliopidae) in two shallow lakes from the Buenos Aires province, Argentina

ABSTRACT The larval digenean assemblages in snail hosts are influenced by biotic and abiotic factors and by environmental disturbances due to human activities. Given their susceptibility to different types of impact, they can be useful tools for the study of temporal variations in parasite communities. The study of temporal dynamics in prevalence and species richness of larval digenean assemblages of Heleobia parchappii (D’Orbigny, 1835), in two Pampean lakes, provides a good opportunity to test the supposition that seasonal variations in digenean assemblages are determined by a series of biotic and abiotic factors that operate interdependently. To analyze the temporal variations, and to evaluate how local factors influence these digenean assemblages in Los Padres and La Brava lakes (Buenos Aires province, Argentina), 2,400 specimens of H. parchappii were collected seasonally, during one year. The digenean assemblages in Los Padres and La Brava lakes were composed of 13 and 12 species respectively. These larval digenean assemblages showed similarities in the number and in the seasonal frequency of occurrence of species (eight of which were present in both lakes). However, despite these similarities, the assemblages showed different temporal dynamics in La Brava and Los Padres lakes and, also, different correlations with the abiotic and biotic factors analyzed during this study (temperature, high of the water column and snail relative abundance). Temporal dynamics in prevalence and species richness of larval digenean assemblages of H. parchappii in both lakes seems to be influenced by a series of factors (diversity and abundance of definitive hosts, intermediate and definitive host location, snail relative abundance and anthropogenic disturbances). Our results highlight the importance of analyzing the role and interaction of local factors, especially in studies dealing with spatiotemporal fluctuations or with distance decay of similarities in species richness of parasite assemblages.

Prokaryotic diversity and biogeochemical characteristics of benthic microbial ecosystems at La Brava, a hypersaline lake at Salar de Atacama, Chile.

Benthic microbial ecosystems of Laguna La Brava, Salar de Atacama, a high altitude hypersaline lake, were characterized in terms of bacterial and archaeal diversity, biogeochemistry, (including O2 and sulfide depth profiles and mineralogy), and physicochemical characteristics. La Brava is one of several lakes in the Salar de Atacama where microbial communities are growing in extreme conditions, including high salinity, high solar insolation, and high levels of metals such as lithium, arsenic, magnesium, and calcium. Evaporation creates hypersaline conditions in these lakes and mineral precipitation is a characteristic geomicrobiological feature of these benthic ecosystems. In this study, the La Brava non-lithifying microbial mats, microbialites, and rhizome-associated concretions were compared to each other and their diversity was related to their environmental conditions. All the ecosystems revealed an unusual community where Euryarchaeota, Crenarchaeota, Acetothermia, Firmicutes and Planctomycetes were the most abundant groups, and cyanobacteria, typically an important primary producer in microbial mats, were relatively insignificant or absent. This suggests that other microorganisms, and possibly novel pathways unique to this system, are responsible for carbon fixation. Depth profiles of O2 and sulfide showed active production and respiration. The mineralogy composition was calcium carbonate (as aragonite) and increased from mats to microbialites and rhizome-associated concretions. Halite was also present. Further analyses were performed on representative microbial mats and microbialites by layer. Different taxonomic compositions were observed in the upper layers, with Archaea dominating the non-lithifying mat, and Planctomycetes the microbialite. The bottom layers were similar, with Euryarchaeota, Crenarchaeota and Planctomycetes as dominant phyla. Sequences related to Cyanobacteria were very scarce. These systems may contain previously uncharacterized community metabolisms, some of which may be contributing to net mineral precipitation. Further work on these sites might reveal novel organisms and metabolisms of biotechnological interest.

TAPHONOMIC DIFFERENCES IN MOLLUSCAN SHELL PRESERVATION IN FRESHWATER ENVIRONMENTS FROM THE SOUTHEASTERN PAMPAS, ARGENTINA

Actualistic studies in freshwater environments are scarce, limiting the interpretation of paleoenvironmental information obtained from the fossil record. The objectives of this study are to assess the taphonomic factors that affect the formation of mollusk assemblages in freshwater environments of the pampean region. Twenty sites were analyzed at regional (La Brava and Nahuel Ruca) and environmental (lentic and lotic) scales. Shells were primarily affected by loss of proteinaceous parts, fragmentation, and fine-scale surface alteration. Taphonomic differences were observed in dead shell condition related to environmental conditions and faunistic composition (thin-/thick-shelled species proportion) in spite of the dominance of one species, Heleobia parchappii. The differences were related to extrinsic (environmental) factors probably due to differential influence of organic decay, microbioerosion, and/or dissolution. However, intrinsic factors, especially those related to differential preservation and input rates of thin-/thick-shelled species, may be also biasing the compositional fidelity of death assemblages. Although the degree of taphonomic alteration across locales and environments was evident, all mollusk assemblages still preserved their biological signature from the precursor communities.

