14 – University of Venice ECASA modelling workshop, Dunstaffnage Laboratory, Oban 26-27 January 2006

outline BRNS (sediment remineralization) model; Tapes philippinarum model; Sparus aurata (Gilthead seabream) model; Off-shore mussel farming in the Adriatic sea ecological model;

Model description Sparus aurata individual-based growth model (Libralato S., M.Sc. Thesis, University of Venice). Water temperature is the only external forcing; Present efforts are focused on the dependence of fish growth from quantity and quality of the ingested food. Growth is described by means of the same class of ODE equation proposed by Ursin (1967).

Model description Model state variable, w, is the wet weight of the individual; dw/dt dR/dt (1-) dR/dt k(T) wn   dR/dt (1-)  dR/dt  dR/dt Ingested food

State of implementation CODE/NUMERICAL METHODS: model equation was numerically solved by means of a 4th order Runge-Kutta scheme (Press et al., 1987); the model is coded in FORTRAN77 and MATLAB; a Visual Basic user friendly interface is being developed; PARAMETERS: parameters that specify the basal metabolism were calibrated using oxygen consumption measures from Guinea & Fernandez (1997). The function which specifies the dependence of energy assimilation on the water temperature was best-fitted on the basis of the data published by Petridis & Rogdakis (1996). FORCING DATA: time series of water temperature feed quality & quantity can be also taken into account

model testing The model was recently tested against a set of water temperature and Wet Weight data collected by ICRAM-Roma The model failed in describing the growth at low temperatures (Jan-March)

model testing Parameters which specifies the dependance of energy assimilation on the water temperature were re-calibrated. The minimum of the cost function (least squares) was found by means of a simplex algorithm.

Plans for use in ECASA In the framework of the ECASA project, UNIVE – Sparus aurata growth model will be further tested on the field data collected in the Adriatic Sea by participant 11 ICRAM-Roma More model testing Interesting sites are those with a wide temperature range

outline BRNS (sediment remineralization) model; Tapes philippinarum individual based model; Sparus aurata individual based model; Adriatic sea hydrodynamic-ecological model focused on off-shore mussel farming ;

Impacts of mussel farming in the Adriatic Sea 1) Impacts due to biodeposition of faeces and pseudofaeces – modified DEPOMOD+BRNS approach 2) Impacts on the water column – phytoplankton depletion;

Individual growth model Population dynamic model Faeces and pseudofaeces production Water column Deposition model Organic Matter flux Early diagenesis model Sediment

Model description Model is designed for scale B HYDRODYNAMIC MODEL ECOLOGICAL MODEL Temperature; Irradiance & Nutrient concentration WATER COLUMN Phytoplankton & Zooplankton concentrations Mussel density Model is designed for scale B

Model description Italy Italy Adriatic Adriatic Sea Sea Site 1: Po river 7.5 103 T y-1 Current data Adriatic Adriatic Sea Sea Site 2: Water quality, mussel growth & farm structure data

Model description – ECOLOGICAL sub-model 4 state variables: 2 functional groups of phytoplankton; 2 functional groups of zooplankton. Primary production Respiration grazing mortality , where P and Z are phytoplankton and zooplankton concentrations grazing mortality f1(T) , where T is water temperature T f1(T) f2(N) , where N is nutrient concentrations N f2(N) I f3(I) P f4(P) f4(P) , where P is phytoplankton concentration f3(I) , where I is irradiance

Model description A short term simulation, considering a steady state biomass of bivalves was performed as a first attempt to model the impact of farmed mussel on phytoplankton stock. Mussel dry weight was recalculated from shell length using the allometric coefficients published from Ceccherelli & Rossi (1984). Mussel Cleareance Rate was set in accordance with the measurements performed from Sarà et al. (1998) and Martincic (1997).

Model description – hydrodynamic barotropic sub-model The model is based on shallow water equations, adopting a general coordinate and boundary fitted domain discretization. Forcing at the lateral open boundary are the tidal components M2, S2, K1, O1 and at the surface layer is included the wind stress component, derived from QuickScat/Ncep Analysis data. Grid dimension is 276 x 960 points, with a variable stepsize (Δmin= ~150 m , Δmax= ~ 4000 m) which provides a high resolution for coastal areas. Time step used 120 s.

State of implementation CODE: Ecological and hydrodynamic models are both coded in FORTRAN77; FORCING DATA: Silicate concentration, Phosphate concentration and water temperature are routinely monitored along the Adriatic coast by the Italian Ministry of the Environment; Irradiance data were provided from the National Research Council; Mussel lenght and husbandry data were provided by MARE Scarl; Tidal forcings: OSU Tidal inversal model-Mediterranean Sea Wind stress component: QuickScat/Ncep Analysis data

Preliminary results – ECOLOGICAL sub-model Model parameters have been set in accordance with literature ranges. The maximum production rate, µmax, was calibrated on field data. Calibration: The minimum of a least squares goal function was determined by means of a simplex algorithm

simulation characteristics The simulation starts at the beginning of April; Boundary conditions for phytoplankton and zooplankton were interpolated from field data. Cattolica Farming area Phytoplankton concentration measured in situ at t=t0 was taken as initial condition.

preliminary results Phytoplankton concentration after 20 days of simulation - 20% Inside farming area with respect to the nearby concentration

Work in progress 1. Include mussel dynamics in the ecological sub-model: one suitable approach is a modification of the one proposed from Gangery et al. (2004). The model which simulates the dynamics of cultured mussel population (recently developed from IFREMER) will be coupled with an individual-based ODE model of Mytilus galloprovincialis.

Plans for use in ECASA In the framework of the ECASA project, this integrated model could be tested on a set of field data collected at in VISMA (Venice) site (WP5)

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