Climate change leads to a tipping point "no return" to the ecology of the Azores lakes, according to researchers

Oct. 16 () –

The increase in temperature that is causing Climate change is endangering the lake ecosystems of the Azores archipelago. These lakes, which are important for the population because they are water reserves, contribute to water regulation, tourism and leisure activities and are essential to preserve the biodiversity of the islands, are losing part of their biodiversity and their capacity to provide these ecosystem servicesas reported by the National Museum of Natural Sciences.

This is confirmed by the study carried out on the island of San Miguel where they have verified how the number of species of diatoms, unicellular algae that are at the base of the food chain, was reduced by 27% in all the lakes on the island starting from 1982, when the temperature in the northern hemisphere increased 0.35ºC compared to the 20th century average. The researchers consider it “probable” that the changes they have detected in the lakes of the archipelago are also occurring in other lake ecosystems around the planet..

In the past there were decreases in diatom biodiversity, but they occurred in specific lakes that recovered quickly, now the loss of species occurs throughout the island. “The most serious thing about these data is not the reduction of almost 30% of diatom species in a lake, but rather it is a decrease that we have seen that has occurred on a regional scale throughout the island.which indicates that homogenization is occurring,” warned the researcher at the National Museum of Natural Sciences, Miguel Matías.

“Thanks to the sedimentary records we have, which in some lakes date back between four and five thousand years, we know that these declines in diatom diversity have occurred in specific lakes due to environmental disturbances, but not on an entire island. as it happens now. Furthermore, they were specific declines from which the ecosystem easily recovered.“, continues the researcher.

According to the work, there are around 20,000 different species of diatoms and it is a group that is used as a reference to know the environmental conditions of an ecosystem, as well as to study the climatic changes that have occurred throughout the history of the Earth.

“In the Azores, changes have already been seen in the communities of these algae since humans began to expand through the archipelago and with this study we have verified that in 1982 a limit was crossed, a point of no return, which has homogenized the lakes at a regional level, which implies the decrease of their ecosystem services“explained the researcher from the Autonomous University of Barcelona and CREAF Sergi Pla-Rabés.

In 1982, when the temperature in the northern hemisphere increased 0.35ºC compared to the 20th century average, biodiversity decreased and ecosystems were simplified and according to research published in the journal ‘Nature Communications earth & environment’, The set of anthropogenic disturbances of the ecosystem has caused the development of phytoplankton formed by smaller algae and cyanobacteria, often accumulated on the surface, which prevent sunlight from penetrating deeper areas of the body of water.

By decreasing the availability of light, the available habitat for benthic diatoms and the number of species are reduced, profoundly simplifying the ecosystem,” comments Vítor Gonçalves from the University of the Azores.

“Our hypothesis is that this homogenization that we have documented on the island of São Miguel is occurring in the lake ecosystems of insular areas and possibly in isolated lake regions of the northern hemisphere and the planet.“says Sergi Pla-Rabés.

ECOSYSTEM RESTORATION

With these data, it is essential to increase ecological restoration processes that allow increasing environmental diversity throughout the island. “The degradation of ecosystems is not something that can be completely reversed, we cannot hope to return to the environmental situation that existed in the past, as if there were no human populations on the islands.“, warned researcher Pedro Raposeiro, also from the University of the Azores.

The team’s proposal to increase the complexity of ecosystems, thus ensuring that the ecosystem services necessary for the island’s population are maintained, is to reduce local pressures that can be controlled. “We consider that it is necessary to focus efforts on points on the island so that livestock farms or infrastructure are maintained outside the lake basins. Ultimately, it is about practicing an ecological restoration that takes into account the economic and social situation of those who live on the island.“concluded the researcher at the University of the Azores, Vítor Gonçalves.

Research personnel from the Autonomous University of Barcelona (UAB), CREAF, the National Museum of Natural Sciences (MNCN-CSIC), Geosciences Barcelona (GEO3BCN-CSIC), the Center for Advanced Studies of Blanes (CEAB-CSIC) have collaborated in this study. ), and the Universities of the Azores, Évora, Coruña and Barcelona.