Ontogenetic and Spatiotemporal Changes in Isotopic Niche of Jumbo Squid (Dosidicus gigas) in the Southeastern Pacific

Jumbo squid (Dosidicus gigas) plays an important role in food webs throughout the eastern Pacific; however, its trophic ecology is complex, because it is a highly migratory and opportunistic predator. In this study, delta C-13 and delta N-15 values were measured along the lateral wall of lower beak to investigate the ontogenetic and spatiotemporal feeding strategy shifts of jumbo squid, respectively. Both year and area had significant influences on delta C-13 (p < 0.01), while sex and stage had no significant influence on delta C-13 (p > 0.05). All explanatory variables (sex, stage, year, and area) had significant influences on delta N-15 (p < 0.05). The differences of niche among life stages indicated that the habitat and feeding habit were likely changed with the growth of individuals. Compared with normal years, the habitat of squids might change during the El Nino year. However, during the strong El Nino year, habitat location changed and niche size decreased compared to normal years. The trophic niche of D. gigas differed between different areas. Stable isotopes in early life stages were most effective for distinguishing different geographic populations. Females and males were likely to inhabit similar geographic areas throughout ontogeny. Unexpectedly, we found evidence to suggest females may have larger habitats and wider trophic niche than males. This study revealed the ontogenetic and spatiotemporal plasticity of habitat and feeding strategy of D. gigas.

Automated summary

Jumbo squid plays a crucial role in the food webs of the eastern Pacific, but its trophic ecology is complex due to its highly migratory and opportunistic predatory behavior. This study investigated the ontogenetic and spatiotemporal shifts in the feeding strategies of jumbo squid using stable isotope analysis. The results showed that both year and area significantly influenced the stable isotope values, while sex and stage had no significant effect on the values. The study also revealed that the habitat and feeding habits of jumbo squid changed with the growth of individuals and differed among different areas.