Pauline Chauvet, Institut Français de Recherche Pour L'exploitation de la Mer, Brest, France
Marjolaine Matabos, Institut Français de Recherche Pour L'exploitation de la Mer, Brest, France
Anna Metaxas, Dalhousie University, Halifax, Canada
Alex Hay, Dalhousie University, Halifax, Canada
Characterization of factors controlling the macrofaunal communities dynamic and biodiversity of Barkley Canyon.
The Barkley canyon area, located along the active continental margin of the Northeast Pacific within the Pacific Oxygen Minimum Zone, provides ideal settings to study factors controlling biodiversity along diverse abiotic gradients. Part of the Ocean Networks Canada deep-sea cabled observatory, the study area encompasses a wide range of environments from the continental shelf (400m) to the continental slope (900m). Since 2010, instruments deployed on the seafloor give access to high frequency, continuous and concomitant environmental and biological data. Previous studies on Barkley canyon (BC) communities were able –on a short term, hourly sampling basis, to show that temporal structures coincided with the ambient current oscillation1. In order to detect temporal structures at larger scales and to increase our knowledge about benthic community dynamics in relation with environmental changes, one year of video (2012-2013) from the upper slope, the wall and axis of Barkley canyon were analyzed. Results revealed a clear distinction between shallow (400m) and deep (900 and 1000m) macrofaunal communities that could be related to environmental factors (i) varying along the depth gradient, such as temperature, or (ii) affected by the canyon’s topography, such as bottom current. . The analysis of recruitment substrates (INDEEP project) also showed some distinctions between sites with a higher diversity on the upper slope. The decomposition of temporal structure at the three locations highlighted three significant times scales in the community variations. While the finest scale (14-30 days) was probably due to biotic interactions currents and changes in water mass significantly contributed to community variation at broader scale, especially on the almost seasonal cycle of 2.5 to 5 months. This seasonal pattern was supported by the occurrence of a seasonal variation in the grooved tanner crabs Chionoecetes tanneri population structure, with the recruitment of small individuals in the fall followed by growth and migration away from the camera, suggesting a seasonal reproduction for this species. Understanding variations in community dynamics at seasonal and inter-annual scales is essential to understand long-term changes in response to environmental forcing and anthropogenic pressure.
1. Matabos, M. et al. High-frequency study of epibenthic megafaunal community dynamics in Barkley Canyon: A multi-disciplinary approach using the NEPTUNE Canada network. J. Mar. Syst. 130, 56–68 (2014).
Theme 3: Biological patterns in submarine canyons: role of scale and heterogeneity
Macrofaunal communities, Temporal variations, Spatial variations, Seasonality, INDEEP