Anthocyanins as Natural Food Colorings: The Chemistry Behind and Challenges Still Ahead.

Anthocyanins are polyphenolic O-glycosides widely responsible for the bright red, purple, and blue colors in the plant kingdom, including a great variety of fruits and vegetables. Hence, they have attracted considerable scientific and industrial interest as potential natural food colorings. However, individual anthocyanins are intrinsically reactive molecules combining electrophilic, nucleophilic, and electron-donating properties. This reactivity may be not only a source of color diversity with, for instance, the formation of new pigments upon winemaking and storage but also a cause of great color instability involving a combination of reversible and irreversible mechanisms (e.g., water addition, autoxidation) leading to colorless products. Hence, using anthocyanin-rich plant extracts as food colorings requires a deep understanding of these color-damaging mechanisms and, no less importantly, of the color-stabilizing mechanisms developed by plants, including π-stacking interactions (self-association, copigmentation), metal binding, and a combination of both. The potential of anthocyanins from deeply colored vegetables, typically acylated by hydroxycinnamic acid residues, will be emphasized in that respect. Moreover, food-grade biopolymers (proteins, polysaccharides) may provide suitable matrices for ready-to-use formulations of anthocyanins as food colorings. In this short review, the mechanisms of color loss and color stabilization are discussed as a function of anthocyanin structure and environment, and some challenges still ahead are outlined.

Dynamics and drivers of mycorrhizal fungi after glacier retreat.

The development of terrestrial ecosystems depends greatly on plant mutualists such as mycorrhizal fungi. The global retreat of glaciers exposes nutrient-poor substrates in extreme environments and provides a unique opportunity to study early successions of mycorrhizal fungi by assessing their dynamics and drivers. We combined environmental DNA metabarcoding and measurements of local conditions to assess the succession of mycorrhizal communities during soil development in 46 glacier forelands around the globe, testing whether dynamics and drivers differ between mycorrhizal types. Mycorrhizal fungi colonized deglaciated areas very quickly (< 10 yr), with arbuscular mycorrhizal fungi tending to become more diverse through time compared to ectomycorrhizal fungi. Both alpha- and beta-diversity of arbuscular mycorrhizal fungi were significantly related to time since glacier retreat and plant communities, while microclimate and primary productivity were more important for ectomycorrhizal fungi. The richness and composition of mycorrhizal communities were also significantly explained by soil chemistry, highlighting the importance of microhabitat for community dynamics. The acceleration of ice melt and the modifications of microclimate forecasted by climate change scenarios are expected to impact the diversity of mycorrhizal partners. These changes could alter the interactions underlying biotic colonization and belowground-aboveground linkages, with multifaceted impacts on soil development and associated ecological processes.

The importance of species addition 'versus' replacement varies over succession in plant communities after glacier retreat.

The mechanisms underlying plant succession remain highly debated. Due to the local scope of most studies, we lack a global quantification of the relative importance of species addition 'versus' replacement. We assessed the role of these processes in the variation (ß-diversity) of plant communities colonizing the forelands of 46 retreating glaciers worldwide, using both environmental DNA and traditional surveys. Our findings indicate that addition and replacement concur in determining community changes in deglaciated sites, but their relative importance varied over time. Taxa addition dominated immediately after glacier retreat, as expected in harsh environments, while replacement became more important for late-successional communities. These changes were aligned with total ß-diversity changes, which were more pronounced between early-successional communities than between late-successional communities (>50 yr since glacier retreat). Despite the complexity of community assembly during plant succession, the observed global pattern suggests a generalized shift from the dominance of facilitation and/or stochastic processes in early-successional communities to a predominance of competition later on.

Local climate modulates the development of soil nematode communities after glacier retreat.

