Ontogenetic dietary changes of green turtles (Chelonia mydas) in the temperate southwestern Atlantic

Green turtle diet is dominated by seagrass in the Western Indian Ocean except amongst gravid females

“…Ontogenetic dietary change is complex and varies regionally (e.g., Cardona et al 2010;Fukuoka et al 2019). Typically, the diet is omnivorous during the early pelagic stages and becomes primarily herbivorous after recruitment to the neritic zone (e.g., Howell et al 2016;Vélez-Rubio et al 2016;Burgett et al 2018). In the Central North Pacific, however, some individuals up to 70 cm curved carapace length (CCL) forage pelagically on a primarily carnivorous diet (Parker et al 2011).…”

Beyond trophic morphology: stable isotopes reveal ubiquitous versatility in marine turtle trophic ecology

“…Several stable isotope studies have addressed the question concerning the timing of ontogenetic shifts from oceanic to neritic habitat. One approach has been to examine stable isotope values in different bone growth layers and translate this into an estimation of size classes in C. caretta (Snover et al, ) and C. mydas (Howell et al, ; Velez‐Rubio et al, ). Yearly somatic growth is recorded in annual marks in humeri cross sections, and a transition from narrow growth marks to wider growth marks indicates a sharp increase in growth rates and a potential shift from oceanic to neritic habitats.…”

“…herbivory versus carnivory), which are unrelated to changes in spatial habitat use (shift from oceanic pelagic prey to neritic benthic prey). Four studies have investigated this question in C. caretta in Atlantic and Indian Ocean populations (Wallace et al, ; McClellan et al, ; Thomson et al, ; Hall et al, ); 19 studies in Atlantic C. mydas (Burgett et al, ; Cardona et al, ; Di Beneditto, Siciliano & Monteiro, ; Gillis et al, ; Gonzales Carman et al, ; Hancock et al, ; Howell et al, ; Velez‐Rubio et al, ; Williams et al, ), Pacific C. mydas (Arthur, ; Barceló, ; Lemons et al, ; Prior, Booth & Limpus, ; Rodríguez‐Barón, ; Sampson et al, ; Santos‐Baca, ; Shimada et al, ), and C. mydas in the Indian Ocean (Burkholder et al, ) and in the Mediterranean (Cardona et al, ); one study in Atlantic D. coriacea (Wallace et al, ), one study in E. imbricata (Ferreira et al, ), and one study in L. olivacea (Peavey et al, ).…”

“…For example, Velez‐Rubio et al . () documented a relationship between diet (a shift between omnivory and herbivory) and body size (gelatinous macrozooplankton in turtles <45 cm CCL, and predominantly herbivory in individuals >45 cm). Another study found a similar pattern, but at a larger body size (CCL >59 cm) (Cardona, Aguilar & Pazos, ).…”

Alometria reprodutiva e isotópica de tartaruga-verde Chelonia mydas (Linnaeus, 1758): relações entre tamanho corporal, dieta e investimento reprodutivo

“…Chelonia mydas é conhecida por ser basicamente herbívora quando adulta. No entanto, diversos estudos têm demonstrado que, apesar de sua dieta ser composta na maioria dos casos por algas e gramas marinhas, ela também pode conter uma relevante presença de matéria animal como cnidários, moluscos e crustáceos (Seminoff et al 2002, 2006a, López Mendilaharsu et al 2005 Baron 2010, Santos et al 2015, Vélez-Rubio et al 2016 A análise de variâncias (ANOVA) mostrou que a variância entre os valores de δ 15 N das amostras (i.e., dos mesmos tecidos de diferentes fêmeas) é significativamente diferente da variância existente entre os tecidos diferentes. De acordo com a análise de médias de δ 15 N (ANOM, Figura 3.2), a maioria dos tecidos apresenta média significativamente similar à média geral, mesmo comparando tecidos de metabolismo mais lento (e.g., queratina da carapaça) e mais acelerado (e.g., plasma).…”