Are we ready to become cannibals and begin relying on the flesh of our neighbors to sustain us nutritionally? Unfortunately that is the reality we are headed for, if a miracle does not occur, in which we drastically reform our current uses and abuses of the natural world. Currently, in the tropical Amazon River, the construction of hydropower dams is erupting. No one creature is more affected than catfish populations, whom use and require the entire length of the 4,000 m of the river, to compete their life cycles.
Currently, there are 191 damns distributed along the length of the river— which begins at the foothills of the Andes mountains in Peru, and empties into the Atlantic Ocean of Brazil’s eastern coast— and 246 that have yet to be completed [4]. It is a challenge to get consistent conservation policies and fishing regulations across the span of the Amazon River due to the fact the river spans across nine different nations. Today, two-thirds of all global rivers are dammed and, biodiversity speaking, damned also. Catfish migrations are instigated by the rainy season. The river rises, and the mature individuals begin the hike upstream from the basin-westward to the whitewater foothills of the Andes, where they spawn. The consequential larvae then float back down the river to where they finally are reared in estuaries.
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Many animals depend on the migrating catfish as a food source, and multiple tree species depend on them to disperse their seeds along their journey. The dams completely dismantle and block this process. Where a dam is placed, lotic water is replaced with lentic. This drastically reduces the flow of the seasonal pulses, which traditionally act as cues for the onset of the ancient migration process. The resulting, more still waters, favor more generalist species over endemics and specialists, and create new threat of predators for many species. |
One-third of local endemic fish are at risk of extinction by the construction of the Belo Monte Dam on Xingu River of Brazil alone. Severe economic downfalls for local fisheries are anticipated. Increasing electricity demands are the driving force behind the dam boom. Alternatives include solar and wind energy, which have their own set of devastating effects, such as the propellers of wind turbines severing migratory birds as they attempt to fly through. However, biodiversity is not severely impacted by these other options as it is by dams.
Hydropower has been the go-to choice for economic reasons, as well as being the most reliable energy source. Brazil has a total of 397 damns either working presently or in the works [4]. The best thing we can do is to revert back to the ancient ways, and not using electricity at all if it comes down to sparing the lives of other species we share the planet with. Devastating outcomes are anticipated indirectly through trophic cascades, resulting from the damming of the Madeira River, which rapidly halts their complex life history strategy [5]. Otiolith Microchemistry has been deployed as a means to determine the specific location of the breeding grounds utilized by individual fish, as well as other habitats occupied by them throughout their life cycles [1]. This method provides proof of their usage of multiple stretches of the river. Strontium signatures are deduced by these means, and compared with known sediment compositions on record for precise mapping. It was determined that there are actually multiple strategies occurring to include resident behavior to certain basins as well as natal homing [2].
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There really hasn’t been extensive research into their behaviors, and for that reason it is negligent—to implement dams without prior study into potentially-expected, resulting effects. It is known that they have integral roles as top-down, apex predators, as well as bottom-up regulators—by dispersing nutrients from floodplains and estuaries-up to the white waters of Bolivia, Colombia, Ecuador and Peru [2]. Their seasonal march to return to the place they started life in order to reproduce is the longest freshwater migration in the world [1]. Other threats to their prosperity include: mining, overfishing, agricultural expansion, and cattle herding [3].
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One effort to encourage compliance of the fishing season regulations is the offering of financial support from the government while the season is closed. Upon completion of the planned dams, the now-unemployed construction workers often get involved in illegal deforestation projects. The vegetation of the Amazon is crucial to the cycle of rains. The erasing of flora results in a more-dry climate, therefore reducing the flow pressure of the river, and essentially the output of hydropower from the dams decreases as well [4]. Environmental impacts are greatest in the lower parts of the Amazon River. It is advised that dams be built in upstream areas where waterfalls already fragment the system naturally. We can only hope conservation can keep up before this unique and delicate river system collaspes entirely!
To read other conservation studies click below:
Sources:
[1] Hegg, J.C., Giarrizzo, T., Kennedy, B.P. 2015. Diverse Early Life-History Strategies in Migratory Amazonian Catfish: Implications for Conservation and Management. PLoS ONE 10:e0129697.
[2] Cañas, C.M., Pine III, W.E. 2011. Documentation of the Temporal and Spatial Patterns of Pimelodidae Catfish Spawning and Larvae Dispersion in the Madre de Dios River (Peru): Insights for Conservation in the Andean-Amazon Headwaters. River Research and Applications 27: 602–611.
[3] Lees, A.C.; C.A. Peres, P.M. Fearnside, M. Schneider & J.A.S. Zuanon. 2016. Hydropower and the Future of Amazonian Biodiversity. Biodiversity and Conservation 25 (3): 451-466.
[4] Alho, C. J.R., Reis, R.E. Aquino, P.P.U.. 2015. Amazonian Freshwater Habitats Experiencing Environmental and Socioeconomic Threats Affecting Subsistence Fisheries 44: 412-425.
