River dolphin deaths indicate worsening climate crisis

29 setembro 2023

The main hypothesis for the deaths is the drying of rivers over the recorded standards, and high temperature of water
By WWF-Brasil and Instituto Mamirauá

The dry season in the Amazonas state is more severe this year. More than a hundred pink river dolphins (Inia geoffrensis) and tucuxi river dolphins (Sotalia fluviatilis) have been found dead in Lake Tefé (Amazonas state) and nearby areas since last Saturday, the 23rd. The situation tends to get worse as we are at the beginning of the dry season and more reports of dead animals arrive all the time. In addition to the fish and river dolphins that suffer from the lack of oxygen and end up dying, the situation directly affects fishermen and those who survive from the entire river's dynamics.

In Tefé, the Research Group on Amazonian Aquatic Mammals from the Mamirauá Institute for Sustainable Development is racing against time to rescue animals (pink dolphins and tucuxis) that still remain in shallow pools of warm water to transfer them to other locations that still keep water fresh water and minimum depth to keep the animals alive. The expert's teams and volunteers with experience in wildlife rescue are joining the emergency action, but the difficult access to the city of Tefé makes the action slower than desired.

“The first effort is to remove the  animals' remains from the water, but with the large number of dead animals it became impossible. Transferring live dolphins to other rivers is not safe, as in addition to water quality, it is necessary to check whether there are any toxins or viruses. We are mobilising partners for collection and analysis, and other institutions that have expertise in animal rescue”, says André Coelho from the Mamirauá Institute for Sustainable Development.

The traditional dry period, which peaks in October, is already affecting 59 municipalities with a reduction in the water level in their rivers, impacting navigability, posing logistical issues and insecurity for the collection and consumption of fish. The situation is expected to worsen over the next 15 days with the severe drought affecting other regions of the middle Solimões river basin, resulting in more deaths of pink dolphins and tucuxis in areas with no teams available for rescue. This makes the problem even greater and more impactful in one of the places with the highest density and abundance of river dolphins in South America.

“The studies we carried out with Amazonian river dolphins indicate that they suffer numerous pressures, such as the impact of hydroelectric plants, mercury contamination, conflict with humans (fishermen and riverside dwellers) mainly in fishing activity, which is considered one of the most serious current threats. Now, these small freshwater dolphins are more directly impacted by the climate issue. We need effective immediate protection action, but in the long term, more research is needed to find out how they are affected by constant climate change and the reduction of water bodies”, says Mariana Paschoalini Frias, Conservation specialist at WWF-Brazil.

The risks related to the lack of water tend to worsen with climate change, according to the IPCC. The group of scientists mapped changing trends and discovered that climate crises caused by human action contributed to the severity of the impact of droughts in many regions of the planet. Water-related risks are estimated to increase with each degree of global warming.

According to the IPCC, between 1970 and 2019, 7% of all disasters worldwide were related to droughts, contributing to 34% of disaster-related deaths. But beyond the lives lost, water is the main victim of climate change. In just three decades, Brazil has already lost the equivalent of 10 times the size of Greater London in water surface, according to Mapbiomas. In the last decade, the nine countries with Amazon rainforest in their territory lost 1 million hectares of water surface – an area comparable to six times that of Greater London – according to Mapbiomas.

The price taken by the climate emergency is high. Water is a strategic element: in addition to survival, it is directly associated with the energy matrix and agriculture, which is responsible for almost half of Brazilian exports. Cultivating water is the solution to an economically and ecologically safer life and this implies directly confronting climate change.

Nature is giving a warning. The climate emergency worsened by the El Niño phenomenon indicates that we will have a dramatic scenario if we continue at the current rate of global warming. The IPCC has already warned that, even in the best scenarios, we could exceed 1.5°C in temperature in the next decade. Events such as the reduction of rivers, lack of rain, floods and heat waves like those that recently affected central-southern Brazil, may become the normality of the seasons.

There is a small gap of time if we want to reverse the warming curve and keep temperatures at safe levels and guarantee the amount and quality of natural resources. This fight involves, as a priority, zero deforestation and reducing the use of fossil fuels.
Cientistas resgatam boto nas margens do lago Tefé
More than a hundred river dolphins appeared dead in Lake Tefé (AM), since the day 23/09. The main hypothesis of the deaths is the drought of the rivers above the standards already recorded and the high temperature of the water
© Miguel Monteiro / Instituto Mamirauá
O tradicional período de estiagem que tem seu ápice em outubro, já está afetando 59 municípios com a redução do nível de água em seus rios
The traditional drought season, which peaks in October, is already affecting 59 municipalities with the reduction of the water level in their rivers
© André Muzak / Instituto Mamirauá