This variation directly affects the frequency and biogeography of a group of pelagic fish, which includes the sardine (Sardina pilchardus), anchovy (Engraulis encrasicolus), horse mackerel (Trachurus trachurus) and mackerel (Scomber scombrus), among others, which feed off phytoplankton and zooplankton and that are the staple diet of large predators such as cetaceans, large fish and marine birds.