Sharks are a survivor, but not all sharks. Now human overfishing for ther fins for soup in Asia is killing off tens of thousands yearly,.an ecological danger as they are a "keystone" speices
Photo Credit: Ari S. Friedlaender

Marine extinctions past, and in the future

Ancient fossil record helps to understand species vulnerability today

An international study of extinctions of marine life millions of years ago may point to extinction risk hot spots today.

Derek Tittensor (PhD) is a senior marine biodiversity scientist at the United Nations Environment Programme World Conservation Monitoring Centre and adjunct professor at Dalhousie University in Halifax

Listen The study “Paleontological baselines for evaluating extinction risk in the modern oceans” was published in the online journal Science on May 1st

null
Derek Tittensor (PhD) is a senior marine biodiversity scientist at the United Nations Environment Programme World Conservation Monitoring Centre and adjunct professor at Dalhousie University in Halifax © Dalhousie

The premise is that by studying what kinds of species became extinct millions of years ago and how long they existed will indicate what kinds of species are susceptible to extinction today.  The study also looked at these extinctions geographically to establish a baseline of species and locales. This gave a map of areas and of species that have experienced the most extinctions, without the influence of man

According to the fossil record, sharks and corals tended to be more resilient species, while whales, dolphins and seals were more prone to extinction. Species with smaller geographic ranges were also more prone to extinction.

The study then looked at the added stressors of human activity and how that may increase the extinction risk. Professor Tittensor noted that human activity is adding to the natural extinction risks and he says other recent studies indicate that human activities are increasing the risk by a factor of 100 to 1000 times over the average “background” or natural risk of extinction rate.

In the fossil record, whales, dolphins and seals show higher risk of extinction than sharks or invertebrates such as corals. Clams and mussels — so-called bivalves — had about one-tenth the extinction risk of mammals.

null
Modern echinoid- some groups like corals, molloscs, which have survived for eons, are less at risk of natural extinction. © Simon Coppard
null
A fossil echinoid (sand dollar or sea urchin) © Aaron O’Dea

By overlaying the past maps of the natural or intrinsic extinction risk, and present “maps”, of current threats from humans and climate change to obtain a global map of potential future hotspots of extinction risk

The rich biodiversity, high impact levels, and concentration of extinction-vulnerable species in areas like the Caribbean and Indo-Pacific, led to them being identified as extinction hotspots in the study.

null
Fossil shark tooth. while sharks are an ancient species, some have become extinct, and some modern sharks are more susceptible to extinction than others. © Jorge Carrillo Briceño

“Historically, the species in these areas had higher natural extinction risks,” said Tittensor. “Today, they may be increasingly prone to accelerated extinction rates because of pressures like overfishing, pollution and climate change.”

The idea is that, armed with this data, about which species are at an elevated risk of extinction today, and in which “riskier” regions, actions may be taken to mitigate the loss

Another co-author, Heike Lotze, also from Dalhousie University says, “Areas that have naturally high extinction risk may need extra management and conservation efforts, especially if they also face high pressure from human activities in today’s ocean.”

null
Exposures of Pliocene sediments containing marine fossils in California. Data from fossil localities like this from around the globe were analyzed by Finnegan and co-authors in their study of extinction risk in the oceans. © Seth Finnegan (lead author)

Other researchers in the international study are from; University of California in Berkley; University of Massachusetts in Boston; Mount Allison University in Sackville, New Brunswick; University of Oslo in Norway; College of William and Mary in Williamsburg, VA; University of Washington, Seattle; Smithsonian Tropical Research Institute in Panamá; and University of Queensland in St. Lucia, Australia.

Categories: Environment & Animal Life, International, Internet, Science & Technology, Society
Tags: , , , , , ,

Do you want to report an error or a typo? Click here!

For reasons beyond our control, and for an undetermined period of time, our comment section is now closed. However, our social networks remain open to your contributions.