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1. Functional traits provide new insight into recovery and succession at deep‐sea hydrothermal vents

   https://doi.org/10.1002/ecy.3418  

   Dykman, Lauren N.; Beaulieu, Stace E.; Mills, Susan W.; Solow, Andrew R.; Mullineaux, Lauren S. (July 2021, Ecology)

   Abstract Investigation of communities in extreme environments with unique conditions has the potential to broaden or challenge existing theory as to how biological communities assemble and change through succession. Deep‐sea hydrothermal vent ecosystems have strong, parallel gradients of nutrients and environmental stress, and present unusual conditions in early succession, in that both nutrient availability and stressors are high. We analyzed the succession of the invertebrate community at 9°50′ N on the East Pacific Rise for 11 yr following an eruption in 2006 in order to test successional theories developed in other ecosystems. We focused on functional traits including body size, external protection, provision of habitat (foundation species), and trophic mode to understand how the unique nutritional and stress conditions influence community composition. In contrast to established theory, large, fast‐growing, structure‐forming organisms colonized rapidly at vents, while small, asexually reproducing organisms were not abundant until later in succession. Species in early succession had high external protection, as expected in the harsh thermal and chemical conditions after the eruption. Changes in traits related to feeding ecology and dispersal potential over succession agreed with expectations from other ecosystems. We also tracked functional diversity metrics over time to see how they compared to species diversity. While species diversity peaked at 8 yr post‐eruption, functional diversity was continuing to increase at 11 yr. Our results indicate that deep‐sea hydrothermal vents have distinct successional dynamics due to the high stress and high nutrient conditions in early succession. These findings highlight the importance of extending theory to new systems and considering function to allow comparison between ecosystems with different species and environmental conditions. 

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2. Resilience of a Fire-Maintained Pinus palustris Woodland to Catastrophic Wind Disturbance: 10 Year Results

   https://doi.org/10.3390/f12081051  

   Goode, J. Davis; Kleinman, Jonathan S.; Hart, Justin L. (August 2021, Forests)

   Increased interest in ecosystem recovery and resilience has been driven by concerns over global change-induced shifts in forest disturbance regimes. In frequent-fire forests, catastrophic wind disturbances modify vegetation-fuels-fire feedbacks, and these alterations may shift species composition and stand structure to alternative states relative to pre-disturbance conditions. We established permanent inventory plots in a catastrophically wind-disturbed and fire-maintained Pinus palustris woodland in the Alabama Fall Line Hills to examine ecosystem recovery and model the successional and developmental trajectory of the stand through age 50 years. We found that sapling height was best explained by species. Species with the greatest mean heights likely utilized different regeneration mechanisms. The simulation model projected that at age 50 years, the stand would transition to be mixedwood and dominated by Quercus species, Pinus taeda, and P. palustris. The projected successional pathway is likely a function of residual stems that survived the catastrophic wind disturbance and modification of vegetation-fuels-fire feedbacks. Although silvicultural interventions will be required for this system to exhibit pre-disturbance species composition and structure, we contend that the ecosystem was still resilient to the catastrophic disturbance because similar silvicultural treatments were required to create and maintain the P. palustris woodland prior to the disturbance event. 

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3. Deep seafloor hydrothermal vent communities buried by volcanic ash from the 2022 Hunga eruption

   https://doi.org/10.1038/s43247-024-01411-w  

   Beinart, Roxanne A.; Arellano, Shawn M.; Chaknova, Marcus; Meagher, Jasper; Davies, Andrew J.; Lopresti, Joseph; Cowell, Emily J.; Betters, Melissa; Ladd, Tanika M.; Plowman, Caitlin Q.; et al (May 2024, Communications Earth & Environment)

   Abstract Mass mortality of marine animals due to volcanic ash deposition is present in the fossil record but has rarely been documented in real time. Here, using remotely-operated vehicle video footage and analysis of ash collected at the seafloor, we describe the devastating effect of the record-breaking 2022 Hunga submarine volcanic eruption on endangered and vulnerable snail and mussel species that previously thrived at nearby deep-sea hydrothermal vents. In contrast to grazing, scavenging, filter-feeding, and predatory vent taxa, we observed mass mortality, likely due to smothering during burial by thick ash deposits, of the foundation species, which rely on symbiotic chemosynthetic bacteria for the bulk of their nutrition. This is important for our broad understanding of the natural disturbance of marine ecosystems by volcanic eruptions and for predicting the effects of anthropogenic disturbance, like deep-sea mining, on these unique seafloor habitats. 

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4. Disturbance alters transience but nutrients determine equilibria during grassland succession with multiple global change drivers

   https://doi.org/10.1111/ele.14229  

   DeSiervo, Melissa H.; Sullivan, Lauren L.; Kahan, Larissa M.; Seabloom, Eric W.; Shoemaker, Lauren G. (May 2023, Ecology Letters)

   Abstract Disturbance and environmental change may cause communities to converge on a steady state, diverge towards multiple alternative states or remain in long‐term transience. Yet, empirical investigations of successional trajectories are rare, especially in systems experiencing multiple concurrent anthropogenic drivers of change. We examined succession in old field grassland communities subjected to disturbance and nitrogen fertilization using data from a long‐term (22‐year) experiment. Regardless of initial disturbance, after a decade communities converged on steady states largely determined by resource availability, where species turnover declined as communities approached dynamic equilibria. Species favoured by the disturbance were those that eventually came to dominate the highly fertilized plots. Furthermore, disturbance made successional pathways more direct revealing an important interaction effect between nutrients and disturbance as drivers of community change. Our results underscore the dynamical nature of grassland and old field succession, demonstrating how community properties such as diversity change through transient and equilibrium states. 

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5. Tracking Crustal Permeability and Hydrothermal Response During Seafloor Eruptions at the East Pacific Rise, 9°50’N

   https://doi.org/10.1029/2021GL095459  

   Barreyre, T.; Parnell‐Turner, R.; Wu, J. ‐N.; Fornari, D. J. (February 2022, Geophysical Research Letters)

   Abstract Permeability controls energy and matter fluxes in deep‐sea hydrothermal systems fueling a 'deep biosphere' of microorganisms. Here, we indirectly measure changes in sub‐seafloor crustal permeability, based on the tidal response of high‐temperature hydrothermal vents at the East Pacific Rise 9°50’N preceding the last phase of volcanic eruptions during 2005–2006. Ten months before the last phase of the eruptions, permeability decreased, first rapidly, and then steadily as the stress built up, until hydrothermal flow stopped altogether ∼2 weeks prior to the January 2006 eruption phase. This trend was interrupted by abrupt permeability increases, attributable to dike injection during last phase of the eruptions, which released crustal stress, allowing hydrothermal flow to resume. These observations and models suggest that abrupt changes in crustal permeability caused by magmatic intrusion and volcanic eruption can control first‐order hydrothermal circulation processes. This methodology has the potential to aid eruption forecasting along the global mid‐ocean ridge network. 

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