New research consider this predator as a key element in the structuring of the marine ecosystems of Patagonia.
Daniela Jofré, IDEAL Center. The Cosmasterias lurida starfish exists throughout the Chilean and Argentinian Patagonia, being one of the most important predators at the benthic level of the southern zone. It has a carnivorous diet, and despite its wide geographic and bathymetric distribution, there was no further information on its trophic ecology, concentrating mainly on its reproductive cycle. For this reason, a team of scientists decided to investigate what happened to their foraging behavior, considering that C. lurida feeds largely on mitilids (the entire mussel group,) becoming a possible inconvenience for the fishing industry.
The hypothesis put forward by the study suggested that C. lurida was a generalist predator, that is, it fed on the species that were available to it in the environment. However, the work led by researcher Ignacio Garrido, from the Center for Dynamic Research on High Latitude Marine Ecosystems (IDEAL) of the Austral University of Chile (UACh) found new evidence on their dietary behavior.
“Observational studies on this animal, carried out in the Beagle Channel, had identified it as a generalist predator. What we did was a comparison of what the starfishes were eating with respect to the environmental offer,” explains the researcher.
It was believed that preys consist of a wide range of organisms, such as sponges, sea anemones, mollusks, polychaetes, crustaceans, and even other stars. “However, we realized that C. lurida was not eating the most abundant things around it, but that it was selecting a particular prey, mussels, even reaching greater depths to capture them,” comments Garrido.
The work carried out with specimens from the Reloncaví basin, in the region of Los Lagos, determined that among the prey preferred by this predator are, in first place, the mussels Aulacomya ater, Mytilus chilensis and the so-called slipper limpets (Crepipatella sp.)
C. lurida has even been observed up to 600 meters deep, where Garrido raises the question: What are they feeding on and what is the role of predators in deeper areas?
The feeding behavior and its selectivity to choose its prey, classify Cosmasterias lurida as a key predator in the structuring of subtidal benthic communities in Patagonia, explains Garrido.
“These studies help us knowing what would happen when an important predator, which shapes biological communities, disappears or lowers its abundance. In this case, it is possible that the seabed, where this star has influence, would become very different in species composition and, therefore, the underwater landscape would change. That is why this type of predator is called community structuring,” explains Dr. Luis Pardo, researcher at the IDEAL Center and director of the Graduate School of the Faculty of Sciences of the UACh, who participated in the study.
Given this, Garrido also assures that human activity in marine ecosystems should be considered (such as coastal urbanization and the fishing industry,) since the destruction of these habitats could significantly affect starfish populations and its impact on the trophic structure and the role of subtidal communities.
Future work, in order to understand the feeding behavior of C. lurida and its importance as a predator in the ecosystem, will be to understand its environmental context. “We hope to make in situ observations of this species in the Magallanes Region, since the environmental offer in that area is different and of greater variety, thus determining the importance in benthic communities on a larger scale,” concludes Garrido.
The research was published in the scientific journal Frontiers in Marine Science, as part of a special issue on the 500th anniversary of the “discovery” of the Strait of Magellan.
Read the study here.