Was this reef protected?
The caption under the image on the Digital Globe website identifies the location as Fiery Cross Reef.

Multiple sites identify what's going on as the Chinese government building an airstrip and related facilities on the site to solidify its claim to the South China Sea.

According to this 2015 BBC story:


  China claims almost the whole of the South China Sea, resulting in
  overlapping claims with several other Asian nations including Vietnam
  and the Philippines.


That story is based on a Jane's 360 analysis of satellite images:


  The 23 March images show a paved section of runway 503 m by 53 m on
  the northeastern side of Fiery Cross Reef, which China began to turn
  into an island in late 2014. Paving and ground preparation of other
  sections of the runway has also begun further along the island. In
  addition, workers have paved about 400 m by 20 m of apron.


According to the Permanent Court of Arbitration on the wider South China Sea territorial dispute between China and the Philippines: (PDF)


  ...China had caused severe harm to the coral reef environment and
  violated its obligation to preserve and protect fragile ecosystems and
  the habitat of depleted, threatened, or endangered species.


But it didn't seem that the reef in question was explicitly protected by any governmental action, especially given the dispute over which country governed the territory. China does not recognize the jurisdiction of the court.