Even though there is no wake when anchored, it would definitely have an environmental impact known as sediment and seabed disturbance.
While on a number of oceanographic missions, I noticed freshwater or brackish water marine species that live on the seabed. Anchorages disrupt and destroy these habitats, which could harbour sensitive species. I would advise you to ask biologists to identify the species more accurately. Anchorage has a direct impact on seabed sediments.
As for the communities, landscapes can be transformed by the presence of these ships. One example is ships that were anchored for an extended period in the Beauharnois region, and which ended up becoming a blot on the landscape.
Before coming to any long-term decisions, it's important to recall that this mobility and temporary anchorage can certainly diminish the quality of life for residents. These should be factored into things like the impact matrix of cost-benefit analyses.