Something is hiding in the seafloor of Patagonia. A recent expedition in the waters of the Melimoyu reserve detected a concerning expansion of Metridium senile, a surprising invasive species that preys on and displaces native underwater species.
This could affect both the biodiversity of the area and the key fishing resources in the zone. What is this species that threatens the marine bottom of southern Chile?
Metridium senile: the surprising silent invasive species
Local species such as sea urchins, barnacles, and other marine invertebrates are being threatened in Patagonia by the increase of an invasive anemone known as Metridium senile. This finding was made in the Aysén region, in the Melimoyu reserve, by the expedition of the Cortés Solari Philanthropy, through a scientific team from the Meri Foundation.
Although its presence in central Chilean Patagonia was first confirmed in 2005, and in Northern Patagonia in 2011, in the last decade its abundance has increased significantly.
This surprising invasive species, also known as plumose or feathery anemone, is originally found in the seas of Northwestern Europe and on the east and west coasts of North America. However, in the depths of the Chilean sea, it is considered an invasive species.
Behavior and reproduction of Metridium senile
Metridium senile attaches to rocks, boulders, and almost any type of marine surface. The smaller forms inhabit beneath stones and in shaded areas. At greater depths, larger forms are sometimes abundant on piles, submerged pipes, dock supports, and port walls.
It is a predator that traps small organisms floating in the current. Its diet consists mainly of copepods, worm larvae, mollusks, ascidians, amphipods, and barnacles.
Additionally, the anemone is a protandrous hermaphrodite, which means it begins life as a male and changes to female as it ages. It can also increase its numbers through asexual reproduction.
An individual can split into two organisms through binary fission or develop buds that become new individuals before detaching. Fragmentation, or basal laceration, is another mechanism by which the number of individuals can rapidly increase.
Impact on the ecosystem and control measures
“Today, it occupies large areas of benthic substrate, displacing important commercially valuable species like the red sea urchin. In some areas, it covers almost 100% of the rocky bottom and is particularly abundant between 5 and 15 meters deep in this channel.
This severely affects benthic communities and transforms habitats previously dominated by native invertebrates,” explains Alejandro Pérez Matus, a researcher at the Pontificia Universidad Católica de Chile, advisor to FCS, and leader of the expedition.
The rapid spread of this anemone is due to its asexual reproduction, which allows for the formation of dense clonal groups, giving it a competitive advantage over other sessile species such as corals, sponges, and algae that provide habitat for many other species. “Its reproductive capacity and its resistance to different environmental conditions make it a serious threat to marine biodiversity,” warns Pérez.
The species is highly tolerant to variations in temperature, salinity, and dissolved oxygen, allowing it to thrive in disturbed environments. It can efficiently compete with other benthic species, displacing them in fragile ecosystems like the Patagonian fjords.
According to the researcher, aquaculture, especially the transport of mussels (Mytilus chilensis), has facilitated the expansion of Metridium senile by providing vectors for its dispersion and releasing available substrate after bivalve harvesting. Additionally, global environmental changes could be creating more favorable conditions for its establishment and proliferation in new areas.
“It is urgent to implement monitoring plans and regulations in aquaculture to control its expansion and reduce its impact on marine biodiversity in Patagonia,” emphasizes Pérez.
Monitoring Expedition in Melimoyu Bay
This discovery is part of the expedition led by the Meri Foundation, whose goal is to monitor the biodiversity of Melimoyu Bay. The aim is to establish an ecological baseline to assess the state of the ecosystem and the potential impacts of human activities and natural phenomena in the area.
“For over five years, we have been researching the benthic resources and corals of Northern Patagonia, collecting information and taking photographic and audiovisual records of the existing biodiversity in this area. This information is very concerning. It is an alert that calls us to deepen and maintain monitoring of this area, rich in biodiversity and ecology,” says Francisca Cortés Solari, executive president of Cortés Solari Philanthropy and Meri Foundation.
Furthermore, she adds that more research is needed to determine the threats to our ecosystem and understand the mechanisms of introduction and spread of invasive species, which can generate irreversible impacts on marine ecosystems and the communities that depend on them.
Source: La Tercera
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