MANAUS, AM (FOLHAPRESS) – The unprecedented mortality of fish in a floodplain region of the Amazon River in Pará, shown by Folha de S.Paulo, was caused by low oxygen levels in the water, which generated “competition “among animals. in bodies of water that had high temperature, drastic volume reduction, high turbidity values, reduced light penetration and decomposition of organisms.
The conclusion comes from the hydrometeorological monitoring core of the Semas (Secretariat of Environment and Sustainability), of the Government of Pará, which published this Friday (29) the technical report prepared after the on-site inspection of the fish mortality.
The State Secretary of the Environment, Raúl Protázio, and technicians from the secretariat traveled to Santarém, in western Pará, and visited the community of Igarapé do Costa, in the alluvial plain of the Amazon River, directly affected by the environmental tragedy.
The visit took place on Wednesday (27), one day after the publication of the Folha de S.Paulo report that revealed the magnitude of fish mortality, the consequences for seven communities where 500 families live and the lack of answers until that moment. – about the causes of the environmental tragedy. The journalist was at the scene of the animals’ death the previous Friday (22nd).
The MMA (Ministry of Environment and Climate Change) also announced the adoption of measures following the publication of the report. According to the ministry chaired by Marina Silva (Rede), a research vessel from the ICMBio (Chico Mendes Institute for the Conservation of Biodiversity) will be used to collect biological data.
The Semas report indicates that the dissolved oxygen in the Aramanaí canal was around 0.15 mg/l, while the normal level is not less than 5 mg/l.
“The values are extremely low, indicating hypoxic or anoxic conditions, possibly resulting from increased decomposition of organic matter and decreased water circulation due to low volume,” the report says. “This caused the extinction of aerobic aquatic organisms (which depend exclusively on oxygen dissolved in water).”
An extreme weather event, a prolonged drought in the region, caused a reduction in the volume of the lake and low oxygen levels in the water were the main cause of fish death, the report concludes. “Reducing dissolved oxygen is essential for fish and other aerobic organisms.”
The report also points out high turbidity values, lower light penetration (with consequences for photosynthesis), reduced space due to the drying of water masses and competition for oxygen.
“The death and decomposition of organisms in the water generated substances that worsened the already compromised environmental conditions, such as changes in pH and food supply to bacteria that further reduce oxygen levels,” cites the document released by Semas.
In addition to the fish, alligators, turtles and rays died. There was a foul smell in the places where organic matter accumulated, as well as a sea of flies. A giant stain in what was left of a stream was formed by dead animals on the surface, covering the water.
It was a scenario never seen before – not even in these proportions – in this part of the Brazilian Amazon, the so-called alluvial plain of the Amazon River, 30 minutes from Santarém in a boat with a high-power motor.
On the 11th, fishermen from the Costa Igarapé community began to notice a mortality rate of fish that, during the following days, took on alarming dimensions.
First, more fragile fish died, such as hake, cujuba and bacuzinho. Then, fish of high commercial value and widely consumed in the region, such as surubim. Finally, the strongest and most resistant animals, such as the pirapitinga and the giant arapaima, a symbol of sustainable management in the Amazon.
It was necessary to rescue turtles that were dying in lifeless waters and take them to puddles that still resisted the inclement heat and lack of rain. For days in a row, this transfer was carried out by members of the community.
There is no longer a lake in the Costa stream and the stream itself has become a trickle of water. The same thing happened with two other important water courses, fundamental for the subsistence of around 500 families from seven communities: the Pitomba stream and the Aramanaí canal.
The fishermen were in a race against time to capture animals that were still alive in the Costa stream, such as the arapaima. Days before, they dragged tons of dead fish and dumped this organic matter in several piles on the shore, then set them on fire.
The feeling that mortality would continue, with new waves of mass losses of fish and other animals, was inevitable for anyone who looked at the water. The fish sought the surface in search of oxygen, mainly mites; Bubbles burst on the horizon of the remaining water.
The Santarém region has been under dense smoke for days due to forest fires. The prolongation of the drought, without rain, aggravates the problem.
