| Dosidicus gigas is an important oceanic economic cephalopod,widely distributed in the eastern Pacific Ocean.Dosidicus gigas is an active predator,the common prey animals are copepods,flat feet and so on,feeding range with its growth and constantly changing.It is both the most important fishery in the southeastern Pacific and a key player in the pelagic ecosystem,producing more than800,000 tons a year in recent years,according to the FAO.Stable isotope analysis is a new method to study nutrient pathways and migration patterns of Marine organisms.Recently,more and more scholars use stable isotope technique to study cephalopod information.It has been shown that stable isotope analysis of different tissues of cephalopods can predict the food source,habitat environment and migration path of cephalopods.Stable isotope analysis is a powerful tool in ecological research,including reptiles,arthropods,birds and mammals.Based on the research results of stable isotopes of cephalopods by scholars at home and abroad,this paper focuses on the study of stable isotopes in different tissues of cephalopods,and analyzes the difference of stable isotopes among tissues of Dosidicus gigas,aiming to grasp the study of stable isotopes as a whole and promote its application in the biology of cephalopods.The main findings are as follows:?1?According to the research results of stable isotopes of cephalopods by scholars at home and abroad,Several major stable isotopes commonly found in cephalopod studies are summarized.Stable isotopes from different sources are introduced and different form the source of stable isotopes are introduced,emphasis from feeding ecology of stable isotopes,habitat,migration and other aspects in cephalopod fishery ecology study and master its application in cephalopods biology and ecology.?2?In order to explore the influence of lipid removal on carbon and nitrogen stable isotopes of Dosidicus gigas and the difference of stable isotopes between different soft tissues,degrease and non degrease three kinds of soft tissues,such as muscle,gonad and digestive gland,were used to measure and analyze the stable isotopes in their tissues.The results showed that the?13C and C/N of the three soft tissues were significantly different before and after lipid removal?P<0.05?,and the?15N of the muscle and gonad were significantly different before and after lipid removal?P<0.05?,but the?15N of the digestive gland was not significantly different before and after lipid removal?P>0.05?.The?13C,?15N and C/N showed significant differences between the three tissues before and after lipid removal?P<0.05?.The content of stable isotopes in different tissues was compared:?13Cbefore:muscle>digestive gland>gonad,?13Cafter:muscle>digestive gland>gonad,?15Nbefore:muscle>digestive gland>gonad,?15Nafter:muscle>digestive gland>gonad;C/Nbefore:gonad>digestive gland>muscle,C/Nafter:digestive gland>gonad>muscle.The results provide a basis for the analysis of the changes of stable isotopes between soft tissues and the offset of stable isotopes before and after lipid removal,and hope that these results provide a reference for the study of cephalopod feeding ecology.?3?Hard tissue has stable morphological characteristics,good information storage and corrosion resistance.beak,eyes and gladius are important hard tissues of cephalopod and good information carriers.In this paper,three kinds of hard tissue were studied for analysis of the overall stable isotopes and specific sites.The results showed that there were significant differences between the rostrum and the periphery of the lateral wall,the core and the edge of eye lens,the near conus and away from conus of gladius?P<0.05?.The?13C value was-19.91?-18.75,and the?15N value was0.41?3.18in beaks.The?13C value was-19.54?-18.72,and the?15N value was5.22?8.08in eyes.The?13C value was-19.79?-19.05,and the?15N value was 4.12?5.48in gladius.There was no overlap between the rostrum and the periphery of the lateral wall,there was overlap between the core and the edge of eye lens, and there was also overlap between the near conus and away from conus of gladius.?4?the beak,eyes and gladius of cephalopods are good information carriers,and their growth and development are irreversible and can be seen throughout the whole life cycle.Stable isotope is one of the effective methods to study cephalopod habitat and nutrient ecology.In this study,the beaks,eyes and gladius of the Dosidicus gigas in the equatorial waters were truncated along the growth direction,and the stable isotope values of carbon and nitrogen were determined.The study results showed that the?13C value of the the upper hood was-20.52?-18.62,with an average value of-19.54,and the?15N value was 0.08?4.95,with an average value of 1.69.?13C value of the the upper crest was-19.93?-18.60,with an average value of-19.44,?15N value was 0.44?4.92,with an average value of 2.57.The?13C value of gladius sample was-20.54?-18.37,with an average of-19.14,?15N value was 2.97?5.93,with an average of 4.01.The?13C value of the eye lsample was-20.28?-18.62,with an average value of-19.40,?15N value was 4.39?10.07,with an average value of 6.52.Ecological niches were drawn according to beakss,eyes and gladiuss,showing that most of the samples had overlapping ecological niches. |
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