Scielo RSS <![CDATA[Revista chilena de historia natural]]> vol. 92 num. lang. en <![CDATA[SciELO Logo]]> <![CDATA[Fragmentation of Chilean Andean rivers: expected effects of hydropower development]]> Abstract Background: Fragmentation (establishment of barriers e.g., hydropower dams, reservoirs for irrigation) is considered one of the greatest threats to conservation of river systems worldwide. In this paper we determine the fragmentation status of central Chilean river networks using two indices, namely Fragmentation Index (FI) and Longest Fragment (LF). These are based on the number of barriers and their placement as well as river length available for fish movement. FI and LF were applied to eight Andean river basins of central Chile in order to assess their natural, current (2018) and future (2050) fragmentation at the doorstep of a hydropower boom. Subsequently, we exemplify the use of these indices to evaluate different placement scenarios of new hydropower dams in order to maximize hydropower use and at the same time minimize impact on fish communities. Results: In the natural scenario 4 barriers (waterfalls) were present. To these 4 barriers, 80 new ones of anthropogenic origin were added in the current (2018) scenario, whereas 377 new barriers are expected in near future (2050). Therefore, compared to the ‘natural’ scenario, in 2050 we expect 115-fold increase in fragmentation in analysed river systems, which is clearly reflected by the increase of the FI values in time. At the same time, the LF diminished by 12% on average in the future scenario. The fastest increase of fragmentation will occur in small and medium rivers that correspond to 1st, 2nd and 3rd Strahler orders. Finally, case study on configuration of potential hydropower plants in the Biobio basin showed that hydropower output would be maximized and negative effects on fish communities minimised if new hydropower plants would be located in tributaries of the upper basin. Conclusions: Fragmentation of Chilean Andean river systems is expected to severely increase in near future, affecting their connectivity and ecological function as well as resilience to other anthropogenic stressors. Indices proposed here allowed quantification of this fragmentation and evaluation of different planning scenarios. Our results suggest that in order to minimise their environmental impact, new barriers should be placed in tributaries in the upper basin and river reaches above existing barriers. <![CDATA[Breeding strategies of open-cup-nesting birds in sub-Antarctic forests of Navarino Island, Chile]]> Abstract Background: There is limited knowledge about the breeding strategies of birds inhabiting in South American temperate forests. This is particularly true for open-cup forest passerines breeding at high latitudes (&gt; 42°). To better understand the ecology of these species, in this study we described and compared the breeding strategies (i.e., nest dimensions, nest height from the ground, egg laying rhythm, clutch size, length of the developmental periods, breeding phenology, and diversity of nesting substrate) of five passerine birds that inhabit sub-Antarctic ecosystems. Methods: During three breeding seasons (2014-2017), we monitored 103 nests of the five most abundant open-cup forest-dwelling passerines (Phrygilus patagonicus, Anairetes parulus, Turdus falcklandii, Elaenia albiceps, and Zonotrichia capensis) on Navarino Island (55°S), Cape Horn Biosphere Reserve, southern Chile. Additionally, we compared the breeding strategies of T. falcklandii to another population breeding at lower latitude (39°S). Results: Most of the species started laying eggs the last week of September; only E. albiceps started 2 months later. During the breeding season of 2016-2017 both E. albiceps and Z capensis started laying eggs earlier than the previous year. Anairetes parulus and Z. capensis were the most specialized in terms of nesting substrate. Turdus falcklandii had larger clutch sizes and nested closer to the ground on Navarino Island compared to the northern population, which might put this and other ground nesting species of this island at a higher risk of predation by the recently introduced American mink (Neovison vison). Conclusions: Our five study species breed exclusively in open-cups (not in cavities) in sub-Antarctic forests, and some of them built their nests closer to the ground compared to populations breeding at lower latitudes. This may be associated with the lack of terrestrial predators on Navarino Island. Our study opens further questions about the mechanisms driving differences in breeding strategies among populations. <![CDATA[Comparison of organic matter in intermittent and perennial rivers of Mediterranean Chile with the support of citizen science]]> Abstract Background: Although intermittent rivers account for over half of the global fluvial network and could increase in length and quantity in Mediterranean climates (in response to climate changes), there is little documentation of organic matter input to them. This study was made possible by the cooperation of the Concepción Chiguayante School community and the Explora project (Chile), with the support of citizen science. The aim was to compare coarse particulate organic matter quantities and types in the Lonquén basin. Methods: Samplings were performed in two perennial rivers and two intermittent rivers. First, the riparian vegetation of the streams was characterized through photointerpretation and subsequently the organic matter accumulated in the selected river beds was quantified and typified. Spearman's correlation was used. Results: The riparian vegetation was similar in both types of rivers, though significantly greater (p &lt; 0.05) plant material accumulation was found in intermittent rivers compared to perennial rivers (1029 and 337 g m−2, respectively). Likewise, there was a significant relationship among leaves, smaller organic matter, seeds, herbs and shrubs in intermittent rivers. Conclusions: The results reveal the importance of the intermittent rivers that were sampled as transitory reservoirs of organic matter with high productive potential, especially in the first flood pulses, when this material is transported downstream.