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September 12, 2012

Exotic species: invaders of the seas


They are often beautiful, but also dangerous. Invasive species are increasingly common on land and at sea, and in many cases their presence in inappropriate places has to do with human activities. Some arrive in ballast water from visiting vessels, others escape from aquariums or travel through artificial channels, and their stocks are expanding and migrating into new areas because of climate change.

Without competitors, or predators, these species displace native species and colonize habitats that are not theirs. Thus, altering the food chain and endangering both commercial and other species that have ecological value or are endemic.

In the Mediterranean, studies have identified the existence of 745 invasive species. One of which is the Caulerpa racemosa, a plant that every year spreads at the expense of native seagrasses. Oceana has documented this species numerous times during our expeditions.

If you’re a fan of our on board expedition diaries, you’ve seen we’ve also found invasive algae, ctenophores, corals … In fact, here is a gallery of invasive species that we have found in recent years.