Some marshes look darker and grayer this spring, but that’s a good thing, biologists and wetlands experts say.
A tough winter, with lots of wind, cold, ice and inundation by flood tides has brought algae, marsh mud and other nutrients up onto old spartina grasses, said retired marine biology teacher Hans Toft. That will help them decompose faster to feed new spartina growth this spring, he said.
“I have seen it before, but it’s more pronounced this year,” said Toft, who taught at Cape May County Technical High School and whose home overlooks marshes on Sluice Creek in Dennis Township.
Toft said cold, dry wind dried out the marsh mud and turned it into a powdery gray silt and clay of very fine particles, which were then blown across the marsh grass.
On the mud’s surface are blue-green algae, bacteria and different types of microalgae, he said.
“I ran a wet finger across (the dried grass), and the coloration comes off. It’s a gray marsh color, but you also see green in it,” Toft said. “There’s a lot of growth and life going on there. You can smell the marsh growing.”
He said the fine mud particles are fertilizer for that growth.
Lenore Tedesco, executive director of the Wetlands Institute in Middle Township, said she hasn’t noticed a grayer coloration of marsh grasses in the Stone Harbor area.
But she has seen more flattening of old marsh grass this year. The marshes were covered in ice for longer this winter, and that pushed last year’s growth down into a mat.
“The winter marsh was bent down in a weird pattern,” Tedesco said. “It’s almost like crop circles out there.”
She said the marsh is starting to green up, as new sparti na grasses begin to slowly grow from the mud.
The frequent inundation from extra-high tides during four nor’easters in March didn’t do much damage, she said, partly because three of the four storms had mostly westerly winds that helped push water out to sea faster.
“I would argue it’s more ice than nor’easter damage,” she said, speaking from a regional conference in Delaware on the beneficial uses of dredge materials.
Stewart Farrell, of Stock-ton University’s Coastal Research Center, credits algae with changing the color of the marsh now.
“We are getting towards mid-April, and the first algal bloom peaks in May. So with all of the high tides we’ve had where marsh has been flooded ... whatever is in the water column is now on the marshes,” Farrell said.
An algal bloom, also known as a marine bloom or water bloom, is a rapid increase in the algae population in an aquatic system.
While marshes can drown in place if sea level rises too fast, low marsh grass is “pretty special in how much submergence and salinity it can handle,” Farrell said. High marsh plants, however, may have been stressed more.
“If it doesn’t happen again, they should recover by midsummer,” he said of high marsh grasses and plants.