Gonad volume assessment in the oyster Crassostrea gigas: Comparison between a histological method and a magnetic resonance imaging (MRI) method

Abstract

Previous studies comparing Crassostrea gigas selected lines with different susceptibility to summer mortality concluded that the higher the reproductive effort the lower the survival. But they were lacking individual follow up of this reproductive effort which would be of great interest to help us to understand the physiology of the oysters facing summer mortalities. The most frequently used method for assessing the volume of the gonad is to measure the area it occupies on histological sections. Gonad measurement by magnetic resonance imaging, in contrast, is non-destructive and therefore makes it possible to assess individual evolution as well as to compare individuals. The present study compared the values of gonad volume by this method with the values of gonad surface obtained by the histological method. The two methods were used successively to assess the volume of the gonads of the same individual oysters at different maturation stages. There is a very highly significant linear relation between the results of these two methods. The estimated uncertainty about the volume value is 29%. Causes of this uncertainty are considered and discussed. Highlights► How to measure the gonad development of one oyster Crassostrea gigas? ► Gonad volume on MRI and gonad surface on histological slides are highly correlated. ► Uncertainty of the measure by use of MRI is estimated. AbbreviationsANOVA, Analysis of variance ; MRI, Magnetic resonance imaging ; ROI, Region of interest

Evaluation of Mud Worm (Polydora spp.) Infestation in Cupped (Crassostrea gigas) and Flat Oyster (Ostrea edulis) Broodstocks: Comparison between Magnetic Resonance Imaging and Computed Tomography

“…MRI allowed for the visualization of the advanced status of the lesions when blisters occupy the inner side of the shell and can impact the health status and the economic value of the mollusk. According to a previous study [29], there is a highly significant linear correlation between the results obtained from MRI and those from histology. The use of MR imaging and CT scanning also proved to be highly valuable tools in determining the condition index of live oysters [30].…”