Reciprocal Caulerpa invasion: Mediterranean native Caulerpa ollivieri in the Bahamas supported by human nitrogen enrichment

The genus Caulerpa is known for its invasion of tropical, subtropical, and temperate coastal waters. Whereas the role of humans as vectors for the introduction of Caulerpa has been well documented, other anthropogenic factors that may mediate the success of an invasion are poorly understood. We provide evidence that a recent invasion of Caulerpa ollivieri into shallow Bahamian seagrass meadows is facilitated by anthropogenic nitrogen enrichment from sewage. Considering the accelerating nitrogen enrichment of coastal waters worldwide, our results suggest that reduction of anthropogenic nitrogen inputs must be achieved as a means of controlling similar biotic invasions.