DIGESTIÓN DIFERENCIAL DE PRESAS Y DIETA: EL CASO DEL DELFÍN FRANCISCANA (Pontoporia blainvillei)

BAGNATO, R; DENUNCIO, P; RODRIGUEZ, D

Mastozoología Neotropical

SAREM

Lugar: Mendoza; Año: 2020 vol. 27 p. 23 - 29

ABSTRACT. Dierential prey digestion and diet: the case of the franciscana dolphin (Pontoporiablainvillei). The Franciscana dolphin is the most endangered cetacean in the Southwestern Atlantic Ocean.Knowing its biology and ecology is crucial to promote measures to prevent its bycatch, and the study of its diet contributes to the knowledge of its ecology. However, most of these studies are performed from hard remains found in stomach contents and these contents have dierent digestion and retention rates, which could lead to an overestimation of some prey. However, the analysis of undigested portions of the stomach content is implemented in marine predators whose diet consists in rapid digestion invertebrates.This method avoids the eect of digestion and accumulation of measurable hard remains. Consequently, an analysis of the P. blainvillei diet was performed in order to determine dierences between both diet study methods, which allow to determine the eect of the dierential digestion of prey and the accumulation of hard remains with taxonomic value. The study was conducted on 41 stomach contents, whose results showed great dierences in the diet following both methods. Indigestible beaks of Loligo sanpaulensis and robust sagittal otoliths of Cynoscion guatucupa accumulate in the stomach, and thus, overestimatethe importance of these prey. Moreover, the analysis evidence a rapid digestion of Engraulis anchoita and Trachurus lathami, which are underestimated. In turn, the results suggest changes in the characterization of trophic habits of P. blainvillei, in its nutrition, and in the degree of overlapping with the sheries of the area. This latter one is crucial for the Franciscana dolphin because of the high accidental mortality rate in shing nets