Dabrowski Tomasz - Ifremer

Symposium Biarritz 2011 - “Vulnerability of coastal ecosystems to global change and extreme events”Biarritz, 18-21 October 2011Application of DEB theory to model the growthof Mytilus edulis and influence of itscultivation on ecosystem functioningTomasz DabrowskiMarcel CuréKieran LyonsGlenn NolanMarine Institute, Ireland

Symposium Biarritz 2011, 18-21 October 2011IntroductionEASYCO – Collaborative European Atlantic Water Quality Forecasting SystemAims to build a Polycentric Infrastructure for Operational Ocean Modelling inthe whole Atlantic SpaceAims to integrate modelling approaches, design common interfaces for ease ofexchange of models modulesDownscaling of solutions from globalregional local modelsWide range of end-users, e.g. navigation safety, fisheries, aquaculture, coastalmanagement, meteorology, etc.Models can be used to predict shellfish growth and carrying capacity – focus ofthis research“Investing in ourcommon future.”

Aquaculture – global changeSymposium Biarritz 2011, 18-21 October 2011Aquaculture is still the fastest growing food-producing sector in the world –total annual production in 2008 of 52.5 million tonnes (FAO, 2010)In Ireland, production doubled in years 1990-2007, and rope musselproduction recorded a growth of c.230%Shellfish cultivation provokes environmental changes in coastal ecosystemsEffective management methods are required to ensure the sustainability,economic viability and minimization of negative impacts on both human healthand the environment – carrying capacity. Why is it important? -disastrous year 2007 for Chilean aquaculture.Models can be used as supporting tools“Investing in ourcommon future.”

Symposium Biarritz 2011, 18-21 October 2011Modelling frameworkRegional model (NE Atlantic): ROMS (Regional Ocean Modelling System) of1.2-2.5km spatial resolution and 40 vertical levelsLocal model (SW coast of Ireland): ROMS of c.250m resolution and 20 verticallevelsPHYSICS BIOGEOCHEMISTRY DEBBiogeochemical model: NPZD by Fennel et al. (2006), 7-12 state variables, N-based• DEBShellfish model: DEB – any cell in 3D can be populated with required density“Investing in ourcommon future.”

Symposium Biarritz 2011, 18-21 October 2011Coupling of DEB with NPZDProcesses included:• Uptake of food (chl_a as a proxy, work on inclusion of POM as food source, with POC/PON as qualitydeterminants is undergoing)• Oxygen utilisation• CO 2 respiration• Ammonia excretion• Faeces production• Assimilation of N and C in flesh and organic shell fractionAll processes are balanced to ensure mass conservation (paper submitted to Journal of WAS)CO 2DEBO 2“Investing in ourcommon future.”

Symposium Biarritz 2011, 18-21 October 2011DEB-NPZD test runsSimulations were carried out in a 0D mode (self contained box) for variousbivalve densities and for ‘typical’ winter, spring and summer conditions to testthe systemFigure. Allocation of N throughout the model’s state variables after 100 days:1210State variable [mmol N m^3]864200 15 30 45 60 75Bivalve density [ind m^2]“Investing in ourcommon future.”

Symposium Biarritz 2011, 18-21 October 2011Can we estimate carrying capacity?Spring conditions – test run5.5700L [cm]5.455.45.355.35.25600500400300200100Phy B [mg C m2] & PP [mg C m2 d]LPhyBPP5.20 10 20 30 40 50 60 70 80Bivalve density [ind m2]0“Investing in ourcommon future.”

Symposium Biarritz 2011, 18-21 October 2011Implementation to Bantry BaySampling programme for the calibration of all model modulescompletedCalibration of a DEB model987Shell length [cm]654321014/07/10 13/08/10 12/09/10 12/10/10 11/11/10 11/12/10 10/01/11 09/02/11 11/03/11 10/04/11 10/05/11 09/06/11Date“Investing in ourcommon future.”