A high-resolution palaeoclimate record for the last 4800 years from lake la Brava, SE pampas plains, Argentina

Climatic changes are reflected in variations of different parameters. Sequences of lake sediments are good sources of this information because they provide continuous and detailed records of palaeoclimatic changes. In order to determine the changes in climate in SE Pampas plain, in this paper we present a series of rock magnetic studies performed on a bottom core collected from Lake La Brava (Argentina).In order to establish lake level variations, we also measure total sulphur, organic and inorganic carbon (TS, TOC and TIC) content, alkaline elements, light and heavy metals and changes in vegetation communities. Five radiocarbon age determinations were made from samples of organic-rich clay and calibrated ages were calculated. The averaged sediment accumulation rate is 1.3mm/yr and the sequence represents a temporal extent of about 4800 calibrated years before the present (cal. BP).The main aim was to reconstruct the hydrological balance of the lake, the changes in erosional strength and sediment supply within the catchment area since the Middle Holocene, and to explore the extent to which these may be linked to changes in climate and/or human activities. The results of this work and previous studies suggest periodic changes from cooler to warmer and humid conditions. Relationships between submerged and emergent plants are consistent with the behaviour of magnetic susceptibility. TOC changes suggest wet environment during magnetic enhancement. Floods and lower lake level events were identified in detail. Changes in sediment contribution and depositional processes for the last 50cal. BP are caused by human impact, particularly by the use of natural resources.

Mid-late Holocene lake levels and trophic states of a shallow lake from the southern Pampa plain, Argentina

Changes in trophic status of the shallow Lake La Brava (southeastern Pampa plain of Argentina) are evaluated based on geochemical, biological and sedimentological data. Based on a conceptual framework, we propose that the lake level defines the water column mixing conditions, affecting internal lake processes and determining the transparency of lake water. The shift between alternative states is reconstructed for the last ~4800 years. Four main lake stages have been recognized, although short term shifts characterize all stages. A turbid phytoplankton-dominated state prevailed between ~4700-4500 cal yr before present (BP). Drier conditions and low lake levels pushed the lake to a clear state until 2000 cal yr BP. Afterwards the lake switched back to a turbid state, and these conditions persisted until ~200 cal yr BP. In the last 200 years, the lake switched back and forth between clear and turbid states. The latter represents the modern conditions of the lake since ~1950 AD. These shifts can be attributed mainly to climatic drivers.

Characterization of bacterial diversity associated with microbial mats, gypsum evaporites and carbonate microbialites in thalassic wetlands: Tebenquiche and La Brava, Salar de Atacama, Chile

In this paper, we report the presence of sedimentary microbial ecosystems in wetlands ofthe Salar de Atacama. These laminated systems, which bind, trap and precipitate mineral include: microbial mats at Laguna Tebenquiche and Laguna La Brava, gypsum domes at Tebenquiche and carbonate microbialites at La Brava. Microbial diversity and key biogeochemical characteristics of both lakes (La Brava and Tebenquiche) and their various microbial ecosystems (non-lithifying mats, flat and domal microbialites) were determined. The composition and abundance of minerals ranged from trapped and bound halite in organic-rich non-lithifying mats to aragonite-dominated lithified flat microbialites and gypsum in lithified domal structures. Pyrosequencing of the V4 region of the 16s rDNA gene showed that Proteobacteria comprised a major phylum in all of the microbial ecosystems studied, with a marked lower abundance in the non-lithifying mats. A higher proportion of Bacteroidetes was present in Tebenquiche sediments compared to La Brava samples. The concentration of pigments, particularly that of Chlorophyll a, was higher in the Tebenquiche than in La Brava. Pigments typically associated with anoxygenic phototrophic bacteria were present in lower amounts. Organic-rich, non-lithifying microbial mats frequently formed snake-like, bulbous structures due to gas accumulation underneath the mat. We hypothesize that the lithified microbialites might have developed from these snake-like microbial mats following mineral precipitation in the surface layer, producing domes with endoevaporitic communities in Tebenquiche and carbonate platforms in La Brava. Whereas the potential role of microbes in carbonate platforms is well established, the contribution of endoevaporitic microbes to formation of gypsum domes needs further investigation.

