Persistent effects of disturbance on larval patterns in the plankton after an eruption on the East Pacific Rise

Abstract

To predict how benthic communities will respond to disturbance, it is necessary to understand how disturbance affects the planktonic larval supply available to recolonize the area. Deep-sea hydrothermal vent fauna along the East Pacific Rise (EPR) experience frequent local extinctions due to tectonic and magmatic events, but the effects on regional larval abundance and diversity are unknown. We had been monitoring larvae at 9° 50' N on the EPR prior to the 2006 eruption and were able to resume collections shortly afterward. We found that many species that were common before the eruption became significantly less so afterward, whereas a few other species experienced a transient spike in abundance. Surprisingly, overall species richness in the plankton was high 9 mo after the eruption, but then decreased sharply after 1 yr and had not returned to pre-eruption levels after 2 yr. These results suggest that recovery from disturbance may continue to be affected by limited larval supply even several years after a disturbance event. This delay in recovery means that larvae of pioneer species may dominate potential colonists, even after benthic habitats have transitioned to conditions that favor later-successional species. Moreover, the combined effects of natural and anthropogenic disturbance (e.g. mining) would be likely to cause more profound and long-lasting changes than either event alone. Our results indicate that we do not have sufficient data to predict the timing of recovery after disturbance in the deep sea, even in a well-studied vent system.