Functional biodiversity loss along natural CO2 gradients

Nuria Teixidó,Enric Ballesteros,Valeriano Parravacini,Kristy Kroeker,Fiorenza Micheli,Sebastien Villéger,Maria Cristina Gambi

doi:10.1038/s41467-018-07592-1

Abstract

The effects of environmental change on biodiversity are still poorly understood. In particular, the consequences of shifts in species composition for marine ecosystem function are largely unknown. Here we assess the loss of functional diversity, i.e. the range of species biological traits, in benthic marine communities exposed to ocean acidification (OA) by using natural CO2 vent systems. We found that functional richness is greatly reduced with acidification, and that functional loss is more pronounced than the corresponding decrease in taxonomic diversity. In acidified conditions, most organisms accounted for a few functional entities (i.e. unique combination of functional traits), resulting in low functional redundancy. These results suggest that functional richness is not buffered by functional redundancy under OA, even in highly diverse assemblages, such as rocky benthic communities.

Highlights

The effects of environmental change on biodiversity are still poorly understood
The total number of benthic species decreases with acidification, from 55 species in the ambient pH zones to 45 in the low pH zones and 22 in the extreme low pH zones, representing 76%, 62%, and 31% of the global pool (Fig. 1). These pH zones are delimited based on spatial variability in CO2 venting intensity: the pH and carbonate system in the ambient pH zones is comparable to current conditions, whereas the low pH zones are most comparable to projections for the acidification of the near-future surface ocean, and the extreme low pH zone regimes are most comparable to more extreme distantfuture scenarios
Our results show that functional diversity (FE richness, functional richness as the volume surrounding the functional entities (FE)) decreases with acidification and that functional loss is more pronounced than the corresponding decrease in taxonomic diversity

Summary

Introduction

The effects of environmental change on biodiversity are still poorly understood. In particular, the consequences of shifts in species composition for marine ecosystem function are largely unknown. We assess the loss of functional diversity, i.e. the range of species biological traits, in benthic marine communities exposed to ocean acidification (OA) by using natural CO2 vent systems. Natural carbon dioxide vents provide an unparalleled opportunity to assess species and whole-ecosystem responses to a projected global change driver[17,18,19,20,21] These systems can provide novel insights into how oceans will function under future OA scenarios. Applying functional-trait-based approaches[34] to entire benthic marine assemblages at natural CO2 vents can provide new insights into mechanisms of resilience to OA across taxa, as well as functional changes in diverse ecosystems and geographic regions

Methods

Results

Conclusion