OSU Identifies Beneficial Seafloor Terrain for Kelp Forest Restoration

A recent study by Oregon State University researchers found that kelp forest restoration efforts are most effective in areas of the bedrock seafloor that are highly contoured.  

Successful kelp forest restoration is important because the algae, which has a large impact on the global economy and ecology, is currently struggling to fight the effects of climate change and overgrazing by sea urchins.  

“Sites with a lot of physical structure along the seafloor showed resilience – the forested state was able to persist, even when similarly disturbed compared to the flat locations,” said recent OSU graduate Zachary Randell, who led the study during his time as a doctoral student. 

Randell found that kelp forests were more stable in areas of rougher terrain due to the ability to retain a larger quantity of detached pieces of kelp – ”drift algae” – which urchins seem to prefer over live algae. Their preference keeps the live kelp safe from widespread destruction and helps restoration efforts. 

In addition to the urchins’ overgrazing tendencies, a warming ocean is also an issue. Kelp, which lives in almost half of the Earth’s marine ecoregions, does best in cold water – making climate change a threat to their existence. 

“Kelp forests are declining worldwide due to different combinations of environmental change and lower numbers of the predators that control urchins, like sea stars, cod and sea otters,” said Randell. “More and more kelp forests are transitioning into what are known as ‘urchin barrens,’ an alternative arrangement of the ecosystem with dramatically fewer species.” 

With the newfound information, Randell says a part of future restoration efforts could include manufacturing artificial reefs and targeting highly contoured areas of the seafloor. 

“Those artificial reefs could also be the focus of outplanting recovery efforts of sea urchin predators, such as the captive rearing and release of sea stars,” said Randell. “The reefs could be constructed as optimal environments for urchin predators and also for urchins and the drift algae that urchins eat.” 

By Momoko Baker