Research determines how the simple presence of one species can modify the structure of an entire marine community. The work was published in the Journal of Animal Ecology.
In terrestrial and marine ecosystems, most of the research has focused on elucidating the impact of direct consumption by predators on their prey, a key ecological process. However, these animals can also indirectly affect their prey through the effects of non-consumption. When the hunted species is a habitat-forming species, this process could affect the entire community that depends on its existence.
The response to the risk of predation of a species with these characteristics was studied by a group of scientists, who analyzed how the indirect effects of predators can modify the structure of an entire community. The study was led by Alexis Catalán, PhD in Marine Biology.
Through manipulative laboratory and field experiments, the researchers analyzed the influence of the sea snail Acanthina monodon on Perumytilus purpuratus (purple mussel), which inhabits from the coasts of Perú to Tierra del Fuego, and of which a wide variety of invertebrates and algae depend on.
“There are several studies that analyze the indirect effect of predators on their prey. However, there is little research that also evaluates what happens to the species that depend on this endangered organism,” explained Dr. Nelson Valdivia, researcher at the Center for Dynamic Research of High Latitude Marine Ecosystems (IDEAL) of the Austral University of Chile (UACh), co-author of the investigation.
During four months, the P. purpuratus specimens were exposed to the presence of the predator, in the rocky intertidal zone of Calfuco, in the Los Ríos Region. The results showed that the presence of A. monodon increased the abundance of crustaceans and bivalves associated with the purple mussel, while the biomass of algae decreased, thus altering the structure of the entire community. Furthermore, using the same experimental design in the UACh laboratories, the researchers showed that signals transmitted by A. monodon limited the consumption of larvae and filtration rates of P. purpuratus.
“Our hypothesis is that there is a cascade-type effect on the community, since this mussel, when facing its predator, closes its valves and therefore cannot feed or eliminate waste, which affects many other species that depend on it, who inhabit on and between the shells of this species,” commented Dr. Valdivia.
The researcher commented that although P. purpuratus is not consumed by humans, it is important from the ecological point of view, since it generates resources (habitat to live, organic matter and nutrients) for many other species with economic importance such as the Chilean abalone (Concholepas concholepas), mussels and seaweed. Works based on this research will be focused on measuring at organism level, the effect of this “ecology of fear” in those who depend on the “prey” animal.
“Our study showed for the first time that a predator can indirectly affect the structure of an entire community through the effects of non-consumption on a habitat-forming species. Given that these organisms play a key role in maintaining diversity in coastal systems, understanding predation risk could help to understand community regulation in systems structured by these species,” stated Dr. Catalán.
The scientific work was recently published in the Journal of Animal Ecology, in which researchers from the Institute of Marine and Limnological Sciences of the UACh and the Department of Biology of St. Francis Xavier University (Canada) participated.