About

Sarah Haley is an Associate Professor in the Department of History at Columbia University. She earned her Ph.D. from Yale University in 2010 and her B.A. from Vassar College in 2001. Her research interests include the history of gender and women, carceral history, Black feminist history and theory, prison abolition, and feminist archival methods. Haley is the author of 'No Mercy Here: Gender, Punishment, and the Making of Jim Crow Modernity,' published by the University of North Carolina Press in 2016, which received awards from multiple organizations including the Association of Black Women Historians, the American Historical Association, and the National Women’s Studies Association. Her work was also selected for the National Book Foundation’s 2020-2021 Literature for Justice Reading List. She has co-edited a special issue of Souls: A Critical Journal of Black Politics, Culture, and Society and has published in various journals such as Signs, The Journal of African American History, GLQ, and Women & Performance. Currently, she is working on a book titled 'The Carceral Interior: A Black Feminist Study of American Punishment, 1966-2016.' Prior to her academic career, Haley worked as a paralegal, an organizer with the hospitality workers’ union UNITE HERE, and was the founding director of the Black Feminism Initiative at UCLA.

Research topics

• Biology
• Ecology
• Geology
• Oceanography

Selected publications

• Quantification of dissolved carboxylate- and phosphate-containing marine metabolites via aniline derivatization with liquid chromatography-tandem mass spectrometry

  ChemRxiv · 2026-03-27

  articleOpen access

  Metabolites dissolved in seawater are important analytical targets that act as substrates for microbial growth, mediate microbial interactions, and connect microbes to global elemental cycles. However, measuring dissolved metabolites is challenging due to their low concentrations (pM – nM) within a complex and high salt matrix (mM). Dissolved metabolites are often extracted from seawater prior to analysis, but standard extraction methods poorly capture polar metabolites, which have a higher affinity for seawater than typical extraction resins. To address these challenges, we optimized a method for derivatizing carboxylate- and phosphate-containing metabolites using aniline and 1-ethyl-2-(3-dimethylaminopropyl)carbodiimide (EDC), followed by solid-phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics. Aniline derivatization reduced sample volume requirements by almost three orders of magnitude, improved extraction efficiency and chromatographic separation, and enhanced quantification with analyte-paired internal standards created using isotopically labeled aniline. With this method, we measured a suite of 47 dissolved metabolites with picomolar to nanomolar limits of detection, 19 of which cannot be measured in seawater by pre-existing extraction or derivatization methods. Where comparisons are possible, aniline derivatization yields comparable results to previously measured values. Finally, we tested this method by quantifying dissolved metabolites in two cultures of marine phytoplankton and in field samples from coastal and open ocean sites, demonstrating new possibilities for characterizing the role of marine microbes and their metabolites in global carbon cycling.

  PublisherOA PDFDOI

• Characterization of phytoplankton-excreted metabolites mediating carbon flux through the surface ocean

  Proceedings of the National Academy of Sciences · 2026-03-17

  articleOpen access

  The marine labile dissolved organic carbon (DOC) pool is a dynamic reservoir of thousands of molecules that cycles approximately one-quarter of Earth’s primary production within days to weeks. After excretion by phytoplankton and other microbes, metabolites are rapidly consumed, resulting in low standing concentrations (picomolar to low nanomolar). Despite the decades-long search for labile DOC sources and molecular identities, marine phytoplankton exometabolomes are not well characterized, largely due to difficulties in measuring small polar molecules in saline water. Here, we profiled the exometabolomes of six axenic phytoplankton species representing key functional groups including a diatom ( Thalassiosira pseudonana CCMP1335), a picoeukaryote ( Micromonas commoda RCC299), a coccolithophore ( Gephyrocapsa huxleyi CCMP371), a diazotrophic cyanobacterium ( Crocosphaera watsonii WH8501), and two picocyanobacteria ( Prochlorococcus marinus MIT9301 and Synechococcus WH8102). From these cultures, we quantified 56 amine- and alcohol-containing exometabolites representing 11 compound classes which in sum comprised up to 23.4% of phytoplankton-excreted DOC. We estimated that these phytoplankton-derived exometabolites could supply up to 5% of the daily carbon quota of the dominant heterotrophic bacterium SAR11 in the surface ocean. Substantial variations in exometabolite identity and concentration across phytoplankton taxa underscore taxonomic diversity as a key driver in the supply and composition of labile DOC. This taxonomic variation predicts geographic and seasonal differences in the distribution of marine dissolved metabolites that underpin the cycling of labile DOC back to carbon dioxide (CO 2 ). Overall, our work suggests that phytoplankton exometabolites are key chemical currencies that mediate significant carbon fluxes within the ocean’s carbon cycle.

