It wasn’t supposed to show up here. In fact the hybrid plant was a sort of a mistake.
It occurred after an oceanic seagrass called Zostera pacifica was planted near a different kind of seagrass in Mission Bay, and mated with it.
Malia Moore is an oceanographer and researcher at the Salk Institute. She said a scientist friend was snorkeling in the bay and saw some seagrass that looked kinda weird.
“So I swam out there. Dove in there," Moore said. "And immediately the grass looked different.”
The Zostera marina eelgrass commonly found in Mission Bay has thin leaves. Moore said these leaves were thicker. Genetic testing showed the genesis of this hybrid grass dated back to an earlier restoration effort.
An oceanic seagrass, called Zostera pacifica, grows below 50 to 100 feet of water. Some of that was planted in Mission Bay to see if it could survive in the murkier water better than the native Zostera marina species. It didn’t work because the pacifica plant died off.
“But the hybrid formed first," Moore said. "So while the pacifica was there, when it was ephemerally there, it hybridized with Zostera marina and created the hybrid. So it was kind of a human accident, actually.”
Seagrasses that grow in San Diego’s bays and estuaries are under threat from human activities — dredging and runoff — that have made their waters much more murky. The grasses are very important to the environment, providing food and habitat for fish, preventing erosion and storing carbon.
Salk researchers hope this hybrid plant — this accident, as Moore described it — can better survive in those dark waters and perhaps provide the key to restoring damaged seagrass meadows in San Diego.
Salk Institute research professor Todd Michael was senior author of a paper he cowrote with Moore that was published in the journal Nature Plants. He said the ability of this plant to exist in lower light conditions is key to its ability to survive. It comes thanks to genes inherited from its oceanic parent, Zostera pacifica.
“What we found is that it turns on its photosynthesis genes longer than the Zostera marina,” Michael said. “That led us to hypothesize that what might actually be happening here is that the circadian clock enables Zostera pacifica to capture light all the way through most of the day instead of just capturing it when the sun comes up.”
It’s too early to know how well the hybrid will do in this environment, long term. It has to be sustainable and this one might have some reproductive issues.
Consider another hybrid species, the mule.
Its parents are a horse and a donkey and it carries qualities of both. But the mule typically cannot sexually breed and produce more mules. Is this hybrid seagrass like a mule, which can only create one generation?
Like many seagrasses, the hybrid has created new clones through its root system. But clonal reproduction may not be sustainable.
“It’s great that it reproduces clonally,” Moore said. “That’s awesome. But you also want it to reproduce sexually so it can mix and create genetic diversity and spread faster and respond to stress.”
Michael adds that there is a lot they still don’t know, but their finding is significant.
“The core finding is that the hybrid itself takes genes from the Pacifica genome and provides low-light tolerance to the plant overall,” he said, adding that could make it easier to restore seagrass meadows.
“Being able to plant Zostera and being able to restore Zostera that’s attuned to a very specific environment could decrease the failure rate of the restoration,” Michael said.
One bonus factor to restoring eelgrass meadows is this eelgrass does taste pretty good. Michael says some native communities in Baja dine on their seeds, called eelgrass grains. And some restaurateurs are taking notice.
