Efficacy of calcein as a chemical marker of green‐lipped mussel ( P erna canaliculus ) larvae and its potential use for tracking larval dispersal

An optimal chemical shell marking protocol was developed for the N ew Z ealand green‐lipped mussel, P erna canaliculus with a view to its future use in larval tracking experiments. Larval P . canaliculus aged either 10, 15 or 19 days post fertilization were immersed in treatments of 50, 100 and 200 mg L −1 of calcein for a period of 24 h before measurements of shell mark brightness were taken. There was 100% marking success in all calcein treatments for all age classes, with 19‐day larvae immersed in 200 mg L −1 calcein producing the brightest mark. Growth was not affected by calcein immersion; however, 10‐day larvae exhibited significantly higher levels of mortality compared with 15‐ and 19‐day larvae suggesting a reduced resilience to the marking protocols in younger larvae. In a mass staining experiment, a solution of 100 mg L −1 calcein was used to successfully stain15.6 million hatchery reared P . canaliculus larvae. Calcein, therefore, offers a low impact method with which to stain the sensitive early life stages of this species thus providing a rapid method for identifying individuals of interest, i.e. individuals released in the wild or specific family lines within a hatchery environment.