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Background and aims: Soil properties and climate influence leaf chemical traits producing intraspecific variation in plants. Studies evaluating their importance in the South American Temperate Forest (STF) species are scarce. This study aimed to evaluate the intraspecific differences in five evergreen species of the rainforest considering two contrasting areas (i.e. temperature and precipitation), linking soil and climate with plants traits. Methods: Soil properties (Corg%, N%, C/N, δ13C, δ15N, pH and temperature), climate variables (mean annual precipitation and temperature [MAP; MAT]) and leaf chemical traits (C%, N% and P%, C/N, N/P, δ13C and δ15N) were measured and compared between two areas in the Northern Patagonia (42°- 44°S). In addition, the relationship of leaf chemical traits with soil and climate was assessed. Results: Significant differences were found in soil (Corg%, C/N and pH; p < 0.05) and climate (p < 0.05), with MAP identified as the most common factor controlling soil properties (Corg%, C/N and δ15N). Intraspecific differences in leaf chemical traits were found between areas, but not in all traits. The most common leaf chemical trait with significant differences was C%. Higher mean C% values were found in the island in plants and soils. High number of correlations (n = 13 correlations; p < 0.05) were found between leaf chemical traits. On the other hand, only MAP was a significant predictor of δ13C in the leaves. Conclusion: The leaf chemical traits variability suggests a species-specific response to the soil and climate conditions, with important influence of precipitation as the most common predictor of soil properties and δ13C in the leaves. [ABSTRACT FROM AUTHOR]

In this study, we evaluated the isotopic niche dynamics in resident and migratory populations of facultative amphidromous fish Galaxias maculatus (Jenyns, 1842). We hypothesised that the isotopic niche space occupied by its populations differs between resident and migratory populations and among river ecosystems. To evaluate these hypotheses, we compared the isotopic niches of G. maculatus populations along the longitudinal gradient in five river systems in the central–southern Chile. Our results revealed differences among the isotopic niches of migratory and resident populations with greater diversity of carbon sources (wider isotopic niches) in amphidromous populations and narrower isotopic niche spaces in resident populations. Galaxias maculatus is a species with complex ecological characteristics that is frequently abundant in temperate river ecosystems of the Southern Hemisphere. The dynamics of its isotopic niches and carbon sources seems to strongly relate to life-history strategy employed by specific populations and mediates trophic structure and energy flow in river ecosystems where they are abundant. [ABSTRACT FROM AUTHOR]

Researchers and economic development practitioners regard microenterprises (MEs) as pivotal actors for economic development, poverty alleviation, and job creation. Notwithstanding the importance of MEs in the economy, there is no consistent definition of MEs, and thus, there is no consensus on the appropriate measurement and criteria that should be used to evaluate MEs formation. Two of the most commonly accepted standards criteria to determine MEs are the number of employees and total annual revenues. Although there is a growing body of research conducted on ME formation using the employment criteria to determine the firm size, fewer studies have used the revenue criteria. These criteria will be compared in a regional activity model at different units of geographic scale (state, county, and census tract level) using data from US businesses. Results suggest that there are no statistically significant changes in the estimated model when the criteria are changed for the same geographic unit of scale. However, for the same criteria (employment-based or revenue-based), a change in the unit of geographic aggregation produces different and sometimes contradictory results. These results imply that evaluations of MEs and their factors are more sensitive to scale than to criteria, raising awareness that for proper program evaluation, the unit of data aggregation matters. [ABSTRACT FROM AUTHOR]

Longitudinal movement plays fundamental role in habitat colonization and population establishment of many riverine fish species. Movement patterns of amphidromous fish species at fine-scales that would allow characterizing the direction of movement and factors associated with the establishment of specific life-history strategies (resident or amphidromous) in rivers are still poorly understood. We assess fine-scale longitudinal movement variability patterns of facultative amphidromous fish species Galaxias maculatus in order to unfold its life-history variation and associated recruitment habitats. Specifically, we analyzed multi-elemental composition along core to edge transects in ear-bones (otoliths) of each fish using recursive partitions that divides the transect along signal discontinuities. Fine-scale movement assessment in five free-flowing river systems allowed us to identify movement direction and potential recruitment habitats. As such, resident recruitment of G. maculatus in freshwater (71%) and estuarine (24%) habitats was more frequent than amphidromous recruitment (5%), and was linked to availability of slow-flowing lotic or lentic habitats that produce or retain small-bodied prey consumed by their larvae. We postulate that life-history variation and successful recruitment of facultative amphidromous fish such as G. maculatus in river systems is driven by availability of suitable recruitment habitats and natural hydrologic connectivity that allows fish movement to these habitats. [ABSTRACT FROM AUTHOR]

