Multiscale spatial analysis of headwater vulnerability in South-Central Chile reveals a high threat due to deforestation and climate change.

Headwaters represent an essential component of hydrological, ecological, and socioeconomical systems, by providing constant water streams to the complete basin. However, despite the high importance of headwaters, there is a lack of vulnerability assessments worldwide. Identifying headwaters and their vulnerability in a spatially explicit manner can enable restauration and conservation programs. In this study, we assess the vulnerability of headwaters in South-Central Chile (38.4 to 43.2°S) considering multiple degradation factors related to climate change and land cover change. We analyzed 2292 headwaters, characterizing multiple factors at five spatial scales by using remote sensing data related to Land Use and Cover Change (LUCC), human disturbances, vegetation cover, climate change, potential water demand, and physiography. We then generated an index of vulnerability by integrating all the analyzed variables, which allowed us to map the spatial distribution of headwater vulnerability. Finally, to estimate the main drivers of degradation, we performed a Principal Components Analysis with an Agglomerative Hierarchical Clustering, that allowed us to group headwaters according to the analyzed factors. The largest proportion of most vulnerable headwaters are located in the north of our study area with 48.1 %, 62.1 %, and 28.1 % of headwaters classified as highly vulnerable at 0, 10, and 30 m scale, respectively. The largest proportion of headwaters are affected by Climate Change (63.66 %) and LUCC (23.02 %) on average across all scales. However, we identified three clusters, in which the northern cluster is mainly affected by LUCC, while the Andean and Coastal clusters are mainly affected by climate change. Our results and methods present an informative picture of the current state of headwater vulnerability, identifying spatial patterns and drivers at multiple scales. We believe that the approach developed in this study could be useful for new studies in other zones of the world and can also promote Chilean headwater conservation.

Long-term responses of macroinvertebrate assemblages to the 2011 eruption of the Puyehue-Cordón Caulle volcanic complex, Chile.

In June 2011 the Puyehue-Cordón Caulle volcanic complex (PCCVC) erupted, ejecting around 950 million metric tons of volcanic ash and pyroclastic rock, generating habitat destruction, environmental deterioration and devastation of ecological communities in rivers near the volcanic fissure. We evaluate the long-term effect of this eruptive event on the recovery of the diversity of aquatic macroinvertebrates, collecting biological and environmental information from 2011 to 2018 in visibly impacted Chilean rivers (Gol-Gol and Nilahue) and not visibly impacted rivers (Calcurrupe and Chanleufu). With the macroinvertebrate records we developed a recovery coefficient based on their diversity before and after the eruption. The results show that before the eruption (2009-2010), the accumulated family richness and mean diversity in the Gol-Gol River were higher than that observed post-eruption in rivers visibly impacted and not visibly impacted. Between 2013 and 2018, 17 families recolonized the Gol-Gol River, as well as 10 new families that were not recorded before the eruption. The richness of families post-eruption was negatively related to the increase in the concentration of total suspended solids, affecting the successional changes and recovery in the medium term. The recovery coefficient indicates that seven years after the eruption the diversity of macroinvertebrates still shows lower levels than those recorded before the eruptive event, with predominance of a slow recovery phase. Families of orders Ephemeroptera, Plecoptera and Trichoptera that were dominant before the eruption of the PCCVC began to recover the richness of taxa two years later, Plecoptera reaching 50% recolonization in 2018, Ephemeroptera 33.3% and Trichoptera 30%. In contrast, Diptera reached 100% recovery by 2018 and chironomids increased since 2015, becoming the dominant taxon during intermediate recovery in the Gol-Gol River. The recovery of macroinvertebrates in the Gol-Gol River is related to their modes of dispersal, feeding and the decrease in ash concentration.

Application of the Lake Biotic Index (LBI) in the ecological characterization of a North Patagonian lake in Chile.

Increased pollution and degradation of water resources and their associated ecosystems has stimulated the development of tools and methodologies to characterize, estimate, predict, and reverse the environmental impact of anthropic effects on water bodies. The Secondary Water Quality Standards (NSCA) adopted in Chile have incorporated the use of bioindicators complementary to physicochemical analyses, in order to determine the ecological condition of lotic and lentic environments. Our research used the "Lake Biotic Index" (LBI) to establish the ecological condition of Lake Rupanco using benthic macroinvertebrates. The results indicated an Oligo-Eubiotic condition for this lake given the high concentration of oxygen and low organic matter content in sediments, in addition to low biogenic potential and good taxa preservation in both the autumn and spring surveys. Features of the ecological condition obtained through the application of the LBI (benthic subsystem) conform to the results of physicochemical and microalgae analyses undertaken previously in Lake Rupanco (pelagic subsystem). Based on these results, we support application of the LBI index as a complementary tool for the integrated management of lentic ecosystems.