Ocean acidification increases iodine accumulation in kelp-based coastal food webs

Research output: Contribution to journalArticle


Kelp are main iodine accumulators in the ocean, and their growth and photosynthesis are likely to benefit from elevated seawater CO2 levels due to ocean acidification. However, there are currently no data on the effects of ocean acidification on iodine metabolism in kelp. As key primary producers in coastal ecosystems worldwide, any change in their iodine metabolism caused by climate change will potentially have important consequences for global geochemical cycles of iodine, including iodine levels of coastal food webs that underpin the nutrition of billions of humans around the world. Here, we found that elevated pCO2 enhanced growth and increased iodine accumulation not only in the model kelp Saccharina japonica using both short-term laboratory experiment and long-term in situ mesocosms, but also in several other edible and ecologically significant seaweeds using long-term in situ mesocosms. Transcriptomic and proteomic analysis of S. japonica revealed that most vanadium-dependent haloperoxidase genes involved in iodine efflux during oxidative stress are down-regulated under increasing pCO2 , suggesting that ocean acidification alleviates oxidative stress in kelp, which might contribute to their enhanced growth. When consumed by abalone (Haliotis discus), elevated iodine concentrations in S. japonica caused increased iodine accumulation in abalone, accompanied by reduced synthesis of thyroid hormones. Thus, our results suggest that kelp will benefit from ocean acidification by a reduction in environmental stress however; iodine levels, in kelp-based coastal food webs will increase, with potential impacts on biogeochemical cycles of iodine in coastal ecosystems.


  • Dong Xu
  • Georgina Brennan
  • Le Xu
  • Xiao W Zhang
  • Xiao Fan
  • Wen T Han
  • Thomas Mock
  • Andrew McMinn
  • David A Hutchins
  • Naihao Ye
External organisations
  • Qingdao National Laboratory for Marine Science and Technology
  • Bangor University
  • Yellow Sea Fisheries Research Institute Chinese Academy of Fishery Science
  • University of East Anglia
  • Ocean University of China
  • University of Southern California
  • University of Tasmania
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Climate Research


  • Animals, Chlorophyta/metabolism, Climate Change, Food Chain, Gastropoda/metabolism, Hydrogen-Ion Concentration, Iodine/metabolism, Kelp/metabolism, Oceans and Seas, Seawater/chemistry
Original languageEnglish
Pages (from-to)629-639
Number of pages11
JournalGlobal Change Biology
Issue number2
Publication statusPublished - 2018 Oct 8
Publication categoryResearch
Externally publishedYes

Bibliographic note

© 2018 John Wiley & Sons Ltd.