Biological Studies On The Chilean Sea-Urchin Loxechinus Albus (Molina) (Echinodermata- Echinoidea) IV.- Maturation Cycle And Seasonal Biochemical Changes In The Gonad

Critical thermal maximum and osmotic pressure of the red sea urchin Strongylocentrotus franciscanus acclimated at different temperatures

“…franciscanus responds the same as Loxechinus albus in the South Hemisphere and both species are associated to macro-algae on which they feed (e.g. Gigartina armata, Eisenia arborea, Laminate farlowii (Tegner and Dayton, 1981)) but the most important food source is Macrocystis pyrifera (Mottet, 1976;Bu¨ckle et al, 1977Bu¨ckle et al, , 1978Bu¨ckle et al, , 1980Palleiro, 1987).…”

An ovotestis event in the gonochoric sea urchin Loxechinus albus (Echinodermata: Echinoidea)

“…In gonochoristic invertebrates, the sex ratio (male:female) is usually very close to 1:1 (Olive, 2002), as in echinoids, similar as observed here in for L. albus (0.9:1) from Antofagasta, Chile (23°38'S, 70°24'W), which would be ratifying that there is no predominance of males on females, then sex change corresponds to an isolated situation detected. However, to other L. albus population more to the south at Valparaiso, Chile (33°02'S, 71°36'W) with 516 males (50%), 652 females (39.7%) and 132 undifferentiated (10.1%) representing a sex ratio 0.8:1 (m/f) that differ significantly from a sex ratio 1:1 (χ 2 c = 7.80, p = 0.005) (Buckle et al, 1978). Marked deviations from this 1:1 ratio suggest some modification of the normal breeding pattern (Olive, 2002).…”

“…As part of a study about the reproductive cycle of L. albus, adult sea urchins were collected monthly during 18 months covering 2000-2001 (from rocky subtidal area at II Region, Antofagasta, Chile (23°38'S, 70°24'W) at 5-15 m depth. All collected sea urchins (n=950) were above 45 mm in test diameter 'TD', i.e., they are adults that had already reached the size at maturity 'TD m50% ' (Buckle et al, 1978), hence in fulfillment with the reproductive cycle. Standard histological procedures were performed and stained using the routine Harris hematoxylin-eosin regressive method "HHE 2 " (Howard and Smith, 1983).…”

Reproductive cycle of <i>Loxechinus albus</i> (Echinodermata: Echinoidea) in two areas of the Magellan Region (53ºS, 70-72ºW), Chile

“…They reported that the spawning period occurs later in the year as latitude increases. For example, in Caleta Coloso (23°S) the spawning period occurs in June (Zegers et al, 1983), in Punta Lagunillas (30°S) during the period June-August (Zamora and Stotz, 1992), in Valparaíso and Quisco (32-33°S) during AugustNovember (Buckle et al, 1978;Guisado and Castilla, 1987), and in Chiloé and Guaitecas Islands (42-45°S) during the period November-December (BaySchmith et al, 1981). Urchin populations inhabiting areas surrounding Punta Arenas (53°S) are an exception to this pattern since their spawning period occurs from July to September (this study), September-October (Bay-Schmith et al, 1981) and AugustSeptember (Arana et al, 1996).…”