Damming the Amazon: new hydropower projects put river dolphins at risk

A little while ago I wrote about the plight of Amazon river dolphins in the face of dam-building across the region. Here’s the opening few lines, but to read the whole piece please follow the link to the original on Mongabay. A National Geographic photographer kindly let us use some of his pictures, so it is worth a look!

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A dam-building boom is underway in the Amazon. More than 400 hydroelectric dams are in operation, being built, or planned for the river’s headwaters and basin. Scientists know that tropical dams disrupt water flow and nutrient deposition, with negative consequences for aquatic animals, especially migratory species. But little detailed knowledge exists as to the impacts of dams on specific species, or as to the best mitigations to prevent harm.

A recent study that tries to fill in that knowledge gap zeroes in on Brazil’s river dolphins. It found that as many as 26 dams could negatively impact dolphin populations and their prey.

The research, led by Dr Claryana Araújo of the Federal University of Goiás, Brazil, focused on two freshwater species: the Amazon River Dolphin, or boto (Inia geoffrensis), which is sometimes famously pink; and the Tucuxi (Sotalia fluviatilis).

The river dolphins of South America are charismatic emblems of rainforest biodiversity, and have captured the public imagination. Swimming in rivers, lagoons, and among submerged tree trunks in flooded forests to chase down prey, they can be found as far inland as the upper reaches of Amazonian tributaries, more than 2,600 kilometers (1,615 miles) from the Atlantic Ocean.

To continue reading, click here.

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Dawn, dusk, dolphins and downpours

When we could, we would watch twilight rise and fall over the Tiputini river. Getting up in the dark, we would go and sit on the steps rising up from the dock, and then wait as the sky brightened and the forest woke up. In the evenings, tired from the day, we would watch dusk descend. One morning, the hypnotic flow of the river was broken by the quiet breaching and breathing of pink river dolphins. We heard them more than we saw them, and would often turn to see only ripples on the water’s surface, but it was magical to witness their journey past the research station at the start of the day. In the evening, we would watch as woolly monkeys busied themselves in the highest branches of huge trees on the opposite riverbank, finally settling down to sleep, and in the morning we were up before them, and saw them slowly wake up in the morning sun. Macaws would screech as they flew high above the river to their night-time roosts, and bats would emerge when it was almost too dark to distinguish them skittering over the surface of the river.

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One night distant thunderclouds and flashes of lightning, and fireflies close by, added to the drama. That night, in our pitch dark cabin, we listened to the sound of one metre of rain falling over the course of just six hours. The complete darkness meant we were unable to see even a hand in front of our faces, or the outline of our cabin window, and the deafening roar of torrential rain was such that even the loudest scream would have gone unheard. It was a strange, claustrophobic night, we felt blind, deaf, and mute, and each time we woke it was the same never-ending darkness and noise. The light of daybreak and the easing of the rain came as a relief, and we finally slept well in the cool rainy morning, before heading out into the wet and froggy forest in the afternoon.

tiny jungle frogjungle frogtree roots jungly 2 jungly 1 jungle vines 2 jungle vines

One afternoon Jose took us on a long walk through the forest, sharing his great depth of knowledge with us. We knocked on the trunk of a tree that sounded hollow, and learnt it was the balsa tree, with cotton-like seeds. We found blobs of natural rubber, tested the insect-bite soothing properties of one vine, and kept our distance from another that was used on the tip of poison darts. We learnt that termites are great engineers, modifiying not only their nests but also the trees that they build them on, to funnel water away quickly so they avoid flooding.

termites

We saw a sleepy spider monkey lounging on a branch, and a puffbird with a large spider in its beak. We crept up to a clay lick and watched three red howler monkeys silently climb up and away from the clay. Finally, at the end of the walk, and the end of our time with Jose, he took a palm frond, extracted lengths of fibre from it, spun it into a thread, and then wove an intricate bracelet which he presented as a parting gift, now a most treasured reminder of our time in the jungle.

Our return to Quito came far too soon, and we drank in the jungle on our early morning journey back up the misty Tiputini river. It was now much higher, and flowing much faster, after the rain, and the riverbanks were submerged. A small arboreal anteater called a tamandua was battling to swim across the current, and we celebrated this final rare sighting.

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