Embryonic development, feeding and intracapsular oxygen availability in Trophon geversianus (Gastropoda: Muricidae)

CUMPLIDO, MARIANO; PAPPALARDO, PAULA; FERNANDEZ, MIRIAM; AVERBUJ, ANDRES; BIGATTI, GREGORIO

JOURNAL OF MOLLUSCAN STUDIES

OXFORD UNIV PRESS

Lugar: Oxford; Año: 2011 vol. 77 p. 429 - 436

0260-1230

Large scale patterns of encapsulated embryo development and causal factors determining developmental success in the marine environment has been a relevant issue of research for decades. We studied the embryonic development and intracapsular oxygen availability of Trophon geversianus in egg capsules from northern Patagonia (Golfo Nuevo, Argentina). The intracapsular embryonic development had a mean duration of 112 days (at controlled water temperature of 12 - 14 ¨¬C). The initial number of eggs per capsule was 197 uncleaved eggs (mean diameter= 270 ¥ìm), but on average only 4 embryos reached the juvenile stage. Embryos fed on nurse eggs (which disintegrated spontaneously 48 h after oviposition). A temporary sequence of the intracapsular embryos stages was obtained from egg to juvenile, hatching at crawling stage with a mean length of 2.8 mm. The maximum growth was observed at the veliger stage, which can be explained by a higher consumption of nurse eggs. Other important change in embryo size was reported between pre-hatching and hatching, where a decrease in embryo number was observed. Cannibalism was registered in an egg cpsule containing a pre-hatching embryo, evidenced by signs of shell drilling by the accessory boring organ (ABO). Intracapsular oxygen availability decreased from 90% during the cleavage stage to 45% of air saturation at the final stages of development (at 13¡ÆC). Abnormal embryos were recognized in egg capsules, probably associated to food competition or oxygen limitations inside the egg capsules.