Trait‐based approach to monitoring marine benthic data along 500 km of coastline

Aurélien Boyé,Céline Houbin,Marion Maguer,Pierre Legendre,Jacques Grall,Caroline Broudin,Gabin Droual,Vincent Le Garrec,Éric Thiébaut,Olivier Gauthier

doi:10.1111/ddi.12987

Abstract

AbstractAimβ diversity and its linkages with ecosystem functioning remain poorly documented. This impedes our capacity to predict biodiversity changes and how they affect ecosystem functioning at scales relevant for conservation. Here, we address the functional implications of ongoing seafloor changes by characterizing at regional scale the taxonomic and functional α and β diversities of benthic habitats currently threatened by biotic homogenization.LocationWestern Europe.MethodsCombining a trait‐based approach to benthic community monitoring data covering a 7‐year period and 500 km of coast, we explored the mechanisms governing community assembly in habitats associated with two types of foundation species, intertidal seagrass and subtidal maerl beds, compared to bare sediment at similar tidal level. We assessed their spatial and temporal variability and linked these mechanisms to their repercussions at regional scale through analyses of taxonomic and functional β diversity.ResultsFoundation species locally promote taxonomic and functional diversity. Maerl fine‐scale heterogeneity promotes niche diversity and leads to high functional redundancy for the whole subtidal compartment, providing insurance for seafloor functioning. Seagrass high diversity seems more reliant on transient species and is associated with redundancy of only a few functions. Maintaining the seascapes in which seagrass are embedded seems essential to ensure their long‐term functioning. At regional scale, the locally poorer bare sediment harbour similar functional richness as biogenic habitats because of higher within‐habitat β diversity.Main conclusionsOur study reinforces the conservation value of biogenic habitats but highlights that different mechanisms underlie their local diversity, which has implications for the vulnerabilities of their associated communities. Accounting for β diversity at regional scale also stressed a potential underrated conservation value of bare sediment for benthic ecosystem functioning. Coupling trait‐based approaches to monitoring data can help link broad‐scale β diversity to its underlying drivers, bringing local mechanistic understanding closer to the scales at which biodiversity loss and management actions occur.

Highlights

Earth is profoundly marked by the imprints of anthropic activities (Steffen et al, 2011)
We develop a trait‐based approach focused on Polychaeta (Phylum Annelida), a phylogenetically diverse class comprised of a great di‐ versity of species exhibiting a wide range of ecological strategies (Giangrande, 1997; Jumars, Dorgan, & Lindsay, 2015) and having a critical role in ecosystem functioning through activities such as bioturbation (Queirós et al, 2013)
Biogenic habitats emerged as a major factor governing the structure and composition of polychaete assemblages at the regional scale, consistently promoting their α diversity across dis‐ parate environments

Summary

| INTRODUCTION

Earth is profoundly marked by the imprints of anthropic activities (Steffen et al, 2011). To better apprehend the potential consequences of their degradation, we compare their taxonomic and functional α and β diversities to those of bare sed‐ iment using monitoring data covering three years (2007, 2010 and 2013) and the whole Brittany seaboard (France; Figure 1a), a highly diverse environmental mosaic (Boyé et al, 2017) For this purpose, we develop a trait‐based approach focused on Polychaeta (Phylum Annelida), a phylogenetically diverse class comprised of a great di‐ versity of species exhibiting a wide range of ecological strategies (Giangrande, 1997; Jumars, Dorgan, & Lindsay, 2015) and having a critical role in ecosystem functioning through activities such as bioturbation (Queirós et al, 2013). The balance of these two processes is difficult to predict, leading to uncertainties regarding the contribution of each habitat to regional diversity

| METHODS

| DISCUSSION

Findings

| CONCLUSIONS