Making thirsty cities sustainable: A nexus approach for water provisioning in Quito, Ecuador

In view of accelerated climate change and urban demographics, balancing human and ecosystem needs for water resources is a critical environmental challenge of global significance. Since water, agriculture, health, and energy are inextricably linked, sustainable development goals (SDGs) actions in one policy area commonly have impacts on the others, as well as on the ecosystems that natural resources and human activities ultimately depend upon. Managing urban water supply systems therefore requires a nexus approach that integrates goals across sectors, reduces the risk that SDG actions will undermine one another, and ensures sustainable resource use. We developed a transdisciplinary methodological framework based on a Pareto frontier analysis to define the sustainable solutions of a multi-objective optimization among four competing criteria, water provision, water quality, energy cost, and biodiversity conservation. The study was applied to three mountainous headwater basins in the Ecuadorian Andes, which provide around 30% of Quito's total water supply. We found that an optimized management of water intake structures would meet current consumption needs while reducing the probability of emergence of water pathogens and limiting the impact on aquatic biodiversity by 30% and 9% respectively, without any increase in energy costs for pumping water from other sources. Nonetheless, under future scenarios of climate change and water demand, higher energy consumption, and therefore an increase in operating costs, would be needed to meet urban demand and preserve environmental conditions. Overall, the range of Pareto optimal water supply strategies across the water-health-energy-biodiversity nexus provides valuable information for decision makers and offers support for achieving sustainable management of water resources.

Linking global climate change to local water availability: Limitations and prospects for a tropical mountain watershed

Bridging the gap between the predictions of coarse-scale climate models and the fine-scale climatic reality is a key issue of hydrological research and water management. While many advances have been realized in developed countries, the situation is contrastingly different in most tropical regions where we still lack information on potential discrepancies between measured and modeled climatic conditions. Consequently, water managers in these regions often rely on non-academic expertise to help them plan their future strategies. This issue is particularly alarming in tropical mountainous areas where water demand is increasing rapidly and climate change is expected to have severe impacts. In this article, we addressed this issue by evaluating the limitations and prospects in using regional climate models for evaluating the impact of climate change on water availability in a watershed that provides Quito, the capital of Ecuador, with about 30% of its current water needs. In particular, we quantified the temporal and spatial discrepancies between predicted and observed precipitation and temperature, and explored underlying mechanisms at play. Our results provide a strong critique of the inappropriate use of regional models to inform water planning with regard to adaptation strategies to face climate change. As a multidisciplinary group composed of hydrologists, ecologists and water managers, we then propose a framework to guide future climate change impact studies in tropical mountain watersheds where hydro-climatological data are scarce.

Distance makes the difference in thermography for ecological studies

Surface temperature drives many ecological processes and infrared thermography is widely used by ecologists to measure the thermal heterogeneity of different species' habitats. However, the potential bias in temperature readings caused by distance between the surface to be measured and the camera is still poorly acknowledged. We examined the effect of distance from 0.3 to 80m on a variety of thermal metrics (mean temperature, standard deviation, patch richness and aggregation) under various weather conditions and for different structural complexity of the studied surface types (various surfaces with vegetation). We found that distance is a key modifier of the temperature measured by a thermal infrared camera. A non-linear relationship between distance and mean temperature, standard deviation and patch richness led to a rapid under-estimation of the thermal metrics within the first 20m and then only a slight decrease between 20 and 80m from the object. Solar radiation also enhanced the bias with increasing distance. Therefore, surface temperatures were under-estimated as distance increased and thermal mosaics were homogenized at long distances with a much stronger bias in the warmer than the colder parts of the distributions. The under-estimation of thermal metrics due to distance was explained by atmospheric composition and the pixel size effect. The structural complexity of the surface had little effect on the surface temperature bias. Finally, we provide general guidelines for ecologists to minimize inaccuracies caused by distance from the studied surface in thermography.

Wing shape variations in an invasive moth are related to sexual dimorphism and altitude

Wing morphology has great importance in a wide variety of aspects of an insect's life. Here, we use a geometric morphometric approach to test the hypothesis that variation, in insect wing morphology patterns, occurs between sexes and along altitudinal gradients for invasive species, despite their recent association to this environment. We explored the variation in wing morphology between 12 invasive populations of the invasive potato pest, Tecia solanivora, at low and high altitude in the central highlands of Ecuador. After characterizing sexual dimorphism in wing shape, we investigated if moths at higher elevations differ in wing morphology from populations at lower altitudes. Results indicate wing shape and size differences between sexes and between altitudinal ranges. Females showed larger, wider wings than males, while high altitude moths showed larger, narrow-shaped wings by comparison to low-altitude moths. GLM analyses confirmed altitude was the only significant determinant of this gradient. Our study confirms a sexual dimorphism in size and wing shape for the potato moth. It also confirms and extends predictions of morphological changes with altitude to an invasive species, suggesting that wing morphology variation is an adapted response contributing to invasion success of the potato moth in mountainous landscapes. Ours is one of the first studies on the morphology of invasive insects and represents a valuable contribution to the study of insect invasions because it both offers empirical support to previous genetic studies on T. solanivora as well as proving broader insight into the mechanisms behind morphological evolution of a recently introduced pest.

