Stacy A. Krueger-Hadfield

Associate Professor; Assistant Director, Eastern Shore Laboratory

Email: [[v|sakh]]
Phone: (757) 787-8105
Office: AC10, 40 Atlantic Avenue, Wachapreague
Section: Natural Resources
Unit: Eastern Shore Laboratory
Lab Website: {{}}

  • B.S., magna cum Laude, California State University Northridge, 2006
  • M.S., with honors, California State University Northridge, 2008
  • Ph.D., with highest honors, Université Pierre et Marie Curie Paris VI-Sorbonne Université (Station Biologique de Roscoff)
  • Ph.D., with highest honors, Pontificia Universidad Católica de Chile
Research Interests

I am an evolutionary ecologist, classically trained in phycology. My research program centers on resolving one of the great paradoxes in biology – the evolution of sex – in which we integrate approaches from population genetics, physiology, and population and community ecology in marine, freshwater, and alpine micro- and macroalgae, with the occasional invertebrate thrown in. The central thread of our research has direct implications for understanding biodiversity, transcending taxonomic designations. All organisms pass through different stages in their life cycle because of sex. These stages often differ profoundly in the number of cells and the arrangement of genetic information due to meiosis, recombination, and fertilization. When, where, and how these stages alternate is affected by genetic and phenotypic factors. Understanding these factors can help us understand the maintenance of eukaryotic biodiversity. Moreover, by focusing on the life cycle, we can compare diverse taxa from apicomplexans to oysters to algae. While theory predicts how sex evolves, there remains a dearth of empirical work confirming these predictions in nature. Marine macroalgae – our focal organismal group – are emerging commodities in the blue bioeconomy. Yet, we lack basic macroalgal biological knowledge, often readily available in other organisms of ecological or economic importance. This is compounded by the absence of macroalgal expertise in soft sediment habitats as compared to rocky shores – an acute issue in the Chesapeake where the last macroalgal species list was published more than 40 years ago. These gaps restrict the responsible development and management of algal resources, but also exacerbate our ability to forecast the consequences of climate change in important primary producers in this region.

Current Projects
2022-2024 National Fish and Wildlife Foundation Papahānaumokuākea Research and Conservation Fund - Management solutions to mitigate the spread of Chondria tumulosa in Papahānaumokuākea (#74235)
2022-2027 NSF Division of Environmental Biology Evolutionary Processes CAREER: At the convergence of life cycles and reproductive systems: insights into eukaryotic diversity (DEB-2141971)
2021-2024 NSF Division of Environmental Biology Evolutionary Processes Collaborative Research: EAGER: Developing tools to assess the evolutionary implications of partial clonality in alpine snow algae (DEB-2113745)
Select Publications

(full publication list – see or Google Scholar)

  • Schroeder DC, KM Schoenrock, TA McHugh, J Ray, SA Krueger-Hadfield (2023) Phaeovirus found in recovering Nereocystics leutkeana kelp forest community. Journal of Phycology 59: 818-821.
  • van Hees D, C Hanneman, S Paradis, A Camara, M Matsumoto, T Hamilton, SA Krueger-Hadfield, R Kodner (2023) Patchy and Pink: dynamics of a Chlainomonas sp. (Chalmydomonadales, Chlorophyta) algal bloom on Bagley Lake, North Cascades, WA. FEMS Microbiology Ecology 99: fiad106.
  • Krueger-Hadfield SA, AP Oetterer, LE Lees, JM Hoffman, EE Sotka, CJ Murren (2023) Phenology in a free-floating, non-native Gracilaria vermiculophylla population: ploidy ratios, reproductive state, and thallus size. Journal of Phycology 59: 926-938.
  • Borg M, SA Krueger-Hadfield, C Destombe, J Collén, A Lipinska, SM Coelho (2023) Red algae in the genomic era. New Phytologist 240: 471-488.
  • Lipinska AP*, SA Krueger-Hadfield*, O Godfory, S Dittami, L Ayres-Ostrock, G Bonthond, S Coelho, E Corre, G Cossard, C Destombe, S Faugeron, E Ficko-Blean, V Flores, L Guéguen, E Lavaut, A Le Bars, F Marchi, S Mauger, G Michel, P Potin, D Scornet, EE Sotka, F Weinberger, M de Oliveira, ML Guillemin, E Plastino, M Valero (2023) The Rhodoexplorer Platform for red algal genomics and whole-genome assemblies for several Gracilaria species. Genome Biology and Evolution 15: evad124.                        *equal co-authors
  • Heiser S, CD Amsler, S Stoeckel, JB McClintock, BJ Baker, SA Krueger-Hadfield (2023) Tetrasporophytic bias coupled with heterozygote deficiency in the Antarctic Plocamium sp. (Florideophyceae, Rhodophyta). Journal of Phycology 59:681-697.
  • Bonthond G, AK Neu, T Bayer, SA Krueger-Hadfield, S Künzel, F Weinberger (2023) Non-native hosts of an invasive seaweed holobiont have more stable microbial communities compared to native hosts in response to thermal stress. Ecology and Evolution 13: e9753.
  • Bonthond G, A Barilo, R Allen, M Cunliffe, SA Krueger-Hadfield (2022) Fungal endophytes vary by species, tissue type, and life cycle stage in intertidal macroalgae. Journal of Phycology 58: 330-342.
  • Albecker MA*, LGE Wilkins*, SA Krueger-Hadfield, SM Bashevkin, MW Hahn, MP Hare, H Kindsvater, MA Sewell, K Lotterhos, AM Reitzel (2021) Does a complex life cycle promote or constrain adaptation to environmental change? Genome-informed approaches and insights for characterizing selection across stages of a life cycle. Proceedings of the Royal Society B: Biological Sciences 288: 20212122.                                   *equal co-authors
  • Krueger-Hadfield SA, ML Guillemin, C Destombe, M Valero, S Stoeckel (2021) Exploring the genetic consequences of clonality in haplodiplontic taxa. Journal of Heredity 112: 92-107.
  • Stoeckel S, S Arnaud-Haond, SA Krueger-Hadfield (2021) The combined effect of haplodiplonty and partial clonality in population genetics. Journal of Heredity 112: 78-91.
  • Krueger-Hadfield SA, BA Flanagan, O Godfroy, KM Hill-Spanik, CC Nice, CJ Murren, AE Strand, EE Sotka (2021) Using RAD-seq to develop sex-linked markers in a haplodiplontic alga. Journal of Phycology 57: 279-294.
  • McCoy SJ, SA Krueger-Hadfield, N Mieszkowska (2020) Towards a macroalgal species conceptual framework. Journal of Phycology 56: 1404-1413.
  • Olsen KC, WH Ryan, AA Winn, ET Kosman, Moscoso JA, SA Krueger-Hadfield, SC Burgess, DB Carlon, RK Grosberg, S Kalisz, DR Levitan (2020) Inbreeding shapes the evolution of marine invertebrates. Evolution 74: 871-882.
  • Krueger-Hadfield SA (2020) What’s ploidy got to do with it? Understanding the evolutionary ecology of macroalgal invasions necessitates incorporating life cycle complexity. Evolutionary Applications 13: 486-499.