Using ecological trajectories to track long‐term taxonomic and functional changes in benthic shallow soft‐bottom communities (Bay of Saint‐Brieuc, English Channel)

Taxonomic and functional trajectories of benthic assemblages were studied in shallow soft-bottom sediments in the bay of Saint-Brieuc (Western English Channel). Changes were assessed at different spatial and temporal scales using a macrobenthic dataset based on 38 stations sampled in 1987 and 2019, coupled with data from one station sampled annually between 2005 and 2019 as part of the European Water Framework Directive monitoring programme.

Taxonomic trajectories indicated 1) changes in the structure and distribution of benthic assemblages, 2) an homogenization of the assemblages, and 3) significant functional shifts.

Fishing activities and nutrient enrichment are probably strong drivers of the observed changes, as suggested by the higher mortality rate of fragile, flexible, tubiculous and burrowing species, and the increase in the abundance of opportunistic species in the assemblages. Certain populations of macroinvertebrates seem jointly controlled by climate change and by the aforementioned local factors of disturbance.

The Community Trajectory Analysis framework appears as a new and interesting method to track ecological changes in marine ecosystems by measuring change with respect to a baseline state, to help define ecological recovery (station returning to the initial ecological state) and departure (station presenting increased changes over time), and to analyse trajectory similarity.

According to the degradation of habitat over time, we identify the need for the implementation of knowledge-based conservation strategies, especially within Natura 2000 sites.


benthic assemblages, community trajectory analysis, conservation, ecological trajectories, eutrophication, long-term changes, macrofauna, Natura 2000, scallop dredging

Full Text

Publisher's official version
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Data S1. Appendix A: Dredging rules and fishing effort
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Data S2. Appendix B: Categories of functional traits
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Data S3. Appendix C: Map of the sediment properties in the 38 ResTroph stations between 1987 and 2019
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Data S4. Appendix D: Evolution of sediment properties at station R from 2005 to 2019
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Data S5. Appendix E: General description of the benthic macrofauna according to sampling campaigns
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Data S6. Appendix F: Map of the distribution and abundance of the main bivalve species
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Data S7. Appendix G: Station R functional factor map
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Data S8. Appendix H: Evolution of the wave regime over the last 30 years close to station R (SHOM)
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Author's final draft
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How to cite
Sturbois Anthony, Cormy Gaetan, Le Moal Alexandre, Schaal Gauthier, Broudin Caroline, Thiébaut Eric, Ponsero Alain, Le Mao Patrick, Jones Auriane, Riera Pascal, Gauthier Olivier, Desroy Nicolas (2021). Using ecological trajectories to track long‐term taxonomic and functional changes in benthic shallow soft‐bottom communities (Bay of Saint‐Brieuc, English Channel). Aquatic Conservation-marine And Freshwater Ecosystems. 31 (11). 3013-3033.,

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