Maggie Johnson, Ph.D.


Assistant Professor of Marine Science

Research Interests

Dr. Maggie Johnson is an Assistant Professor of Marine Science in the Red Sea Research Center. Prof. Johnson's research is at the intersection of coral reef ecology, global change biology, and phycology. Broadly, her research interests are centered on the impacts of environmental change on coral reef ecosystems. She uses a combination of field and laboratory based approaches to 1) evaluate and monitor the structure and function of coral reef ecosystems, 2) quantify inherent natural heterogeneity in key environmental parameters including temperature, dissolved oxygen, and pH , 3) explore the implications of environmental variability for ecophysiology of coral reef primary producers, 4) and determine the implications of local and global environmental change for these foundational coral reef taxa.

Prof. Johnson uses calcifying reef algae as model taxa to identify and monitor coral reef ecosystem responses in an era of rapid environmental change. While her research involves taxa ranging from fleshy algae to corals, she primarily focuses on calcifying algae - particularly crustose coralline algae. She studies a variety of processes of environmental change in nature and in the lab, and typically focuses on ocean acidification, ocean deoxygenation, and warming.

Selected Publications

  • Rapid ecosystem-scale consequences of acute deoxygenation on a Caribbean coral reef. MD Johnson, JS Scott, M Leray, N Lucey, LM Rodriguez Bravo, W Wied, AH Altieri. Nature Communications, 12: 4522, (2021)
  • Differential susceptibility of reef-building corals to deoxygenation reveals remarkable hypoxia tolerance. MD Johnson, SD Swaminathan, EN Nixon, V Paul, AH Altieri. Scientific Reports,11: 23168, (2021)
  • Environmental legacy effects and acclimatization of a crustose coralline alga to ocean acidification. MD Johnson, LM Rodriguez Bravo, N Lucey, AH Altieri. Climate Change Ecology, 100016, (2021)
  • Resilience of tropical ecosystems to ocean deoxygenation. AH, MD Johnson, SD Swaminathan, H Nelson, K Gedan (2021) Trends in Ecology and Evolution, (2021)
  • Ecophysiology of coral reef primary producers across an upwelling gradient in the tropical central Pacific. MD Johnson, MD Fox, ELA Kelly, B Zgliczynski, SA Sandin, JE Smith. Plos One, 15: 2 (2020)
  • pH variability exacerbates effects of ocean acidification on a Caribbean crustose coralline alga. MD Johnson, LM Rodriguez, SE O'Connor, NF Varley, AH Altieri. Frontiers in Marine Science, 6: 150 (2019).
  • Diel population and functional synchrony of microbial communities on coral reefs. Wegley Kelly, AF Haas, CE Nelson, D Naliboff, S Calhoun, CA Carlson, RA Edwards, MD Fox, M Hatay, MD Johnson, YW Lim, S Macherla, ZA Quinlan, S Genivaldo, MJA Vermeij, SA Sandin, JE Smith, F Rohwer. Nature Communications, 10 :1691, (2019) 
  • Nitrogen enrichment offsets the direct negative effects of ocean acidification on a reef-building crustose coralline alga. MD Johnson, RC Carpenter. Biology Letters, (2018)
  • Complex and interactive effects of ocean acidification and temperature on epilithic and endolithic coral reef turf algal assemblages. Coral Reefs, (2017)
  • Contrasting effects of ocean acidification on tropical fleshy and calcareous algae. MD Johnson, NN Price, JE Smith. PeerJ, 2: e411, (2014)


  • Ph.D. in Marine Biology, Scripps Institution of Oceanography, 2011-2016
  • M.S. in Biology, California State University, Northridge, 2008-2011
  • Prof. M.S. in Marine Biology, Northeastern University Three Seas Program, 2005-2007
  • B.A. in Biology, Colby College 2001-2005

Professional Profile

  • 2021-current: Assistant Professor of Marine Science, KAUST, Saudi Arabia
  • 2021-current: Guest Investigator, Woods Hole Oceanographic Institution, USA
  • 2020-current: Research Associate, Smithsonian Tropical Research Institute, Panama
  • 2020-current: Research Associate, Smithsonian Marine Station, USA
  • 2019-2021: Postdoctoral Scholar, Woods Hole Oceanographic Institution, USA
  • 2016-2019: Postdoctoral Fellow, Smithsonian Institution (MarineGEO) & Smithsonian Tropical Research Institute, Florida USA & Panama

Scientific and Professional Membership

  • International Coral Reef Society (ICRS), Association for the Sciences of Limnology and Oceanography (ASLO),
  • Phycological Society of America (PSA), Western Society of Naturalists (WSN)


  • Postdoctoral Scholarship, Woods Hole Oceanographic Institution
  • Postdoctoral Fellowship, Smithsonian Institution Marine Global Earth Observatory (MarineGEO)

KAUST Affiliations

  • Red Sea Research Center (RSRC)
  • Biological and Environmental Science and Engineering Division (BESE)

Research Interests Keywords

Coral reef ecology Global change biology Ocean acidification Ocean deoxygenation Warming Climate Change Phycology Calcifying algae Crustose coralline algae