The worldwide retreat of glaciers is causing a faster than ever increase in ice-free areas that are leading to the emergence of new ecosystems. Understanding the dynamics of these environments is critical to predicting the consequences of climate change on mountains and at high latitudes. Climatic differences between regions of the world could modulate the emergence of biodiversity and functionality after glacier retreat, yet global tests of this hypothesis are lacking. Nematodes are the most abundant soil animals, with keystone roles in ecosystem functioning, but the lack of global-scale studies limits our understanding of how the taxonomic and functional diversity of nematodes changes during the colonization of proglacial landscapes. We used environmental DNA metabarcoding to characterize nematode communities of 48 glacier forelands from five continents. We assessed how different facets of biodiversity change with the age of deglaciated terrains and tested the hypothesis that colonization patterns are different across forelands with different climatic conditions. Nematodes colonized ice-free areas almost immediately. Both taxonomic and functional richness quickly increased over time, but the increase in nematode diversity was modulated by climate, so that colonization started earlier in forelands with mild summer temperatures. Colder forelands initially hosted poor communities, but the colonization rate then accelerated, eventually leveling biodiversity differences between climatic regimes in the long term. Immediately after glacier retreat, communities were dominated by colonizer taxa with short generation time and r-ecological strategy but community composition shifted through time, with increased frequency of more persister taxa with K-ecological strategy. These changes mostly occurred through the addition of new traits instead of their replacement during succession. The effects of local climate on nematode colonization led to heterogeneous but predictable patterns around the world that likely affect soil communities and overall ecosystem development.

Fat-soluble vitamin and phytochemical metabolites: Production, gastrointestinal absorption, and health effects.

Consumption of diets rich in fruits and vegetables, which provide some fat-soluble vitamins and many phytochemicals, is associated with a lower risk of developing certain degenerative diseases. It is well accepted that not only the parent compounds, but also their derivatives formed upon enzymatic or nonenzymatic transformations, can produce protective biological effects. These derivatives can be formed during food storage, processing, or cooking. They can also be formed in the lumen of the upper digestive tract during digestion, or via metabolism by microbiota in the colon. This review compiles the known metabolites of fat-soluble vitamins and fat-soluble phytochemicals (FSV and FSP) that have been identified in food and in the human digestive tract, or could potentially be present based on the known reactivity of the parent compounds in normal or pathological conditions, or following surgical interventions of the digestive tract or consumption of xenobiotics known to impair lipid absorption. It also covers the very limited data available on the bioavailability (absorption, intestinal mucosa metabolism) and summarizes their effects on health. Notably, despite great interest in identifying bioactive derivatives of FSV and FSP, studying their absorption, and probing their putative health effects, much research remains to be conducted to understand and capitalize on the potential of these molecules to preserve health.

Is a seasonally reduced growth potential a convergent strategy to survive drought and frost in plants?

BACKGROUND: Plants have adapted to survive seasonal life-threatening frost and drought. However, the timing and frequency of such events are impacted by climate change, jeopardizing plant survival. Understanding better the strategies of survival to dehydration stress is therefore timely and can be enhanced by the cross-fertilization of research between disciplines (ecology, physiology), models (woody, herbaceous species) and types of stress (drought, frost). SCOPE: We build upon the 'growth-stress survival' trade-off, which underpins the identification of global plant strategies across environments along a 'fast-slow' economics spectrum. Although phenological adaptations such as dormancy are crucial to survive stress, plant global strategies along the fast-slow economic spectrum rarely integrate growth variations across seasons. We argue that the growth-stress survival trade-off can be a useful framework to identify convergent plant ecophysiological strategies to survive both frost and drought. We review evidence that reduced physiological activity, embolism resistance and dehydration tolerance of meristematic tissues are interdependent strategies that determine thresholds of mortality among plants under severe frost and drought. We show that complete dormancy, i.e. programmed growth cessation, before stress occurrence, minimizes water flows and maximizes dehydration tolerance during seasonal life-threatening stresses. We propose that incomplete dormancy, i.e. the programmed reduction of growth potential during the harshest seasons, could be an overlooked but major adaptation across plants. Quantifying stress survival in a range of non-dormant versus winter- or summer-dormant plants, should reveal to what extent incomplete to complete dormancy could represent a proxy for dehydration tolerance and stress survival. CONCLUSIONS: Our review of the strategies involved in dehydration stress survival suggests that winter and summer dormancy are insufficiently acknowledged as plant ecological strategies. Incorporating a seasonal fast-slow economics spectrum into global plant strategies improves our understanding of plant resilience to seasonal stress and refines our prevision of plant adaptation to extreme climatic events.

