New Research Reveals Seaweed as Misleading Indicator of Coral Reef Health

New research suggests that seaweed, which has long been used as an indicator of coral reef health, can provide false information. The study, which analyzed data from more than 1,200 oceanic sites, showed that different species of macroalgae react differently to pollution, which can mask signs of stress on coral and misguided conservation efforts.

Scientists have used seaweed as an indicator of coral reef health for decades.

But what if the seaweed led them astray?

New research from the University of British Columbia reveals that this is so, and scientists need new ways to determine whether human activity is damaging certain coral reefs.

“This is especially important at this time, given that coral reefs are globally threatened by climate-induced stress,” said Dr. Sarah Cannon, a postdoctoral fellow at the UBC Institute for Oceans and Fisheries and lead author of the study.

Local species behave differently

Seaweed belongs to a group of organisms called macroalgae. Macroalgae at sea level have long served as a proxy for the health of coral reefs, because they are relatively fast and easy to measure. Since the 1970s, scientists have hypothesized that local human impacts increased macroalgae while destroying dormant coral reefs.

However, the research has just been published in Global change biology It looked at data from more than 1,200 sites in the Indo-Pacific over 16 years and revealed that this approach is misleading and may contain subtle signs of coral stress.

For example, the coverage of macroalgae is highly dependent on[{”attribute=””>speciesgrowinginaparticulararea[{”attribute=””>speciesgrowinginaparticularareaSargassum is less likely to grow in water contaminated by agricultural runoff, but Halimeda will thrive. In both cases, a reef will suffer.

The global research team concluded that using macroalgae coverage as an indicator of local human impacts can actually obscure how much our actions are harming reefs, and cause scientists to misidentify the reefs most in need of intervention.

Reference: “Macroalgae exhibit diverse responses to human disturbances on coral reefs” by Sara E. Cannon, Simon D. Donner, Angela Liu, Pedro C. González Espinosa, Andrew H. Baird, Julia K. Baum, Andrew G. Bauman, Maria Beger, Cassandra E. Benkwitt, Matthew J. Birt, Yannick Chancerelle, Joshua E. Cinner, Nicole L. Crane, Vianney Denis, Martial Depczynski, Nur Fadli, Douglas Fenner, Christopher J. Fulton, Yimnang Golbuu, Nicholas A. J. Graham, James Guest, Hugo B. Harrison, Jean-Paul A. Hobbs, Andrew S. Hoey, Thomas H. Holmes, Peter Houk, Fraser A. Januchowski-Hartley, Jamaluddin Jompa, Chao-Yang Kuo, Gino Valentino Limmon, Yuting V. Lin, Timothy R. McClanahan, Dominic Muenzel, Michelle J. Paddack, Serge Planes, Morgan S. Pratchett, Ben Radford, James Davis Reimer, Zoe T. Richards, Claire L. Ross, John Rulmal Jr., Brigitte Sommer, Gareth J. Williams and Shaun K. Wilson, 5 April 2023,Global Change Biology.
DOI: 10.1111/gcb.16694

2023-07-14 10:29:10
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