Community-based participatory research helps farmers and scientists to manage invasive pests in the Ecuadorian Andes

Participatory research has not been a conspicuous methodology in developing nations for studying invasive pests, an increasing threat to the sustainable development in the tropics. Our study presents a community-based monitoring system that focuses on three invasive potato tuber moth species (PTM). The monitoring was developed and implemented by young farmers in a remote mountainous area of Ecuador. Local participants collected data from the PTM invasion front, which revealed clear connection between the abundance of one of the species (Tecia solanivora) and the remoteness to the main market place. This suggests that mechanisms structuring invasive populations at the invasion front are different from those occurring in areas invaded for longer period. Participatory monitoring with local people may serve as a cost-effective early warning system to detect and control incipient invasive pest species in countries where the daily management of biological resources is largely in the hands of poor rural people.

Temperature as a key driver of ecological sorting among invasive pest species in the tropical Andes

Invasive species are a major threat to the sustainable provision of ecosystem products and services, both in natural and agricultural ecosystems. To understand the spatial arrangement of species successively introduced into the same ecosystem, we examined the tolerance to temperature and analyzed the field distribution of three potato tuber moths (PTM, Lepidoptera: Gelechiidae), that were introduced in Ecuador since the 1980s. We studied physiological responses to constant temperatures of the three PTM species under laboratory conditions and modeled consequences for their overall population dynamics. We then compared our predictions to field abundances of PTM adults collected in 42 sites throughout central Ecuador. Results showed that the three PTM species differed with respect to their physiological response to temperature. Symmetrischema tangolias was more cold tolerant while Tecia solanivora had the highest growth rates at warmer temperatures. Phthorimaea operculella showed the poorest physiological performance across the range of tested temperatures. Overall, field distributions agree with predictions based on physiological experiments and life table analyses. At elevations >3000 m, the most cold-tolerant species, S. tangolias, was typically dominant and often the only species present. This species may therefore represent a biological sensor of climate change. At low elevations (<2700 m), T. solanivora was generally the most abundant species, probably due to its high fecundity at high temperatures. At mid elevations, the three species co-occurred, but P. operculella was generally the least abundant species. Consistent with these qualitative results, significant regression analyses found that the best predictors of field abundance were temperature and a species x temperature interaction term. Our results suggest that the climatic diversity in agricultural landscapes can directly affect the community composition following sequential invasions. In the tropical Andes, as in other mountain ecosystems, the wide range of thermal environments found along elevational gradients may be one reason why the risks of invasion by successively introduced pest species could increase in the near future. More data on potential biological risks associated with climatic warming trends in mountain systems are therefore urgently needed, especially in developing nations where such studies are lacking.

Escape performance decreases during ontogeny in wild crickets

Increasing the ecological relevance of studies relating to the performance of organisms has been a central issue for functional biologists over the last few years. Of particular concern are changes in performance throughout the life cycle as selective forces act differently on various life stages. We addressed this issue experimentally by following ontogenic variations in the escape performance of crickets threatened by artificial predatory signals. We measured their performance under natural settings, which is a necessary approach yet one that is undocumented in insects. We analysed numeric film sequences obtained using a high-speed video camera at 1000 frames s(-1) to quantify wild cricket performance and behaviour in the field. We detected significant differences in cricket escape performance throughout ontogeny. Escape performances were higher in juvenile crickets than older instars. Complementary behavioural measurements for escaping crickets suggest that these variations may be related to the lower predatory risk perceived by large adults than by juveniles. We expect that our analysis of size-refuge will also improve our understanding in the development of performance, given its importance in community and population ecology theories.

Air-flow sensitive hairs: boundary layers in oscillatory flows around arthropod appendages

The aim of this work is to characterize the boundary layer over small appendages in insects in longitudinal and transverse oscillatory flows. The problem of immediate interest is the early warning system in crickets perceiving flying predators using air-flow-sensitive hairs on cerci, two long appendages at their rear. We studied both types of oscillatory flows around small cylinders using stroboscopic micro-particle image velocimetry as a function of flow velocity and frequency. Theoretical predictions are well fulfilled for both longitudinal and transverse flows. Transverse flow leads to higher velocities than longitudinal flow in the boundary layer over a large range of angles between flow and cylinder. The strong spatial heterogeneity of flow velocities around filiform-shaped appendages is a rich source of information for different flow-sensing animals. Our results suggest that crickets could perceive the direction of incoming danger by having air-flow-sensitive hairs positioned around their entire cerci. Implications for biomimetic flow-sensing MEMS are also presented.