Spatial decision support system for assessing lake pollution hazard: southeastern pampean shallow lakes (Argentina) as a case study

This study gives an account of the implementation of a decision support system as a logical framework for assessing lake pollution hazard. The use of this system is demonstrated with an example from two lake watersheds, each one with different land-use, soil and topographic characteristics and also management regulations for natural resource protection. Lake pollution hazard is assessed as a function of two primary topics: hydrologic and soil conditions. This model shows the state of each evaluated subwatershed with respect to its potential contribution to lake pollution hazard based mainly on easily measurable and commonly used parameters: drainage density, hydraulic gradient, water table depth, soil media, land-cover and topography. Mapped outputs from the logic model allowed the identification of several subwatersheds in each lake system as the main water resource protection areas. La Brava Lake Watershed results reasonably fit the natural conditions of the watershed, identifying those subwatersheds with a moderate to high drainage density, high hydraulic gradient and extensive agricultural activities. Regarding Los Padres Lake Watershed, moderate to high drainage density, a high to a very high hydraulic gradient, shallow water depth, silt-loam soil texture and intensive agricultural and residential lands, contributed to a high lake pollution hazard. Results highlighted differences between both freshwater systems, being Los Padres Lake Watershed a more vulnerable ecosystem, requiring decision maker’s intervention based on accurate and up-to-date information.

Hydrogeochemistry and isotope techniques to determine water interactions in groundwater-dependent shallow lakes, Wet Pampa Plain, Argentina

This paper gives an account of the implementation of hydrochemical and isotopic techniques to identify and explain the processes that govern solute exchange in two groundwater-dependent shallow lakes in the Southeastern Pampa Plain of Argentina. Water samples (lakes, streams, spring water and groundwater) for hydrochemical and stable isotopic determination were collected and the main physical–chemical parameters were measured. The combination of stable isotope data with hydrogeochemical techniques was used for the identification of sources and preferential recharge areas to these aquatic ecosystems which allowed the explanation of the lake water origin. The hydrochemical processes which explain Los Padres Lake water chemistry are evaporation from groundwater, CO2 input, calcite dissolution, Na+ release by Ca2+ and Mg2+ exchange, and sulfate reduction. The model that best aligns with La Brava Lake hydrochemical constraints includes: mixing, CO2 and calcite dissolution, cationic exchange with Na+ release and Mg2+ adsorption, and to a lesser extent, Ca/Na exchange. This model suggests that the fractured aquifer contribution to this water body is greater than 50 %. An isotopic-specific fingerprint for each lake was identified, finding a higher evaporation rate for La Brava Lake compared to Los Padres Lake. Isotopic data demonstrate the importance of these shallow lakes as recharge areas to the regional aquifer, becoming areas of high groundwater vulnerability. The Tandilia Range System, considered in many hydrogeological studies as the impermeable bedrock of the Pampean aquifer, acts as a fissured aquifer in this area, contributing to low salinity waters and with a fingerprint similar to groundwater isotopic composition.

GIS-based pollution hazard mapping and assessment framework of shallow lakes: southeastern Pampean lakes (Argentina) as a case study

The assessment of water vulnerability and pollution hazard traditionally places particular emphasis on the study on groundwaters more than on surface waters. Consequently, a GIS-based Lake Pollution Hazard Index (LPHI) was proposed for assessing and mapping the potential pollution hazard for shallow lakes due to the interaction between the Potential Pollutant Load and the Lake Vulnerability. It includes easily measurable and commonly used parameters: land cover, terrain slope and direction, and soil media. Three shallow lake ecosystems of the southeastern Pampa Plain (Argentina) were chosen to test the usefulness and applicability of this suggested index. Moreover, anthropogenic and natural medium influence on biophysical parameters in these three ecosystems was examined. The evaluation of the LPHI map shows for La Brava and Los Padres lakes the highest pollution hazard (≈30% with high to very high category) while Nahuel Rucá Lake seems to be the less hazardous water body (just 9.33% with high LPHI). The increase in LPHI value is attributed to a different loading of pollutants governed by land cover category and/or the exposure to high slopes and influence of slope direction. Dissolved oxygen and biochemical oxygen demand values indicate a moderately polluted and eutrophized condition of shallow lake waters, mainly related to moderate agricultural activities and/or cattle production. Obtained information by means of LPHI calculation result useful to perform a local diagnosis of the potential pollution hazard to a freshwater ecosystem in order to implement basic guidelines to improve lake sustainability.