Symposium Biarritz 2011, 18-21 October 2011Results – mussel growthBantry Bay model nested in NE Atlantic model (both hydro and bgc passed on)Hindcast run February 2010 – June 2011In July 2010 computational cells were populated with mussels to the value ofreported tonnage of c.5,300 tonnes7L [cm]6543According to the farmers‘Snave’ is one of theworst sites in Bantry BayLOpenHighLowCloseL_modelShell length [cm]217014/07/201013/08/201012/09/201012/10/201011/11/201011/12/201010/01/201109/02/201111/03/201110/04/201110/05/201109/06/201165432According to the farmers1‘Ghearies’ is one of the best0sites in Bantry BayDateShell length [cm]June 201114/07/201013/08/201012/09/201012/10/201011/11/201011/12/201010/01/201109/02/201111/03/201110/04/201110/05/201109/06/2011Datecommon future.”“Investing in our

Symposium Biarritz 2011, 18-21 October 2011Influence on ecosystem functioningChlorophyll a765chla [mg/m**3]432no_farmswith farmsin situin situ1012/01/10 22/04/10 31/07/10 08/11/10 16/02/11 27/05/11Date“Investing in ourcommon future.”

Symposium Biarritz 2011, 18-21 October 2011Influence on ecosystem functioningPhytoplankton biomass43.53phy [mmol N/m**3]2.521.51no_farmswith_farms0.5012/01/10 22/04/10 31/07/10 08/11/10 16/02/11 27/05/11Date~ 42% reduction“Investing in ourcommon future.”

Influence on ecosystem functioningSymposium Biarritz 2011, 18-21 October 2011Primary Productivity65PP [mmol N/m**3 day-1]4321no_farmswith_farms012/01/10 22/04/10 31/07/10 08/11/10 16/02/11 27/05/11Day Year 2010“Investing in ourcommon future.”

Symposium Biarritz 2011, 18-21 October 2011Influence on ecosystem functioningOxygen330310O2 [mmol O2/m**3]290270250no_farmswith_farms23021012/01/10 22/04/10 31/07/10 08/11/10 16/02/11 27/05/11Date“Investing in ourcommon future.”

Influence on ecosystem functioningSymposium Biarritz 2011, 18-21 October 2011NH410.90.8NH4 [mmol N/m**3]0.70.60.50.40.3no_farmswith_farms0.20.1012/01/10 22/04/10 31/07/10 08/11/10 16/02/11 27/05/11Date“Investing in ourcommon future.”

Symposium Biarritz 2011, 18-21 October 2011Influence on ecosystem functioningDetritus0.40.35LDetN [mmol N/m**3]0.30.250.20.150.1no_farmswith_farms0.05012/01/10 03/03/10 22/04/10 11/06/10 31/07/10 19/09/10 08/11/10 28/12/10Date“Investing in ourcommon future.”

Symposium Biarritz 2011, 18-21 October 2011Influence on ecosystem functioningChlorophyll a765chla [mg/m**3]432no_farmsreport_tonn_all_baysin situ indirectin situ direct1012/01/10 22/04/10 31/07/10 08/11/10 16/02/11 27/05/11Day Year 2010“Investing in ourcommon future.”

Symposium Biarritz 2011, 18-21 October 2011Influence on ecosystem functioningPhytoplankton biomass43.53phy [mmol N/m**3]2.521.51no_farmswith_farms0.5012/01/10 22/04/10 31/07/10 08/11/10 16/02/11 27/05/11Day Year 2010~ 18 % reduction“Investing in ourcommon future.”

Symposium Biarritz 2011, 18-21 October 2011Summary - modelling system functionalitiesModelling of ocean physics, biogeochemistry and shellfish growth and their impacts onthe environment (easily adaptable to other species)Examine impacts on productivity and the ecosystem locally, at the bay level and at theregional level – estimate ecological and production carrying capacity• Relocate farms• Add / remove farms• Increase / decrease stockModels are run operationally and the outputs are publicly available through a dedicatedserverBut:It needs an expert user – an ocean modeller to run. Bantry Bay application iscomputationally expensive (~5 mln computational cells), requires access to HPCfacilities. Requires downscaling of solutions due to complex frontal dynamics (attained tothrough EASYCO project) for accuracy.“Investing in ourcommon future.”

Symposium Biarritz 2011, 18-21 October 2011Thank You !common future.”“Investing in our