Dr Martin Marzloff1, Dr Philippe Cugier1, Dr Carmen David1,2, Raphaël Clément1, Dr Anthony Knights3, Céline Cordier1, Dr Stanislas Dubois1, Dr Louise Firth3, Dr Flavia Nunes1
1Ifremer, DYNECO-LEBCO, Brest, France, 2Marine Animal Ecology Group, Wageningen University, Wageningen, The Netherlands, 3School of Biological and Marine Sciences, University of Plymouth, Plymouth, United Kingdom
In temperate marine systems, reef-forming species are critical for conservation as they support a wide range of species and promote biodiversity and ecosystem functioning. Locally, coastal biogenic habitats persistence and recovery from perturbations depend on colonization by new recruits. Thus, characterising larval dispersal among distant reefs is key to understand how connectivity shapes metapopulation structure and determines network coherence. We used a biophysical transport model to simulate larval/seed dispersal of several key habitat-formers (including the reef-building polychaete Sabellaria alveolata) along the French western coastline. We combined dispersal modelling, genetics and network analysis to identify key reef areas and critical dispersal pathways, whose presence in the network are vital to its overall coherence. We explored ways to reconcile hydrodynamics connectivity with population genetics on different model species. For instance, we compared alternative dispersal pathways defined by increasing connectivity thresholds (i.e., minimum dispersal rate for the presence of a connection) to genetic distances. We also tested scenarios of sequential loss of reefs: randomly, by habitat quality (a score for reef status and occupancy in an area) or by betweenness centrality metric (i.e. the proportion of shortest paths between pairs of areas that pass through a given node). We found that the network of S. alveolata reefs forms two main regional clusters, the Atlantic coast and the English Channel, which are connected only through weak sporadic dispersal events. Within each cluster, the network is characterized by relatively high connectivity among neighbouring areas with reefs, maintained even under higher connectivity thresholds. Simulating scenarios of sequential loss of reefs further identified high centrality reefs as key to network coherence. Effective conservation of important reef habitat requires a network of protected areas designed to sustain a combination of locally-important source reefs and those that act as stepping-stones connecting distant reefs.
Presentation Slides PDF – Martin Marzloff
Biography:
To be consolidated.
MSc in fisheries sciences from Agrocampus, Rennes, France
PhD in quantitative marine ecology from the joint University of Tasmania / CSIRO QMS programme. Modelling shifts from kelp beds to sea urchin barrens in SE Australia and estimating ecological thresholds
ARC postdoc at IMAS, university of Tasmania on distribution and range shifts in deep reef habitat forming species in eastern Australia
Since 2016 : research scientist in ecosystem modelling at Ifremer Brest, France. Diversity of projects from modelling individual processes (such as connectivity – topic of today’s talk) to community dynamics or even to participatory modelling with stakeholders
