The reproductive cycle of the non-indigenous mytilid Musculista senhousia was studied over a one-year period in the Sacca di Goro, a lagoon in the Po River deltaic area, where the species was recently accidentally introduced. Four main stages were recognized: gonad spent, developing, ripe, and spawning. Oocytes in previtellogenesis appeared in March and coexisted with growing oocytes. Spermatogenesis preceded oogenesis, and sperm clusters were observed from May. Yolk-filled eggs were present from June, but, instead of being spawned, underwent summer degeneration. Conversely, spawning started in mid-September, coinciding with water temperature decrease, and lasted to November, after which the gonads were spent. The species is strictly gonochoric. Both the cohort-of-the-year and the survivors of the cohort-of-the-previous-year started maturation. Such an overlap of reproducing generations is probably an adaptation for survival in a variable environment. The reproductive output of M. senhousia was determined following stimulation trials using hydrogen peroxide. Emission of gametes was completed within 4 h, and a single female might release as many as 137•103 egg cells. Swimming D-shaped larvae appeared within 24 h of fertilization. Larval life had a duration of approximately 15-18 d.
Sexual maturation and larval development of the immigrant Asian date mussel, Musculista senhousia, in a Po River deltaic lagoon
ROSSI, Remigio;MISTRI, Michele
2002
Abstract
The reproductive cycle of the non-indigenous mytilid Musculista senhousia was studied over a one-year period in the Sacca di Goro, a lagoon in the Po River deltaic area, where the species was recently accidentally introduced. Four main stages were recognized: gonad spent, developing, ripe, and spawning. Oocytes in previtellogenesis appeared in March and coexisted with growing oocytes. Spermatogenesis preceded oogenesis, and sperm clusters were observed from May. Yolk-filled eggs were present from June, but, instead of being spawned, underwent summer degeneration. Conversely, spawning started in mid-September, coinciding with water temperature decrease, and lasted to November, after which the gonads were spent. The species is strictly gonochoric. Both the cohort-of-the-year and the survivors of the cohort-of-the-previous-year started maturation. Such an overlap of reproducing generations is probably an adaptation for survival in a variable environment. The reproductive output of M. senhousia was determined following stimulation trials using hydrogen peroxide. Emission of gametes was completed within 4 h, and a single female might release as many as 137•103 egg cells. Swimming D-shaped larvae appeared within 24 h of fertilization. Larval life had a duration of approximately 15-18 d.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
