Unique Colonization Time Series Reveals Long-Term Successional Changes in the Functional Traits of a Deep-Sea Hydrothermal Vent Invertebrate Community

The recovery of biological function after disturbance, though an important component of resilience, has rarely been studied in the marine environment. Hydrothermal vent invertebrate communities at fast-spreading plate boundaries are challenged by frequent volcanic disturbance. Dispersal, colonization, and succession are crucial to the resilience of these communities and the maintenance of local and regional diversity. Using a unique twelve-year colonization data set, we characterized the compositional change of functional traits following a catastrophic eruption at the 9º50'N vent field on the East Pacific Rise (EPR). Our results indicate eruptive disturbance on the EPR opens space for functionally distinct species. Following the eruption, colonists were primarily grazing deposit feeders or endosymbiont hosts with planktonic dispersal and larger body size. After eight years, the community began to resemble pre-disturbance functional composition. Predators and suspension feeders were more prevalent, indicating increased food web complexity. Colonists with small body size, brooding, and benthic development became more prevalent over time, whereas foundation species became less prevalent. We also clustered species into functional guilds based on their similarity in expression of twelve traits. Guild composition changed markedly over succession, demonstrating the power of functional clustering to simplify community-level data without losing valuable ecological information. Both species and guild diversity returned to baseline levels over the twelve-year time series. Species diversity peaked around ten years post-eruption, while guild diversity continued to increase. By combining functional trait analysis with long-term colonization data, this study reveals that the function of a recovering vent community changes significantly over more than a decade after catastrophic disturbance. Such quantitative long-term observations are critical to assess the resilience of naturally-disturbed benthic communities and potential impacts of deep seabed mining.