Mussels are broadcast spawners; the eggs and sperm of adult mussels are released into the water column and combine to form pelagic larvae that float in the ocean for weeks until ready to settle. These late-stage mussel larvae eventually look to settle on filamentous structures like seaweeds (filamentous means threadlike or ropey, usually many times longer than wide). The initial movement of mussels from the water column to fine, filamentous structures is called primary settlement. A series of further migrations are made as mussels grow (‘secondary settlement’), until the juveniles find their way back to an adult mussel bed or another suitable seafloor habitat.

We know that mussels exist in the water column of the Gulf, but they aren’t forming adult beds. This means there is a ‘bottleneck’ in the lifecycle of green-lipped mussels, and it’s possible that a lack of settlement structure (like seaweeds!) could be a limiting factor in mussel recruitment. Gaining a better understanding of this process, the timing, and settlement preferences of mussel larvae on different types of seaweeds could help restoration practitioners at Revive Our Gulf get more mussels to thrive on the seafloor.