A team of researchers from the Institute of Palaeontology at the University of Vienna has shown that shark and ray diversity has decreased substantially since the Eocene period, 45 million years ago.
The latest discovery contradicts the prevailing narrative that up until recent times, diversity has been stable or increasing. To determine that it has been in decline well before the existence of humans on the planet is a truly remarkable discovery.
Discussing the work, Manuel Staggl from the Institute of Palaeontology at the University of Vienna stated:
“Cartilaginous fish, which include today’s sharks and rays, have existed on our planet for over 400 million years. They have survived several mass extinction events during this time, yet today, over a third of neoselachians (i.e. modern sharks and rays) are at risk of extinction. To develop effective conservation measures, we must understand which environmental factors have influenced their diversity in the past.These animals proved to be amazingly resilient and recovered quickly from the catastrophe.”
Staggl added, discussing the role of carbon dioxide:
“In a nutshell: moderate CO2 levels were beneficial for shark and ray biodiversity in the past, but excessive levels were harmful. This highlights the danger posed by current ocean acidification caused by human-induced climate change. In the past, sharks and rays had time to adapt to changes or migrate to other areas. However, the current changes are happening far too quickly. In this respect, the situation today is unprecedented.”
You can read the original research to find out more information.
