Ecology, Climate Change and Related News

Conservation Science for a Healthy Planet

Restoring seagrass under siege

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/ Elizabeth Devitt  see full article here

Seagrasses are disappearing at rates that rival those of coral reefs and tropical rainforests, losing as much as seven percent of their area each year. Replanting success rates have been unpredictable — but scientists are making new advances that could change that…

….In the Bay Area, the long strands of eelgrass provide shelter for fish nurseries, prime substrate for the sticky eggs of herring, and food for the small “grazers” that eat the algae coating on the grass. The plant beds also forestall erosion by trapping sediments and slowing down waves or currents. Although researchers estimate around 9,490 hectares (more than 23,000 acres) of the San Francisco coastline could support eelgrass beds, these plants grow on less than one percent of that shoreline. “There are so many different environs in San Francisco Bay, we’d like to come up with a template that helps us determine what methods would work best for each site,” says Boyer, who keeps her office at the Romberg Tiburon Center for Environmental Studies stocked with wetsuits….

…One failure, still unexplained, occurred in Corte Madera Bay, where healthy grass beds died suddenly after years of apparently healthy persistence. Although Boyer wants to keep looking for an answer, she says there isn’t time for that — not if scientists plan to meet the goal of getting 36 more acres of seagrass planted before the nine-year project ends.

If there have been surprising failures, there have also been unexpected successes. Eelgrass is thriving in Elkhorn Slough, an estuary about 100 miles south of San Francisco. Bordered by agricultural fields, the runoff is rich with fertilizer, making the water prone to algal blooms that usually kill seagrass. When algae coats the eelgrass, it diminishes the light available for photosynthesis and plant survival. Despite these conditions, the eelgrass in the Slough is abundant. That anomaly made Brent Hughes, a marine biologist from the University of California at Santa Cruz, wonder: Why?…

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