Marine parasites at island-like, disturbed hydrothermal vents

Parasite diversity is sensitive to habitat disturbance and isolation, yet these expectations have rarely been tested in extreme environments. I studied the metazoan parasite community at hydrothermal vents at 9°50’N on the East Pacific Rise – an island-like, frequently disturbed, successional habitat where few parasite species had yet been discovered. I surveyed the vent community and compared its parasite diversity to other marine ecosystems that differ in their isolation and disturbance (atoll sandflat and kelp forest). The vent community overall had fewer parasite species because there were fewer vertebrate predators (fish) and shorter food chains. Contrary to expectation, parasites with complex (multi-host) life cycles were relatively diverse at vents, and several stages of multiple species were linked using morphology and genetics. These findings demonstrate that taxonomically and functionally diverse parasites inhabit extreme environments, with implications for the resilience of obligate symbionts to natural disturbance.