We’ve screwed up the coasts so badly that an invasive species is a plus

Enlarge (credit: European Network on Invasive Alien Species)

Across the globe, invasive species have caused no end of trouble. Their populations can explode because they have no natural predators. Or they are predators themselves who push native species to the brink of extinction. They can upset ecosystems that had evolved a fine balance.

But, according to a new study published this week in PNAS, not every invasive species is a negative. In some cases where we've wiped out a key component of the local ecosystem, an invasive species can take its place. The study's example? An invasive algae can restore lost habitat to coastal ecosystems, providing a nursery for species like crab and shrimp.

The work that led to this conclusion took place in tidal flats on the coast of North Carolina. Normally, this type of geography is broken up by distinct habitats provided by different organisms: coral reefs, beds of sea grass, and oyster reefs. The habitats formed by these species provide shelter for other species, allowing entire ecosystems to develop. But, over the last century or so, many of these habitats have been wiped out, leaving bare sediment behind.

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