Weldrick Christine K, Trebilco Rowan, Davies Diana M, Swadling Kerrie M
Institute for Marine and Antarctic Studies University of Tasmania Hobart Tasmania Australia.
Antarctic Climate and Ecosystems Cooperative Research Centre University of Tasmania Hobart Tasmania Australia.
Ecol Evol. 2019 Jun 20;9(14):8119-8132. doi: 10.1002/ece3.5380. eCollection 2019 Jul.
Pteropods are a group of small marine gastropods that are highly sensitive to multiple stressors associated with climate change. Their trophic ecology is not well studied, with most research having focused primarily on the effects of ocean acidification on their fragile, aragonite shells. Stable isotopes analysis coupled with isotope-based Bayesian niche metrics is useful for characterizing the trophic structure of biological assemblages. These approaches have not been implemented for pteropod assemblages. We used isotope-based Bayesian niche metrics to investigate the trophic relationships of three co-occurring pteropod species, with distinct feeding behaviors, sampled from the Southern Kerguelen Plateau area in the Indian Sector of the Southern Ocean-a biologically and economically important but poorly studied region. Two of these species were gymnosomes (shell-less pteropods), which are traditionally regarded as specialist predators on other pteropods, and the third species was a thecosome (shelled pteropod), which are typically generalist omnivores. For each species, we aimed to understand (a) variability and overlap among isotopic niches; and (b) whether there was a relationship between body size and trophic position. Observed isotopic niche areas were broadest for gymnosomes, especially , whose observed isotopic niche area was wider than expected on both δC and δN value axes. We also found that trophic position significantly increased with increasing body length for . We found no indication of a dietary shift toward increased trophic position with increasing body size for f. . Trophic positions ranged from 2.8 to 3.5, revealing an assemblage composed of both primary and secondary consumer behaviors. This study provides a comprehensive comparative analysis on trophodynamics in Southern Ocean pteropod species, and supports previous studies using gut content, fatty acid and stable isotope analyses. Combined, our results illustrate differences in intraspecific trophic behavior that may be attributed to differential feeding strategies at species level.
翼足类动物是一类小型海洋腹足纲动物，对与气候变化相关的多种压力源高度敏感。它们的营养生态学尚未得到充分研究，大多数研究主要集中在海洋酸化对其脆弱的文石壳的影响上。稳定同位素分析与基于同位素的贝叶斯生态位指标相结合，有助于描述生物群落的营养结构。这些方法尚未应用于翼足类动物群落。我们使用基于同位素的贝叶斯生态位指标，研究了从南大洋印度海域克尔格伦高原南部地区采集的三种共生翼足类物种的营养关系，该地区具有生物学和经济重要性，但研究较少。其中两种物种是裸壳翼足类（无壳翼足类动物），传统上被视为其他翼足类动物的特化捕食者，第三种物种是有壳翼足类（有壳翼足类动物），通常是广食性杂食动物。对于每个物种，我们旨在了解：（a）同位素生态位之间的变异性和重叠；以及（b）体型与营养级之间是否存在关系。裸壳翼足类动物的观测同位素生态位面积最广，尤其是 ，其观测同位素生态位面积在δC和δN值轴上均比预期的要宽。我们还发现， 的营养级随着体长的增加而显著增加。对于 f. ，我们没有发现随着体型增大，营养级向更高营养级转变的饮食变化迹象。营养级范围从2.8到3.5，表明该群落既有初级消费者行为，也有次级消费者行为。这项研究对南大洋翼足类物种的营养动力学进行了全面的比较分析，并支持了之前使用肠道内容物、脂肪酸和稳定同位素分析的研究。综合来看，我们的结果说明了种内营养行为的差异，这可能归因于物种水平上不同的摄食策略。
