Publication Date:
2022-05-25
Description:
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Applied Ocean Science & Engineering at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2019.
Description:
Under global climate change, our oceans are warming at an unprecedented rate. Increased temperatures represent a severe source of stress for many marine organisms. This thesis aims to understand how corals and anemones respond to changing temperatures across different timescales and investigates mechanisms that can facilitate persistence in light of environmental
change, from selection and adaptation across generations to phenotypic plasticity within a single individual’s lifespan. In this context, I explore three case studies of thermal stress in corals and anemones. I begin with massive Porites lobata corals from the central Pacific. Here, reefs that are most affected by El Niño, such as Jarvis and the northeast Phoenix Islands maintain genetic
diversity indicating recruitment from nearby reefs may occur. Yet, they show significant genetic differentiation (FST) from farther areas, suggesting this dispersal may be limited. Thermal variability in this region may also favor plasticity over adaptation, as we do not find differences in bleaching histories among genetic groups. Next, I investigate genetic connectivity and adaptation to chronically elevated temperatures across a natural temperature gradient within the Palauan archipelago. Combining genetic data and historical growth measurements from coral cores, I find that Palau’s warmest reefs harbor unique genetic subpopulations of Porites lobata and find evidence for a genetic basis of their higher thermal tolerance. Lastly, I explore if parents can modulate parental effects to increase the thermal tolerance of their offspring over short time scales, using the estuarine anemone Nematostella vectensis. Indeed, I find parents exposed to increased temperatures quickly produce more thermally tolerant larvae. In fact, offspring from these Massachusetts parents show thermal thresholds that are indistinguishable from more southern populations. This thesis highlights the ability and potential of corals and anemones to persist under variable conditions over different timescales. Nevertheless, a compelling effort to reduce rates of warming worldwide will be imperative to the survival and integrity of key marine ecosystems such as coral reefs.
Description:
Funding for this research came from the National Science Foundation (Awards OCE-1537338, OCE-1605365, OCE-1220529, and OCE-1031971), the Link Foundation, Bermuda Institute of Ocean Sciences Grants-in-Aid, the Tiffany & Co. Foundation, the Nature Conservancy, the Dalio Foundation, Inc., through the Dalio Explore Fund, and Ray Dalio through the WHOI Access to the Sea Fund, all to Anne Cohen; and a Gordon and Betty Moore Foundation grant (#4033) to Ann Tarrant.
Funding to H. Rivera was provided by the Charles M. Vest Presidential Fellowship, the National Defense Science and Engineering Graduate Fellowship, American Association for University Women’s American Dissertation Fellowship, MIT’s Martin Family
Foundation Fellowship, the Gates Millennium Scholars Program, WHOI’s Coastal Ocean Institute Grants, WHOI’s Grassler Family Foundation Grants, WHOI’s Ocean Ventures Fund, the MIT-BIOS Fund, and the MIT-WHOI Academic Programs Office.
Keywords:
Global warming
;
Corals
;
Anemones
;
Marine organisms
;
Thermal stresses
;
Marine ecology
Repository Name:
Woods Hole Open Access Server
Type:
Thesis
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