Effects of Dams on Vertebrate Diversity: A Global Analysis

Abstract

Dams are crucial for water supply in human populations and are becoming more common globally for hydroelectric power generation. Dams alter natural habitats and their biodiversity; however, studies are inconclusive about their effects on them. This study aimed to examine the effects of dams on vertebrates and the determinants of changes in global biodiversity and their relationship with critical areas for conservation. We evaluated the effects of dams on vertebrate richness and abundance. We performed a meta-analysis based on 120 case studies. We evaluated the overall effect on richness and abundance and examined these effects regarding taxa, disturbance type, latitudinal zone, zoogeographic zone, biodiversity hotspots, dam size and purpose, and species extinction risk. We conducted an overall analysis that included all species, and then we conducted separate analyses for terrestrial and aquatic species. Dams had a negative effect on vertebrate richness but not on vertebrate abundance. These effects were influenced by larger dams with fragmentation and were more pronounced within hotspots and in countries with a low species extinction risk. Such negative effects were explained by terrestrial vertebrates (particularly birds and mammals) because species richness and the abundance of aquatic vertebrates (fish) were not affected by dams in any case. Our results showed that habitat fragmentation created by large dams changes vertebrate communities, negatively affecting species richness in some areas of conservation concern. We propose implementing reservoirs in areas where they would have a lower impact on biodiversity and avoiding large dams in priority areas for conservation and where endangered species inhabit.

In-Reservoir Physical Processes Modulate Aqueous and Biological Methylmercury Export from a Seasonally Anoxic Reservoir

“… 2 However, while the socioeconomic benefits of reservoirs are clear, reservoirs also dramatically alter natural flows and the ecosystem structure. 3 , 4 …”

“…2 However, while the socioeconomic benefits of reservoirs are clear, reservoirs also dramatically alter natural flows and the ecosystem structure. 3,4 Seasonal anoxia from decomposing organic matter is common in reservoirs around the world and is expected to increase with climate and land-use change. 5−8 Anoxia is a key driver of (MeHg) production and increased concentrations in metalimnion and hypolimnion.…”

“…Global construction of reservoirs is expected to increase in the coming decades to meet the water supply and renewable energy needs of a growing and economically developing human population . However, while the socioeconomic benefits of reservoirs are clear, reservoirs also dramatically alter natural flows and the ecosystem structure. , …”

The direct and indirect effects of damming on the Hippopotamus amphibius population abundance and distribution at Bui National Park, Ghana

“…The abundance and distribution of species are affected by these modifications, impacting their ecology and conservation (Lima et al 2018;Brum et al 2021). Specifically, the building of dams can result in local extinctions (Clavero and Hermoso 2011;Bohada-Murillo et al 2021;Muniz et al 2021). In general, large vertebrates are the most affected by damming because their ability to complete their life cycles relies on the extent of river connectivity (Hermoso et al 2018;He et al 2021).…”

Dams Pose a Critical Threat to Rivers in Brazil’s Cerrado Hotspot

“…The conversion of lotic habitats into semi-lentic habitats creates novel environments that are inhospitable to many species, particularly those adapted to flowing waters (rheophilic) and seasonal flood pulses [17][18][19][20][21][22][23][24][25]. This can trigger important negative impacts on ecosystem functioning, with cascading effects on biodiversity and the livelihoods of local populations, both of which are adapted to the natural seasonality of the rivers [24][25][26][27][28].…”