Brooding and development of <Emphasis Type="Italic">Anasterias minuta</Emphasis> (Asteroidea: Forcipulata) in Patagonia,Argentina |
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Authors: | Damián G Gil Graciela Escudero Héctor E Zaixso |
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Institution: | 1.Instituto de Desarrollo Costero,Universidad Nacional de la Patagonia San Juan Bosco (UNPSJB),Comodoro Rivadavia,Argentina;2.Departamento de Biología General,FCN—UNPSJB,Comodoro Rivadavia,Argentina;3.Centro Nacional Patagónico (CENPAT),Puerto Madryn,Argentina;4.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET),Buenos Aires,Argentina |
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Abstract: | Brooding, embryonic and larval development, and the influence of environmental and biological factors in tidepool habitats
were studied in the sea star, Anasterias minuta, at various sites along ~220 km of the Patagonian coast. This species has a benthic, lecithotrophic development that includes
eight distinct developmental stages. A larval organ, the connection cord, is developed from a small preoral lobe at early
stages of development and becomes larger and thinner at advanced stages. Fecundity and average egg size increased with female
body size. The regression of log egg number to log sea-star size and weight at different sites had a slope significantly less
than 3.0, resulting in negative allometry and indicating that brood capacity was limited in large females. Development was
generally synchronous among sites, but varied within each brood at advanced stages, with more developed brooded larvae located
at the periphery of the brood mass. Brooding was synchronous among various populations at different years and spatial scales,
and extended over a period of 8 months. The highest proportion of brooding females occurred during May and June (austral winter).
Juveniles were released mainly during September. The likelihood of finding brooding sea stars decreased with increasing sea
water temperature, tidal height, and wave exposure, and increased with increasing body size. Both body size of brooding females
and brooding rate were higher in the infralittoral fringe than at midlittoral levels. A revision of the current model of brooding
behavior and development among forcipulate sea stars is given. |
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