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. <![CDATA[Community signals of the effect of <em>Didymosphenia geminata</em> (Lyngbye) M. Schmidt on benthic diatom communities in Chilean rivers]]> Abstract Background: Didymosphenia geminata (Lyngbye) M. Schmidt is a freshwater invasive benthic diatom native to oligotrophic systems of the Northern Hemisphere. Since 2010, freshwater systems of south-austral Chile, have experienced a progressive invasion of this species between 37° 18’ S and 54° 30’ S. This invaded area is characterized by biogeographic heterogeneity, anthropic pressure and lack of knowledge. The objective of this study was to analyze the effect of D. geminata on the community structure of benthic diatoms and the variability of this effect in Chilean rivers. Methods: The data were collected between 2010 and 2017 and pre-treated using fourth-root transformation to construct a Bray-Curtis similarity matrix and a Principal Coordinate Analysis to identify groups of sites. The α diversity and β diversity were estimated and compared using univariate indexes and the Mann-Whitney test, respectively. We used Permutational multivariate analyses of variance (PERMANOVA) and PERMDISP to estimate the spatial variation of communities, and an Analysis of Percentage Similarity (SIMPER) was performed to identify the species which contributed to the similarity between the groups of sites. Results: The results suggest significant differences between invaded and noninvaded rivers (54% of the total variation); the univariate indexes showed greater richness (S), greater diversity (H’), and less species turnover in invaded rivers. The PERMANOVA indicated significant interaction between D. geminata and the basins; there was also a significant effect on the internal dispersion in the basins. The SIMPER analysis showed that the groups composed exclusively of invaded sites had high mean similarity in all basins and small pedunculated benthic diatoms showed a significant response to the presence of D. geminata. Conclusion: We found high variability in the community structures, that determine a strong segregation between noninvaded and invaded sites by D. geminata, and that the main effect of D. geminata on diatoms benthic was the homogenization of the communities. This is reflected in the increase in density of small stalked diatoms and the reduction of species turnover among rivers in the same basin, leading to the loss of community heterogeneity that overcomes the spatial heterogeneity in the area invaded in Chile. <![CDATA[A five-year retrospective study on patterns of casuistry and insights on the current status of wildlife rescue and rehabilitation centers in Chile]]> Abstract Background: Human activities are permanently threatening wildlife. Wildlife Rescue and Rehabilitation Centers (WRRC) have served for the rescue, rehabilitation and reinsertion of affected and recovered animals. Methods: We reviewed the casuistry of five wildlife rescue and rehabilitation centers in Chile over 5 years, and described the main causes of admission, most affected taxonomic groups and final outcomes of the admitted individuals, shedding light into general patterns and relevant factors currently affecting wildlife in Chile. To understand the current work and status of WRRC system in Chile, we also conducted a qualitative survey to WRRC personnel and Agricultural and Livestock Service (SAG) regional offices regarding their operation. Results: A total of 3418 cases of animals admitted to WRRC were obtained; 95.3% corresponded to native species. Of native animal cases, 86.0% corresponded to birds, 12.3% were mammals and 1.7% reptiles. Trauma was the most frequently observed cause of admission in all three native fauna groups (35.8% in birds, 23.2% in mammals, 27.8% in reptiles). Conclusions: WRRC are a tool for conservation and education of wild animal species in Chile, however WRRC and SAG regional office personnel highlighted several deficiencies in the current system and suggested opportunities for improvement. The current WRRC system needs modernization and financial support from the Chilean state to fulfil their relevant mission. <![CDATA[Density-dependent effect of allelopathy on germination and seedling emergence in two <em>Ipomoea</em> species]]> Abstract Background: Density in inter and intraspecific plant-plant interactions affects the action modes of allelopathy (autotoxicity, negative and positive allelopathy). Some seeds exude compounds that inhibit the germination of others. Ipomoea murucoides and I. pauciflora are sympatric tree species that form patches at the local scale where one or the other dominates, possibly due to allelopathy in the seeds. The objective of this study was to determine the possible density-dependence of the allelopathic effect among seeds of these species through the measure of seed germination and seedling emergence. Methods: In both species, allelopathy was measured as: a) germination in mixed sowing of both species at different proportions, b) germination in single-species trials at different densities after adding seed extracts of both species, and c) seedling emergence in seed mixtures of both species sown at different proportions beneath canopies of the two Ipomoea species. Results: Seed germination of I. murucoides was increased by the presence of I. pauciflora and diminished at higher densities of its own seeds; however, seed germination of I. pauciflora was not affected by the presence of I. murucoides seeds. The addition of extracts (either from conspecifics or congeneric) diminished the germination of both species and at higher seed densities the germination was lower. Seedling emergence did not depend on the species under which the seeds were sown nor on the density of the seeds. Conclusions: The germination experiments evidenced positive allelopathy and/or autotoxicity, while there was no evidence of allelopathic effects in seedling emergence. The allelopathic activity is reported in the seeds of these species for the first time. <![CDATA[Movement behavior of the Monito del monte (<em>Dromiciops gliroides</em>): new insights into the ecology of a unique marsupial]]> Abstract Background: Behavior and activity patterns largely determine animal's fitness and their ecological roles. Those patterns depend on many factors, being body mass, sex and age the most relevant in mammals. Particularly, those factors altogether with environmental conditions could influence movement behavior of mammals that hibernate, such as the Monito del monte (Dromiciops gliroides). Methods: To evaluate its movement behavior and activity we radio-tracked D. gliroides 12 individuals (8 females and 4 males, corresponding to 5 adults and 7 sub-adults) during the austral summer. With the estimated locations we estimated home ranges, core areas and their relationship with body mass. We also assessed movement speed during early (19:00 to 01:00 h), peak (01:00 to 03:00 h) and late (03:00 to 07:00 h) activity periods. This study was conducted at the San Martín experimental forest (Valdivia, southern Chile). Results: Estimated home range areas were 1.04 ± 0.20 ha, and core areas were 0.27 ± 0.06 ha; we found no significant differences between males and females, nor between adults and sub-adults. Home range and core areas were independent of body mass in females but showed positive relationships in males. Core area overlap was larger between sub-adult and adult individuals (35%) than between adult males and females (13%). Average movement D. gliroides speed was 1.45 m/min, reaching its lowest value during the peak activity period (01:00 to 03:00 h), but being faster during early and late activity periods. Those speed differences may be related to travelling and foraging activities. Conclusion: Home range and core areas estimated here showed a large variability, which can be related to environmental factors. Home range size was positively correlated with body mass on males but not on females. Also, lower movement speeds at the peak activity period suggest that D. gliroides concentrates feeding activities at this time. As D. gliroides disperses the seeds of at least 16 native plant species, its movement behavior also has important consequences at the community level.