Brooding of the sub-Antarctic heart urchin, <Emphasis Type="Italic">Abatus cavernosus</Emphasis> (Spatangoida: Schizasteridae), in southern Patagonia |
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Authors: | Damián G Gil Héctor E Zaixso Javier A Tolosano |
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Institution: | (1) Instituto de Desarrollo Costero (IDC), Universidad Nacional de la Patagonia San Juan Bosco (UNPSJB), Ruta 1, Km 4, CP 9000 Comodoro Rivadavia, Chubut, Argentina;(2) Departamento de Biología General, FCN-UNPSJB, Comodoro Rivadavia, Chubut, Argentina;(3) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina |
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Abstract: | The reproductive cycle of the sub-Antarctic spatangoid sea urchin, Abatus cavernosus, was examined during a 2-year period in southern Patagonia, Argentina. The population studied is the northernmost known coastal
population in the austral oceans, and is influenced by a greater annual range of seawater temperature than other Abatus species. The sex ratio of the overall A. cavernosus population did not differ significantly from 1:1, but was not homogeneous across size classes. A clearly defined annual reproductive
cycle was found. Spawning occurred from May to July and was synchronous between sexes. Females were observed to be brooding
within a 9-month period, from May to February. Juveniles were released during the austral summer, from January to February.
The length at which 50% of the females were brooding occurred at a test length of 25.9 mm. A. cavernosus had a large egg size (mean diameter = 1.4 mm) and low fecundity (maximum = 57 eggs per female) compared to closely related
species. The number of eggs within each brood pouch was highest in larger anterior brood pouch, which is close to two gonopores,
as opposed to the other anterior and two smaller posterior pouches. Significant interannual variation was observed in gonad
cycles, fecundity, and embryo development such as: brood size decreased during 2001; adjusted gonad dry weight and fecundity
were higher during 2003. Hypotheses concerning the gonadal and brooding cycles and fecundity of sub-Antarctic and Antarctic
Schizasteridae are discussed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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