Ecohydrodynamics of cold-water corals - Juan moreno-Navas
Ecohydrodynamics of cold-water coral.Juan Moreno Navas.Heriot -Watt University. UK
EcohydrodynamicsThe determination of the hydrodynamic constraints onecosystems with different time and length scale hasbeen coined by the term Ecohydrodynamics.This concept also encompasses the physical, chemicaland biological characteristics of the water bodiessurrounding marine ecosystems.
Ecohydrodynamics of cold-water coral.• The Ecohydrodynamic conditions around the coral reefs determine the supply of food particles and larvae.• The interactions between currents, internal waves, upwellings/donwelllings and the topography creates suitable conditions for the development of suspension-feeding cold water corals.• The lateral and vertical advection of particles may therefore play an important role in the functioning of coral ecosystem.• The suspension-feeding cold-water coral communities rely on the delivery of phytoplankton, zooplankton and organic matter derived from near- surface primary productivity.
Located to the east of the island of Mingulay inthe Sea of Hebrides, UK.Each reef is formed by seabed mounds up tofive metres high that likely have been growingsince the early Holocene (Roberts et al. 2005).High dynamic area Barra Sea of the Hebrides Mingulay Reef mounds
Ecohydrodynamics. Sea of the Hebrides (a) (b) (c)Analysis of colour fronts using 23-30 Apr. 2011 MERIS FR composites: (a) Chl-a;(b) enhanced colour; (c) simplified Chl-a front map.
Ecohydrodynamics. Sea of the Hebrides %Mean all-seasons : (a) thermal fronts; (b) 300m Chl-a fronts; (c) 1km Chl-a fronts
Ecohydrodynamics of Mingulay Reef complex• Previous studies revealed two dominant food supply mechanisms to the reefs, a regular rapid downwelling of surface water delivering pulses of warm water and periodic advection of high turbidity bottom waters(Davies et al. 2009).• A 3D ocean model has been applied to provide an adequate assessment of the water circulation, water exchange and renewal in the Mingulay Reef complex.
Mathematical modelThe Mass and Momentum equations solutions. Momentum equation - x u1 u j u1 1 pa f u2 g dz t x x x1 x Tim e derivative j coriolis z 1 1 barotropic atmospheric advective baroclinic pressure u1 1 S11 z 1 S12 z Kj xj xj x1 x2 turbulent diffusion radiation stresses (waves) Mass equation – 3D Mass equation – 2D U1 U2 D u1 u2 u3 0 0 t x1 x2 t x1 x2 x3
Initial condition. Vertical & horizontal discretization. Physical parameter Numerical value Time step: 2s Grid mesh: 300, 100m 3D Sigma coordinate with Horizontal cells (x,y): 193, 244 4 layers Vertical coordinate: Sigma Vertical Vertical layers: 8 Horizontal Eddy Viscosity: 4.3810 Vertical Eddy viscosity: 0.001 Drag coefficient: 0.0025 River discharge: No Salinity: 35 psu Temperature: 11c Forced: Tide from FES2004Horizontal
Ecohydrodynamics of Mingulay Reef complex3D ocean model : two different grid resolution. Mingulay 1 A 300 m A B Mingulay 5 100 m animation slices
3D ocean model results. Currents are tidally driven Time scale: tidal cycle Lenght scale: 20x20 Km
3D ocean model results.High turbulence in the Reefs area. High turbidity bottom waters(Davies et al. 2009). Mingulay 1 Mingulay 5
Downwelling of surface water delivering pulses of warm water.Scanfish dataDmitry Aleynik & Mark Inall (SAMS)Murray Roberts (Heriot-Watt
3D ocean model results.Downwelling of surface water delivering pulses of warm water (Davies et al. 2009)and high particle delivery to the bottom every 6 hours.
3D ocean model and GIS.This modelled information has been integrated into a 3D GIS Mingulay 1 Mingulay 1 Mingulay 5
3D ocean model and GIS. Colour-coded habitat classification map (Roberts et al. 2005) The significant decline in richness with easting (Henry et al 2010)
ConclusionsThe model and remote sensing techniques provide thespatial and temporal aspect of water circulation in the reefcomplex (turbulence, Downwelling).The model will provide better understanding of food supply,larvae transport, community composition and sedimentdynamics.This modelled information has been integrated into a 3D GIS,thus providing a user interface for visualization interrogation ofresults and as an input into other spatial and ecologicalmodeling projects.