Dams versus habitat: predicting the effects of dams on habitat supply and juvenile rainbow trout along the Santa Cruz River, Patagonia

Abstract

Because of their remote location and lack of supporting infrastructure, large glacial rivers of southern Patagonia have remained free of dams. But this is bound to change: two dams proposed for the Santa Cruz River would supply 16% of Argentina's hydropower and five dams planned for the Pascua and Baker Rivers could supply over 20% of Chile's hydropower. In this paper, we project the losses of habitat and juvenile Oncorhynchus mykiss, a recreationally important species, following the construction of the two dams in the Santa Cruz River. We applied a two-stage fitting approach, using generalized additive models and generalized lineal models (GLMs) sequentially to describe habitat-species relationships based on data collected through an intensive field survey of fish and environmental variables along 310 km of river. A simplified GLM trout model based on wetted width, substrate size, and river kilometer was selected which represents the observed geographic distribution very well and with the lowest predictive error. Based on this model, we estimated that habitat supporting 86% of current juvenile trout production will be lost to flooding by the dams. Our data generate a rare opportunity to perform a dam impact assessment by comparison with potential post-dam conditions.

Modelling Tools to Analyze and Assess the Ecological Impact of Hydropower Dams

“…Existing ecological models are able to assess the impact of changing hydrological regimes and water quality on the habitat suitability of fish, macroinvertebrates and algae (e.g., Fullerton et al [36], Kocovsky et al [110], Quiroga et al [111]). …”

“…In sixteen papers, no model validation procedure was reported. For example, Quiroga et al [111] developed a model to predict the loss of fish habitat by the construction of two larger hydropower dams, but no model validation was performed due to a lack of validation data. Classic model validation included a model comparison between predictions and observations from an independent dataset [62].…”

First spatio-temporal study of macroinvertebrates in the Santa Cruz River: a large glacial river about to be dammed without a comprehensive pre-impoundment study

“…Furthermore, since the most sensitive macroinvertebrate taxa (located in those areas) are important components of the diet of salmonids and galaxiids present in the Santa Cruz River , profound changes in food webs are expected to occur in the new lakes. Thus, we consider that a detailed study on aquatic communities combined with existing extensive research of patterns of macroinvertebrate abundances, relationships between fish and their environment Quiroga et al, 2015) should be evaluated to project the likely effects of dams in the Santa Cruz River.…”

Biodiversity and Distribution Patterns of Free-Living Nematodes Communities in Balai River, Bentre Province

“…Addition, dam construction and operation can make a substantial contribution to ecosystem hazards, things like loss of forests and wildlife habitats, loss of aquatic diversity, including upstream and downstream fisheries, interruption of fish migration and loss of the services of downstream wetlands, riverine and estuarine ecosystems [40,41]. Ecologically, dams have the ability to change river's physicochemical characteristics that are the major reasons for change in the aquatic communities structure [42].…”