Riverguy -
An interesting read and the reported lack of monitoring is concerning.

That said I would remind folks that Zostera japonica like the spartina is an exotic plant (historically found along the Asian coast). While I don't know much about either species of eel grass I can certainly see a situation where controlling the "duckgrass" would be necessary to allow the native (marina) eel grass and the ecosystem benefits it provides the opportunity to recover.