Ocean urea fertilization for carbon credits poses high ecological risks

Patricia M. Glibert, Rhodora Azanza, Michele Burford, Ken Furuya, Eva Abal, Adnan Al-Azri, Faiza Al-Yamani, Per Andersen, Donald M. Anderson, John Beardall, G. Mine Berg, Larry Brand, Deborah Bronk, Justin Brookes, Jo Ann M. Burkholder, Allan Cembella, William P. Cochlan, Jackie L. Collier, Yves Collos, Robert DiazMartina Doblin, Thomas Drennen, Sonya Dyhrman, Yasuwo Fukuyo, Miles Furnas, James Galloway, Edna Granéli, Dao Viet Ha, Gustaaf Hallegraeff, John Harrison, Paul J. Harrison, Cynthia A. Heil, Kirsten Heimann, Robert Howarth, Cécile Jauzein, Austin A. Kana, Todd M. Kana, Hakgyoon Kim, Raphael Kudela, Catherine Legrand, Michael Mallin, Margaret Mulholland, Shauna Murray, Judith O'Neil, Grant Pitcher, Yuzao Qi, Nancy Rabalais, Robin Raine, Sybil Seitzinger, Paulo S. Salomon, Caroline Solomon, Diane K. Stoecker, Gires Usup, Joanne Wilson, Kedong Yin, Mingjiang Zhou, Mingyuan Zhu

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed.

Original languageEnglish (US)
Pages (from-to)1049-1056
Number of pages8
JournalMarine Pollution Bulletin
Issue number6
StatePublished - Jun 2008


  • Carbon credits
  • Carbon sequestration
  • Cyanobacteria
  • Harmful algae
  • Hypoxia
  • Ocean fertilization
  • Sulu Sea
  • Toxic dinoflagellates
  • Urea dumping

ASJC Scopus subject areas

  • Aquatic Science
  • Oceanography
  • Pollution


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