Insufficient yet improving involvement of the global south in top sustainability science publications.

The creation of global research partnerships is critical to produce shared knowledge for the implementation of the UN 2030 Agenda for Sustainable Development. Sustainability science promotes the coproduction of inter- and transdisciplinary knowledge, with the expectation that studies will be carried out through groups and truly collaborative networks. As a consequence, sustainability research, in particular that published in high impact journals, should lead the way in terms of ethical partnership in scientific collaboration. Here, we examined this issue through a quantitative analysis of the articles published in Nature Sustainability (300 papers by 2135 authors) and Nature (2994 papers by 46,817 authors) from January 2018 to February 2021. Focusing on these journals allowed us to test whether research published under the banner of sustainability science favoured a more equitable involvement of authors from countries belonging to different income categories, by using the journal Nature as a control. While the findings provide evidence of still insufficient involvement of Low-and-Low-Middle-Income-Countries (LLMICs) in Nature Sustainability publications, they also point to promising improvements in the involvement of such authors. Proportionally, there were 4.6 times more authors from LLMICs in Nature Sustainability than in Nature articles, and 68.8-100% of local Global South studies were conducted with host country scientists (reflecting the discouragement of parachute research practices), with local scientists participating in key research steps. We therefore provide evidence of the promising, yet still insufficient, involvement of low-income countries in top sustainability science publications and discuss ongoing initiatives to improve this.

Encapsulation of phenolic acids into cyclodextrins: A global statistical analysis of the effects of pH, temperature and concentrations on binding constants measured by ACE methods.

Affinity capillary electrophoresis was used for the simultaneous measurement of the pKa values and of the binding constants relative to the encapsulation of naturally occurring phenolic acids (rosmarinic and caffeic acids) with cyclodextrins. A thorough study as a function of pH and temperature was coupled to a detailed statistical analysis of the resulting experimental data. A step-by-step curve fitting process was sufficient for obtaining individual binding constant for each experimental condition, but the influence of temperature remained unclear. A quantitative and qualitative gain was then obtained by supplementing this initial analysis with global multiparameter optimization. This leads to the estimation of both entropy and enthalpy of reaction and to the full description of the binding reactions as a function of pH and temperature. The encapsulation was shown to be very sensitive to pH and temperature, with optimal complexation occurring at low pH and low temperature, gaining up to a factor of 3 by cooling from 36 to 15°C, and up to a factor of 10 by lowering the pH from 7 to 2.

A whole-ecosystem experiment reveals flow-induced shifts in a stream community.

The growing threat of abrupt and irreversible changes to the functioning of freshwater ecosystems compels robust measures of tipping point thresholds. To determine benthic cyanobacteria regime shifts in a potable water supply system in the tropical Andes, we conducted a whole ecosystem-scale experiment in which we systematically diverted 20 to 90% of streamflow and measured ecological responses. Benthic cyanobacteria greatly increased with a 60% flow reduction and this tipping point was related to water temperature and nitrate concentration increases, both known to boost algal productivity. We supplemented our experiment with a regional survey collecting > 1450 flow-benthic algal measurements at streams varying in water abstraction levels. We confirmed the tipping point flow value, albeit at a slightly lower threshold (40-50%). A global literature review broadly confirmed our results with a mean tipping point at 58% of flow reduction. Our study provides robust in situ demonstrations of regime shift thresholds in running waters with potentially strong implications for environmental flows management.

Reducing adverse impacts of Amazon hydropower expansion.

Proposed hydropower dams at more than 350 sites throughout the Amazon require strategic evaluation of trade-offs between the numerous ecosystem services provided by Earth's largest and most biodiverse river basin. These services are spatially variable, hence collective impacts of newly built dams depend strongly on their configuration. We use multiobjective optimization to identify portfolios of sites that simultaneously minimize impacts on river flow, river connectivity, sediment transport, fish diversity, and greenhouse gas emissions while achieving energy production goals. We find that uncoordinated, dam-by-dam hydropower expansion has resulted in forgone ecosystem service benefits. Minimizing further damage from hydropower development requires considering diverse environmental impacts across the entire basin, as well as cooperation among Amazonian nations. Our findings offer a transferable model for the evaluation of hydropower expansion in transboundary basins.

