Light-induced shell pigmentation in post-larval Mytilus edulis and its use as a biological tag

Abstract

It was found that shell pigmentation in post-larval (< 1.5 mm) Mytilus eddis L. is controlled by light intensity. This relationship was used to develop a method for tagging cohorts of these post-larvae. It was also used to infer the light regime experienced by wdd post-larvae in the field. Growth was temporarily slowed during the light phase of the tagging process. No effect of the tag on subsequent survival was seen. Since the tag consists of a pigment band in both the periostracum and the prismatic shell layers, it persists until these layers erode away. The utility of the tag in a field trial is described.