• ArtsandLectures twitter avatar
    Fascinating! #Sapiens + #HomoDeus author #YuvalNoahHarari predicts humankind’s future: https://t.co/5P25xtpyRQ via… https://t.co/TIAzFchgfI
    49 min 25 sec ago
  • ArtsandLectures twitter avatar
    RT @AshleyyySb: Only on Twitter to continue to absorb all insight and research from @DrSidMukherjee || Stoked to attend his lecture @Artsan
    1 hour 4 min ago
  • brenucsb twitter avatar
    Does location affect how pines react to climate change? Bren PhD student Ian McCullough shares answer #BrenPhDTalks https://t.co/6zVyQetm2t
    1 hour 10 min ago
  • UCSBgauchos twitter avatar
    Softball: Fifth-Inning Dooms Gauchos in 6-4 Loss to Purdue https://t.co/XWYKVl9UPx
    1 hour 11 min ago
  • UCSB_GradPost twitter avatar
    Register for 2017 Graduate Division Commencement before May 5! https://t.co/IDP1WGLGik #UCSB #ucsbgradpost
    1 hour 18 min ago
  • brenucsb twitter avatar
    Bren PhD student Jessica Perkins' research answers: "What Makes an #LCA Study Influential?" https://t.co/HatfwVTKV4 #BrenPhDTalks
    1 hour 19 min ago
  • brenucsb twitter avatar
    Runsheng Song shares strategies to estimate chemicals' life cycle inventories with little data #BrenPhDTalks https://t.co/gUsRney8nC #LCI
    1 hour 30 min ago
  • brenucsb twitter avatar
    #BrenPhDTalks: Bren PhD student Ying Wang looks at nanomaterial accumulation in soybeans & nitrogen-fixing bacteria https://t.co/85xiy6EmAY
    1 hour 40 min ago
  • brenucsb twitter avatar
    Bren PhD student Yuwei Qin uses US potato production to show how to model marginal production in #LCA https://t.co/jDyW0Fkzbx #BrenPhDTalks
    1 hour 49 min ago
  • brenucsb twitter avatar
    Bren PhD student Chris Heckman's research shows how soil water storage eases #climate change effects https://t.co/cflpEuiAmV #BrenPhDTalks
    2 hours 8 sec ago
  • brenucsb twitter avatar
    Bren PhD student Niklas Griessbaum proposes ways to improve data citation with big data https://t.co/74ETLON0N2 #BrenPhDTalks
    2 hours 10 min ago
  • brenucsb twitter avatar
    Bren PhD student Mengya Tao models the release of #chemicals in consumer products w limited data https://t.co/FO73hy4Zjn #BrenPhDTalks
    2 hours 19 min ago
  • brenucsb twitter avatar
    Bren PhD student Caroline Vignardi on how pesticides w/copper-based nanoparticles affect aquatic life #BrenPhDTalks https://t.co/ys5p48wexI
    2 hours 40 min ago
  • brenucsb twitter avatar
    Most fish stocks are either fully or overexploited: Bren PhD student Julie Lawson proposes solutions #BrenPhDTalks https://t.co/ycgxS8HCde
    2 hours 45 min ago
  • brenucsb twitter avatar
    Bren PhD student Elizabeth Hiroyasu shares effect of message framing on invasive species policy & mgmt https://t.co/c2Yvj4s38Q #BrenPhDTalks
    3 hours 2 sec ago

Sea Change

James Kennett and colleagues use a sediment core to examine seafloor ecosystem biodiversity in response to past abrupt climate changes
Monday, March 30, 2015 - 12:00
Santa Barbara, CA

R:V Melville.jpg

R/V Melville

The Santa Barbara Basin sediment core was collected aboard the now retired R/V Melville.

Photo Credit: 

Sarah Moffitt

Kennett SB Basin.jpg

James Kennett

Behind James Kennett is the Santa Barbara Basin where the core sample was extracted.

Photo Credit: 

Sonia Fernandez

Sarah Moffitt_MED.jpg

Sarah Moffitt

Lead author Sarah Moffitt, a postdoctoral scholar at UC Davis, at work in the lab. 

Photo Credit: 

WAYNE FREEDMAN

With one of the highest-quality climate and environmental archives in the world’s oceans, the Santa Barbara Basin presents the ideal natural laboratory for researchers studying the global climate record on a variety of time scales, from last year to a million years ago. That’s according to UC Santa Barbara geologist James Kennett.

Exploring this data-rich area off the coast of Southern California, Kennett and his colleagues at UC Davis and the San Francisco-based California Academy of Sciences found that abrupt climate changes caused small decreases in seawater oxygenation that in turn led to extensive seafloor ecosystem reorganizations. What’s more, recovery from these reorganizations took up to 1,000 years.

Their study, which appears today in the online Early Edition of the Proceedings of the National Academy of Sciences, is the first to quantitatively examine broad ecosystem responses in the deep-sea sediment record.

“We were surprised to learn that this microfossil record is richer and more useful than first expected,” said co-author Kennett, UCSB professor emeritus of earth and marine science. “As a result, we were able to test the response time of different members of the bottom-dwelling ecosystem to both abrupt warming and cooling episodes. We were also surprised to discover just how long some took to recover.”

The research team analyzed more than 5,400 invertebrate microfossils — including sea urchins, clams, snails and crustaceans — from the offshore Santa Barbara sample. The sediment core — essentially a tube of material that covers a period between 3,400 and 16,100 years ago — provided a before-and-after snapshot of what happened during the global warming that occurred at the end of the last glacial period. This was 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 took for ecosystems to begin the process of recovering from such a dramatic episode of climate change.

“These past events show us how sensitive ecosystems are to changes in Earth’s climate; it commits us to thousands of years of recovery,” said lead author Sarah Moffitt, a postdoctoral scholar at UC Davis in its Bodega Marine Laboratory and its Coastal and Marine Sciences Institute.

“Our analysis demonstrates that ocean sediments harbor metazoan fossil material that can be used to reconstruct the response of seafloor biodiversity to global-scale climate events,” Kennett explained. “We show that the last deglaciation — the most recent episode of climate warming — was accompanied by abrupt reorganizations of continental margin seafloor ecosystems through expansions and contractions of the subsurface low-oxygen zones.”

The history lesson told by the sediment core is one of initially abundant, diverse and well-oxygenated seafloor ecosystems, followed by a period of warming and oxygen loss in the oceans and then by a rapid loss of diversity. In fact, microfossils nearly disappeared from the record during those times of low oxygen.

The researchers found that oceanic oxygen levels fell by between 0.5 and 1.5 mL/L over a period of less than 100 years, demonstrating that relatively minor changes in oxygen levels could result in dramatic shifts and reorganizations for seafloor communities. Kennett noted that these results suggest that future global climate change may result in ecosystem-level effects with millennial-scale recovery periods.

“It shows us what we’re doing now is a long-term shift; there’s not a recovery we have to look forward to in my lifetime or my grandchildren’s lifetime,” said Moffitt. “It’s a gritty reality we need to face as scientists and people who care about the natural world and who make decisions about the natural world.”

The research was funded by the National Science Foundation as well as the University of California Multicampus Research Programs and Initiatives.

Contact Info: 

Julie Cohen
julie.cohen@ucsb.edu
(805) 893-7220

Topics: