It turns out when sea otters are foraging for dinner, they’re also doing a huge favor to the ecosystem.
According to new research, the critters have positive effect on sea grass meadows, a crucial part of the underwater environment that help stabilize the ocean floor, improve water quality and serve as food for some species and habitat for others.
Sea otters disturb these meadows when they dig for clams, and their presence is marked by bare patches and indentations from all the digging, according to National Geographic. Though some might assume that means otters aren’t so great for the grass, ecologist Jane Watson noticed in the 1990s that where sea otters thrived, so did sea grass, The New York Times reported.
Decades later, Watson’s idea inspired her former student, Erin Foster, to lead a study on the matter. Watson, who conducted the seagrass research while completing a PhD at the University of Victoria, co-authored a paper on the findings, which was published Friday in the journal Science.
As it turned out, Watson was right all along. The researchers studied meadows of eelgrass ― a type of sea grass ― in British Columbia, and found that they had significantly higher genetic diversity in areas where otters were present. Not only that, but the longer that otters had been living in a particular area, the higher the genetic diversity among the eelgrass.
So how do otters do this? The answer has to do with the fact that eelgrass can reproduce two ways ― clonally or sexually. Clonally basically means that each new plant is genetically identical to its predecessor; sexually means that the plants reproduce via pollination, and that each new plant has genetic material from each of its parent plants. The researchers believe that otters disturbing the grass specifically encourages sexual reproduction in the eelgrass, which creates a more genetically diverse meadow.
That’s good news for the grass, which is vulnerable to numerous threats, from climate change-fueled ocean acidification and warming water temperatures to pollution from fertilizer runoff and severe disruption from human activities like dredging for development. More genetic diversity gives the grass a better shot of long-term survival.
“Genetic diversity typically builds resilience to change, and considering the challenges we’re facing ... this will be important for eelgrass meadows,” Foster told National Geographic.