A new study explains that one of the world's large marine animals could go extinct in the next century. The most at-risk from climate change, the megafauna and 18 percent of the largest marine animals could be lost forever by the year 2120, according to UK scientists.

If all currently endangered marine megafauna- including sharks, whales, polar bears, sea turtles, and emperor penguins-are eventually lost, this could rise to 40 percent beyond this timeframe.

Possible consequences of impending losses

Marine megafaunas play a big role in ocean ecosystems. They eat smaller animals, and transport nutrients via waste and connect habitats during long migrations. Although they are the largest animals in the oceans with a body mass that is more than 45 kilograms, human activity and climate change threatens their existence.

Losing them forever could lead to losses in functional diversity or their influence on how an ecosystem operates, according to Dr. John Griffin, study co-author from Swansea University.

It is a message that we need to act now to minimize the growing human pressures on these large marine animals, including climate change, while also nurturing their population into recovery.

The researchers compiled a dataset based on all of 334 species of living marine megafauna's traits to better understand the consequences of impending losses. They simulated two possible extinction scenarios.

One of these is based on the estimated probability of extinction for each species within 100 years given their current IUCN status and the other one assumes the extinction of all threatened IUCN species.

We could lose 18 percent of marine megafauna species on average, according to the current trajectories provided by IUCN. This means that we could lose 11 percent of the extent of ecological functions performed by species in a community, called 'niche space.'

However, if all currently endangered species were to go extinct, 40 percent of marine megafauna and 48 percent of niche space could also become extinct or no longer available forever.

Greater projected losses in 'niche space' will greatly affect the sharks as these could not be filled by other species.

We can still save them

There is still time to resuscitate the megafauna and ecosystems that are on the brink of extinction since only a few of them have already been driven to extinction.

Dr. Catalina Pimiento of Swansea University said that their previous work showed that as sea levels oscillated several million years ago, the large marine animals have suffered an unusually intense period of extinction.

But their new work suggests the unique and varied ecological roles of the megafauna species are facing an even larger threat from human species. The researchers wanted to know if other species could perform a similar ecological task if the animals go extinct.

So they created a new metric system to measure an endangered megafauna's importance to functional diversity. The researchers first compiled a dataset for al known megafauna species to understand the extent of their role in the marine systems and then stimulated future extinction scenarios and the potential impact it will have on the functional diversity.

Published in Science Advances, they were able to come up with an index called FUSE or functionally unique, specialized endangered that will inform conservation priorities. The researchers classified five marine animals with the highest score on FUSE.

These animals include the green sea turtle, the dugong, sea otter, giant clam, and Jullien's golden carp. A renewed focus on these species as well as other high-score FUSE animals will help in making sure of the maintenance of ecological functions by the marine megafauna.