Bio


I am a 5th year PhD Candidate at Stanford University under the mentorship of Dr. Stephen Palumbi, based at Hopkins Marine Station in Monterey, CA. I am generally interested in understanding how organisms function under normal and perturbed environmental conditions and in intense and variable environments. I currently study coral thermal resilience, looking at mechanistic links between heat resistance and recoverability. I primarily use genetics, genomics, and physiological assays to study resilience.

Education & Certifications


  • B.A., Harvard College, Organismic and Evolutionary Biology, secondary (minor) in English (2016)

Current Research and Scholarly Interests


I am generally interested in better understanding how cnidarians (e.g. corals, sea anemones, and jellyfish) are able to function under normal and high stress conditions. Currently, I am primarily using genomics, genetics, and physiology techniques and applications to study climate change resilience in coral reefs. My current research focus is on not just identifying, but also challenging, what makes "strong" corals by studying both coral thermal resistance and recovery.

All Publications


  • Widespread variation in heat tolerance and symbiont load are associated with growth tradeoffs in the coral Acropora hyacinthus in Palau. eLife Cornwell, B., Armstrong, K., Walker, N. S., Lippert, M., Nestor, V., Golbuu, Y., Palumbi, S. R. 2021; 10

    Abstract

    Climate change is dramatically changing ecosystem composition and productivity, leading scientists to consider the best approaches to map natural resistance and foster ecosystem resilience in the face of these changes. Here we present results from a large-scale experimental assessment of coral bleaching resistance, a critical trait for coral population persistence as oceans warm, in 221 colonies of the coral Acropora hyacinthus across 37 reefs in Palau. We find that bleaching resistant individuals inhabit most reefs but are found more often in warmer microhabitats. Our survey also found wide variation in symbiont concentration among colonies, and that colonies with lower symbiont load tended to be more bleaching resistant. By contrast, our data show that low symbiont load comes at the cost of lower growth rate, a tradeoff that may operate widely among corals across environments. Corals with high bleaching resistance have been suggested as a source for habitat restoration or selective breeding in order to increase coral reef resilience to climate change. Our maps show where these resilience corals can be found, but the existence of tradeoffs with heat resistance may suggest caution in unilateral use of this one trait in restoration.

    View details for DOI 10.7554/eLife.64790

    View details for PubMedID 34387190

  • Differential Gene Expression during Substrate Probing in Larvae of the Caribbean Coral Porites astreoides. Molecular ecology Walker, N. S., Fernandez, R., Sneed, J. M., Paul, V. J., Giribet, G., Combosch, D. 2019

    Abstract

    The transition from larva to adult is a critical step in the life history strategy of most marine animals. However, the genetic basis of this life history change remains poorly understood in many taxa, including most coral species. Recent evidence suggests that coral planula larvae undergo significant changes at the physiological and molecular levels throughout development. To investigate this, we characterized differential gene expression (DGE) during the transition from planula to adult polyp in the abundant Caribbean reef-building coral Porites astreoides: i.e., from non-probing to actively substrate-probing larva, a stage required for colony initiation. This period is crucial for the coral, because it demonstrates preparedness to locate appropriate substrata for settlement based on vital environmental cues. Through RNA-Seq we identified 860 differentially expressed holobiont genes between probing and non-probing larvae (P ≤ 0.01), the majority of which were upregulated in probing larvae. Surprisingly, differentially expressed genes of endosymbiotic dinoflagellate origin greatly outnumbered coral genes, compared to a nearly 1:1 ratio of coral-to-dinoflagellate gene representation in the holobiont transcriptome. This unanticipated result suggests that dinoflagellate endosymbionts may play a significant role in the transition from non-probing to probing behavior in dinoflagellate-rich larvae. Putative holobiont genes were largely involved in protein and nucleotide binding, metabolism, and transport. Genes were also linked to environment sensing and response and integral signaling pathways. Our results thus provide detailed insight into molecular changes prior to larval settlement and highlight the complex physiological and biochemical changes that occur in early transition stages from pelagic to benthic stages in corals, and perhaps more importantly, in their endosymbionts.

    View details for DOI 10.1111/mec.15265

    View details for PubMedID 31596993