When it comes to restoring some Bay grasses, the secret to success may rest in learning from Mother Nature.
Finding an effective way to plant eel grass beds, the dominant form of submerged aquatic vegetation in high salinity portions of the Bay, has been a problem for restoration efforts. Unlike other species, eel grass hasn’t been propagated in the laboratory, which means pulling plants from healthy beds — something people want to avoid.
In recent years, Bob Orth, a seagrass expert at the Virginia Institute of Marine Science, and his colleagues have been trying to plant eel grass beds the way Mother Nature does it — by spreading seeds. “I’m trying to get away from digging plants and am using seeds instead,” he said. “You can’t dig that many plants if you want to get eel grass to come back over large areas.”
This spring, they collected about 6.6 million seeds from eel grass beds and distributed them on about 47 acres in different locations around the Bay, its tributaries and seaside.
Unlike transplanting, where results can be quickly seen, it takes time to see results from seed planting. The results from this year’s seeds won’t be known until next spring. Previous work, though, has shown that only a fraction of the seeds actually sprout. The highest percentage Orth has seen is about 20 percent at a site. “The average,” he said, “is between 5 and 10 percent.”
That seemingly poor success has discouraged restoration work with seeds, Orth said. “People have thought that seeds are relatively unimportant in the big picture, and they figure the only way to get a bed going really quickly is with adult plants.”
But Orth said his recent work with seeds has shown that seeded areas can often be quickly filled with plants, even though only a handful of seeds ever take root. “The interesting thing is when they do grow, it is phenomenal how fast they grow.”
Through continued research, Orth hopes to learn more about the optimal seeding techniques and conditions to promote plant growth and survival. The research is being funded by the Virginia Saltwater Recreational Fishing License Fund and Virginia’s Coastal Resources Management Program in the Department of Environmental Quality.
If the techniques can become perfected, Orth said it holds promise for replanting large areas because it requires far less manpower to collect and disperse seeds than it takes to do transplanting. “How does Mother Nature do it?” Orth asked. “She does it by seeds.”
But no effort will work, he stressed, unless the water is cleaned up to allow grasses to make a comeback. “The bottom line of the entire effort to restore grasses, regardless of whether we are getting grasses back through restoration or naturally, is water quality.”