Jordan Coelho
Ph.D. Candidate, USC Marine & Environmental Biology

Pangenomics identifies the enrichment of
polyphenol metabolism among marine SAR116 bacteria

Abstract: Marine dissolved organic matter (DOM) is a nebulous pool of carbon that is both produced by and altered by marine microbes. Although analytical chemistry has profoundly advanced our knowledge of the chemical composition of the DOM pool, a central challenge in marine biogeochemistry is to determine which compounds are produced, consumed, or exchanged by microorganisms. Advancements in microbial genomics and pathway annotation have enabled large-scale metabolic reconstructions that now facilitate microbially-informed predictions about significant substrates within the DOM pool. Here, we leveraged pangenomics of 349 SAR116 genomes to identify diversified metabolisms and putative interactions with the DOM pool. SAR116 are important because of their abundance, cosmopolitan distribution, and diversity throughout the global oceans. Through SAR116 metabolic reconstruction, including profiling SAR116 genomes through a new annotation package, CAMPER (Curated Annotations for Microbial Polyphenol Enzymes and Reactions), we identified that SAR116 genomes are enriched in genes for the degradation of complex and recalcitrant aromatic and polyphenolic compounds. Polyphenols are typically associated with terrestrial systems due to their association with plant physiology, however the significant genetic evidence of their degradation among SAR116 genomes highlights that polyphenols are likely ecologically significant among marine systems and require further attention.

Jenna Dilworth
Ph.D. Candidate, USC Marine & Environmental Biology

Does morphological plasticity trade off
with thermal tolerance in Acropora cervicornis?

Abstract: The staghorn coral, Acropora cervicornis, has become central to many Caribbean restoration efforts due to its fast-growing, branching morphology. While survival and growth of different genotypes of A. cervicornis after outplanting to the reef is highly variable, morphological plasticity, or the ability of a single genotype to show different growth phenotypes depending on their environment, appears to be adaptive. Under ambient conditions, this morphological plasticity does not trade off with growth or survival in the field. However, calcification is an energetically expensive process and could be associated with physiological costs under stress. As marine heatwaves triggering mass bleaching events become more common and severe as a result of climate change, understanding potential tradeoffs between morphological plasticity and survival during acute stress events is key.To better understand how morphological plasticity may trade off with thermal tolerance, we outplanted 10 replicates of 10 genotypes of A. cervicornis known to have varying degrees of morphological plasticity to two environmentally distinct reef sites in the Lower Florida Keys. After outplanting in October 2022, these outplants experienced ambient conditions for 9 months, during which fine-scale growth metrics were monitored via 3D-photogrammetry. Beginning in July 2023, the outplants experienced an extreme thermal stress event during which tissue samples and color score photos were taken. Using integrated metrics of bleaching stress and mortality, we show that growth and morphological plasticity under ambient conditions have a negative relationship with responses to thermal stress, indicating that morphological plasticity may not be adaptive in all contexts.

Tuesday, January 28
11:30 AM
AHF 153 (Torrey Webb Room)