Fountain Valley-based hospital operator MemorialCare Health System said today that it bought Nautilus Healthcare Management Group in Newport Beach, which provides management services for Greater Newport Physicians. Terms were not disclosed.

MemorialCare owns Orange Coast Memorial Medical Center and Saddleback Memorial Medical Center.

It said that Greater Newport Physicians, which has 400 doctors, will be affiliated with its MemorialCare Medical Foundation, a nonprofit medical management organization that includes 135 physicians and more than 800 contracted specialists.

Greater Newport said that the deal with MemorialCare offers it the “ability to expand our network of hospitals and providers in Los Angeles and Orange counties” and puts it under contract with more health plans, which will allow a greater chance for patients to remain with the group even if their insurance coverage changes.