[5] Duponchelle, et al. 2016. Journal of Applied Ecology 53: 1511-1520.
Picture Credits:
[1] https://upload.wikimedia.org/wikipedia/commons/6/6c/New_vessel_for_Fort_Tango%2C_on_the_Congo_River.jpg
[2]https://commons.wikimedia.org/wiki/File:Mascarenhas_de_Moraes_Dam.jpg
[3] Matias Appel https://www.flickr.com/photos/mathiasappel/24505802445/in/photolist-DkuDig-qua6oe-4Exs4V-dPd6c2-gHfusm-aefuWj-gHg3B3-6Fzv7s-qu1JqQ-gHgi9r-qLqzu2-8UKYNN-a9HKGj-9Qeonp-ec8eKt-qu1F8s-dPd5XF-pPNzd8-hTkwnM-bun719-wFu5Jy-qJi5e9-ad2ztT-gQE1oM-bun3nL-qLzAhF-a9ZiDY-a9L6HV-bwV3V6-ad5qvs-qLvk5b-gHgDp6-qu8P94-rygRf-a9HLGs-zFbY23-acyKXD-fQwoYu-bwVBwc-hkA4aJ-bwVHnR-bwVLVn-pPNE9R-aecQPK-a9EYWk-dZQSVX-qu2s4w-auhkR9-5wJnj8-a9HKbf
[4] Cliff https://www.flickr.com/photos/nostri-imago/2892681894/in/photolist-6XcmFG-DkuDig-pURoRZ-QyTh1-5pBKxL-75pQvC-5oeJdu-5Ng2VM-pV2bnK-dWQG4A-75maVF-bfw7A8-dWK2FM-5CEegx-dWQFLU-75m6fz-dWK2o2-75m86t-5CJzMw-75pVxo-75q9Uy-5CJwMW-6VTNQe-75pKy1-JDpne2
[1] Hegg, J.C., Giarrizzo, T., Kennedy, B.P. 2015. Diverse Early Life-History Strategies in Migratory Amazonian Catfish: Implications for Conservation and Management. PLoS ONE 10:e0129697.
[2] Cañas, C.M., Pine III, W.E. 2011. Documentation of the Temporal and Spatial Patterns of Pimelodidae Catfish Spawning and Larvae Dispersion in the Madre de Dios River (Peru): Insights for Conservation in the Andean-Amazon Headwaters. River Research and Applications 27: 602–611.
[3] Lees, A.C.; C.A. Peres, P.M. Fearnside, M. Schneider & J.A.S. Zuanon. 2016. Hydropower and the Future of Amazonian Biodiversity. Biodiversity and Conservation 25 (3): 451-466.
[4] Alho, C. J.R., Reis, R.E. Aquino, P.P.U.. 2015. Amazonian Freshwater Habitats Experiencing Environmental and Socioeconomic Threats Affecting Subsistence Fisheries 44: 412-425.
[5] Duponchelle, et al. 2016. Journal of Applied Ecology 53: 1511-1520.
Picture Credits:
[1] https://upload.wikimedia.org/wikipedia/commons/6/6c/New_vessel_for_Fort_Tango%2C_on_the_Congo_River.jpg
[2]https://commons.wikimedia.org/wiki/File:Mascarenhas_de_Moraes_Dam.jpg
[3] Matias Appel https://www.flickr.com/photos/mathiasappel/24505802445/in/photolist-DkuDig-qua6oe-4Exs4V-dPd6c2-gHfusm-aefuWj-gHg3B3-6Fzv7s-qu1JqQ-gHgi9r-qLqzu2-8UKYNN-a9HKGj-9Qeonp-ec8eKt-qu1F8s-dPd5XF-pPNzd8-hTkwnM-bun719-wFu5Jy-qJi5e9-ad2ztT-gQE1oM-bun3nL-qLzAhF-a9ZiDY-a9L6HV-bwV3V6-ad5qvs-qLvk5b-gHgDp6-qu8P94-rygRf-a9HLGs-zFbY23-acyKXD-fQwoYu-bwVBwc-hkA4aJ-bwVHnR-bwVLVn-pPNE9R-aecQPK-a9EYWk-dZQSVX-qu2s4w-auhkR9-5wJnj8-a9HKbf
[4] Cliff https://www.flickr.com/photos/nostri-imago/2892681894/in/photolist-6XcmFG-DkuDig-pURoRZ-QyTh1-5pBKxL-75pQvC-5oeJdu-5Ng2VM-pV2bnK-dWQG4A-75maVF-bfw7A8-dWK2FM-5CEegx-dWQFLU-75m6fz-dWK2o2-75m86t-5CJzMw-75pVxo-75q9Uy-5CJwMW-6VTNQe-75pKy1-JDpne2