From the origin of the species to the paths of invasion
Although it looks like a flower and doesn’t move around, the sun coral is an animal. It belongs to a group of species known scientifically as Tubastraea spp., which are part of the large group of Cnidarians – aquatic animals with relatively simple body organization, but great beauty.
Originally from the Pacific and Indian Oceans, these corals have become a notable presence in different parts of the world. They have been introduced through human activity in the oceans, for example by adhering to and being transported on the hulls of ships.
Because it poses a threat to the local biodiversity of these environments, where it is not native, the sun coral is considered an exotic and invasive species in these areas.
Brazil is currently facing an environmental challenge with the invasion of two species of sun coral: Tubastraea coccinea, which has an orange color, and Tubastraea tagusensis, which has yellowish tones.
The sun coral is a fascinating organism with unique characteristics that contribute to its success as an invasive species. Although they do not form reefs, they make up colonies that occur in aggregate form and are attached to a variety of substrates, both natural and artificial.
This ability to establish itself in different types of materials is crucial to the success of the invasion. As well as occurring on natural substrates such as rocky shores, the sun coral can be found in great abundance on a variety of artificial substrates, such as dock pilings, buoys, shipwrecks, artificial reefs and on oil platforms.
Another important feature of the species is the great ecological tolerance of these corals in Brazil. They resist high temperatures and desiccation when they are exposed to air. This ability allows them to occupy a wide variety of environments, from the shallowest to tens of meters deep.
But the success of the sun coral invasion in the South Atlantic is also attributed, in part, to the absence or reduced predation of Tubastraea spp. when compared to their regions of origin. The absence of predators has allowed these corals to proliferate very well here.
The sun coral is also special because it has the ability to reproduce in different ways, which facilitates its rapid spread into new environments. They are hermaphrodites (the same individual can produce both male and female gametes) and can reproduce both sexually and asexually.
Corals produce many larvae throughout their lives, up to 300 larvae per cm² of colony, especially through asexual reproduction. In addition, they start reproducing when they are very young, only about 2 months old.
Its small larvae float in the water for a while and can swim actively for up to 20 days (in the case of T. tagusensis) and 14 days (in the case of T. coccinea). Some of them can live for up to 100 days. These larvae turn into groups of small corals called polyps, which together form beautiful colonies. What’s more, they grow very quickly. In just one year, the colony can grow by up to eight polyps.
The sun coral also spreads in other ways. The polyps can leave the colony, leaving the skeleton behind and settling elsewhere, where they grow again. This process takes place especially in T. coccinea.
In addition, both species have the incredible ability to recover from pieces of skeleton with tissue. This means that even if parts of them break, they can regenerate. These abilities help the sun coral to adapt quickly and conquer new places, making it a successful invasive species in different environments.
The two species of sun coral that are currently invasive in Brazil have origins very far from here.
While T. tagusensis was first described in the Galapagos (Ecuador), T. coccinea was described in Bora Bora, French Polynesia. These are the so-called “type localities” of these two species. In other words, the specific locations where the organism was originally collected and described as the basis for the description of the new species.
Despite the importance of the sun coral populations in these standard localities as a reference for the biology of these species, there are many more studies on these species in invaded places than in their places of origin. This is probably due to the impact these species have outside their native geographical area.
The tool allows anyone to share underwater photo or video recordings from anywhere in the world. This is valuable information for understanding and controlling this invasive species.
In Brazil, for example, the presence of the sun coral is known to modify the community of organisms associated with the marine substrate, such as rocky shores and reefs. Over the years on Ilha Grande, the sun coral, which at first was a rare organism, has become dominant, expanding by about 2 kilometers a year.
The environmental challenge posed by the sun coral invasion is so worrying that it has been prioritized by Ibama. The agency named these species as one of the three invasive species with the highest priority for control and monitoring in the country.
However, the dispersal of the sun coral around the world did not begin in Brazil, nor is it limited to it. In addition to Bora Bora, T. coccinea is also native to other locations in the Indo-Pacific and has also dispersed to the Caribbean, Gulf of Mexico and Florida.
T. tagusensis is native not only to the Galapagos, but also to the Cocos, Palau and Nicobar islands in India, and has also spread to the Gulf of Mexico and Brazil.
The invasion of these species in the South Atlantic began in the 1980s and was first recorded on oil platforms in the Campos Basin in Rio de Janeiro. Later, in 1998, they were identified for the first time on natural substrates, such as rocky shores, in Arraial do Cabo, also on the coast of Rio de Janeiro.
Currently, the sun coral occupies artificial and/or natural substrates in eight Brazilian states, from the southern limit in Santa Catarina to the north in Ceará. They are: Santa Catarina, Paraná, São Paulo, Rio de Janeiro, Espírito Santo, Bahia, Sergipe and Ceará. These areas of occurrence include Conservation Units in five states (SC, PR, SP, RJ and BA), which highlights the need for preventive and containment actions to protect marine biodiversity on our coast.
