Resumen.-Se analizó la gametogénesis y la variación temporal en la asignación de energía a diferentes órganos de Aulacomya atra del Canal Beagle (Tierra del Fuego). El periodo de desove de A. atra se extendió desde el final del invierno hasta la primavera, cuando el MGI (Índice gónada-manto) resultó mínimo y el número de individuos desovados, máximo. En los machos maduros el incremento del MGI coincidió con un descenso en la densidad energética del manto-gónada (ED MG), lo que está relacionado con un aumento de masa con menor energía. En hembras maduras el incremento de MGI se relaciona con un aumento de masa con valores más altos de energía, que determina el aumento de la ED MG. Durante la maduración gonadal existen diferentes estrategias de asignación de energía en ambos sexos, aunque se alcanza similar contenido de energía en el manto-gónada; los machos mantienen gónadas más grandes, pero con menos energía por unidad de masa que las hembras. Además, en los individuos maduros desciende el valor del índice de la glándula digestiva (DGI), incrementa el MGI, y tiende a la depleción de la ED y del contenido energético, sugiriendo que este órgano actuaría como reservorio de energía.
2012): Effects of physical disturbance on a sub-Antarctic middle intertidal bivalve assemblage, Marine Biology Research, 8:10, 937-953 To link to this article: http://dx.
This study presents for the first time the factors governing the recruitment in a rocky intertidal community of the Beagle Channel, Tierra del Fuego (54°51′S 68°29′W), Argentina. The aim of this study was to examine the effect of grazers and predators, free substrate availability and crustose coralline algae on the recruitment of the main sessile components of the intertidal:Notochthamalus scabrosus, Notobalanus flosculus, Mytilus chilensis, Perumytilus purpuratusandAulacomya atraat three intertidal levels. For barnacles, the probability of recruitment was higher with grazers, while the contrary was observed for bivalves. The number ofN. flosculusrecruits was higher with increased substrate availability, whileN. scabrosusrecruited more with reduced free substrate in the first sampling. Mussel recruitment was higher with reduced free substrate. The highest probability of recruitment ofN. scabrosuswas observed at the upper level. Notably, this probability and the recruits per plot were higher at the mid level under uncaged-ORP treatment than expected for the mid level. The probability of bivalve andN. flosculusrecruitment was higher at upper and lower levels, respectively. At the lower level, barnacle recruitment was higher on bare rock than on crustose coralline algae. Our results suggest that grazers increase the probability of barnacle recruitment, while the presence of sessile organisms enhances the density of mussel recruits. Almost no recruitment of bivalves was observed in ORPs over one year, showing that the secondary succession is slow in this environment.
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