Oliver Thomas A.

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Oliver
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Thomas A.
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  • Article
    Heterotrophy of oceanic particulate organic matter elevates net ecosystem calcification
    (American Geophysical Union, 2019-08-22) Kealoha, Andrea K. ; Shamberger, Kathryn E. F. ; Reid, Emma C. ; Davis, Kristen A. ; Lentz, Steven J. ; Brainard, Russell E. ; Oliver, Thomas A. ; Rappe, Michael S. ; Roark, E. Brendan ; Rii, Yoshimi M.
    Coral reef calcification is expected to decline due to climate change stressors such as ocean acidification and warming. Projections of future coral reef health are based on our understanding of the environmental drivers that affect calcification and dissolution. One such driver that may impact coral reef health is heterotrophy of oceanic‐sourced particulate organic matter, but its link to calcification has not been directly investigated in the field. In this study, we estimated net ecosystem calcification and oceanic particulate organic carbon (POCoc) uptake across the Kāne'ohe Bay barrier reef in Hawai'i. We show that higher rates of POCoc uptake correspond to greater net ecosystem calcification rates, even under low aragonite saturation states (Ωar). Hence, reductions in offshore productivity may negatively impact coral reefs by decreasing the food supply required to sustain calcification. Alternatively, coral reefs that receive ample inputs of POCoc may maintain higher calcification rates, despite a global decline in Ωar.
  • Article
    Repeat bleaching of a central Pacific coral reef over the past six decades (1960–2016)
    (Nature Publishing Group, 2018-11-08) Barkley, Hannah C. ; Cohen, Anne L. ; Mollica, Nathaniel R. ; Brainard, Russell E. ; Rivera, Hanny E. ; DeCarlo, Thomas M. ; Lohmann, George P. ; Drenkard, Elizabeth J. ; Alpert, Alice ; Young, Charles W. ; Vargas-Ángel, Bernardo ; Lino, Kevin C. ; Oliver, Thomas A. ; Pietro, Kathryn R. ; Luu, Victoria
    The oceans are warming and coral reefs are bleaching with increased frequency and severity, fueling concerns for their survival through this century. Yet in the central equatorial Pacific, some of the world’s most productive reefs regularly experience extreme heat associated with El Niño. Here we use skeletal signatures preserved in long-lived corals on Jarvis Island to evaluate the coral community response to multiple successive heatwaves since 1960. By tracking skeletal stress band formation through the 2015-16 El Nino, which killed 95% of Jarvis corals, we validate their utility as proxies of bleaching severity and show that 2015-16 was not the first catastrophic bleaching event on Jarvis. Since 1960, eight severe (>30% bleaching) and two moderate (<30% bleaching) events occurred, each coinciding with El Niño. While the frequency and severity of bleaching on Jarvis did not increase over this time period, 2015–16 was unprecedented in magnitude. The trajectory of recovery of this historically resilient ecosystem will provide critical insights into the potential for coral reef resilience in a warming world.