One-Step Extraction of Olive Phenols from Aqueous Solution Using ß-Cyclodextrin in the Solid State, a Simple Eco-Friendly Method Providing Photochemical Stability to the Extracts.

The extraction of phenolic compounds from olive mill wastes is important, not only to avoid environmental damages, but also because of the intrinsic value of those biophenols, well-known for their high antioxidant potential and health benefits. This study focuses on tyrosol (Tyr) and hydroxytyrosol (HT), two of the main phenolic compounds found in olive mill wastes. A new, simple, and eco-friendly extraction process for the removal of phenolic compounds from aqueous solutions using native ß-cyclodextrin (ß-CD) in the solid state has been developed. Several ß-CD/biophenol molar ratios and biophenol concentrations were investigated, in order to maintain ß-CD mostly in the solid state while optimizing the extraction yield and the loading capacity of the sorbent. The extraction efficiencies of Tyr and HT were up to 61%, with a total solid recovery higher than 90% using an initial concentration of 100 mM biophenol and 10 molar equivalents of ß-CD. The photochemical stability of the complexes thus obtained was estimated from ∆E*ab curve vs. illumination time. The results obtained showed that the phenols encapsulated into solid ß-CD are protected against photodegradation. The powder obtained could be directly developed as a safe-grade food supplement. This simple eco-friendly process could be used for extracting valuable biophenols from olive mill wastewater.

The response of culturally important plants to experimental warming and clipping in Pakistan Himalayas.

The relative effects of climate warming with grazing on medicinally important plants are not fully understood in Hindukush-Himalaya (HKH) region. Therefore, we combined the indigenous knowledge about culturally important therapeutic plants and climate change with experimental warming (open-top chambers) and manual clipping (simulated grazing effect) and compared the relative difference on aboveground biomass and percent cover of plant species at five alpine meadow sites on an elevation gradient (4696 m-3346 m) from 2016-2018. Experimental warming increased biomass and percent cover throughout the experiment. However, the interactive treatment effect (warming x clipping) was significant on biomass but not on percent cover. These responses were taxa specific. Warming induced an increase of 1 ± 0.6% in Bistorta officinalis percent cover while for Poa alpina it was 18.7 ± 4.9%. Contrastingly, clipping had a marginally significant effect in reducing the biomass and cover of all plant species. Clipping treatment reduced vegetation cover & biomass by 2.3% and 6.26%, respectively, but that was not significant due to the high variability among taxa response at different sites. It was found that clipping decreased the effects of warming in interactive plots. Thus, warming may increase the availability of therapeutic plants for indigenous people while overgrazing would have deteriorating effects locally. The findings of this research illustrate that vegetation sensitivity to warming and overgrazing is likely to affect man-environment relationships, and traditional knowledge on a regional scale.

Discovery of a natural cyan blue: A unique food-sourced anthocyanin could replace synthetic brilliant blue.

The color of food is critical to the food and beverage industries, as it influences many properties beyond eye-pleasing visuals including flavor, safety, and nutritional value. Blue is one of the rarest colors in nature's food palette-especially a cyan blue-giving scientists few sources for natural blue food colorants. Finding a natural cyan blue dye equivalent to FD&C Blue No. 1 remains an industry-wide challenge and the subject of several research programs worldwide. Computational simulations and large-array spectroscopic techniques were used to determine the 3D chemical structure, color expression, and stability of this previously uncharacterized cyan blue anthocyanin-based colorant. Synthetic biology and computational protein design tools were leveraged to develop an enzymatic transformation of red cabbage anthocyanins into the desired anthocyanin. More broadly, this research demonstrates the power of a multidisciplinary strategy to solve a long-standing challenge in the food industry.

Acylated Anthocyanins from Red Cabbage and Purple Sweet Potato Can Bind Metal Ions and Produce Stable Blue Colors.

