Mangrove roots can cover the corals.

Alien species are a BIG threat to the coral reefs. Alien species are brought in illegally by people and accidentally by watercrafts. These animals are introduced to increase fisheries and also to start commercial marine sales. Some of these alien species that you can see everyday are algae, upside down jellies, barnacles and mangroves. Mangroves and foreign algae are abundant in bays like Kaneohe Bay. With the introduction of alien species, our native corals and other reef animals often have to fight for sunlight, space, and food. When aliens start to control the ways of the reef waters, the ecosystem undergoes change. The once balanced system becomes unsteady with either too many prey or too many predators. Alien organisms reproduce quickly and double when introduced to bays and harbors.