Hydropower barriers are among the most conspicuous anthropogenic alterations to natural riverine connectivity, resulting in species-specific effects linked to dispersal abilities, especially swimming performance. They may present a particular problem for small-bodied 'non-sport fish', such as those that characterize the freshwater communities of temperate regions in the Southern Hemisphere. Recent studies have suggested that nature-like fishways could ensure passage of diverse fish assemblages through hydropower barriers. Through experiments performed in a swim tunnel, we present, for the first time, fishway design criteria for two non-sport species endemic to Chile, a country experiencing rapid hydropower development. In`cremental velocity tests showed that Cheirodon galusdae and juveniles of Basilichthys microlepidotus were capable of very similar standardized critical swimming speeds of 69.7 and 69.6 cm s À1 , respectively. When expressed in units of body lengths, C. galusdae was capable of very high critical speeds of 16.2 bl s À1, whereas for B. microlepidotus, this was 7.6 bl s À1 . However, fixed velocity tests revealed that the swimming endurance of the latter species was slightly higher. Dimensionless analysis showed a clear relationship between fatigue time and fish Froude number, similar to that already described for subcarangiforms. Based on these results, we present fishway design curves indicating a transition from sustained to prolonged swimming at a fishway length of 15 m. Our results show that the swimming capacity of these species is well-suited to the mean flow velocity field described for nature-like fishways. However, more work is required to understand the effects of turbulence on the passage of non-sport species.

The magnitude of hydropower developments in emerging regions threatens the sustainability of their riverine landscapes. Fragmentation of river networks by multiple barriers and the imposition of new hydrological regimes influences the ability of these river ecosystems to absorb and adapt to these developments and other stressors. Direct transfer of paradigms built from a restricted geographical base to a global context is fraught with issues because of regional differences in eco‐hydro‐geomorphology, biological communities, and nonlinear interactions between the two. In this manuscript, some impacts of hydropower development on Chilean riverine ecosystems are presented. To understand the context of hydropower, we provide the political context of energy development in Chile. Interactions between hydropower generation and Chilean river ecosystems with special reference to native Chilean fish fauna are outlined. Three case studies are presented that considers: (a) habitat alteration downstream of the Rucúe Dam, (b) the effects of daily hydropeaking in the Biobío River, and (c) mitigation strategies to reduce habitat alteration upstream of the San Pedro Dam. These case studies illustrate the expanding scientific knowledge on Chilean riverine landscapes. Finally, new measures to reduce ecosystem impacts of hydropower development on native Chilean fish communities are outlined. Although specific scientific information is available, developing regional ecohydrological models and improving knowledge of ecosystem and sustainability science is required. The scientific approach on which solutions are sought to address present and future river ecosystem problems in Chile are inherently interdisciplinary nature.

No abstract

No abstract

No abstract