Red cabbage (RC) and purple sweet potato (PSP) are naturally rich in acylated cyanidin glycosides that can bind metal ions and develop intramolecular π-stacking interactions between the cyanidin chromophore and the phenolic acyl residues. In this work, a large set of RC and PSP anthocyanins was investigated for its coloring properties in the presence of iron and aluminum ions. Although relatively modest, the structural differences between RC and PSP anthocyanins, i.e., the acylation site at the external glucose of the sophorosyl moiety (C2-OH for RC vs. C6-OH for PSP) and the presence of coordinating acyl groups (caffeoyl) in PSP anthocyanins only, made a large difference in the color expressed by their metal complexes. For instance, the Al3+-induced bathochromic shifts for RC anthocyanins reached ca. 50 nm at pH 6 and pH 7, vs. at best ca. 20 nm for PSP anthocyanins. With Fe2+ (quickly oxidized to Fe3+ in the complexes), the bathochromic shifts for RC anthocyanins were higher, i.e., up to ca. 90 nm at pH 7 and 110 nm at pH 5.7. A kinetic analysis at different metal/ligand molar ratios combined with an investigation by high-resolution mass spectrometry suggested the formation of metal-anthocyanin complexes of 1:1, 1:2, and 1:3 stoichiometries. Contrary to predictions based on steric hindrance, acylation by noncoordinating acyl residues favored metal binding and resulted in complexes having much higher molar absorption coefficients. Moreover, the competition between metal binding and water addition to the free ligands (leading to colorless forms) was less severe, although very dependent on the acylation site(s). Overall, anthocyanins from purple sweet potato, and even more from red cabbage, have a strong potential for development as food colorants expressing red to blue hues depending on pH and metal ion.

Polyphenols bind to low density lipoprotein at biologically relevant concentrations that are protective for heart disease.

There is ample evidence in the epidemiological literature that polyphenols, the major non-vitamin antioxidants in plant foods and beverages, have a beneficial effect on heart disease. Until recently other mechanisms which polyphenols exhibit such as cell signaling and regulating nitric oxide bioavailability have been investigated. The oxidation theory of atherosclerosis implicates LDL oxidation as the beginning step in this process. Nine polyphenols from eight different classes and several of their O-methylether, O-glucuronide and O-sulfate metabolites have been shown in this study to bind to the lipoproteins and protect them from oxidation at lysosomal/inflammatory pH (5.2), and physiological pH (7.4). Polyphenols bind to the apoprotein at pH 7.4 with Kb > 106 M-1 and the number of molecules of polyphenols bound per LDL particle under saturation conditions varied from 0.4 for ferulic acid to 13.1 for quercetin. Competition studies between serum albumin and LDL show that substantial lipoprotein binding occurs even in the presence of a great molar excess of albumin, the major blood protein. These in vitro results are borne out by published human supplementation studies showing that polyphenol metabolites from red wine, olive oil and coffee are found in LDL even after an overnight fast. A single human supplementation with various fruit juices, coffee and tea also produced an ex vivo protection against lipoprotein oxidation under postprandial conditions. This in vivo binding is heart-protective based on published olive oil consumption studies. Relevant to heart disease, we hypothesize that the binding of polyphenols and metabolites to LDL functions as a transport mechanism to carry these antioxidants to the arterial intima, and into endothelial cells and macrophages. Extracellular and intracellular polyphenols and their metabolites are heart-protective by many mechanisms and can also function as potent "intraparticle" and intracellular antioxidants due to their localized concentrations that can reach as high as the micromolar level. Low plasma concentrations make polyphenols and their metabolites poor plasma antioxidants but their concentration in particles such as lipoproteins and cells is high enough for polyphenols to provide cardiovascular protection by direct antioxidant effects and by other mechanisms such as cell signaling.

Iron-induced peroxidation of trilinolein nano-emulsions under model gastric conditions and its inhibition by dietary phenolic antioxidants.

