Evaluating on the possibilities of modelling dispersal of Pacific oyster larvae (Crassostrea gigas) in the Limfjord - including the hydrodynamic MIKE21 model as input parameters

Jens Davids, Urd Steendahl Grandorf & Jeppe Olsen

Studenteropgave: Semesterprojekt

Abstrakt

The possibilities of developing a dispersion model of the Pacific Oyster (Crassostrea gigas) larvae in the Limfjord, Denmark were evaluated. DHIs hydrodynamic model MIKE21 was evaluated, in order to identify possible limitations of the model, because background knowledge about biology of C. gigas states that hydrodynamic is the most important parameter influencing dispersal of the larvae. The evaluation was done by developing a simplified dispersion model in ESRI’s software ArcMap, using current direction and velocity as the only input, in order to identify the dynamics of both the model and the system. This was done by simulating dispersal at different spatial and dynamic scales. Furthermore, suggestions to what other parameters to include in relation to dispersal of C. gigas larvae, and advantages of different types of dispersal models are discussed. The evaluation of MIKE21 involved an analysis of measured and modelled salinities used for calibration of the model, which showed a tendency of the model to overestimate at low salinities and to underestimate at high salinities, suggesting the model to have difficulties coping with salinity extremities in the Limfjord. The simplified dispersion model of C. gigas larvae showed that changes in the spatial scale affect the model output and that the 10 minutes steps had highest possible resolution practically applicable. Experiences from this study are that it is very important to clarify the purpose of ecological models, consider the scale and the many physical and biological parameters involved. This study can be seen as a pilot project, which can help in the decision making prior to a model development to assist in finding the purpose, and which parameters to include in a dispersion model.

UddannelserGeografi, (Bachelor/kandidatuddannelse) Bachelor el. kandidat
SprogEngelsk
Udgivelsesdato12 jan. 2011
VejlederePaul Thorn

Emneord

  • dispersal
  • Modelling
  • hydrodynamics
  • Crassostrea gigas