Abstract

Changes in the condition of broodstock, presence of larvae, and post-larval settlement of A. ater in Punta Arenas Cove (Antofagasta Region, Chile) were used to determine its reproductive cycle. The condition used as a spawning indicator shows that these events occur in three periods throughout the year (May-July, August-November, and December-February). Intense periods recorded in October-November and December-February coincided with periods in which the water temperature descended to less than 13 A degrees C. Simultaneously, plankton samples indicated constant presence of A. ater larvae at this site, with large increases in abundance during August and between October and January, reaching a maximum of 2,192 larvae m(-3) in October. The periods of increase in larval abundance coincide with spawning periods; however, the greatest abundances were recorded before the start of the descent of the spawning indicator of the population under study. Monthly installation and replacement of collectors, after recording the first spawning, showed the permanent settlement of A. ater post-larvae over the course of the study, with a period of greater intensity occurring from the end of August to the end of January, registering peaks in October and November with 5,667 and 4,183 post-larvae x 600 cm(2) collector(-1), months which also coincide with the greatest larval abundance. The presence of larvae and post-larvae of the mytilids Choromytilus chorus and Semimytilus algosus was also recorded alongside A. ater larvae and post-larvae. Ch. chorus presented a cycle very similar to that of A. ater in both stages, with a maximum abundance of 4,531 larvae m(-3) in November and 13,533 post-larvae x 600 cm(2) collector(-1) in December.