Physical and chemical tagging methods for the sea urchin Paracentrotus lividus (Echinodermata: Echinoidea)

Abstract

The sea urchin Paracentrotus lividus (Lamarck, 1816) (Echinodermata: Echinoidea) is an important economic resource in Europe, but intense harvesting has led to the collapse of several natural populations. Echinoculture, associated with restocking and stock enhancement practices, is an alternative to this problem. In these procedures, reliable individual identification through tagging is a valuable source of information. However, very few studies address the effect of tagging methods on P. lividus and the tagging of marine invertebrates still presents several challenges: decreased growth, high mortality rates and low tag retention rates. Under laboratory conditions, the present study evaluated the effectiveness of three tagging methods (passive integrated transponders [PIT-tags], coded wire tags [CWTs] and calcein) on wild P. lividus for 60 days in terms of total wet weight, total weight gain (mg ind.−1 day−1), survival and tag retention. The final total wet weight was significantly higher in the untagged (control) group than in the PIT-tagged group. Survival rate was 100% for the PIT-tag, calcein and control groups, and 97% for the CWT group. Tag retention differed significantly according to the tagging method: 100% in the calcein group, 76.7% in the PIT-tag group and 38.0% in the CWT group.

Pilot studies for stock enhancement of purple sea urchins (Paracentrotus lividus, Lamarck, 1816): usefulness of refuges and calcein marking for the monitoring of juveniles released into the natural environment

“…To distinguish the released animals from the wild ones and monitor the success of the operation, after the 15 days of acclimation sea urchins were marked by exposure to calcein, a method already tested to mark and detect large numbers of small sea urchins without sacrificing the animals (Johnson et al, 2013;Santos et al, 2022). This method offers high effectiveness for the development of field studies, since calcein tagging shows high success marking rate (Santos et al, 2022) and the produced fluorescent mark can be viewed under blue light portable flashlights (e.g., GoBe NIGHTSEA Fluorescence Exploration Light; 440-460 nm range) with appropriate filter glasses (Lü et al, 2020). To ensure that the fluorescent mark was recognisable either on sea urchins oral and aboral surface, and at any field conditions (sunny and cloudy days), animals were submersed in a well-aerated calcein sea water solution of 150 mg L À1 for a period of 48 hr, during which they were not fed.…”