Trophic role of Illex argentinus in the ecosystem

LUIS RIGOBERTO ROSAS; AUGUSTO CÉSAR CRESPI ABRIL

Congreso; World Congress of Malacology; 2013

Illex argentinus, as several other ommastrephid squids, has been considered a keystone species in the marine ecosystem of the Southwestern Atlantic Ocean. Several papers have been published describing the prey spectrum of I. argentinus through the entire geographical distribution; we reviewed and compared the prey spectrum of I. argentinus between different regions using material (stomach samples 2012) and data of identified content (all published papers), determining that I. argentinus diet was mainly composed by myctophid fish (34% of the diet). Eight myctophid species were observed as prey items and the presence in the feeding habits of I. argentinus changed according to the latitudinal distribution. Gymnoscopelus and Protomyctophum genus were present in the diet of the southern distribution while Diaphus genus in the northern. The presence of amphipods, copepods and euphausiids increased in the southern (39% of the diet). Cephalopods as prey items were preset in the whole area (27%) but they were more important in the northern. In a preliminary Ecopath model developed with these data we observed that I. argentinus plays an important role in the ecosystem as a transfer of energy from the lower to higher levels with a trophic level of 3.95 being one of the most important predators of demersal fish, crustaceans and other cephalopods (mainly species of the Doriteuthis genus).