长江口禁捕初期三种主要虾类的营养生态位及其空间差异

TROPHIC NICHE AND SPATIAL VARIATION OF THREE DOMINANT SHRIMP SPECIES DURING THE EARLY PERIOD OF FISHING BAN IN THE YANGTZE RIVER ESTUARY

  • 摘要: 虾类是长江口食物网结构中的重要饵料生物, 为探究优势饵料虾类间营养相互作用, 本研究对2022年11月在长江口南、北支水域采集到的3种优势虾类安氏白虾(Exopalaemon annandalei)、葛氏长臂虾(Palaemon gravieri)和脊尾白虾(Exopalaemon carinicauda)肌肉样本进行δ13C和δ15N测定, 计算营养生态位宽度和重叠, 从营养关系角度解析它们的种间竞争和共存机理及其空间分化特征。研究结果表明: (1) 3种虾类中葛氏长臂虾摄食偏底栖食性, δ13C值最富(–17.05±3.23)‰; 安氏白虾偏浮游食性, δ13C值最贫(–20.19±1.50‰); 脊尾白虾个体偏大, δ15N值最高(10.28±0.55)‰; (2)安氏白虾的δ13C值和δ15N值在南、北支水域差异显著(P<0.05), 显示出安氏白虾摄食具有空间差异性, 也间接表明其环境适应性较好; (3)安氏白虾的CR值(5.62)、NR值(4.43)和SEAc值(3.07)均最大, 表明其具有更广泛的基础食源、更多元的营养水平以及更高的资源利用能力; (4)安氏白虾与另两种虾类的生态位重叠较小, 食物资源维度呈现一定的生态位分化, 而葛氏长臂虾和脊尾白虾的生态位重叠较大, 表明两者饵料来源相似, 食性竞争激烈, 但摄食差异保证了种间共存。当前禁捕初期, 长江口三种优势虾类中以安氏白虾占据资源的能力最强, 在河口的环境适应性最佳。

     

    Abstract: Shrimp play a crucial role as significant food sources in the Yangtze River estuary. This study focused on three dominant shrimp species: Exopalaemon annandalei, Palaemon gravieri, and Exopalaemon carinicauda, which collected from the southern and northern branches of the Yangtze River estuary in November 2022. Muscle samples were analyzed for δ13C and δ15N to calculate their trophic niche widths and overlaps, elucidating interspecies competition mechanisms and coexistence patterns, as well as their spatial differentiation characteristics from a nutritional ecology perspective. The research findings demonstrated that: (1) Among the three species, P. gravier exhibited a benthic feeding preference with the highest δ13C value (–17.05±3.23)‰, while E. annandalei leaned towards planktonic feeding with the lowest δ13C value (–20.19±1.50)‰. E. carinicauda, with larger individuals, had the highest δ15N value (10.28±0.55)‰. (2) There was a statistically significant difference (P<0.05) in δ13C and δ15N values between the southern and northern branches for E. annandalei, indicating spatial differences in its feeding habits and indirectly suggesting a relatively high environmental adaptability. (3) E. annandalei had the largest CR value (5.62), NR value (4.43), and SEAc value (3.07), implying it had the broadest basal food resources, more diverse nutritional levels, and higher resource utilization capacity compared to the other two species. (4) The ecological niche overlap between E. annandalei and the other two shrimp species was relatively small, showing a certain degree of ecological niche differentiation in terms of food resources. Conversely, P. gravier and E. carinicauda had a larger ecological niche overlap, suggesting they share similar food sources and experience intense dietary competition. However, feeding differences ensure interspecific coexistence. At the beginning of the current closure period, among the three dominant shrimp species in the Yangtze River estuary, E. annandalei is the most capable of occupying resources and has the best environmental adaptation in the estuary.

     

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