Learn about marine bioinvasion – basic science

By Larissa Pires-Teixeira

How the arrival of a new species can ruin the environment


Anyone studying marine biology observes a growing threat to the balance of the oceans, the name of which “Aliens of the Seas” could well be the title of a science fiction film. It could, but it isn’t: the phenomenon is real. Little known, but increasingly dangerous. These “alien species” travel long distances, mostly with some form of transport, hitchhiking on the hull of a ship or on oil platforms.

This trip can be problematic if the newly arrived tenant, when he finds favorable conditions at the new place of residence and settles there, causes some imperceptible or difficult to undo environmental damage and then an invasive type.

Most often, humans are primarily responsible for the intentional or unintentional displacement of species, both by land and by sea. This is the case with the invasive corals of the genus Tubastraea, popularly known as sun coral. Natives of the Pacific Ocean and viewed as invaders in the Caribbean Sea and the Gulf of Mexico, they sailed – and arrived in Brazil – hitchhiking on the submerged pillars of oil platforms to which they were attached.

Recent research shows species transported in ship hulls and in water stored in ships, in navigation buoys, amphibious or seaplanes, and even in floating marine debris. (In other words, what is thrown into the sea not only pollutes, but can also facilitate the introduction of invasive species.) Other human activities that allow access to a non-native species are open-sea cultivation of oysters, clams , Scallops, crabs, lobsters, fish or algae, offering organisms as food for other species and accidental or intentional disposal of aquarium species. The soft coral Sansibia sp. For example, it has a blue color that attracts any marine animal lover and makes it a common item in marine aquariums. Unfortunately, this species was found on the seabed in Angra dos Reis, Rio de Janeiro, in 2017, and research suggests that the introduction came after the illegal disposal of organisms from a private saltwater aquarium.

The ecological effects of bioinvasion can be seen as one of the main culprits for the global loss of biodiversity. However, the complications are not limited to environmental impacts, as the arrival and establishment of a new species can cause economic problems and even human health. For example, the Caribbean mollusk Isognomon bicolor, which was introduced to Brazil in the 1990s, lives on the rocky coast and kills other species of molluscs, including economically important species used for cultivation and human consumption. Another mollusk, the land snail Achatina fulica, was illegally imported into Brazil in the 1980s to serve as a replacement for the famous snail, when breeders realized that Brazilians were not in the habit of consuming this type of food, putting the snails in place into nature freely. In a short time, this mollusk destroys vegetable gardens and gardens and can transmit diseases such as meningitis.

In 2020 a survey was carried out by myself and Dr. Joel Creed, another researcher studying marine bioinvasion, identified 138 marine species introduced to Brazil, a number that represents a 160% increase in the number of invasive alien species since the last study a decade ago. There are efficient ways to avoid or reduce the effects of bioinvasion that together can provide a solution to this problem. Studying the habits of introduced species and identifying the means of transport are some of the alternatives to prevent new introductions. Effective public policy, awareness and updated lists of introduced species also help.


Larissa Pires-Teixeira is a biologist, professor of natural sciences and biology and a doctoral candidate in the Postgraduate Program in Ecology and Evolution at UERJ.

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