In the hyperarid Atacama Desert, water availability plays a crucial role in allowing plant survival. Along with scant rainfall, marine advective fog frequently occurs along the coastal escarpment fueling isolated mono-specific patches of Tillandsia vegetation. In this study, we investigate the lipid biomarker composition of the bromeliad Tillandsia landbeckii (CAM plant) to assess structural adaptations at the molecular level as a response to extremely arid conditions. We analyzed long-chain n-alkanes and fatty acids in living specimens (n = 59) collected from the main Tillandsia dune ecosystems across a 350 km coastal transect. We found that the leaf wax composition was dominated by n-alkanes with concentrations (total average 160.8 ± 91.4 µg/g) up to three times higher than fatty acids (66.7 ± 40.7 µg/g), likely as an adaptation to the hyperarid environment. Significant differences were found in leaf wax distribution (Average Chain Length [ACL] and Carbon Preference Index [CPI]) in the northern zone relative to the central and southern zones. We found strong negative correlations between fatty acid CPI and n-alkane ACL with precipitation and surface evaporation pointing at fine-scale adaptations to low moisture availability along the coastal transect. Moreover, our data indicate that the predominance of n-alkanes is reflecting the function of the wax in preventing water loss from the leaves. The hyperarid conditions and good preservation potential of both n-alkanes and fatty acids make them ideal tracers to study late Holocene climate change in the Atacama Desert. [ABSTRACT FROM AUTHOR]

Warming across the globe is expected to alter the strength and amount of regional precipitation, but there is uncertainty associated with the magnitude of these expected changes, and also how these changes in temperature and the hydrologic cycle will affect humans. For example, the climate in central-south Chile is projected to become significantly warmer and drier over the next several decades in response to anthropogenically driven warming, but these anthropogenic changes are superimposed on natural climate variability. The stable isotope composition of meteoric water provides significant information regarding the moisture source, pathways, and rain-out history of an air mass, but precipitation samples suitable for stable isotope measurements require long-term placement of field equipment making them difficult to obtain. The International Atomic Energy Agency (IAEA) Global Network of Isotopes in Precipitation (GNIP) stations generate isotopic and ancillary data of precipitation from many locations around the world, but remote areas of developing countries like Chile typically have sparse networks of meteorological stations, which inhibit our ability to accurately model regional precipitation. Central-south Chile, in particular, has a sparse network of GNIP stations and, as a result, the isotopic composition of meteoric water is underrepresented in the global database complicating efforts to constrain modern day hydroclimate variability as well as paleohydrologic reconstruction for southern South America. In this study, we measured the stable isotope compositions of hydrogen (δ2H) and oxygen (δ18O) in surface lacustrine waters of central-south Chile to determine what physical and/or climatic features are the dominant controls on lacustrine δ18O and δ2H composition, assess whether or not the isotopic composition of the lakes record time-averaged isotope composition of meteoric water, and determine whether an isoscape map based on lake surface waters could predict the H and O isotope compositions of precipitation at the few GNIP stations in the region. [ABSTRACT FROM AUTHOR]

The study of fatty acid biomarkers in trophic structures at sub-polar latitudes is fundamental in describing energy fluxes across ecosystems characterized by complex inter-specific interactions. Due to the presence of certain essential fatty acids obtained exclusively from predator–prey interactions, fatty acid biomarkers are widely used to identify trophic interactions. This study analyzed fatty acid compositions in three species inhabiting a relatively pristine Patagonian fjord. This fjord is geographically difficult to access, so there are very little sampling opportunities, biological and oceanographic information. In the three species collected (Ctenodiscus australis (Loven in Lütken 1871) (Echinodermata, Asteroidea, Ctenodiscidae); Munida gregaria (Fabricius 1793) (Arthropoda, Malacostraca, Munididae); Eleginops maclovinus (Cuvier 1830) (Chordata, Actinopterygii, Eleginopsidae)) along this remote area were evaluated their fatty acid trophic markers as a tool to differentiate dietary components and dietary habits. The study reported significant differences in the amount of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA), with the highest concentrations of all fatty acids in M. gregaria. The last suggests that M. gregaria is considered as a good quality food source or biological component that might support the fjord trophic web in the Southern Hemisphere. The results describe diet compositions in sampled species, and differences among species for fatty acid compositions and proportions. This provides an initial basis for future modeling or projecting how benthic ecosystems of fjords and Patagonian channels respond to food intake, particularly in environments associated with glacial systems characterized by a low phytoplankton biomass and greater sensitivity to climate variability. [ABSTRACT FROM AUTHOR]

