Sea stars: The benthic equal to the polar bear

A nationwide analysis group led by researchers on the University of Manitoba has proven that polar bears share the place of prime predator of the coastal Arctic marine ecosystem with seastars.

Within the framework of the Southampton Island Marine Ecosystem Project (SIMEP, 2018 and 2019 oceanographic analysis cruises aboard the RV William Kennedy), led by C.J. Mundy, and extra government-and university-based pattern collections pushed by D.J. Yurkowski, R. Amiraux and collaborators investigated 1580 samples of the wildlife round Southampton Island, Hudson Bay, Nunavut.

“The objective of the SIMEP project was to better understand the structure and function of the Southampton Island marine ecosystem that will help local through national governing bodies and organizations decide on how to best conserve and protect this important marine environment, currently an Area of Interest under consideration to become a Marine Protected Area,” explains C.J. Mundy, Associate Professor at UM.

The marine meals net: A paradigm shift

Food webs are a central idea in ecology that has supplied appreciable perception into ecosystem functioning. At the bottom of the meals net, primary producers assist decrease trophic ranges (i.e., feeding positions in a meals net) that switch the power as much as prime predators. Generally, the trophic construction of organisms floating or swimming within the seawater, referred to as pelagic organisms that embrace phytoplankton, invertebrates, fishes, and marine mammals, are studied extensively, whereas these inhabiting the seafloor, referred to as benthic organisms, are studied a lot much less typically and sometimes assumed to solely include a truncated meals chain with decrease trophic degree species corresponding to mollusks and sponges.

R. Amiraux and collaborators refuted this assumption, displaying that organisms inhabiting the ocean floor can have all of the constituents of a whole trophic chain, i.e., major producers fueling a number of trophic ranges from herbivores to predators, with notably the presence of a prime predator: sea stars.

“We proved that the wildlife inhabiting the seawater and those inhabiting the sediment form two distinct but interconnected subwebs, together constituting the marine food web. It’s a shift in our view of how the coastal Arctic marine food web works,” says R. Amiraux, Postdoctoral fellow on the University of Manitoba.

Sea stars: The world’s prime seafloor predators?

Around Southampton Island, Amiraux and collaborators noticed an incredible range of sea stars occupying varied ecological niches. However, solely the Pterasteridae household contained prime predators. The authors argue that this household thrive as prime predators as a result of their developed protection mechanism related to a weight-reduction plan of different predators, together with marine mammal carcasses that settle onto the ocean flooring.

However, members of the Pterasteridae household of seastars are current in the entire World’s oceans the place they exert a predatory affect on the native ecosystem. Therefore, it’s seemingly that this household of sea stars is the highest predator of a lot of the World’s ocean flooring. Consequently, if within the Arctic these sea stars are the benthic prime predator counterpart to the polar bear, it’s seemingly that also they are the benthic prime predator counterpart in different oceans of the world the place completely different pelagic prime predators are prevalent, e.g., orca, shark, and so forth.

Sea stars: Small organisms with large impacts on ecosystem perform

The presence of prime benthic predators just isn’t insignificant and may have an incredible influence on the functioning of our ecosystems. For instance, if the highest predator sea stars have been to extend predation on the bivalves, i.e., clams, that walruses feed on, we will anticipate a lower within the inventory of bivalves with results propagating to the pelagic compartment on the walrus shares, and in flip, cascading as much as polar bears.

This explains the quite a few research highlighting the worldwide deleterious impact of backside trawling of benthic species on the pelagic subweb and strongly means that marine conservation initiatives mustn’t overlook the benthic compartment.

The paper is revealed within the journal Proceedings of the National Academy of Sciences.