Hydroclimatic and anthropogenic factors in climate change scenarios contribute to ecological changes of harmful cyanobacterial algal blooms in lakes. This study describes the variability of the bathymetric and temporal distribution of cyanobacterial communities in a deep oligotrophic lake. An increase of two to nine in the detection of CyanoHABs potential was observed, likely linked to nitrogen contributions to Lake Rupanco during the last 36 years related to changes in land use and the cultivation of salmonids. We recorded an unusual bloom of Microcystis aeruginosa in winter, 2017 at 30 m during the total mixing period of the lake, associated with the highest N/P index (16.24), the increase of total nitrogen (75 μg/L) and climatic conditions that favored the availability of nitrogen of this cyanobacterium. This study provides information on the causes of increased cyanobacteria in a deep oligotrophic lake. Long-term information on the composition of cyanobacterial communities is very helpful in determining ecological changes.

En Chile existen más de 40,000 humedales (^{WCS, 2019}), sin embargo, solo 13 de ellos presentan medidas de conservación (^{MMA, 2018}). La baja protección es debida a la escasa información sobre la estructura biótica de los humedales y de su funcionamiento integral (^{Gallardo et al., 2018}), siendo necesario ampliar el conocimiento faunístico en los humedales, siendo una herramienta fundamental para su conservación y gestión (^{Acosta & Murúa, 2002}). Hoy en día, existen muchos humedales que no presentan medidas de protección ni de conservación, como es el caso del humedal de Trumao. Este humedal es un área de importancia para las aves acuáticas, especialmente anátidas (patos silvestres) (^{SAG, 2015}), se encuentra fuertemente amenazado por la expansión urbana, caza ilegal de aves, pesca furtiva, presencia de especies invasoras como el Neovison vison Schreber, 1777 (visón) y la contaminación por parte de la industria agropecuaria y acuícola, sumado al hecho del escaso conocimiento de las aves acuáticas que habitan en estos humedales y su estado de conservación. La ejecución de programas de conservación de fauna implica la prospección y evaluación de toda la riqueza faunística a proteger (^{Martori et al., 2002}). Por lo anterior, los objetivos de este estudio fueron describir el ensamble de aves del humedal de Trumao, centro-sur de Chile y determinar su variación estacional durante periodos secos estivales (primavera 2017 y verano 2018) e inundados invernales (inviernos 2017 y 2018), además, evaluar el uso de hábitat de las especies registradas durante las fluctuaciones hidrológicas del humedal.

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.

Phytoplankton communities are excellent indicators of the environmental status of shallow lakes since changes in diversity alert us to potential deterioration. To assess the environmental condition of a shallow lake with strong anthropogenic pressure from forest monocultures, alpha and beta diversities were determined. Three monitoring stations were established in the shallow Kusrüpuyewe Lake, southern Chile, which were monitored during the 2021 austral summer and winter. Alpha diversity was high indicating a stable environmental condition. In total, 103 species in summer, 96 species in winter and a high species diversity (Shannon index: H′ > 5 bits/ind) were recorded. Beta diversity indicated that this ecosystem is seasonally heterogeneous, is potentially productive and has a high species turnover. Based on the large species inventory, we conclude that this shallow lake is stable and diverse. Although it is threatened by the presence of forest monocultures, it maintains a stable environmental condition, mainly due to the ability of the phytoplankton present to self-regulate through the species turnover. This study provides the relevant background information to establish conservation measures around the shallow lake, an ecosystem that provides various ecosystem services for the local indigenous communities.

Although planktonic diatoms are one of the most abundant taxonomic groups in coastal wetlands, their assemblages have not been used to determine the environmental health of these ecosystems. Studies of ecosystem environmental health have been based on other taxonomic groups; we propose that diatom genera diversity represents a viable alternative for this purpose. Thus, our aim was to determine the alpha and beta diversities of the planktonic diatom assemblage present in Caulín Bay, Chiloé Island (41° 49’S; 73° 38’W), southern Chile, during the austral winter and spring of the years 2012 and 2014. Caulín Bay is an important site for aquatic bird observation and conservation, hunting is prohibited on a national scale and, internationally, the site has been declared an Important Bird and Biodiversity Area (IBA). Our results indicate different diversities between sampling stations, but not between the years studied. In total, we recorded 53 diatom genera, of which the most abundant were Coscinodiscus (21.99%) and Cocconeis (16.23%). The study area presented high genera diversity (i.e., H’_(log2) >3.74) and beta diversity indicated that Caulín presents a low level of heterogeneity and is a low genera replacement environment. Consequently, we infer that Caulín Bay is a productive and environmentally stable ecosystem. This leads us to conclude that diatom diversity determination is a viable alternative to establish aquatic ecosystem environmental health and we recommend that future conservation strategies be established for Caulín Bay.