β-Diversity and Species Accumulation in Antarctic Coastal Benthos: Influence of Habitat, Distance and Productivity on Ecological Connectivity

Simon F Thrush,Alf Norkko,Mariachiara Chiantore,Judi E Hewitt,Vonda J Cummings,A Peter Klimley

doi:10.1371/journal.pone.0011899

Abstract

High Antarctic coastal marine environments are comparatively pristine with strong environmental gradients, which make them important places to investigate biodiversity relationships. Defining how different environmental features contribute to shifts in β-diversity is especially important as these shifts reflect both spatio-temporal variations in species richness and the degree of ecological separation between local and regional species pools. We used complementary techniques (species accumulation models, multivariate variance partitioning and generalized linear models) to assess how the roles of productivity, bio-physical habitat heterogeneity and connectivity change with spatial scales from metres to 100's of km. Our results demonstrated that the relative importance of specific processes influencing species accumulation and β–diversity changed with increasing spatial scale, and that patterns were never driven by only one factor. Bio-physical habitat heterogeneity had a strong influence on β-diversity at scales <290 km, while the effects of productivity were low and significant only at scales >40 km. Our analysis supports the emphasis on the analysis of diversity relationships across multiple spatial scales and highlights the unequal connectivity of individual sites to the regional species pool. This has important implications for resilience to habitat loss and community homogenisation, especially for Antarctic benthic communities where rates of recovery from disturbance are slow, there is a high ratio of poor-dispersing and brooding species, and high biogenic habitat heterogeneity and spatio-temporal variability in primary production make the system vulnerable to disturbance. Consequently, large areas need to be included within marine protected areas for effective management and conservation of these special ecosystems in the face of increasing anthropogenic disturbance.

Highlights

Characterising how different measures of diversity change with scale is fundamental to defining many ecological relationships, such as meta-community assembly and ecological connectivity [1,2,3]
New techniques for estimating species richness that explicitly incorporate species turnover [11,12] allow investigations of how different environmental features contribute to shifts in species richness across ecological landscapes [13]
Relationships between species richness and productivity often vary with taxonomic groups, habitats and scales of sampling [20,21], with the only generalisation being that productivity-diversity relationships change with spatial scale [17]

Summary

Introduction

Characterising how different measures of diversity change with scale is fundamental to defining many ecological relationships, such as meta-community assembly and ecological connectivity [1,2,3]. B–diversity has gained considerable value as a conservation tool, by representing either species turnover in space or time, or ecological connectivity as defined by the difference between local diversity and the regional species pool [6,7,8,9]. Relationships between species richness and productivity often vary with taxonomic groups, habitats and scales of sampling [20,21], with the only generalisation being that productivity-diversity relationships change with spatial scale [17]. These factors emphasize the importance of teasing apart relationships incorporating both local and broad-scale factors [18]

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