A recent UVic study has found that eelgrass has a unique relationship with otters that helps it grow and become more diverse.
The paper, by Ph.D. graduate Erin Foster, was posted in the journal Science and shows that when otters disturb the eelgrass preventing them from getting to clams, it allows the eelgrass to more easily reproduce and leads to more diversity.
“Sea otter digging disturbs the eelgrass roots and promotes conditions that favour sexual (over asexual) reproduction, enhancing genetic diversity,” said Foster in a press release. “With asexual reproduction, new plants are genetically identical to the parent, but with sexual reproduction, almost every single seed will be genetically different, since the genes of the two parent plants mix.”
Foster said in areas where otters have been around for 20 to 30 years, eelgrass diversity was up to 30 per cent higher than in areas without otters.
Eelgrass plays various roles in the environment, according to Foster. She says it prevents shorelines from eroding provides a habitat for herring and nurseries for rockfish and salmon.
She says the higher diversity can help eelgrass survive environmental stressors.
“The more variety there is in the genetic composition of each individual, the more likely that some individuals will be able to sustain environmental stressors,” said Foster. “Some individuals, for example, might be very tolerant to heat waves, others to disease, and yet others may tolerate heavy grazing or ocean acidification.”
Foster added eelgrass is also culturally important to Indigenous peoples as a source of starch and seeds that can be ground into flour.
She hopes that her research will make more people think about the effects large animals have on ecosystems.