Spatial diff erence in net growth rate of Yesso scallop Patinopecten yessoensis revealed by an aquaculture ecosystem model

Identifying the main factors on spatial diff erences in net growth rate of Yesso scallop(Patinopecten yessoensis)in culture system is the key to eff ective aquaculture management and development.Coupling a 3D ecosystem model(ROMS-CoSiNE)with a dynamic energy budget model for scallops,a Yesso scallop culture ecosystem(YeSCE)model was established with which scallop growth was simulated with real seeding density and juvenile size from local aquaculture experiments from December 1,2012 to November 30,2013.Results show that the YeSCE model has reasonably simulated the environmental variation and scallop net growth rate in the Changhai sea area.The growth of scallops was slow in winter and midsummer and was limited mainly by temperature.Food availability was a key factor that contributed to the fast growth of the scallops during spring to early summer and in autumn.Generally,the scallops cultured in the north part of the Changhai sea area grew faster than those in the south;and the net growth rate for scallops cultured near the island was signifi cantly higher compare to the others,which is probably correlated to the spatial distribution of food availability.Based on the correlation analysis,the spatial diff erences of the net growth rate were largely aff ected by the length of the match timing of temperatures and food availability.The results of this study provide a scientifi c support for optimizing bottom culture planning and adjusting bottom culture methods.

Rapid changes in the near-bottom temperature of the bottom aquaculture area around the Zhangzi Island in summer

Rapid changes in the near-bottom water temperature are important environmental factors that can significantly affect the growth and development of species in the bottom culture.The object of this research is to investigate the mechanism causing these rapid changes within a bottom culture area near the Zhangzi Island.The hydrographic transects observations in the North Yellow Sea(NYS)suggest that our mooring station is very close to the tidal mixing front.The horizontal advection of the tidal front has induced the observed tidal change of bottom temperature at the mooring station.Analysis of the mooring near-bottom temperature and current measurements show that the angle between the tidal current horizontal advection and the swing of the tidal front is crucial in determining the variation trend of temperature.When the angle equals 90°,the horizontal tidal current advects along the isotherms so the temperature remains the same.When the angle is between 0°and 90°,the seawater moves from deep water to the warmer coastal zone and the temperature decreases.In contrast,the horizontal tidal advection moves the coastal warm water to the mooring station and the water temperature increases when the angle is between 90°and 180°.The amplitude of the temperature change is proportional to the magnitude of the horizontal temperature gradient and the tidal excursion in the direction of the temperature gradient.This study may facilitate the choice of culture area in order to have a good aquaculture production.