Erosion control is a good idea, right? Maybe not. “Hardened” water fronts may hurt the Bay. This includes rip rap and bulkheading and is perfectly legal. Landowners are not breaking the law by doing this (assuming they have a permit), but more and more are doing this and it is having a cumulative impact. It keeps the water cleaner and reduces erosion, so why is it so bad?
Specialized Environment
The shoreline is a special environment. These new structures are reducing the places where terrapins, crabs and fish can find food and shelter. It can even help the increase in sea nettles (stinging nettles) and aid in the spread of an invasive species of marsh grass.
That We are Rapidly Changing
In several rivers near Baltimore, 50% or more of the shoreline has been modified. A study was done looking at 50 places around the Bay to compare and see how changes to shorelines affect the estuaries.
There also seems to be an effect on submerged aquatic vegetation (SAV) or what some people call seaweed. They are important because geese and ducks feed on them. Also, crabs and fish hide in them. This is particularly important for crabs that are sloughing and becoming soft shell crabs temporarily.
The SAVs are beginning to come back but the study seems to indicate the SAVs are smaller and less dense in front of hardened shoreline. This is probably because waves reflect off the hard walls and the extra turbulence can uproot or make conditions more difficult for the underwater grasses.
Also, there tends to be more nutrient runoff where there are hardened shorelines because these then to be put where there are lawns or fields vs. natural landscapes.
More Sea Nettles – Yuck!
The hard surfaces give more places for sea nettle larvae to settle which increases the sea nettle population. It also makes it harder for wetlands to establish themselves and increases the chances of the invasive grass, phragmites, invading.
When Grass is Bad
Phragmites likes disturbed soil and loves nutrients. So when the shoreline is altered by hardening it, it disturbs the soil and as said earlier, these locations tend to have high nutrient runoff. Just what phragmites loves. It can grow so thickly that it crowds out all native vegetation and is generally not as good a habitat for native animals as native plants are.
Since 2008 people have been required to put in living shorelines instead of hardened shorelines. Unfortunately, the study didn’t look at these closely enough to draw any conclusions.
The study authors think that when future shoreline projects are evaluated for permits in the future that they should not be looked at independently but how the fit into the bigger picture on each river / estuary.