  PublisherOA PDFDOI

• Characterization of Phytoplankton-Excreted Metabolites Mediating Carbon Flux through the Surface Ocean

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-11-05

  preprintOpen access

  Abstract The marine labile dissolved organic carbon (DOC) pool is a dynamic reservoir of thousands of molecules that cycles approximately one-quarter of Earth’s primary production within days to weeks. After excretion by phytoplankton and other microbes, metabolites are rapidly consumed, resulting in low standing concentrations (picomolar to low nanomolar). Despite the decades-long search for labile DOC sources and molecular identities, marine phytoplankton exometabolomes are not well characterized, largely due to difficulties in measuring small polar molecules in saline water. Here, we profiled the exometabolomes of six axenic phytoplankton species representing key functional groups including a diatom ( Thalassiosira pseudonana CCMP1335), a picoeukaryote ( Micromonas commoda RCC299), a coccolithophore ( Gephyrocapsa huxleyi CCMP371), a diazotrophic cyanobacterium ( Crocosphaera watsonii WH8501), and two picocyanobacteria ( Prochlorococcus marinus MIT 9301 and Synechococcus WH8102). From these cultures, we quantified 56 amine- and alcohol-containing exometabolites representing 11 compound classes which in sum comprised up to 23.4% of phytoplankton-excreted DOC. We estimated that these phytoplankton-derived exometabolites could supply up to 5% of the daily carbon quota of the dominant heterotrophic bacterium SAR11 in the surface ocean. Substantial variations in exometabolite identity and concentration across phytoplankton taxa underscore taxonomic diversity as a key driver in the supply and composition of labile DOC. This taxonomic variation predicts geographic and seasonal differences in the distribution of marine dissolved metabolites that underpin the cycling of labile DOC back to CO 2 . Overall, our work suggests that phytoplankton exometabolites are key chemical currencies that mediate significant carbon fluxes within the ocean’s carbon cycle. Significance Statement Phytoplankton exometabolites are key components of the marine labile dissolved organic carbon (DOC) pool, which drives major a fraction of the oceanic carbon flux. Yet, their composition and flux are poorly constrained. Leveraging new methods, we quantified amine- and alcohol-containing exometabolites in diverse phytoplankton and found they varied taxonomically. These exometabolites accounted for up to 23.4% of excreted DOC, potentially supporting a sizable fraction of the global heterotrophic growth. Integrating our results with ecological models suggest that exometabolite composition varies geographically and seasonally in response to changing phytoplankton community structures. Our findings illuminate the long-standing “black box” of labile DOC and link taxonomic diversity to the chemical currencies underpinning the microbe-metabolite networks at the heart of the marine carbon cycle.

  PublisherOA PDFDOI

• Intraspecific Diversity in Thermal Performance Determines Phytoplankton Ecological Niche

  Ecology Letters · 2025-01-01 · 11 citations

  articleOpen access

  ABSTRACT Temperature has a primary influence on phytoplankton physiology and ecology. We grew 12 strains of Gephyrocapsa huxleyi isolated from different‐temperature regions for ~45 generations (2 months) and characterised acclimated thermal response curves across a temperature range. Even with similar temperature optima and overlapping cell size, strain growth rates varied between 0.45 and 1 day −1 . Thermal niche widths varied from 16.7°C to 24.8°C, suggesting that strains use distinct thermal response mechanisms. We investigated the implications of this thermal intraspecific diversity using an ocean ecosystem simulation resolving phytoplankton thermal phenotypes. Model analogues of thermal ‘generalists’ and ‘specialists’ resulted in a distinctive global biogeography of thermal niche widths with a nonlinear latitudinal pattern. We leveraged model output to predict ranges of the 12 lab‐reared strains and demonstrated how this approach could broadly refine geographic range predictions. Our combination of observations and modelled biogeography highlights the capacity of diverse groups to survive temperature shifts.

  PublisherOA PDFDOI

• Nitrogen and phosphorus differentially control marine biomass production and stoichiometry

  Nature Communications · 2025-07-01 · 6 citations

  articleOpen access

  Globally averaged, surface particulate nitrogen and phosphorus approximate the 16:1, N:P “Redfield ratio.” In observations, N:P ratios vary latitudinally at ranges attributable to both phytoplankton community composition and physiological acclimation, but their relative contributions to the N:P ratio remain unclear. Here, results from a 29-day mesocosm experiment highlight how inorganic nitrogen and/or phosphorus nutrient supply can affect the bulk particle stoichiometry of a North Pacific Subtropical Gyre plankton community. Nitrogen additions, with and without phosphorus, increase total productivity and diatom abundance, whereas treatments with just phosphorus additions remain similar to the no-nutrient addition control. Continual nitrogen supply without phosphorus results in higher particulate N:P ratios than expected based on the phytoplankton community present. Several P-stress markers identified in those treatments highlight the importance of acclimation in extending particulate N:P ratios beyond the Redfield ratio. Phytoplankton’s ability to maintain growth under P-stress conditions has implications for global carbon cycling. Mesocosm experiments revealed that both phytoplankton community composition and cellular acclimation influence marine particulate C:N:P ratios, with community shifts more sensitive to nitrogen supply and acclimation to the nutrient N:P supply ratio

  PublisherOA PDFDOI

• <i>Trichodesmium</i> metaproteomes reflect the differential influence of resource availability across ocean regions

