Dams in the Amazon: The importance of maintaining free‐flowing tributaries for fish reproduction

Vasconcelos, Lilian Paula; Alves, Diego Corrêa; Câmara, Luís Fernando da; Hahn, Lisiane

doi:10.1002/aqc.3465

Cited by 29 publications

(22 citation statements)

References 50 publications

(84 reference statements)

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“…The importance of free movement and migration is well understood for fishes (Vasconcelos et al, 2020), particularly for diadromous species that depend on migrations between oceans and fresh water to complete their life cycles (Smialek et al, 2019). The provision of fish passage for charismatic flagship species is often proposed as a solution (Silva et al, 2018a).…”

Section: Effects On Connectivitymentioning

confidence: 99%

“…Thus, in addition to their role as migration corridors, the substitute habitat function of bypass channels must be considered equally, even though their limited space cannot fully compensate for deficits in the main stem (Pander & Geist, 2013). Especially in large, dammed rivers, free‐flowing tributaries are important for the recruitment of rheophilic fishes (Silva et al, 2018b; Vasconcelos et al, 2020). There is also increasing focus on restoring environmental flow (e‐flow) regimes in regulated rivers: i.e.…”

Section: Challenges and Possible Solutions In Hydropower‐related Conservation Managementmentioning

confidence: 99%

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Editorial: Green or red: Challenges for fish and freshwater biodiversity conservation related to hydropower

Geist

2021

Aquatic Conservation

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The global sustainable development goals of the United Nations (United Nations, 2015) and the associated necessary transformations, such as energy decarbonization (Sachs et al., 2019), have resulted in increased hydropower development around the world (Zarfl et al., 2015). Advocates of hydropower point to the important contributions of this form of energy to the reduction of CO 2 emissions, its low cost, and its use as a stable source of energy, justifying it as a 'green' energy that makes an important contribution to electricity supply compared with other forms of regenerative energy. For the year 2018, the International Energy Agency (IEA) lists a global energy supply from hydropower of 4,325,111 GWh, compared with 1,273,409 GWh for wind energy and 554,382 GWh for solar/photovoltaic energy (IEA, 2020). In contrast to wind or solar power, hydropower production is available at any time of day and is less dependent on current weather conditions.According to the Collins Dictionary (www.collinsdictionary.com, accessed 14 February 2021), 'green energy' is defined as 'power that comes from sources that do not harm the environment …'. The debate about how 'green' the green energies really are is controversial (Gibson, Wilman & Laurance, 2017). Opponents of hydropower production often refer to it as a 'red' energy because of the mortalities and injuries that fish face when passing turbines Mueller et al., 2020b), as well as other ecological harm to free-flowing rivers associated with habitat fragmentation and alteration.

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Section: Effects On Connectivitymentioning

confidence: 99%

Section: Challenges and Possible Solutions In Hydropower‐related Conservation Managementmentioning

confidence: 99%

Editorial: Green or red: Challenges for fish and freshwater biodiversity conservation related to hydropower

Geist

2021

Aquatic Conservation

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“…In the social sector, indigenous and traditional riverside communities can lose resources essential for their subsistence, triggering changes to their cultures and ways of life and forcing evictions (Berkun, 2010; Fearnside, 2019; Santos et al, 2020). In the environmental sector, hydropower dams are considered primary threats to freshwater species, as well as the surrounding ecosystems including floodplains and wetlands (Berkun, 2010; Dudgeon, 2000; Vasconcelos et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Impacts of dams on freshwater turtles: a global review to identify conservation solutions

Bárcenas-García

Michalski

Morgan

et al. 2021

Preprint

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Dams create many impacts on freshwater ecosystems and biodiversity. Freshwater turtles are at direct and indirect risk due to changes caused by damming including the loss of terrestrial and aquatic nesting and feeding habitats, changes to resource availability and reduced dispersal. We reviewed the global scientific literature that evaluated the impact of dams on freshwater turtles, and carried out additional searches of literature published in seventeen languages for studies evaluating actions to mitigate the impact of dams. The search produced 43 published articles documenting dam impacts on 29 freshwater turtle species from seven families (Chelidae, Chelydridae, Emydidae, Geoemydidae, Kinosternidae, Podocnemididae and Trionychidae) in 13 countries. More than a third of studies (41.9%, n = 18) focused on nine North American species of the Emydidae. Few studies were found from Europe and Asia and none from Africa. The number of studies, life-history stage studied and threat status differed significantly between temperate and tropical latitudes. Most studies were from temperate latitudes, where studies focused more on adults and less threatened species compared with tropical latitudes. Studies evaluated dam impacts as barriers and changes to water flow and quality, but no studies were found that assessed turtles and changes to land cover or mercury caused by dams. More than half of the studies (59%, n = 24) suggested actions to help mitigate dam impacts. Yet, only four studies on three temperate and one tropical species documented the effect of interventions (dam removal, flow management, artificial pond maintenance and community-based action). These findings demonstrate a lack of documented evidence evaluating dam impacts on freshwater turtles particularly in tropical regions. This lack of evidence reinforces the importance of strengthening and maintaining robust long-term studies of freshwater turtles needed to develop effective conservation actions for this group of vertebrates.

