COOS BAY, Ore. – An army of tiny crustaceans in the tidal waters of Coos Bay is slowly chomping away at shorelines, exacerbating shoreline erosion and threatening marshes needed for salmon recovery.
An Oregon Institute of Marine Biology graduate student, Tim Davidson, hopes his study of the isopod Sphaeroma quoianum, the marine equivalent of the wood louse, will help coastal areas combat the nibblers before they bore too many trenches.
The isopod is a cousin of the pill bug, or “roly-poly,” found in basements and gardens throughout America. It has infested Coos Bay’s waters since the late 1980s, he said.
They are native to Australia and New Zealand and have been in U.S. bays and salty rivers along the West Coast for the last 150 years.
Davidson started studying the crustacean two years ago after he stumbled across an RV-size piece of insulating foam, presumably from a floating dock, bobbing in the bay. It was riddled with thousands of tiny tunnels.
It made him wonder: How many of these little nibblers were in the area? Last week, he donned knee-high boots and plunged his fingers into the murky marsh cliffside near Haynes Inlet.
“Here, here,” he said excitedly, “All of these little interconnected tunnels” … his voice trailing off.
A few feet behind him rested two grassy islands, 2-by-3-feet, he believes broke away from the mainland due, in part, to the chomping isopods.
The critters measure about a centimeter and a half long.
“These guys are definitely doing more harm than good,” he said.
“They will continue to be a pretty significant agent of erosion here,” Davidson said. “Over time, they will chew away a lot of the marsh, sandstone and shoreline … and just keep on going until there is no more.”
Davidson said more than 80 percent of local tidal wetlands already have been destroyed as a result of diking, conversion to agriculture, draining and erosion.
“It’s pretty well established that the salt marshes in Oregon are really the basis of the food web that supports the estuaries,” said Bob Bailey, the director of Oregon’s Coastal Management Program. “It’s a giant refrigerator filled with all kinds of goodies that wash into the bay, feeding plants and other critters.”
One of the more important animals that relies on marshlands are salmon, he said.
“These days, we have really come to learn that salmon really need these marsh areas as juveniles to hang out in,” Bailey said. “We are all concerned about restoring salmon to our coast and we need every bit of marsh we can to make that happen.”
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