Wednesday , March 3 2021

The unknown inhabitants of fresh water that reveal the secrets of Antarctica and Patagonia – worldacuicola



Group of crustaceans inhabits almost all aquatic ecosystems and have grabbed the attention of Chilean researchers (Aquatic World).

Copepods, or also called "super-crustaceans", are surprised by their high resistance and adaptability to extreme environments. Today they give clues to the small terrestrial and freshwater fauna of the white continent and its link with South America.

Its small dimensions are not an impediment to being distributed throughout the planet. They are part of the zooplankton in marine and freshwater environments, as well as playing a key role in the food chain and indicating environmental changes. It is a group of crustaceans that inhabit almost all aquatic ecosystems and that have attracted the attention of Chilean researchers.

Therefore, the Ministry of the Environment published the records of 14 species of copepods of the genus Boeckella that live in Chilean and Argentinean Patagonia, in the sub-Antarctic islands and in the Antarctic. The work was prepared by scientists from the Institute of Ecology and Biodiversity (IEB), University of Chile, University of Magallanes, Costa Humboldt and the British Antarctic Survey (United Kingdom), in order to facilitate research and democratize access to data on the little explored freshwater biodiversity.

"Antarctic terrestrial or freshwater fauna is very scarce and reduced compared to marine biodiversity, since there are no mammals, amphibians or reptiles, and there is only one species of bird. In addition, many believe that the whole continent is frozen, but it has the largest diversity of liquid water systems, such as fjords, lakes, among others, in which copepods inhabit, "says Claudia Maturana, scientist at the Institute of Ecology and Biodiversity, who receives support from CONICYT and the Chilean Antarctic Institute for its investigation.

Although the magallánicos and Antarctic lakes are often oligotrophic, that is, they have few nutrients, they also differ.

While in Patagonia there is a greater wealth of species of Boeckella, on the white continent alone is found Boeckella poppei. It was precisely this last species that aroused the interest of scientists for being the only invertebrate present in the lakes of continental Antarctica, the Antarctic Peninsula and the sub-Antarctic islands.

"While other white copepods exist on the white continent, Boeckella poppei It is the only crustacean that has such a large presence in this territory, "explains Maturana, who explained part of this work a few days ago at the Natural History Museum in London.

Among the main characteristics of these animals is its high strength and adaptability. To get an idea, this arthropod has an intense red color that protects it from UV radiation, and inhabits extensive and deep lakes that connect with marine waters, or in smaller ecosystems and slopes that are nourished by the melting of ice, subjected to at temperatures below 5 ° C, and even below 0 ° C.

"This animal can remain in egg state for many years, as if it hibernated, to survive extreme conditions. In winter, for example, the lakes in Antarctica freeze, then to survive it can go deep down or lower your level of metabolism. "

The IEB researcher adds: "In 2012, a team of Chinese scientists analyzed sediments of a lagoon near its Antarctic base and detected viable eggs from Boeckella poppei, who were 100 years old and could hatch at any time. "

Are they dragged by the whaling industry?

Currently, one of the big questions is how Boeckella poppei He became one of the few representatives of the terrestrial and freshwater fauna of Antarctica.

"There is no certainty about what happened when the continent crossed the last great glaciation more than 20 thousand years ago. While some point to the fact that everything was extinguished, others think that some species survived with the help of shelters, "says Maturana.

Considering its extensive distribution in Antarctica, the Boeckella poppei It is a model to test the two previous hypotheses.

The big question is whether this copepod be colonized by the southernmost continent of the Earth from Patagonia or sub-Antarctic islands, or if it managed to survive by taking refuge in isolated places during the glacial periods and climatic changes that occurred during millennia.

While there is a connection between the populations of Boeckella poppei of Antarctica and Patagonia, this would not be very recent since it would exceed 20,000 years. In any case, it has not yet been clarified how these organisms are displaced. Some of the possible explanations suggest that seabirds that travel between the two continents could become vectors when moving to these crustaceans.

Another possible mechanism would be at the height of the whaling industry in the nineteenth century. The crew of the ships extracted fresh water from the Antarctic lagoons, which was stored in barrels for consumption and other uses. Therefore, when transporting or emptying containers with liquid, cetacean hunters could move copepods to places where they were not previously found.

However, none of these theories have been proven. "The populations of Antarctic copepods remain very pristine and little intervened. We have not detected a greater degree of human impact, "says the scientist.

Despite its obvious attributes of "super-crustacean", there is no clear idea of ​​the mechanisms of differentiation and adaptation to the different ecosystems in which it inhabits. An example of this is that some individuals have experienced a reduction in their body size and the fertility of females, in response to a lower availability of resources in the Antarctic continent.

"While the role of these animals has been studied as a guarantor of climate change or as indicators of water quality, research on the evolutionary patterns of freshwater fauna has been under-explored. That is why it is important to generate and provide information from Chile to learn more about the biodiversity of fresh water at high latitudes, "Maturana said.

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