Symbiodinium (wikipedia.org).

     Non-native algae from the Indian and Pacific ocean now has a foothold in the Caribbean. And while the appearance of Symbiodinium trenchii is often a good sign for reefs, as it is best known for allowing corals to grow in water several degrees higher than usual, researchers worry it may also hamper the growth of coral by as much as 50%. 

     "At face value, the finding of the species in the Caribbean is a good thing," said University of Deleware biologist Tye Pettay, as it increases thermal tolerance. However, since S. trenchii is a newcomer to the Caribbean, researchers are unsure whether it will have an overall positive or negative effect on the coral. 

     According to Pettay more research is needed to understand the effect the algae will have on the Caribbean ecosystem, but they are sure of one thing, the algae is there to stay.