SIGNIFICANCE OF ADVECTIVE TRANSPORT OF ULVA-LACTUCA FOR A BIOMASS BUDGET ON A SHALLOW-WATER LOCATION

Ulva lactuca biomass, growth and grazing rates and drifting biomass wa s measured in the early summer period at a 1 m deep near-shore station in a sheltered bay in Roskilde Fjord, Zealand, Denmark. The expected biomass was calculated for each sampling date and compared with the me asured. Regression analyses were performed between drifting biomass an d the relative difference between measured and calculated biomass (R-2 = 0.65, P < 0.054) and between wind velocities and drifting biomass ( R-2 = 0.42, P < 0.057). Although not significant at the 5% level, the results indicated that advective transport was significant for balanci ng the biomass budget of U. lactuca. It is therefore proposed that dyn amic modelling of U. lactuca should be based on a transport/dispersion model. (C) 1997 Elsevier Science B.V.