南海中西部海域鸢乌贼中型群和微型群的营养生态位

为了深入了解南海鸢乌贼不同种群的碳氮稳定同位素特征及营养生态位之间的关系,于2017年8月在南海中西部海域采集其中型群和微型群样品,分析不同胴长组的碳氮稳定同位素值和营养级变化,并比较其营养生态位差异.结果表明:中型群鸢乌贼的δ^13C范围在-19.54‰^-18.10‰,δ^15N范围在7.79‰~9.45‰,营养级范围在2.72~3.21,平均营养级为2.90;微型群鸢乌贼的δ^13C范围为-19.69‰^-18.43‰,δ^15N范围为8.02‰~8.99‰,营养级范围为2.79~3.08,平均营养级为2.91.两个鸢乌贼种群间δ^13C差异不显著,δ^15N差异显著.胴长显著影响了鸢乌贼的δ^13C和δ^15N值,且随着胴长的增大,δ^15N值有增大的趋势.中型群鸢乌贼的营养生态位宽幅和营养级的多样性程度都大于微型群.

Trophic niche of medium-form and dwarf-form of purple flying squid Sthenoeuthis oualaniensis in the central and western South China Sea

To explore the characteristics of carbon and nitrogen stable isotope and trophic niche between two forms (medium-form and dwarf-form) of the purple flying squid Sthenoteuthis ouala-niensis, we collected samples from the central and western South China Sea in August 2017 to analyze the values of carbon and nitrogen stable isotope and the changes of trophic level for different mantle lengths. We further compared the trophic niche differences of the two forms populations. The results showed that for the medium-form, the δ¹³C value ranged from -19.54‰ to -18.10‰ and the δ¹⁵N value ranged from 7.79‰ to 9.45‰. The average trophic level of medium-form was 2.90 and ranged from 2.72 to 3.21. For the dwarf-form, the δ¹³C value ranged from -19.69‰ to -18.43‰, and the δ¹⁵N value ranged from 8.02‰ to 8.99‰. The average trophic level of the dwarf-form was 2.91 and ranged from 2.79 to 3.08. There were significant differences of δ¹⁵N but no differences of δ¹³C values between the medium-form and dwarf-form of purple flying squid. The mantle length had a significant impact on δ¹³C and δ¹⁵N, with the value of δ¹⁵N increasing with the mantle length. The trophic niche breadth and the trophic level of the medium-form purple flying squid were more diverse than those of dwarf-form.