Macrophyte regional patterns, metrics assessment and ecological integrity of isolated ponds at Austral Patagonia (Argentina).

Anthropogenic and natural changes are threatening pond ecological integrity in Patagonia and tools for bioassessment are required. Macrophytes are good candidates to determine the conservation status of ponds; nevertheless, metric selection procedures should be founded on an adequate knowledge of plant ecological responses. We assessed the main environmental constraints driving variation in macrophyte assemblages, and trophic status at 29 ponds located at the continental and insular Patagonia region. We screened 20 potential macrophyte metrics as indicators of pond condition that included origin (native, endemic, exotic), lifeforms (annual/biannual, perennial), functional groups (submersed, emergent, floating-leaved, landforms), and community attributes. A set of 106 taxa were recorded, and richness per site (10 species) was unexpectedly high for a cold temperate area, reinforcing the value of isolated ponds as habitat for macrophytes in the Patagonian landscape. Natives dominated most assemblages; exotics were present at 24 ponds, contributing with high cover (>45%) at 15% of them. Macrophyte assemblages were driven by natural factors over anthropogenic ones, with temperature, rainfall, pH, conductivity and nutrients explaining most variation in patterns. However, pond eutrophication symptoms (high phosphorous concentration and chlorophyll a) were associated with extensive cattle grazing (manure and trampling) and urbanization (runoff). Generalized linear models captured natural variables (temperature, alkalinity) as most powerful explaining richness measures. Models also indicated that both richness of emergent and endemics were negatively affected by total phosphorous increases. Land cover factors: grasses/herbaceous, mallín and trees (%) in 100 m buffer around ponds appeared as additional ecological drivers of macrophyte patterns, particularly of submersed (>50%) and native richness (36%). Natural and anthropogenic gradients were overlapped, making it difficult to generalize our conclusions. Further studies are needed to test the performance of the macrophyte metrics selected here, which are a vital tool for the conservation of the most austral ponds in South America.

An interdisciplinary approach to perception of water quality for human consumption in a Mapuche community of arid Patagonia, Argentina.

Vital for human consumption, water is a scarce resource, particularly in the arid environments of Patagonia. In this study we analysed local perspectives and the use of different water sources, based on two case studies in rural communities of Mapuche and Creole ancestry inhabiting extra-Andean Patagonia in Chubut, Argentina. Water quality was evaluated using an ethnolimnological, interdisciplinary approach, taking into account local perspectives and scientific contributions. In addition, we analysed appropriation strategies, management and local organoleptic characteristics. The work was based on semi-structured interviews, tours guided by informants, and physicochemical and microbiological analysis of water sources. It was found that 92% of local inhabitants mainly used superficial and subterranean sources of water for consumption, among which stood out: river, streams, springs, wells, and boreholes. Differences were observed between local and scientific perspectives in terms of water quality (chemical and microbiological). Most water sources used by inhabitants presented water of deficient quality for human consumption (61%), whereas locals considered the water to be fresh, delicious, and transparent. Nevertheless, some points of agreement were found in terms of organoleptic characteristics (e.g., odour, colour) and physicochemical parameters in certain water sources. In general, locals do not recognise the deterioration of their water supply, but the importance of organoleptic characteristics in local perception should be highlighted. These aspects speak of a need to promote opportunities for dialogue, and implement effective health measures, taking local perspectives into account.

Quantum anomaly in molecular physics.

The interaction of an electron with a polar molecule is shown to be the simplest realization of a quantum anomaly in a physical system. The existence of a critical dipole moment for electron capture and formation of anions, which has been confirmed experimentally and numerically, is derived. This phenomenon is a manifestation of the anomaly associated with quantum symmetry breaking of the classical scale invariance exhibited by the point-dipole interaction. Finally, analysis of symmetry breaking for this system is implemented within two different models: point dipole subject to an anomaly and finite dipole subject to explicit symmetry breaking.