Project: Effects of Disturbance and Larval Supply on Communities at Hydrothermal Vents

NSF award abstract:
The long-term aim of this project is to understand the effects of disturbance on species occurrence and regional diversity in vent systems. The investigator is working toward that goal by conducting field studies on larval dispersal and colonization processes, and by collaborating with theoretical ecologists. The present project investigates a unique set of field observations gathered from decade-long monitoring of vents before and after a recent catastrophic eruption on the East Pacific Rise (EPR). The specific objectives are to determine whether succession is deterministic (or are there alternative stable states?), and whether disturbance at one vent field can influence community structure on a larger spatial scale. Answering these questions requires characterization of larval exchange between vents and of the effect of pioneer colonists on successional trajectory. The approach is to characterize species composition of larvae and colonists at three vent sites on the EPR: one that was disturbed by the eruption (9 degrees 50 minutes N) and two that remained undisturbed (9 degrees 47 minutes N and 9 degrees 30 minutes N). The investigators are running out of time to process the samples, because they degrade over time and the specimens are at risk of losing morphological detail which is critical for species identification. This award has modest funding to focus specifically on species identification and enumeration, without attempting to interface with models or population genetic analyses. These will come later.

The question of how vent communities persist despite living in patchy, ephemeral habitat has intrigued scientists since the discovery of vents in the late 1970s. A necessary synthesis of the influence of larval connectivity on metacommunity dynamics at the regional scale continues to elude us. This project works toward that synthesis by characterizing critical aspects of larval exchange and community succession at vents on the well-studied EPR. This study has general application to vent systems globally because it challenges the assumption that vent succession is deterministic, and it will contribute to our understanding of spatial scales of larval connectivity. The data on larval exchange and community resilience that will result from this study are precisely the kind needed for metapopulations modeling, for prediction of vent community response to anthropogenic events such as seafloor mining, and to inform management efforts at the Marianas Trench Marine National Monument.