| 摘要: |
| 研究鱼类的种群生态学，破解其数量特征、生境利用、种群结构和动态变化等种群属性是保护和合理开发天然渔业资源的基础。耳石微化学分析是破解鱼类的种群生态学难题的新颖而有力的手段，不仅可以反演鱼类生活史过程中所经历的环境条件，还可溯源资源群起源的产卵场等关键生境，在鱼类资源种群空间结构形成机制研究及动态评估中具有优势。本文在分析耳石元素组成及其沉积特征的基础上，重点介绍了耳石微化学分析在鱼类种群生态学(如反演鱼类生活史、评估种群结构、把握关联性和破解混合群体的构成与来源等)中的应用进展，也客观评述了耳石微化学分析在鱼类种群生态学研究中的局限性与解决途径，并对今后相关技术的发展趋势及需要关注的科学问题进行了展望。 |
| 关键词: 耳石微化学分析 鱼类种群生态学 生活史 生境关联性 |
| DOI：10.19663/j.issn2095-9869.20210528002 |
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| Advances in the Application of Otolith Microchemistry Analysis in Fish Population Ecology |
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XUAN Zhongya,JIANG Tao,LIU Hongbo,CHEN Xiubao,HU Yuhai,YANG Jian
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1.Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, Jiangsu 214081, China;2.Key Laboratory of Fishery Ecological Environment Assessment and Research Conservation in Middle and Lower Reaches of the Yangtze River, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, Jiangsu 214081, China
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| Abstract: |
| Knowledge of fish population ecology is fundamental for understanding population structure, habitat utilization, resource dynamics, and formulating conservation policy for natural fish resources. To date, various technologies have been used to better understand fish population ecology. Among them, otolith microchemistry analysis is one of the most important research approaches. Otoliths (ear bone) are biologically calcified structures in the inner ear of fish, which show continuous growth and are metabolically inert. They usually constitute three pairs of sagittae, lapilli, and asterisci in bony fish. As these hard tissues can record the habitat information that individual fish experience during their lifetime, otoliths are a useful resource for reconstructing the temporal and spatial histories of fish populations. The composition and content of otolith elements (like “fingerprints”) are mainly related to the bioavailability of macro and trace elements (including stable isotopes) in the ambient water and aquatic physical and chemical properties (especially salinity). Increasing scientific evidence has demonstrated that otolith microchemical analysis is a powerful tool to study fish population ecology, revealing the environmental conditions experienced by the organisms and tracing the key habitats (e.g., spawning site, nursery ground, and growing area) throughout their life cycle. Moreover, this approach offers significant advantages in assessing the formation mechanism and spatial structure dynamics of fish stocks. As the ratios of strontium to calcium (Sr/Ca) significantly differ between freshwater and seawater, and among different freshwater tributaries on a fine spatial scale, otolith Sr/Ca ratios are powerful markers for distinguishing freshwater, brackish water, and seawater habitats, and are widely used as a useful tool for revealing the habitat history related to spawning, hatchery, development, and migration of migratory fish. The combined analysis of otolith microchemistry (e.g., otolith line transects of elements) and microstructure (e.g., otolith increment of somatic growth) can be effectively used to quantify the duration and frequency of different habitat requirements by the target fish populations. Otolith microchemistry analysis also provides a good reference for studying population genetics. The core element characteristics of otoliths can separate the different fish sources originating from different spawning sites and obtain more accurate information on population structure. Notably, because of the small size of the fish at early life stages, electronic tags and telemetry technologies are almost impossible to use in life history studies. In contrast, the trace elements assimilated by fish during the ontogeny and growth process are stored in the otolith microstructure, and elemental profiles of the otoliths can indicate habitat clues of fish even at early life stages. The present review highlights the advances in studies on the characteristics of fish otolith elements and the application of otolith microchemistry analysis on fish population ecology, especially of natal origin reconstruction, habitat history inversion, population structure evaluation, and stock connectivity assessment. The limitations of otolith microchemistry analysis and possible solution routes are also discussed. Baseline investigations are suggested to enhance the robustness and interpretability of otolith microchemistry analysis, as several exogenous and endogenous factors may influence the spatio-temporal patterns of otolith chemistry. Additionally, building a multiyear database of otolith chemistry and water elemental signatures is recommended. It is noteworthy that the structure of otoliths in some cartilaginous fish is not suitable for microchemical analysis, and collecting otoliths from endangered or protected fish species is difficult. Alternative hard tissues (e.g., rays, scales, spines, and scutes) can be used to study fish population ecology as non-invasive substitutes of otolith samples. As mentioned, otolith microchemical analysis can accurately distinguish the ecological profiles of migratory fish; if combined analysis of otolith microchemistry and genetic markers is used to reveal the genetic structure and differentiation of fish populations, the results would become more reliable for developing and executing effective management and conservation strategies. At present, with improvements in the otolith microchemistry research, the analysis of otolith microchemistry has been extended to several new fields. The 87Sr/86Sr isotope ratio of otoliths has been utilized to investigate the life history of fish on a wider spatio-temporal scale. Furthermore, the approach of artificial otolith marking by macro and trace elements has strong applicability in the restocking of fisheries and will play a vital role in enhancing commercial and endangered fishery resource in the future. |
| Key words: Otolith microchemical analysis Fish population ecology Life history Habitat connectivity |
