While there is celebration about bay grasses hitting record levels for the third year running across the Chesapeake Bay, Anne Arundel’s rivers saw an overall decline in 2017.
The South and Severn rivers saw grasses disappear, but the Magothy saw a modest increase.
The Chesapeake Bay Program announced in April that the annual aerial survey of submerged aquatic vegetation by the Virginia Institute of Marine Science found a baywide increase to 104,843 acres, topping 100,000 acres for the first time since the survey began in 1984.
Bay grasses are vital to the bay’s health. They keep the water clean by absorbing nutrients, protecting shorelines from wave and wake action and provide habitat for young crabs and fish.
But like grasses on your lawn they need sunlight to survive. And when the bay and its tributaries are clouded by algae blooms or sediment sunlight does not reach the grasses. Human activity like boat wakes, propeller damage, even purposeful removal cause harm.
Bay grasses were once so abundant in the tributaries devices were towed behind boats to cut them and the state even distributed poison to kill grasses off to aid navigation.
But no more. Now increasing grass coverage is a primary goal of the Chesapeake Bay Agreement and the Chesapeake Bay Program aiming to implement the goals in it. Last year’s grass growth took the baywide total 14,843 acres over the 2017 program target and 57 percent of the total goal.
It wasn’t good news everywhere. Many tributaries in the middle of the bay, including the South and Severn rivers here and the Choptank across the bay. saw dramatic losses of SAV.
And a goodly chunk of the bay itself , from the Bay Bridge to just north of the Patapsco, saw a decline as well.
The Severn saw grasses flourish after a positive period of water clarity in 2016. But in 2017, 31 percent of its grasses were gone - dipping from 283 acres to 189.
The South River had seen 14 grasses growing off of South River Farm Park and in Glebe Bay in 2016. In 2017 it was all gone.
“We had that clean water event a couple years ago and the grasses seeded, creating the largest amount of grasses in years. But a lot of rain and mud, sediments and nutrients ran into the river, and we have a 31 percent drop,” said Tom Guay of the Severn River Association. “It was disappointing, we are going backwards.”
He said last year you could see grasses in the shallows all covered with brown algae. “The water was so murky.”
The Magothy saw a bump from 14 acres in 2016 to 23 in 2017.
“We found five different species in the river. It is amazing that we did,” said Paul Spadaro, president of the Magothy River Association.
He said the most grasses have been found near areas of natural shoreline as opposed to areas with bulkhead or rip-rap stone.
“When your bulkhead fails the county lets you rebuild it a few feet into the water, that puts the shore in deeper water where grasses don’t have a chance to grow because they don’t get the light they need,” Spadaro said.
Another likely cause of the decline is species specific.
Most of the grasses lost were beds of widgeon grass, a “boom and bust” species that can rise and fall from year to year. So the widgeon grass-led spike seen in the South and Severn was not guaranteed to last.
The Lower Patuxent, south of Anne Arundel’s shores, was also part of the good news, seeing a whopping 301 percent increase in grass coverage in the VIMS survey. It started with 32 acres and leapt to 131 acres in 2017.