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Growth zones and back-calculation for the sea urchin, Sphaerechinus granularis, from the Bay of Brest, France

Published online by Cambridge University Press:  11 May 2009

L.J.L. Lumingas
Affiliation:
URA CNRS D1513, Laboratoire d'Océanographie Biologique, Institut d'Etudes Marines, Université de Bretagne Occidentals 6 Avenue Le Gorgeu, BP 809, 29285 Brest Cedex, France.
M. Guillou
Affiliation:
URA CNRS D1513, Laboratoire d'Océanographie Biologique, Institut d'Etudes Marines, Université de Bretagne Occidentals 6 Avenue Le Gorgeu, BP 809, 29285 Brest Cedex, France.

Abstract

A procedure for accurately determining age and growth of the sea urchin Sphaerechinus granularis (Lamarck) (Echinodermata: Echinoidea) in the Bay of Brest (France) is described. Readings of growth lines were made from the longitudinal cross-section of interambulacral oral plates of sea urchins collected in February 1993. These results agree with age estimates calculated using the ELEFAN I programme based on diameter-frequency distributions of sea urchins collected from February 1992 to March 1993. A non-linear regression (monomolecular equation) best describes the relationship between test diameter and plate thickness. The diameter-at-age data can be increased by back-calculation, assuming a constant proportional deviation from the mean size of the test. Although von Bertalanffy growth curves fitted to actual observations were similar to those fitted to back-calculated diameter-at-age data, the latter produced a more adequate curve and increased the quality of the growth parameter estimators. The von Bertalanffy growth curve estimated by ELEFAN I shows a pattern similar to the back-calculated von Bertalanffy growth curve.

Information

Type
Research Article
Copyright
Copyright © Marine Biological Association of the United Kingdom 1994

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