Magothy River Continues Slide

Underwater grasses fall to 2 acres from 308 in 5 years

The scientist with the National Oceanic and Atmospheric Administration who compiles the annual State of the Magothy index gave the river a health rating of 22 percent - or a D minus.

Dr. Peter Bergstrom, a biologist with NOAA, looks at three factors when assessing the river's health - water clarity, dissolved oxygen and the number of underwater grasses in the river. He has compiled the index since 2003, and the rating has declined steadily since then.

That's a long-term slide.  But they have a plan!

Volunteers with the Magothy River Association are exploring different ways of cleaning up the river. The association already grows oysters, which filter the water, through the Marylanders Grow Oysters program. In 2009, the volunteers grew 60,000 oysters. But now volunteers are also exploring other species of native bivalves that residents could grow and plant in the fresher parts of the river; oysters can only grow in the saltier lower portions of the river. Spadaro said the MRA hopes to have a new program in place by fall. "Mussels are a much faster and more cost efficient than oyster restoration," he said.

In 2004, another bivalve, the dark false mussel, ended up in the Magothy after Tropical Storm Isabel. The mussels dramatically improved water clarity and led to an increase in underwater grasses. But the mussels died off by 2005, probably eaten by ducks, fish and crabs, Bergstrom said. MRA volunteers are looking for a native bivalve to test in pilot projects, one grown in cages attached to piers until they grow large enough to plant on the bottom of the river or on hard surfaces. One option is the Baltic macoma clam, which is native to Maryland and can grow up to an inch and a half long. That's about as long as a hooked mussel, another possibility that MRA volunteers are investigating.

OK, the mussel idea is interesting, but problematical.  When I worked on the Patuxent River, we had some years when there were huge "blooms" of hooked mussels.  For a year or two, everything was covered with them, but after a few years, they faded back to another ordinary member of the community.  What happened?  We don't know.  Something learned to eat it?  They got a disease?  The special circumstances that caused it to bloom simply didn't reoccur?

How do you base a management strategy on that?