Diversity, Seasonality and Structure of Bird Assemblages Associated with Three Wetlands in the Southeastern Pampas, Argentina

Los Padres, La Brava and Nahuel Ruca lakes are typical wetlands of the Pampean region. These three shallow lakes share certain limnological features (size, mean depth, littoral macrophytes, among others) and the land usage in their basins (e.g. agriculture, cattle ranching and/or touristic activities). We surveyed the bird community at these three wetlands over three years (May 2006-May 2009), using transects and point counts to characterise their species richness, abundance, community composition and seasonality. We recorded a total of 135 species belonging to 41 families. The Relative Importance Index showed that the neotropic cormorant Phalacrocorax olivaceus, the cattle egret Bubulcus ibis, the white-tufted grebe Rollandia rolland and the white-faced ibis Plegadis chihi are the most representative species. Species richness, species composition and abundance differed between wetlands. Such differences could be attributed to particular factors such as proximity to urban centres or other wetlands, and to the impact of recreational activities. Considering that the Pampean region is currently under strong anthropogenic impacts, the present study contributes to the improvement of management plans that are currently in place or under development.

Stakeholder Analysis and Social-Biophysical Interdependencies for Common Pool Resource Management: La Brava Wetland (Argentina) as a Case Study

This article gives an account of the implementation of a stakeholder analysis framework at La Brava Wetland Basin, Argentina, in a common-pool resource (CPR) management context. Firstly, the context in which the stakeholder framework was implemented is described. Secondly, a four-step methodology is applied: (1) stakeholder identification, (2) stakeholder differentiation-categorization, (3) investigation of stakeholders' relationships, and (4) analysis of social-biophysical interdependencies. This methodology classifies stakeholders according to their level of influence on the system and their potential in the conservation of natural resources. The main influential stakeholders are La Brava Village residents and tourism-related entrepreneurs who are empowered to make the more important decisions within the planning process of the ecosystem. While these key players are seen as facilitators of change, there are other groups (residents of the inner basin and fishermen) which are seen mainly as key blockers. The applied methodology for the Stakeholder Analysis and the evaluation of social-biophysical interdependencies carried out in this article can be seen as an encouraging example for other experts in natural sciences to learn and use these methods developed in social sciences. Major difficulties and some recommendations of applying this method in the practice by non-experts are discussed.

Intraspecific variability in life-history traits of a "freshwater shrimp", Palaemonetes argentinus

Intraspecific variability in life-history traits was investigated comparing four geographically isolated populations of the shrimp Palaemonetes argentinus (Crustacea, Caridea, Palaemonidae) in the Province of Buenos Aires, Argentina. One population inhabits a creek (Vivorata Creek, VC), which drains into the brackish coastal lagoon Mar Chiquita; three others live in inland lakes (Lakes Chascomus, LC; La Brava, LB; Los Padres, LP). Female size at the onset of sexual maturity, both realized and actual fecundity (i.e. number of eggs in an early stage of embryonic development and number of freshly hatched larvae per female, respectively), as well as the size of freshly hatched larvae were consistently largest at VC, intermediate at LC and LB, and lowest at LP. The opposite pattern was found in egg loss (estimated as difference between realized and actual fecundity), being lowest at VC, highest at LP, and intermediate in the other two populations. Initial embryonic dry weight (W) was higher at VC than in all other populations. However, the W of freshly hatched larvae was similarly high at VC, LC and LB, but significantly lower at LP. Intraspecific variation in life-history traits, in particular between shrimps from VC (lotic, slightly brackish; highly variable salinities) and those from inland lakes (lentic; low but stable ion concentrations) are discussed in relation to local variation in hydrological and other ecological conditions that may wield differential selection pressures in the life-history evolution of a species with a wide range of ecological and geographic distribution.