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“…Mitigating dam impacts is a priority for the protection and restoration of freshwater biodiversity (Harper et al, 2021;Moran et al, 2018;Tickner et al, 2020). Hydropower developments are among the most significant threats to Amazonian freshwater ecosystems (Castello & Macedo, 2016;Latrubesse et al, 2017) and biodiversity (Dudgeon, 2019;Latrubesse et al, 2020;Vasconcelos et al, 2020). Although hydropower supplies the demand of basic human necessities, hydropower dams result in impacts that produce negative effects and feedbacks that modify freshwater ecosystem processes, functions and services (Dudgeon, 2019;Valiente-Banuet et al, 2015).…”

mentioning

confidence: 99%

“…The structure, composition, functions and services of globally important Amazonian ecosystems are threatened due to expansion of hydropower developments. To date a total of 29 dams (operational capacity > 30 MW) have been installed across Brazilian Amazonia (SIGEL, 2021) and another 750 are planned or under construction (Vasconcelos et al, 2020). This increase is incentivized by increasing energy demand, national and regional politics and international investment (Castello, 2021;Fearnside, 2018;Gerlak et al, 2020).…”

mentioning

confidence: 99%

Amazonian run-of-river dam reservoir impacts underestimated: Evidence from a Before-After Control-Impact study of freshwater turtle nesting areas

Bárcenas-García

Michalski

Gibbs

et al. 2021

Preprint

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1. Although the construction of hydropower dams is widely assumed to generate myriad negative impacts on biodiversity there remains a lack of robust scientific evidence documenting the magnitude of these impacts particularly across highly biodiverse tropical waterways. Hydropower expansion is an increasing threat to the Endangered yellow-spotted river turtle (Podocnemis unifilis) across its tropical South American range. 2. Turtle nesting-areas were monitored as an indicator of dry-season river level changes following run-of-river dam reservoir filling. A Before-After-Control-Impact (BACI) study design was established with multi-year field campaigns monitoring turtle nesting-areas along 66 km of river upstream of the dam, separated into 33 km control and impact zones. 3. The cause and extent of changes in nesting-areas was established using Generalized Additive Models. Nesting-area density was examined in relation to four variables: Before-After, Control-Impact, distance to the dam and precipitation. The extent of changes was examined by comparing the proportion of nesting-areas remaining in subzones during the four years after reservoir filling. 4. Comparison of the proportion of nesting-areas remaining after dam construction showed that a permanent dry season river level rise extended more than 20 km beyond impact assessment limits. On average the density of nesting-areas declined 69% (from 0.48 to 0.15 per km) across 33 km of river directly impacted by the dam. This loss was reflected in a significant BACI interaction. The variation in nesting-areas was not explained by seasonal precipitation, whilst nesting-area density increased significantly further away from the dam. 5. Standardized monitoring of freshwater turtle nesting-areas provided an effective means to quantify impacts of hydropower developments across biodiverse yet rapidly changing waterways. The negative impacts should be preventable by mitigation actions including habitat restoration and dry season flow regulation. Such measures are also likely to benefit multiple species in highly diverse Amazonian rivers increasingly impacted by run-of-river dams.

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Dams in the Amazon: The importance of maintaining free‐flowing tributaries for fish reproduction

Cited by 29 publications

References 50 publications

Editorial: Green or red: Challenges for fish and freshwater biodiversity conservation related to hydropower

Editorial: Green or red: Challenges for fish and freshwater biodiversity conservation related to hydropower

Impacts of dams on freshwater turtles: a global review to identify conservation solutions

Amazonian run-of-river dam reservoir impacts underestimated: Evidence from a Before-After Control-Impact study of freshwater turtle nesting areas

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