Journal Article

Community dynamics and ecosystem simplification in a high-CO₂ ocean

Kroeker, Kristy J., Micheli, Fiorenza, Gambi, Maria Cristina

2013

Overview

Disturbances are natural features of ecosystems that promote variability in the community and ultimately maintain diversity. Although it is recognized that global change will affect environmental disturbance regimes, our understanding of the community dynamics governing ecosystem recovery and the maintenance of functional diversity in future scenarios is very limited. Here, we use one of the few ecosystems naturally exposed to future scenarios of environmental change to examine disturbance and recovery dynamics. We examine the recovery patterns of marine species from a physical disturbance across different acidification regimes caused by volcanic CO ₂ vents. Plots of shallow rocky reef were cleared of all species in areas of ambient, low, and extreme low pH that correspond to near-future and extreme scenarios for ocean acidification. Our results illustrate how acidification decreases the variability of communities, resulting in homogenization and reduced functional diversity at a landscape scale. Whereas the recovery trajectories in ambient pH were highly variable and resulted in a diverse range of assemblages, recovery was more predictable with acidification and consistently resulted in very similar algal-dominated assemblages. Furthermore, low pH zones had fewer signs of biological disturbance (primarily sea urchin grazing) and increased recovery rates of the dominant taxa (primarily fleshy algae). Together, our results highlight how environmental change can cause ecosystem simplification via environmentally mediated changes in community dynamics in the near future, with cascading impacts on functional diversity and ecosystem function.

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: Acidification / Algae / Animal and plant ecology / Animal, plant and microbial ecology / Applied ecology / Biodiversity / Biological and medical sciences / Biological Sciences / Carbon Dioxide / Carbonates / Community structure / Conservation, protection and management of environment and wildlife / Coral Reefs / Echinoidea / Ecological succession / ecosystems / Environmental degradation: ecosystems survey and restoration / functional diversity / Fundamental and applied biological sciences. Psychology / General aspects / global change / grazing / homogenization / Hydrogen-Ion Concentration / landscapes / Marine ecosystems / Ocean acidification / Oceans / Oceans and Seas / Sea urchins / Species / Synecology