Ancient fish teeth and scales preserved in deep-sea mud showed an 85 million-year decline in shark populations, with a sudden drop to “modern” levels nearly 20 million years ago. Scripps Institution of Oceanography at UC San Diego graduate student Elizabeth Sibert will discuss these new findings during a presentation (PP31E-08 • Wednesday, Dec. 16, 9:45 a.m. • Moscone West 2010) at the American Geophysical Union (AGU) 2015 Fall Meeting.
Sibert will present an analysis of fossil fish teeth and shark scales, called ichthyoliths, from sediment cores taken from the North Pacific and South Pacific Ocean gyres that showed the ratio of sharks and fishes have undergone major changes over the past 85 million years. The study found that the ratio of sharks and fishes was stable for tens of millions of years before being reset 66 million years ago during the Cretaceous-Paleogene mass extinction event, and again nearly 20 million years ago to modern day levels. Neither of these shifts was marked by a major climate change event despite many that happen in the intervals between these periods.
“Our results showed that climate change doesn't seem to be a major driver for restructuring the ecosystem, it just changes how much the ecosystem ‘makes,’” said Sibert.
PRESENTATION: PP31E-08 • Wednesday, Dec. 16, 9:45 a.m. Moscone West 2010 “85 MILLION YEARS OF PELAGIC ECOSYSTEM EVOLUTION: PACIFIC OCEAN DEEP-SEA ICHTHYOLITH RECORDS REVEAL FISH COMMUNITY DYNAMICS AND A LONG-TERM DECLINE IN SHARKS”
Scripps Institution of Oceanography at the University of California San Diego, is one of the oldest, largest, and most important centers for global science research and education in the world. Now in its second century of discovery, the scientific scope of the institution has grown to include biological, physical, chemical, geological, geophysical, and atmospheric studies of the earth as a system. Hundreds of research programs covering a wide range of scientific areas are under way today on every continent and in every ocean. The institution has a staff of more than 1,400 and annual expenditures of approximately $195 million from federal, state, and private sources. Scripps operates oceanographic research vessels recognized worldwide for their outstanding capabilities. Equipped with innovative instruments for ocean exploration, these ships constitute mobile laboratories and observatories that serve students and researchers from institutions throughout the world. Birch Aquarium at Scripps serves as the interpretive center of the institution and showcases Scripps research and a diverse array of marine life through exhibits and programming for more than 430,000 visitors each year. Learn more at scripps.ucsd.edu and follow us at Facebook, Twitter, and Instagram.
About UC San Diego
At the University of California San Diego, we constantly push boundaries and challenge expectations. Established in 1960, UC San Diego has been shaped by exceptional scholars who aren’t afraid to take risks and redefine conventional wisdom. Today, as one of the top 15 research universities in the world, we are driving innovation and change to advance society, propel economic growth, and make our world a better place. Learn more at www.ucsd.edu.