An early mechanism for the health benefits of dietary plant phenols is their antioxidant activity in the upper digestive tract. Indeed, these non-essential micronutrients abundant in fruits and vegetables can efficiently fight the iron-induced peroxidation of dietary lipids in the gastric compartment, a recognized form of postprandial oxidative stress. In this work, this phenomenon is investigated through a simple model based on nano-emulsions of trilinoleylglycerol, which permits a direct spectroscopic monitoring and mechanistic insights sustained by extensive kinetic analysis. Polyphenols belonging to the main dietary classes are tested, in particular, flavonols, anthocyanins, flavanols and oligomeric procyanidins. Overall, the common polyphenols tested are good inhibitors of lipid peroxidation induced by metmyoglobin (heme iron) in the early stage of digestion (pH 5-6). For instance, under our peroxidation conditions (2 µM heme, 0.7 mM linoleic acid equivalent, 4.5 mM Brij®35), IC50 concentrations in the range 0.4-1.9 µM were estimated for the set of polyphenols, with oligomeric procyanidins being less inhibitory than the flavanol monomers. However, the polyphenols are ineffective at lower pH (pH 4) when the hematin cofactor is dissociated from its protein (globin). On the other hand, a moderate protection against lipid peroxidation induced by free iron (e.g., released by the oxidative degradation of hematin) persists. This protocol, which combines simplicity and nutritional relevance, could provide a basis for standard tests aimed at assessing the antioxidant capacity of foods and food additives.

An overview of games for entomological literacy in support of sustainable development.

Insects have a significant role towards achieving sustainable development, but the decline of insect knowledge outreach efforts is dampening their impact. Revisiting the perspective and approach to entomological literacy is required to respond to the evolving human needs for sustainable living in light of the decline of insect biomass and biodiversity, and entomology. This is also an opportunity to reflect on the interests about insects in the age of video games. Using games for learning and education can be a viable strategy to advance entomological literacy and support the sustainable development goals by potentially lowering the barriers to accessibility, inclusion and participation. The dearth of research into games for entomological literacy presents opportunities for researchers to explore this domain further.

Diversity patterns of aquatic macroinvertebrates in a tropical high-Andean catchment

Introduction: Glacierised catchments are remote and hostile environments, in which streams from different water sources (e.g., glacier melt, rain/snowmelt, groundwater) converge, creating a complex mosaic of stream sites with varying levels of glacial influence and environmental conditions. This environmental heterogeneity, in turn, influences the assemblage and composition of aquatic communities and produces complex patterns of species diversity at the catchment scale. Objectives: In this contribution, we assessed biodiversity and community composition of aquatic macroinvertebrate communities from 51 stream site types in a glacierised catchment in the tropical Andes. The aim of our study was to: (1) determine diversity, rarity, commonness and spatial distribution patterns of aquatic macroinvertebrate communities from sites with different water sources, and (2) identify which environmental variables influence the density and presence of macroinvertebrate taxa and, in particular, of the subfamilies of the ubiquitous chironomids. Methods: Our study sites were grouped according to their water source and to their percentage of glacier coverage in the catchment (GCC). At each site we sampled aquatic macroinvertebrates, measured environmental variables and assessed community differences and environmental influence with ordination analyses and generalized linear models. Results: Kryal and mixed sites had an important proportion of rare taxa. Mean richness was highest in the mixed sites and lowest in the sites with the highest glacier cover; while sites with an intermediate percentage of glacier cover, had the highest values of α and β diversity. We found that 13 taxa (15.9%) were common to all stream site types. SIMPER analysis showed that Orthocladiinae, Hyalella sp. and Andesiops sp. contributed the most to the dissimilarity between site types (˃ 45% of cumulative contribution). RDA showed that kryal sites were associated with high turbidity and density of Podonomids, and with low temperature, amount of CPOM and densities of both Anomalocosmoecus sp. and Andesiops sp. Orthocladinae was associated with high current velocity and chlorophyll a concentration, whereas Hyalella sp. had a positive relationship with higher pH and streambed stability. Generalized linear models showed that GCC was the main variable explaining all faunal metrics. Current velocity explained macroinvertebrate abundance, water temperature was related to chironomid density and chlorophyll a influenced Orthocladiinae presence-absence. Conclusions: Our results suggest that by favoring the presence of rare taxa and taxa turnover, glacier influence may increase biodiversity in glacierised catchments. In terms of biodiversity conservation, this study confirms an urgent need to increase knowledge of high-Andean stream biodiversity, especially in highly heterogenous glacierised catchments, to better describe regional biodiversity patterns and community composition of these highly vulnerable freshwater ecosystems. Detailed analyses of benthic communities and development of databases are key for conservation strategies. Water management municipalities and/or enterprises should consider water quality and stream types for more sustainable management of these important ecosystems.

