Occurrence of the collector sea urchin Tripneustes gratilla with over-a-decade longevity under rearing

The life expectancy (i.e., an average lifespan in a population) of Tripneustes gratilla has been reported as short as 1 or 2 years in natural environments, which is relatively short among sea urchins. However, some T. gratilla individuals can live for up to 5 years under rearing and 6.85 years in th...

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Veröffentlicht in:Plankton & benthos research 2023/11/27, Vol.18(4), pp.185-189
Hauptverfasser: Tanita, Iwao, Machiguchi, Yuji, Hayashibara, Takeshi, Mamiya, Shizuka, Nema, Kae
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Sprache:eng
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Zusammenfassung:The life expectancy (i.e., an average lifespan in a population) of Tripneustes gratilla has been reported as short as 1 or 2 years in natural environments, which is relatively short among sea urchins. However, some T. gratilla individuals can live for up to 5 years under rearing and 6.85 years in the field, according to previous reports. Until present, the maximum longevity that a certain individual of T. gratilla can physiologically live remains unknown. The present study conducted long-term rearing during 12.2 years of hatchery-produced T. gratilla in tanks to investigate its longevity. We especially focused on whether the maximum longevity among T. gratilla individuals exceeds a decade, as in the case of most sea urchin species. At the end of the rearing period, eight T. gratilla individuals were still alive. In last 9.5 years of the rearing period, during which dead individuals were counted, the mortality was 41% (7 out of 17 individuals). During growth, the body weight was related to the transverse test diameter to a power of 2.84. The asymptotic transverse test diameter and body weight, determined by fitting to the von Bertalanffy growth function, were 95.9 mm and 344 g, respectively. The results of the present study suggest that T. gratilla has the maximum longevity of more than a decade under rearing conditions, and the short-lived characteristics of this species in natural environments are mainly attributed to ecological factors.
ISSN:1880-8247
1882-627X
DOI:10.3800/pbr.18.185