Contacts

LECOB
1, avenue Pierre Fabre
66650 Banyuls-sur-mer
France

Direction adjointe : Stéphane Hourdez
04-30-19-24-46

Formation permanente : Béatrice Rivière
04-68-88-73-82

Assistant de prévention : Erwan Péru
04-68-88-73-66

M2 Intership

Scientific supervisor: GUIZIEN Katell
, DR2 HDR CNRS (Tel : 04 68 88 73 19, e-mail: Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser.),

Hosting laboratory: Laboratoire d’Ecogéochimie des Environnements Benthiques (UMR8222), Observatoire Océanologique de Banyuls S/ Mer, 1 avenue Pierre Fabre, 66650 Banyuls S/ Mer, France

Short description of the internship:

When ocean beds are covered by large obstacles, the classical boundary layer structure is significantly modified. The wakes produced by these obstacles create strong spatial variations in the flow, over a region (embedded within the boundary layer) known as the roughness sublayer (Ghisalberti 2009). Long-lived hard and soft coral species that are able to develop dense patches with a complex, three-dimensional structure form an animal forest canopy (sensu Rossi et al 2017), similar to trees in terrestrial systems (Ghisalberti and Nepf, 2002). Aside from the shelter provided by this canopy to other organisms, the animal forest can significantly modify the local physical and biogeochemical environment (reviewed in Guizien and Ghisalberti, 2017). Flow velocity profiles were measured with a high-resolution Doppler profiler across the 2 meters above the bottom in locations covered by soft corals at differents population densities. In shallow locations, the flow was dominated by waves (oscillatory flow) and in deep locations, by current (steady flow). The objective of the internship is to analyse the near-bottom flow velocity profile measurements with various signal processing methods developping customed Matlab routines in order to quantify the animal forest canopy effect on the flow (steady and unsteady) and test wether it can be related to any animal forest descriptors (height, population density). In the case of steady flows, canopy descriptors as established for atmospherical urban canopies will be considered (Mac Donald, 2000).

Facilities for the intern:
Computing facilities and Matlab software.

Bibliographical references:

  • Mac Donald RW. Modelling the mean velocity profile in the urban canopy layer. Boundary Layer Meteorology 2000 ; 97:25-45.
  • Ghisalberti M Obstructed shear flows: similarities across systems and scales. J. Fluid Mech. 2009 ; 641:51-61.
  • Ghisalberti M, Nepf H. The structure of the shear layer in flows over a rigid and flexible canopies. J. Geophys. Res. Oceans. 2002 ; 107(C2): 3011-1-11.
  • Guizien K., Ghisalberti M. (2017) Living in the Canopy of the Animal forest: Physical and Chemical Aspects. In Marine Animal Forests. The Ecology of Benthic Biodiversity Hotspots. S. Rossi, L. Bramanti, A. Gori, C. Orejas Saco del Valle (Eds) . Springer. ISBN: 978-3-319-17001-5 (Online).
  • Rossi S, Bramanti L, Gori A, Orejas C. (2017) An Overview of the Animal Forests of the World. In Marine Animal Forests. The Ecology of Benthic Biodiversity Hotspots. S. Rossi, L. Bramanti, A. Gori, C. Orejas Saco del Valle (Eds) . Springer. ISBN: 978-3-319-17001-5 (Online).