Aquatic community response to volcanic eruptions on the Ecuadorian Andean flank: evidence from the palaeoecological record

Aquatic ecosystems in the tropical Andes are under increasing pressure from human modification of the landscape (deforestation and dams) and climatic change (increase of extreme events and 1.5 °C on average temperatures are projected for AD 2100). However, the resilience of these ecosystems to perturbations is poorly understood. Here we use a multi-proxy palaeoecological approach to assess the response of aquatic ecosystems to a major mechanism for natural disturbance, volcanic ash deposition. Specifically, we present data from two Neotropical lakes located on the eastern Andean flank of Ecuador. Laguna Pindo (1°27.132′S–78°04.847′W) is a tectonically formed closed basin surrounded by a dense mid-elevation forest, whereas Laguna Baños (0°19.328′S–78°09.175′W) is a glacially formed lake with an inflow and outflow in high Andean Páramo grasslands. In each lake we examined the dynamics of chironomids and other aquatic and semi-aquatic organisms to explore the effect of thick (> 5 cm) volcanic deposits on the aquatic communities in these two systems with different catchment features. In both lakes past volcanic ash deposition was evident from four large tephras dated to c.850 cal year BP (Pindo), and 4600, 3600 and 1500 cal year BP (Baños). Examination of the chironomid and aquatic assemblages before and after the ash depositions revealed no shift in composition at Pindo, but a major change at Baños occurred after the last event around 1500 cal year BP. Chironomids at Baños changed from an assemblage dominated by Pseudochironomus and Polypedilum nubifer-type to Cricotopus/Paratrichocladius type-II, and such a dominance lasted for approximately 380 years. We suggest that, despite potential changes in the water chemistry, the major effect on the chironomid community resulted from the thickness of the tephra being deposited, which acted to shallow the water body beyond a depth threshold. Changes in the aquatic flora and fauna at the base of the trophic chain can promote cascade effects that may deteriorate the ecosystem, especially when already influenced by human activities, such as deforestation and dams, which is frequent in the high Andes

LEFT—A web-based tool for the remote measurement and estimation of ecological value across global landscapes

1.The overall aim in the development of the Local Ecological Footprinting tool (LEFT) was to design a web-based tool that could provide quickly obtained quantitative data to assist landowners when making land-use change decisions and to help them minimise the environmental impact and determine areas of greatest ecological risk in their operations. 2.LEFT works for almost any region in the world and uses freely available satellite imagery, biotic and abiotic data from existing global databases, models and algorithms to deliver a customised report for a selected area within one hour of job submission. 3.Biotic data automatically obtained for a selected landscape includes terrestrial vertebrate and plant species occurrence data, information on their conservation status and remotely sensed vegetation productivity. Abiotic information obtained includes temperature, precipitation, water availability, insolation, topography, elevation, distribution of urban infrastructure, and location of wetlands. 4.The tool performs a number of analyses on the biotic and abiotic data to produce maps for the selected area at a 30m resolution depicting land cover type, numbers of globally threatened terrestrial vertebrate and plant species, beta-diversity of terrestrial vertebrates and plants, habitat intactness, wetland habitat connectivity, numbers of migratory species and vegetation resilience. Results are also aggregated to produce a summary map demonstrating areas of high and low ecological value across the selected area. 5.LEFT has been designed to be intuitive to use, requiring no specialised software or user expertise. Input is extremely easy and requires the user to highlight the area of interest on a map or using grid co-ordinates. Output is delivered via the web application and comprises a customised PDF containing the maps and a zip file of GIS data for the area requested. Users may run an unlimited number of LEFT analyses and download reports free of charge. In addition to the free tool described in this paper, there is also a paid service: individual LEFT analyses can be upgraded for a charge to allow access to the geographically subsetted datasets generated for each report. This data is supplied as a zip file containing raster datasets for the layers in the LEFT analysis in GeoTIFF format. These can be opened and queried in a Geographical Information System (GIS) software package

Temporal and spatial patterns of mitochondrial haplotype and species distributions in Siberian larches inferred from ancient environmental DNA and modeling

Abstract Changes in species’ distributions are classically projected based on their climate envelopes. For Siberian forests, which have a tremendous significance for vegetation-climate feedbacks, this implies future shifts of each of the forest-forming larch (Larix) species to the north-east. However, in addition to abiotic factors, reliable projections must assess the role of historical biogeography and biotic interactions. Here, we use sedimentary ancient DNA and individual-based modelling to investigate the distribution of larch species and mitochondrial haplotypes through space and time across the treeline ecotone on the southern Taymyr peninsula, which at the same time presents a boundary area of two larch species. We find spatial and temporal patterns, which suggest that forest density is the most influential driver determining the precise distribution of species and mitochondrial haplotypes. This suggests a strong influence of competition on the species’ range shifts. These findings imply possible climate change outcomes that are directly opposed to projections based purely on climate envelopes. Investigations of such fine-scale processes of biodiversity change through time are possible using paleoenvironmental DNA, which is available much more readily than visible fossils and can provide information at a level of resolution that is not reached in classical palaeoecology