Little evidence that lowering the pH of concrete supports greater biodiversity on tropical and temperate seawalls

Amanda R. Hsiung, Wen Ting Tan, Lynette H. L. Loke*, Louise B. Firth, Eliza C. Heery, James Ducker, Victoria Clark, Y. Shona Pek, William R. Birch, Ambert C. F. Ang, Rania S. Hartanto, Tiffany M. F. Chai, Peter A. Todd

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)
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Concrete is one of the most commonly used materials in the construction of coastal and marine infrastructure despite the well known environmental impacts which include a high carbon footprint and high alkalinity (~pH 13). There is an ongoing discussion regarding the potential positive effects of lowered concrete pH on benthic biodiversity, but this has not been investigated rigorously. Here, we designed a manipulative field experiment to test whether carbonated (lowered pH) concrete substrates support greater species richness and abundance, and/or alter community composition, in both temperate and tropical intertidal habitats. We constructed 192 experimental concrete tiles, half of which were carbonated to a lower surface pH of 7-8 (vs. control pH of <9), and affixed them to seawalls in the United Kingdom and Singapore. There were 2 sites per country, and 6 replicate tiles of each treatment were collected at 4 time points over a year. Overall, we found no significant effect of lowered pH on the abundance, richness, or community assemblage in both countries. Separate site- and month-specific generalised linear models (GLMs) showed only sporadic effects: i.e. lowered pH tiles had a small positive effect on early benthic colonisation in the tropics but this was later succeeded by similar species assemblages regardless of treatment. Thus, while it is worth considering the modification of concrete from an environmental/emissions standpoint, lowered pH may not be a suitable technique for enhancing biodiversity in the marine built environment.

Original languageEnglish
Pages (from-to)193-205
Number of pages13
JournalMarine Ecology Progress Series
Publication statusPublished - 10 Dec 2020
Externally publishedYes

Bibliographical note

Copyright the Author(s) 2020. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


  • Coastal defences
  • Concrete carbonation
  • Eco-engineering
  • Materials
  • pH
  • Biodiversity
  • Concrete


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