In a recent paper we reconstructed the calcification depth of G. truncatulinoides since the last deglaciation in the Florida Straits. We highlighted a significantly different calcification depth between 8-10 ka and the late Holocene. This migration was found in three different cores over the western North Atlantic American continental margin. This paper presents new Mg/Ca ratio data on G. truncatulinoides in the Florida Strait and new stable isotopic measurements on G. crassaformis in the Gulf of Mexico. Preliminary interpretation to understand the cause of G. truncatulinoides migration in the water column at the beginning of the Holocene is given.