The influence of environmental factors on the growth of Sphaerechinus granularis (Lamarck) (Echinodermata: Echinoidea)

• Published in: Journal of experimental marine biology and ecology 1994-05, Vol.178 (1), p.97-111
• Main Authors: Guillou, Monique, Michel, Christine
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Autoecology; Biological and medical sciences; Echinoid; Echinoidea; Fundamental and applied biological sciences. Psychology; Growth; Marine; Protozoa. Invertebrata; Reproductive cycle; Sphaerechinus granularis; Temperature
• ISSN: 0022-0981; 1879-1697
• DOI: 10.1016/0022-0981(94)90227-5

The main growth period of the sea urchin Sphaerechinus granularis (Lamarck) in Brittany occurs in summer and autumn with a faster growth rate in the juveniles. The growth curve was similar in laboratory and field populations except during the winter phase where growth rate decreased in the field but was negative from the second year-class in laboratory conditions. To determine the factors which regulate somatic growth, the seasonal variations in feeding, gonadal growth and temperature were analysed. The ingestion rate of laboratory urchins and the repletion index of the natural population were low from December to April and at the end of summer irrespective of the age of the sea urchins. The changes however were less obvious in the juveniles. In the adults, the gonad index increased from February to April before spawning. The decrease in the growth rate in October was influenced more by falling sea temperature than by a change in the feeding rate which decreased a month later. Temperature is not the only factor involved in the reinitiation of growth, in April. This coincides with the end of spawning and when the feeding activity recommenced. The resumption of feeding is influenced by the temperature as indicated by a significant correlation between the feeding indices and the seawater temperature one month before.