Towards a trait-based modelling framework to understand and predict consequences of seascape habitat change on temperate reef communitiesResistance, Resilience and Phase Shifts

Martin Marzloff¹, Thomas Benoit¹, Mathieu Chevalier¹, Bastien Mourguiart¹, Aurélien Boyé¹

¹Ifremer, France

Non-trophic interactions are increasingly recognised as pivotal to ecological dynamics, particularly in coastal ecosystems and temperate reef communities where complex feedbacks between seafloor habitats and benthic fauna are ubiquitous. Because habitat-mediated processes (e.g. shelter provision, buffering of environmental changes) are challenging to systematically estimate across all taxa, this work aimed at developing an original modelling approach that relies on habitat-forming species traits to generically capture how they contribute to benthic ecosystem dynamics. Based on both, (i) a workshop to elicit expert knowledge about major dimensions of habitat-mediated processes across scales, as well as (ii) a systematic review of scientific literature on habitat-forming species, we have developed an original framework to characterise how major interactions and feedback between habitat-formers and benthic species contribute to benthic ecosystem dynamics. The expert workshop led to a consensual synthesis of benthic species contributions to seafloor habitat characteristics according to three major dimensions: (1) energy flow (e.g. primary production); (2) spatial structuring (e.g. substrate modification or tri-dimensional complexity); and (3) temporal stability (e.g. buffering of environmental variability to maintain microclimatic conditions). Available trait data collated from the litterature primarily focus on the physical structure dimension rather than on energy flows and temporal stability. This restricts our mechanistic understanding of how species contribute to all three dimensions, and whether trade-offs exists between them. To address these gaps, we consolidated a hierarchical classification of foundation species traits designed to support the creation of an interoperable habitat traits database. This database will enable a systematic quantification across taxa of benthic species’ contribution to seascapes. Building on this systematic typology of species-specific contribution to seascape features, we have developed a suite of original trait-based modelling approaches to (i) capture potential shifts in seascape features; as well as (ii) estimates flow-on effects on benthic species diversity. We illustrate using both conceptual and regional examples how these suite of trait-based modelling approaches can help understand and project future habitat changes in coastal ecosystems, and subsequent effects on reef functioning, community structure and dynamics.