Lake where 154 dolphins have already died breaks new heat record – 10/20/2023 – Environment

The team that monitors red dolphins and tucuxis in an overheated lake in Tefé (AM) detected a record water temperature, found another dead animal —after an interruption of deaths for around ten days— and began testing new ways to scare them away. freshwater dolphins, given the continuation of extreme drought in the region of the middle Solimões River.

The information is in a technical bulletin concluded this Friday (20) by ICMBio (Chico Mendes Institute for Biodiversity Conservation) and the Mamirauá Institute for Sustainable Development, responsible for the animal monitoring operation in Lake Tefé.

The bulletin updates the number of deaths of red dolphins (pink dolphins, as they are popularly known) and tucuxis (another, smaller species of dolphin): 154, since September 23rd. Among the dead individuals, 131 were red dolphins and 23 were tucuxis. There were males, females, cubs, juveniles and adults.

So far, the most likely hypothesis for the deaths is the overheating of Lake Tefé, especially in the Papucu cove, very close to the port of Tefé. The cove is rich in fish, and one of the dolphins’ favorite destinations.

On September 28, there was a record temperature in the cove, according to measurements made by the Mamirauá Institute. The thermometers read 39.1°C. It was on that day that the most porpoises and tucuxis died: 70.

According to the technical bulletin from ICMBio and Mamirauá, the lake’s waters have warmed up in recent days, after cooling caused by scattered rains in the region. In a very shallow part of the lake, where there were no dolphins and tucuxis, a thermometer read 40.9°C.

On Thursday morning (19), the teams involved came across a dead animal again, after days without detecting any deaths. It was a young male red dolphin.

“This new death comes shortly after an extreme temperature event observed the previous day, when water temperatures above 38.8°C were measured”, states the technical bulletin. “This reinforces the hypothesis that water temperature plays an important role in the death of animals.”

A solution found by researchers and civil servants for the extreme situation was the removal of porpoises and tucuxis from the Papucu cove, something that had never been seen in the region.

A Sheet followed the beginning of this process of driving away animals, last Saturday (14).

At the mouth of the cove, wooden stakes were installed side by side, in a V shape. An opening was maintained in the middle of the reinforced grille, for the porpoises to pass through.

With so much food in Papucu, the animals’ departure would not be spontaneous. Thus, after much discussion about the best procedure to be adopted, Mamirauá employees began to guide the passage of a net through the cove, in order to push the porpoises to the exit.

The net was set and dragged, followed by a “slap” — a noise with the rope and the net itself in the water — to prevent the animals from returning. Further down, it was collected and armed again, up to the railing. Some of the dolphins followed the course desired by the researchers, in search of deeper, colder wells.

New techniques began to be tested, given the continued risks to dolphins. One of them consists of emitting sounds designed to scare animals away. The other is the placement of a curtain with objects that prevents dolphins from approaching. “The equipment is adapted from the traditional people of Hawaii”, says the bulletin from ICMBio and the Mamirauá Institute.

Lake Tefé flows into the Solimões River, which has become a desert in a section of the Porto Praia de Baixo Indigenous Land, as reported by the Sheet found out last Friday (13).

Closer to Manaus, the river reached the lowest level in the history of measurements made. The watercourse reached 3.61 m in Manacapuru (AM), according to a bulletin released by the SGB (Brazilian Geological Survey) on Thursday. The previous record was 3.92 m, recorded on October 26, 2010.

The prospect is for a slower rise in the river, and this is already happening. There were rains in Peru and in upper Solimões, where cities such as Tabatinga (AM) and Benjamin Constant (AM) are located, places that will be the first to feel the rise in levels, according to the SGB.

In Tabatinga, the river rose 24 cm in 24 hours, according to the bulletin released by the SGB this Thursday. This should spread through the middle Solimões, where Tefé and Fonte Boa (AM) are located, to Manacapuru.