Ontogeny of air-motion sensing in cricket

Juvenile crickets suffer high rates of mortality by natural predators that they can detect using extremely sensitive air-sensing filiform hairs located on their cerci. Although a huge amount of knowledge has accumulated on the physiology, the neurobiology and the biomechanics of this sensory system in adults, the morphological and functional aspects of air sensing have not been as well studied in earlier life history stages. Using scanning electronic microscopy, we performed a survey of all cercal filiform hairs in seven instars of the wood cricket (Nemobius sylvestris). Statistical analyses allowed us to quantify profound changes in the number, the length and the distribution of cercal hairs during development. Of particular importance,we found a fivefold increase in hair number and the development of a bimodal length-frequency distribution of cercal hairs from the second instar onwards. Based on theoretical estimations of filiform hair population coding, we found that the cercal system is functional for a wide range of frequencies of biologically relevant oscillatory flows, even from the first instar. As the cricket develops, the overall sensitivity of the cercal system increases as a result of the appearance of new hairs, but the value of the best tuned frequency remains fixed between 150 and 180 Hz after the second instar. These frequencies nicely match those emitted by natural flying predators, suggesting that the development of the cercal array of hairs may have evolved in response to such signals.

Effects of stream acidification on fungal biomass in decaying beech leaves and leaf palatability

We examined the effect of surface water acidification on rates of decomposition, ergosterol concentrations (as a measure of fungal biomass), and palatability to shredders of common beech leaves (Fagus sylvatica L.) in five mountain streams (pH 4.7-7.1). Leaf decomposition was significantly faster in the circumneutral streams (pH 6.4-7.1; k > or = 0.00175 d(-1)), when compared to acidic streams (pH 4.7-4.9; k < or = 0.00100 d(-1)). Fungal biomass showed no particular trend along the acidification gradient except that it peaked earlier in the stream closest to neutrality. Leaf palatability, measured as the feeding activity of the leaf-shredding amphipod Gammarus fossarum Koch, varied with the exposure time in the streams. Except for the higher palatability of leaves exposed during 6 weeks at the highest pH, patterns among streams were mostly similar. These results suggest that reduced processing rates in the most acidic streams were not related to differences in fungal biomass associated with decomposing leaves and that microbial conditioning was only slightly delayed by acidification. Possible effects of low pH and related variables (Ca, Al) on microbial decomposition and detritivorous macroinvertebrates are discussed to clarify the inhibition of beech leaf decomposition in the studied systems.

Color stability of commercial anthocyanin-based extracts in relation to the phenolic composition. Protective effects by intra- and intermolecular copigmentation

Anthocyanin extracts are increasingly used as food ingredients. A current challenge is to maintain their color properties. The stability of some colorants has been studied in sugar and non-sugar drink models at three pH values (3, 4, and 5) under thermal and light conditions simulating rapid food aging. At a given pH, color stability mainly depends on the structures of anthocyanins and of colorless phenolic compounds. Colorants rich in acylated anthocyanins (purple carrot, red radish, and red cabbage) display great stability due to intramolecular copigmentation. The protection of red chromophore is higher for diacylated anthocyanins in red radish and red cabbage. For colorants without acylated anthocyanins (grape-marc, elderberry, black currant, and chokeberry), intermolecular copigmentation plays a key role in color protection. Colorants rich in flavonols and with the highest copigment/pigment ratio show a remarkable stability. By contrast, catechins appear to have a negative effect on red colorants, quickly turning yellowish in drink models. This effect is more pronounced when the pH is increased. Finally, color does not seem to be greatly influenced by the addition of sugar.

New aspects of anthocyanin complexation. Intramolecular copigmentation as a means for colour loss?

Two series of structurally related anthocyanins, extracted from the blue flowers of Evolvulus pilosus cv. Blue Daze and from the blue-purple flowers of Eichhornia crassipes, exhibit remarkable colour stabilities in aqueous solution at mildly acidic pH values. All the pigments possess the same chromophore (delphinidin), but a different pattern of glycosylation and acylation. Moreover, one of the pigments has an apigenin 7-glucoside molecule (a flavone) attached to the glycosidic chain by two ester bonds with malonic acid, instead of an aromatic acid and is the only known anthocyanin with such a structure. All the molecules studied, except one which has only a 3-gentiobioside (a disaccharide) as substituent, denote an effect of reduction in the hydration constant when compared with the parent delphinidin 3-glucoside or 3,5-diglucoside molecules, which supports the existence of intramolecular hydrophobic interactions between the chromophoric skeleton and the acyl or flavonoid groups. The role played by the sugar units on the hydrophobicity/hydrophilicity of the pigments is also discussed.