Functional responses of fisheries to hydropower dams in the Amazonian Floodplain of the Madeira River

Abstract

1. Tropical river fisheries support food security for millions of people but are increasingly threatened by hydropower development. How dams affect these fisheries remains poorly known in most regions. Here, we used a functional traits approach to evaluate the extent to which compositions of fishery yields in the Madeira River Basin, the largest sub-basin in the Amazon, respond to dam construction. We also explored how dams affected the monetary value of yields and fishing-based income of the communities.2. We collected fishing data in 17 locations distributed over 300 km across upstream, reservoir and downstream zones during pre-and post-dam construction periods.We interviewed 711 fishers from 13 communities to assess fishing income during pre-and post-dam periods.3. Catch-per-unit effort (CPUE) declined significantly, that is, by 37%, after dam construction. Multivariate analysis yielded six species clusters according to trait syndromes related to life history, migration, swimming performance/habitat-use and economic value that were associated with the environmental data characteristic of pre-and post-dam periods. Comparison of CPUE of each cluster indicated that large species with periodic life-history strategy and regional or long-distance migratory behaviour were most affected by dam construction, with CPUE declining by, on average, 31%. Declines in yields and shifts in functional composition of the fishery yields resulted in average decline of 21% in the monetary value of functional clusters and 30% in fishing income. Synthesis and applications.Our study indicates that the implementation of the dams affected the functional composition of yields and reduced catches, negatively affecting the fishing-based income of communities in the Madeira River.These results imply that hydropower expansion will cause detrimental effects for fisheries and the livelihoods they sustain. Our results underscore the urgent need for considering alternative sources of renewable energy (e.g. solar power and in-stream turbines) to avoid irreversible socio-environmental damages of large dam projects. In river reaches where dams are already in operation or under | 681

The impact of hydropower dam construction on malaria incidence: Space-time analysis in the Brazilian Amazon

“…This paper suggests that, while there are a range of well-known adverse social, environmental and economic consequences of dam construction in the Amazon [ 29 , 37 , 38 , 40 , 41 , 43 , 44 , 52 , 53 ], malaria control appears to have succeeded in our study sites. However, once malaria incidence is reduced as does the funding for surveillance and control, transmission could rebound quickly.…”

“…Besides, there are numerous other socio-environmental damaging consequences of those large infrastructure projects in the region. Examples are losses in social capital and decreasing self-rated health [ 39 ]; increasing injustices to the local populations for not being properly compensated by their losses [ 40 ]; questionable processes of consultation of the host population, lacking effective participation [ 41 ]; displacement of thousands of people, tending to impact marginalized populations more intensely [ 29 , 42 ]; and environmental damage to river ecosystems and to fish biodiversity [ 43 , 44 ].…”

The potential of citizen science to assess migratory patterns of Amazon fish

“…In the Middle Madeira, the number of users and observations was lower than in other areas, and reflects not only the low number of active commercial fishers after the construction of the Santo Antônio HPP reservoir, but also the decrease in catch per fishery. Arantes et al (2021) showed that after the construction of the barriers, the capture per unit of effort decreased, on average, 37%. This decline reflects the low efficiency of the dam transposition system implemented (Hahn et al 2020) and the consequent decrease in the abundance of some species.…”

Seasonal patterns in the structure of the fish larvae assemblages in the lower Amazon River

“…Classifying species according to these groups can help to suggest ecological mechanisms associated with species distribution, feeding and reproduction patterns. Furthermore, increasing or decreasing in fish occurrence or abundance in these functional groups has been related to environmental changes in river systems, including seasonal hydrological variations (Silva et al, 2020), changes in forest cover (Arantes et al, 2018), extreme weather events (Cajado et al, 2022; Röpke et al, 2017) and the implementation of dams (Arantes et al, 2022; Arantes, Fitzgerald, et al, 2019). Individuals were classified based on species‐level information and where data were unavailable, we used data available for genera.…”