invasive species They encroach on the habitats of native species, displacing them and eventually destroying them. This is what’s happening river crab It lives in Spanish ecosystems and has already had 95% of its area occupied by American crayfish, an invasive and exotic competitor.
A scientific team led by the Doñana Biological Station (EBD) of the Higher Scientific Research Council (CSIC) examined changes in the distributions and ecological niches of three crayfish species introduced to Spain throughout history. The study focuses on the Italian crayfish, which was introduced in the 16th century and is considered by many to be native (even though it is not). two North American species, red crab and signal crabIt was introduced in the 70s of the last century.
The results were published in the journal Journal of Animal EcologyThey state that The common niche of these two American species occupies more than 95% of the ecological niche of the Italian crabThis is the only exception, except for small headwaters that serve as refuges for these species, a CSIC note states.
To conduct this study, researchers collected systematic data on the existence of crayfish over the past 200 years using a variety of historical and contemporary sources.
“Although we often hear about native crayfish, in reality there are no native crayfish on the Peninsula,” explains researcher Miguel Clavero from EBD-CSIC. “According to recent research, The species we think is native is actually the Italian crab.scientific name Austropotamobius fulcisanius” he states.
Crabs since the time of Philip II
This species was introduced to King Henry II, who wanted to fill the ponds of his newly opened palaces with these striking animals he encountered in the Dutch and Italian palaces. It was introduced to Spain in the late 16th century at the request of Philip. The privilege enjoyed by the king was disappearing with new introductions, which until now had not yet been fully documented. The species became common food for humans.
Although the distribution of Italian crayfish would increase significantly between 1850 and 1960, its ecological niche in 1850 was fairly representative of the situation in 1960. The introduction of Italian crayfish was plentiful throughout the 20th century, and the Franco regime promoted it heavily. To promote fishing.
“Probably due to overexploitation, many Italian crab populations began to decline or even disappear in the early 1970s,” comments researcher Duarte Viana, first author of the study.
“This triggered a lot of alarm in a society where there is an unbridled love for crabs. supported the introduction of two North American species, red crab and signal crab. “After the arrival of American crabs, the Italian crab’s distribution greatly decreased and its habitat changed to more mountainous, riverine sources and more coastal environments.”
Cancer Plague Carriers
The ecological niches of two American crab species are highly complementary: signal crab (Pacisfastacus leniusculus) are found in colder environments towards the north of the peninsula, while the red crab (Procambarus clarkii) live in warmer, lower altitude areas.
The combination of global warming and the continued expansion of American species could make small streams of water that are a haven for Italian crabs uninhabitable. Moreover, like all American species, These crabs carry the crab plagueA fatal disease for all European crabs, including Italian crabs.
American specimens are carriers of crab plague, a disease fatal to all European crabs.
“Most of the features Ecosystems are constantly changingit is often accelerated in the current global change scenario,” explains Viana. “Species have the ability to thrive in ranges where there are certain minimum or maximum temperatures, a certain extent of forest, the presence of other species, which structure what we call ecological niches. “Although species’ niches are assumed to be fixed, in reality they can change in response to environmental changes, and understanding all these chain changes is relevant to promoting biodiversity conservation,” he emphasizes.
Studies on changes in species’ ecological niches have been limited due to limited long-term data. Because information on biodiversity has only been collected in a standardized way in recent years, many changes that occurred in previous periods are often overlooked.
This study on crayfish is an example of the potential for information derived from historical sources To describe the distributions of organisms and ecological processes in periods little researched by natural sciences. According to the researchers, this long-term vision is key to assessing human impacts on natural systems and providing reference conditions for biodiversity conservation.
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