中东太平洋赤道海域茎柔鱼营养模式年间差异分析

Inter-annual variations in the trophic pattern of jumbo squid Dosidicus gigas from the Central Eastern Pacific Ocean

摘要:

为探究茎柔鱼（Dosidicus gigas）食性和洄游模式的变动规律及其与异常气候事件和捕捞强度变化的潜在关系,本研究选取中东太平洋赤道海域茎柔鱼,通过测定其内壳连续切割片段碳、氮稳定同位素比值（δ¹³C和δ¹⁵N）,结合气候与环境指数,比较分析不同年份茎柔鱼生长过程营养模式的变化规律及其动因。结果显示,2019年茎柔鱼内壳δ¹³C随个体生长显著升高,且营养生态位缩小,可能与该年份厄尔尼诺发生后,茎柔鱼从赤道向南半球高纬度洄游有关。在发生拉尼娜的2018、2020和2021年,茎柔鱼的营养模式存在年间差异。2018年茎柔鱼内壳δ¹³C和δ¹⁵N随个体生长显著升高,但营养生态位无显著变化,体现了茎柔鱼向南半球高纬度洄游但食物来源相对稳定。而实施公海自主休渔的2020和2021年,茎柔鱼δ¹³C和δ¹⁵N随个体生长无显著变化,但生活史后期营养生态位面积较高。说明其生活史过程洄游范围较小、食性稳定且群体生态弹性较高。以上结果表明,异常气候事件和捕捞强度变化可能都会对茎柔鱼的营养模式造成影响,但要确定各因素的影响程度还需进一步深入研究。

关键词:茎柔鱼;营养生态位;稳定同位素;厄尔尼诺;拉尼娜

Abstract:

To explore the changing patterns of the dietary habits and migratory patterns of the jumbo squid （Dosidicus gigas） and their potential relationship with abnormal climate events and variations in fishing intensity.In this study, we selected D.gigas from the Central Eastern Pacific Ocean as research object, and evaluated the sequentialstable isotope values of δ¹³C and δ¹⁵N in sectioned fragments of gladius. Using climate and environmental indices, the inter-annual variations in the ontogenictrophic patterns of the D.gigas were compared and their causes were explored.The results indicated that the δ¹³C values of 2019 D. gigasgladius significantly increased with individual growth, and the trophic niche narrowed, which may be related to the migration from equator to the southern hemisphere after the El Niño occurred. Differences were also found in the trophic patterns of the D.gigascollected in the La Niña periods, i.e., 2018, 2020, and 2021. In 2018, the δ¹³C and δ¹⁵N value of D.gigasgladius significantly increased with individual growth, indicating a southward migration to higher latitudes in the Southern Hemisphere. However, there was no significant change in the trophic niche, suggesting a relatively stable food source for D.gigas. During the implementation of seasonal moratorium in the high seas in 2020 and 2021, there were no significant changes in δ¹³C and δ¹⁵N values with individual growth, while higher trophic niche width during the later stages of life span. This indicated that these individuals had narrow migratory range, stabledietary, and high ecological resilience. These findings illustrate the sensitivity of D.gigas to abnormal climatic events and variation of fishing intensity. However, further research is needed to determine the extent of each factor's influence.

Key words:Dosidicus gigas;trophic ecology;stable isotope;El Niñ;o;La Niñ;a