|
. | . |
|
by Staff Writers San Francisco CA (SPX) Mar 31, 2015
A 30-foot-long core sample of Pacific Ocean seafloor is changing what we know about ocean resiliency in the face of rapidly changing climate. A new study reports that marine ecosystems can take thousands, rather than hundreds, of years to recover from climate-related upheavals. The study's authors - including Peter Roopnarine, PhD, of the California Academy of Sciences - analyzed thousands of invertebrate fossils to show that ecosystem recovery from climate change and seawater deoxygenation might take place on a millennial scale. The revolutionary study is the first of its kind, and is published in the Early Edition of the journal PNAS. The scientific collaborative - led by Sarah Moffitt, PhD, from the UC Davis Bodega Marine Laboratory and Coastal and Marine Sciences Institute - analyzed more than 5,400 invertebrate fossils, from sea urchins to clams, within a sediment core from offshore Santa Barbara, California. "In this study, we used the past to forecast the future," says Roopnarine, Academy curator of invertebrate zoology and geology. "Tracing changes in marine biodiversity during historical episodes of warming and cooling tells us what might happen in years to come. We don't want to hear that ecosystems need thousands of years to recover from disruption, but it's critical that we understand the global need to combat modern climate impacts." The tube-like sediment core is a slice of ocean life as it existed between 3,400 and 16,100 years ago, and provides a before-and-after snapshot of what happened during the last major deglaciation - a time of abrupt climate warming, melting polar ice caps, and expansion of low oxygen zones in the ocean. The new study documents how long it has historically taken for ecosystems to begin recovery following dramatic shifts in climate.
'Complex' invertebrates "The complexity and diversity of a community depends on how much energy is available," says Roopnarine. "To truly understand the health of an ecosystem and the food webs within, we have to look at the simple and small as well as the complex. In this case, marine invertebrates give us a better understanding of the health of ecosystems as a whole." The study's all-important sediment core revealed an ancient history of abundant, diverse, and well-oxygenated seafloor ecosystems, followed by a period of oxygen loss and warming that seems to have triggered a rapid loss of biodiversity. The study reports that invertebrate fossils are nearly non-existent during times of lower-than-average oxygen levels. Moffitt emphasized the importance of using a large, 30-foot core sample from one portion of the seafloor, saying the team "cut it up like a cake" to analyze the full, unbroken record. In periods of fewer than 100 years, oceanic oxygen levels decreased between 0.5 and 1.5 mL/L. Sediment samples during these periods show that relatively minor oxygen fluctuations can result in dramatic changes for seafloor communities.
'New normal' of rapid climate change "Folks in Oregon and along the Gulf of Mexico are all-too-familiar with the devastating impacts of low-oxygen ocean conditions on local ecosystems and economies," says Roopnarine. "We must explore how ocean floor communities respond to upheaval as we adapt to a 'new normal' of rapid climate change. We humans have to think carefully about the planet we are leaving for future generations." The study's co-authors include UC Davis professor Tessa Hill from the Department of Earth and Planetary Sciences and Bodega Marine Laboratory and professor James Kennett from UC Santa Barbara Department of Earth Science.
Related Links California Academy of Sciences Water News - Science, Technology and Politics
|
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service. |