Species diversity and invasion resistance in a marine ecosystem

Theory predicts that systems that are more diverse should be more resistant to exotic species, but experimental tests are needed to verify this. In ex perimental communities of sessile marine invertebrates, increased species r ichness Significantly decreased invasion success, apparently because specie s-rich communities more completely and efficiently used available space, th e limiting resource in this system. Declining biodiversity thus facilitates invasion in this system, potentially accelerating the loss of biodiversity and the homogenization of the world's biota.