Amphiatlantic Dolphins’ Prey: Indicators of speciation, trophic competition and global warming? A review

Abstract

A review of the prey of three amphiatlantic dolphin species, Tursiops truncatus, Stenella coeruleoalba and Delphinus delphis, is carried out. The main objective of this work is to review the feeding of these species in the Atlantic in order to assess the degrees of trophic competition and speciation pressure. A total of 103 fish families, 22 cephalopod families and 19 crustacean families have been counted, from which the species identified to the genus level only included seventy-one fish, twenty cephalopods and five crustaceans, and the total species identified included three-hun- dred-one fish, fifty cephalopods and twenty-six crustaceans. The most consumed prey were fish, followed by cephalopods and crustaceans. The exclusive prey consumed by each of the three dol- phin species, as well as those shared by all or at least two of them, have also been counted. T. trun- catus is the most general; however, the western Atlantic populations exhibit high dietary specializa- tion compared to the eastern Atlantic populations, reflecting strong speciation pressure on both sides of the Atlantic. D. delphis and S. coeruleoalba, despite their amphiatlantism, have hardly been studied in the western Atlantic, except for a few references in the southern hemisphere, so the fun- damental differences between the two species and their comparison with T. truncatus have been established with records from the eastern Atlantic. All three dolphin species have been observed to be expanding, especially D. delphis. This northward expansion and that of their prey is discussed.