Kelp babies can’t take the heat
As climate change sends sea temperatures soaring, our lush underwater forests of kelp are disappearing (see Issue 176, Jul/Aug 2022). Now, University of Otago scientists have homed in on exactly how the heat impacts the microscopic life-cycle stages of New Zealand’s iconic rimurimu giant kelp (Macrocystis pyrifera).
Like a fern, rimurimu reproduces by releasing spores. These then nestle into a crevice and grow into a germ tube, before entering the sexual stage of development.
By turning up the heat on rimurimu samples in the lab, scientists found that higher temperatures triggered the release of more spores. But, once released, the hotter conditions led to significant declines in the number of spores settling on a surface and progressing through germination to become germ tubes. The germ tubes were smaller above 19.8 degrees Celsius, too.
This research adds to our understanding of kelp’s future, the researchers say, and “aids our attempts to help protect and rebuild it”.