头足类角质颚稳定同位素研究进展

Review on the stable isotopes in cephalopod beaks

角质颚作为头足类重要硬组织之一,结构稳定、耐腐蚀、易获取,蕴含着大量的生物与生态学信息,在头足类的年龄鉴定、生长估算、种群划分、摄食生态评估、洄游路线推测以及栖息环境重建等方面受到国内外学者的广泛关注。过去,角质颚的研究主要集中在形态与微结构的分析与应用领域。近年来,随着地球微化学手段的不断创新与进步,角质颚的稳定同位素的研究越来越受到海洋生物与生态学家的重视。本文根据国内外学者对其的研究成果,重点对碳氮稳定同位素在头足类摄食生态评估、栖息环境重建和洄游路线推测等方面的应用进行综述,旨在解读头足类不同生活史阶段的生物与生态信息,其应用前景十分广阔。

Spatial patterns of stable isotopes in organism tissues reflect variations in baseline values as well as trophic effects. Consequently,geographic variations in δ13C and δ15 N in tissues of marine species to some extent,represent differences of both habitat and trophic position. Generally,δ13 C values reflect source of primary productivity,since they typically increase by only 0. 5‰ to 1. 5‰ per trophic level. Thus,the δ13 C values are commonly used to discriminate inshore vs. offshore or pelagic vs. benthic feeding,as well as the lower-vs. higher-latitude plankton in the marine ecosystem. In contrast,consumers are enriched in δ15 N by2‰ to 3. 5‰ relative to their food,providing a possible mechanism to estimate the trophic position.Cephalopod beak,an important feeding apparatus within squid buccal mass,is responsible for masticating preys before they are swallowed. They have been widely concerned by scholars at home and abroad in the study of age, growth, population, feeding ecology, migration and habitat. It records much effective information on biology and ecology for the characteristics of stable morphology,erosion resistantance and easy access. In the past years,the analysis and application of cephalopod beaks has mainly focused on its morphology and microstructure. Stable isotopes analysis of carbon and nitrogen（ δ13 C and δ15 N） has recently emerged as a common and alternative tool to elucidate cephalopod trophic ecology and life history and its application has steadily increased in the last decade. In general,stable isotopes in cephalopod soft tissues（ e.g. mantle） only can reflect the environmental information prior to capture because their relatively quick turnover. In contrast,hard tissues（ e. g. beaks） are inactively metabolic structures whose new molecules lay down continuously with nearly no turnover after synthesis. Consequently,the δ13 C and δ15 N within these structures combine the feeding ecology of individuals over cephalopods lifespan. Recently,with the continuous innovation and progress of geochemical techniques,the study of micro-chemical analysis especially stable isotope analysis of cephalopod beaks has become increasingly popular for more and more biologist or ecologist.Based on previous studies, we reviewed progress in micro-chemistry of beaks from cell composition,pigmentation and stable isotope, especially focusing on the application in trophic ecology, habitat reconstruction and migration routine. The results showed that the investigation of biological and ecological information on different ontogenetic stages recorded in beaks has a broad application prospect.