New insights in Southwestern Atlantic Ocean Oegopsid squid distribution based on juvenile green turtle (Chelonia mydas) diet analysis

Abstract

A total of 52 cephalopod beaks were found in the stomachs and intestines of 17 out of 54 green turtles, Chelonia mydas, stranded on the Uruguayan coast between 2009 and 2013 (frequency of occurrence = 31.5 %). Upper and lower beaks were assigned to at least six Oegopsid species of four different genera, Chiroteuthis, Histioteuthis, Onykia (= Moroteuthis) and Mastigoteuthis. Although the presence of cephalopods in the diet of green turtles has been reported previously, it has been quoted as a sporadic or less important diet category. Our findings suggest that this intake of cephalopods by juvenile green turtles during their oceanic stages may be more common in the Southwestern Atlantic Ocean waters than previously thought. According to our records, two of the six Oegopsid squid species found would have a more extended distribution than previously reported, ranging from circumpolar sub-Antarctic areas to the Brazil-Malvinas confluence zone. We highlight the potential of diet analysis of pelagic predators as a tool to enhance our knowledge of the diversity and distribution of poorly known cephalopod species.