Because kelp draws down carbon dioxide and gives off oxygen as it photosynthesizes, researchers have wondered for years whether a dense enough kelp forest could act as a small, local refuge from ocean acidification — a patch of water measurably less hostile to shellfish, coralline algae and other calcifying species than the water around it. A 2024 study in Port Phillip Bay, Australia, led by Elisabeth Strain, found real evidence of exactly that in one bay. The obvious next question was whether the effect holds up anywhere else, or whether Port Phillip Bay was a special case. A new study published in Annals of Botany in August 2026, co-led by Strain (now at the University of Tasmania’s Institute for Marine and Antarctic Studies) and Pamela Fernández of Universidad de Los Lagos in Chile, went looking for an answer on two different coastlines at once.
The team — which also included Alejandro Buschmann and colleagues from Chile and Australia — set up paired sensors inside and outside giant kelp (Macrocystis pyrifera) forests at seven sites: four around Tasmania and three in Chile, at Concepción and at Ilque and Metri in the Los Lagos region. Through the spring and summer of 2022-23, the instruments logged pH, dissolved oxygen and temperature hour by hour, letting the researchers isolate how much of any difference in water chemistry was actually attributable to the kelp rather than to the site itself. They also compared kelp density against water chemistry at additional sites, and — because the central Chilean coast is regularly hit by upwelling, which pushes cold, carbon-rich, low-oxygen water up from the deep ocean — calculated an upwelling index there to see whether that made the kelp effect bigger or smaller.
The clearest result came out of one of those upwelling events off central Chile. Outside the kelp forest, dissolved oxygen bottomed out at a nearly lifeless 0.43 milligrams per liter and pH dropped to 7.40; inside the forest, at the same time, oxygen measured 3.92 milligrams per liter and pH reached 7.52 — a large enough gap, in the middle of a genuinely corrosive, low-oxygen event, to plausibly matter for animals sheltering nearby. But the pattern wasn’t universal. In Tasmania, denser kelp beds reliably tracked with better water chemistry across sites; in Chile, that density relationship disappeared entirely, and the buffering effect only showed up clearly at the one site experiencing upwelling.
The researchers’ takeaway is more complicated than a simple yes: kelp forests can act as a meaningful, if temporary, chemical refuge, but whether that happens — and how strongly — depends on local kelp density and on regional oceanography like upwelling, not on the mere presence of kelp. Fernández and her co-authors frame it as a case for testing the “kelp refuge” idea site by site rather than assuming it generalizes, especially as more restoration and conservation projects start pointing to acidification buffering as one of kelp’s ecological benefits. It’s a more cautious, patchier picture than the single-bay signal from 2024 — useful for anyone deciding how much weight this particular benefit should carry when they’re arguing for protecting or restoring a given kelp forest.
Further reading: Strain, E.M.A. et al., “Giant kelp-associated variation in coastal seawater chemistry across contrasting sites in Chile and Tasmania,” Annals of Botany (2026); Universidad de Los Lagos, “Estudio entre Chile y Tasmania revela cómo los bosques de huiro gigante modifican la química del agua de mar” (2026).