Introducción: Las cuencas glaciares son entornos remotos y hostiles, en los que los arroyos de diferentes fuentes de agua (p.ej., deshielo de glaciares, lluvia/deshielo, agua subterránea) convergen, creando un mosaico complejo de tramos con diferentes niveles de influencia glacial y condiciones ambientales. Esta heterogeneidad ambiental influye, a su vez, en el ensamblaje y composición de las comunidades acuáticas y produce complejos patrones de diversidad a la escala de la cuenca. Objetivos: En esta contribución, evaluamos la biodiversidad y composición de comunidades de macroinvertebrados acuáticos en 51 sitios de una cuenca glaciar en los Andes tropicales. Los objetivos de nuestro estudio fueron: (1) determinar la diversidad, la contribución de taxones raros y comunes y los patrones de distribución espacial de las comunidades de macroinvertebrados acuáticos en sitios con diferentes fuentes de agua, y (2) identificar qué variables ambientales influyen en la densidad y presencia de taxones de macroinvertebrados y, en particular, de las subfamilias de los omnipresentes quironómidos. Métodos: Agrupamos a nuestros sitios de estudio según su fuente de agua y su porcentaje de cobertura de glaciar en la cuenca (GCC). En cada sitio donde muestreamos macroinvertebrados acuáticos, medimos variables ambientales y evaluamos las diferencias entre comunidades y la influencia ambiental con análisis de ordenación y modelos lineales generalizados. Resultados: Los sitios kryal y mixtos tuvieron una proporción importante de taxones raros. La riqueza media fue más alta en los sitios mixtos y más baja en los sitios con mayor cobertura glaciar; mientras que los sitios con un porcentaje intermedio de cobertura glaciar tuvieron los valores más altos de diversidad α y β. Encontramos que 13 taxones (15,9%) fueron comunes a todos los tipos de sitios de estudio. El análisis SIMPER mostró que Orthocladiinae, Hyalella sp. y Andesiops sp. contribuyeron más a la disimilitud entre tipos de sitios (˃ 45% de la contribución acumulada). El RDA mostró que los sitios kryal estaban asociados con alta turbidez y densidad de podonómidos, y con baja temperatura, cantidad de CPOM y densidad de Anomalocosmoecus sp. y Andesiops sp. Orthocladinae se asoció con una alta velocidad de corriente y concentración de clorofila a, mientras que Hyalella sp. tuvo una relación positiva con pH más alto y estabilidad del lecho del río. Los modelos lineales generalizados mostraron que GCC fue la variable principal para explicar todas las métricas de fauna. La velocidad de corriente explicó la abundancia de macroinvertebrados, la temperatura del agua estuvo relacionada con la densidad de los quironómidos y la clorofila influenció la presencia-ausencia de Orthocladiinae. Conclusiones: Nuestros resultados sugieren que, al favorecer la presencia de taxones raros y la rotación de taxones, la influencia de los glaciares puede aumentar la biodiversidad en cuencas con influencia glaciar. En términos de conservación de la biodiversidad, este estudio confirma la necesidad urgente de incrementar el conocimiento de la biodiversidad en arroyos de la región altoandina, especialmente en cuencas glaciares altamente heterogéneas, para describir mejor los patrones de biodiversidad regional y la composición de las comunidades en estos ecosistemas altamente vulnerables. Análisis detallados de las comunidades bentónicas y el desarrollo de bases de datos son claves para diseñar estrategias de conservación. Los municipios y/o empresas administradoras de agua deben considerar la calidad del agua y los tipos de arroyos para una gestión más sostenible de estos importantes ecosistemas.