Oxygen minimum zones are expanding globally, and at present account for around 20-40% of oceanic nitrogen loss. Heterotrophic denitrification and anammox-anaerobic ammonium oxidation with nitrite-are responsible for most nitrogen loss in these low-oxygen waters. Anammox is particularly significant in the eastern tropical South Pacific, one of the largest oxygen minimum zones globally. However, the factors that regulate anammox-driven nitrogen loss have remained unclear. Here, we present a comprehensive nitrogen budget for the eastern tropical South Pacific oxygen minimum zone, using measurements of nutrient concentrations, experimentally determined rates of nitrogen transformation and a numerical model of export production. Anammox was the dominant mode of nitrogen loss at the time of sampling. Rates of anammox, and related nitrogen transformations, were greatest in the productive shelf waters, and tailed off with distance from the coast. Within the shelf region, anammox activity peaked in both upper and bottom waters. Overall, rates of nitrogen transformation, including anammox, were strongly correlated with the export of organic matter. We suggest that the sinking of organic matter, and thus the release of ammonium into the water column, together with benthic ammonium release, fuel nitrogen loss from oxygen minimum zones. [ABSTRACT FROM AUTHOR]

In the high-permeability, semiarid carbonate aquifer in the Sierra de Gádor Mountains (southeastern Spain), some local springs draining shallow perched aquifers were of assistance in assessing applicability of the atmospheric chloride mass balance (CMB) for quantifying total yearly recharge ( R) by rainfall. Two contrasting hydrological years (October through September) were selected to evaluate the influence of climate on recharge: the average rainfall year 2003-2004, and the unusually dry 2004-2005. Results at small catchment scale were calibrated with estimated daily stand-scale R obtained by means of a soil water balance (SWB) of rainfall, using the actual evapotranspiration measured by the eddy covariance (EC) technique. R ranged from 0.35 to 0.40 of rainfall in the year, with less than a 5% difference between the CMB and SWB methods in 2003-2004. R varied from less than 0.05 of rainfall at mid-elevation to 0.20 at high elevation in 2004-2005, with a similar difference between the methods. Diffuse recharge ( R) by rainfall was quantified from daily soil water content field data to split R into R and the expected concentrated recharge ( R) at catchment scale in both hydrological years. R was 0.16 of rainfall in 2003-2004 and 0.01 in 2004-2005. Under common 1- to 3-day rainfall events, the hydraulic effect of R is delayed from 1 day to 1 week, while R is not delayed. This study shows that the CMB method is a suitable tool for yearly values complementing and extending the more widely used SWB in ungauged mountain carbonate aquifers with negligible runoff. The slight difference between R rates at small catchment and stand scales enables results to be validated and provides new estimates to parameterize R with rainfall depth after checking the weight of diffuse and concentrated mechanisms on R during moderate rainfall periods and episodes of marked climatic aridity. [ABSTRACT FROM AUTHOR]

Liquid wastes from the fish meal and oil processing industries produce serious environmental impacts in coastal embayments on the coasts of Chile and Peru. This article presents an analysis of an environmental monitoring program at Lota Bay, a shallow coastal indentation in central Chile (37°S) exposed to industrial fishing activity. The study of the environmental impact produced by waste effluents permitted making an evaluation of the bay's capacity for seasonal recovery from this impact. Seasonal cruises were carried out during 1994 and in 1996, 1997, and 1998. Variables analyzed included salinity, temperature, dissolved oxygen, ammonium concentration and surface oil and grease. The hydrographic regime of Lota Bay follows a seasonal pattern, where, typical of most SE pacific embayments, waters from subsuperficial oxygen minimum zones moved into the bay. The percentages of dissolved oxygen were critical in the area of organic waste discharge. The impact of wastewater is related to the type and status of the fishery, including: (i) overloads of plant production lines, (ii) maintenance and cleaning of installations, and (iii) degree of shipboard fishing conservation. Major alterations were observed in summer, when the highest discharge of organic load occurred. In winter, an improvement in the re-aeration conditions reduced the impact. Remedial measures implemented beginning in 1997 arose from the monitoring program and had to be separated into two recovery factors including (a) internal management of plants and (b) treatment of plant effluents. [ABSTRACT FROM AUTHOR]