  The ISME Journal · 2025-01-01

  articleOpen access

  The diazotroph Trichodesmium is an important contributor to marine dinitrogen fixation, supplying nitrogen to phytoplankton in typically nitrogen-limited ocean regions. Identifying how iron and phosphorus influence Trichodesmium activity and biogeography is an ongoing area of study, where predicting patterns of resource stress is complicated by the uncertain bioavailability of organically complexed iron and phosphorus. Here, a comparison of 26 metaproteomes from picked Trichodesmium colonies identified significantly different patterns between three ocean regions: the western tropical South Pacific, the western North Atlantic, and the North Pacific Subtropical Gyre. Trichodesmium KEGG submodule signals differed significantly across regions, and vector fitting showed that dissolved iron, dissolved inorganic phosphorus, and temperature significantly correlated with regional metaproteome patterns. Patterns of iron and phosphorus stress marker proteins previously validated in culture studies showed significant enrichment of a phosphorus stress signal in the western North Atlantic and an iron stress signal in the North Pacific. Populations in the western tropical South Pacific appeared to modulate their proteomes in response to both dissolved iron and dissolved inorganic phosphorus bioavailability, with significant enrichment of iron and phosphorus stress marker proteins, concomitant proteome restructuring, and significant decreases in the relative abundance of the dinitrogen fixation protein, NifH. These signals recapitulate established regional patterns of resource stress on phytoplankton communities released from nitrogen stress. Evaluating community stress patterns may therefore predict resource controls on diazotroph biogeography. These data highlight how Trichodesmium modulates its metabolism in the field and provide an opportunity to more accurately constrain controls on Trichodesmium biogeography and dinitrogen fixation.

  PublisherOA PDFDOI

• A tale of two nutrients: how nitrogen and phosphorus differentially control marine biomass production and stoichiometry

  Research Square · 2024-05-06

  preprintOpen access
  PublisherOA PDFDOI

• Author response for "Intraspecific Diversity in Thermal Performance Determines Phytoplankton Ecological Niche"

  2024-08-05

  peer-review
  PublisherDOI

• Author response for "Intraspecific Diversity in Thermal Performance Determines Phytoplankton Ecological Niche"

  2024-11-04

  peer-review
  PublisherDOI

• Intraspecific diversity in thermal performance determines phytoplankton ecological niche

  bioRxiv (Cold Spring Harbor Laboratory) · 2024-02-15 · 4 citations

  preprintOpen access

  Abstract Temperature has a primary influence on phytoplankton physiology and affects biodiversity and ecology. To examine how intraspecific diversity and temperature shape plankton populations, we grew 12 strains of the ecologically-important coccolithophore Gephyrocapsa huxleyi isolated from regions of different temperature for ∼45 generations (2 months), each at 6-8 temperatures, and characterized the acclimated thermal response curve of each strain. Even with virtually identical temperature optima and overlapping cell size, strain growth rates varied between 0.45 and 1 day -1 . While some thermal curves were effectively symmetrical, others had more slowly declining growth rates above the “thermal optimum,” and thermal niche widths varied between 16.7 and 24.8 °C. This suggests that different strains use distinct thermal response mechanisms. We investigated the ecological implications of such intraspecific diversity on thermal response using an ocean ecosystem simulation resolving distinct phytoplankton thermal phenotypes. Resolving model analogs of thermal “generalists” and “specialists” (similar to those observed in G. huxleyi) resulted in a distinctive global biogeography of preferred thermal niche widths with a nonlinear latitudinal pattern. We leveraged the model output to predict the ranges of the 12 strains we studied in the laboratory and demonstrated how this approach could refine predictions of phytoplankton thermal geographic range in situ . Our combination of observed thermal traits and modeled biogeography highlights the capacity of diverse groups to persist through temperature shifts. Significance Statement Intraspecific diversity in the phytoplankton may underpin their distribution. We show that within a single coccolithophore species, thermal response curves have diverse trait parameters. For example, many strains had a variable range of temperatures at which they could survive (thermal niche width). Adding this thermal niche width diversity to an ecosystem model simulation impacted phytoplankton coexistence and overall biomass. These observations show that thermal niche width is a gap in phytoplankton representation in ecosystem models that impacts modeled phytoplankton biogeography and concomitant carbon cycle dynamics. Including thermal tolerance is crucial to predictive modeling as ocean temperature dynamics change.

  PublisherOA PDFDOI

Frequent coauthors

• Sonya T. Dyhrman

  Lamont-Doherty Earth Observatory

  99 shared

• Kyle R. Frischkorn

  Inserm

  22 shared

• Harriet Alexander

  22 shared

• Mónica Rouco

  Columbia University

  20 shared

• Matthew J. Harke

  Gloucester Marine Genomics Institute

  18 shared

• Gwenn Hennon

  University of Alaska Fairbanks

  14 shared

• Subhajit Basu

  Interuniversity Institute for Marine Sciences in Eilat

  12 shared

• Rene Boiteau

  Oregon State University

  12 shared

Education

• Ph.D.

  Yale University

  2010

• B.A.

  Vassar College

  2001

Awards & honors

• Awards from the Association of Black Women Historians
• Awards from the American Historical Association
• Awards from the American Studies Association
• Awards from the National Women’s Studies Association
• Awards from the Southern Association for Women Historians