A sample showing milky ribbon worm damage (Aug. 12, 2015).
One of the more important findings from the 5-year investigation into the cause of the southern Maine clam decline was that in order for clams to survive they need to be protected not only from green crabs, but from milky ribbon worms as well.
Many of our 2014 experiments relied on using nets to protect clams from predation, as DEI has done in many coastal communities since the 1980s. Milky ribbon worms live and forage for their prey in the sediments so nets that cover only the top of the flat do not stop their predatory activities.
A milky ribbon worm thwarted from eating the clams in a recruitment box with a small mesh (PetScreen®) bottom.
When DEI scientists found low survival of soft-shell clam juveniles under nets, they moved to building and deploying wooden boxes that protect clams from the top and bottom, as well as the sides. Using boxes increased the rate of clam survival.
Our research has shown what size of mesh is best to protect clams from milky ribbon worms. For example, 4.2mm (1/6th-inch) aperture is too large to exclude milky ribbon worms. PetScreen® (1.7 mm x 0.9mm), however, does protect clams from these worms. DEI used mesh with an aperture of 2.1mm during our 2017 bioremediation experiment to reduce milky ribbon worm predation on clams. The results from that field experiment showed that 2.1mm mesh deters milky ribbon worm predation while enabling clam growth.
