Effect of shear velocity and flow regimes on scallop post-larval detachment feed on two different diets

Through biological flume experiments, we studied the effect of shear velocity and attachment period on the percent detachment of Pecten maximus post-larvae of different sizes reared on two experimental diets. The first diet, (Pavlova lutheri, Isochrysis galbana, Chaetoceros calcitrans), which served as a reference diet (PTC), is commonly used in bivalve hatcheries; the second is the PTC diet with the addition of Rhodomonas salina (PTCR). Our results indicate that the detachment of post-larvae fed PTCR diet showed significant interactions between scallop length, attachment period and shear stress, while the post-larvae feed with the PTC diet showed only effect of shear stress factor. Furthermore, post-larvae exposed to various flume velocities showed different percentages of detachment according to diet (PTC = 36% and PTCR = 57%) for flow velocities between 1.42 to 2.45 cm s− 1 after 12 h attachment periods. This result could be related to differences in the biochemical composition of post-larvae as discussed.

► Critical shear velocity needed to detach Pecten maximus post-larvae was 1.42 cm s− 1. ► Time allowed to settle increase attachment strength. ► Diet affects the detachment. ► Higher accumulation of lipids and sterol composition affect attachment strength.