High trophic specialization structures the epi- to bathypelagic fish community in the Bay of Biscay

IF 2.3 3区 地球科学 Q2 OCEANOGRAPHY
Liz Loutrage , Anik Brind'Amour , Tiphaine Chouvelon , Jérôme Spitz
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引用次数: 0

Abstract

The deep-pelagic ecosystem is characterized by significant environmental gradients, particularly in food resources. The absence of primary production below the epipelagic zone leads to a decrease in food resources with depth. Two opposite feeding strategies have been described for this community in response to this decline in food resources: stochasticity, with species adopting opportunistic feeding strategies with a generalist diet, and determinism, with species segregating and specializing to mitigate strong interspecific competition through niche partitioning. To test these aspects, we analyzed the isotopic niches of 16 fish species using stable isotope analysis of carbon and nitrogen carried out on muscle samples. The data were collected in canyons of the Bay of Biscay between 25 and 1335 m. Our primary objective was to identify isotopic niche segregation or overlap and determine whether species sharing similar isotopic niches show depth-based segregation by grouping them into trophic guilds and comparing their depth distribution with trawl data. We then used null model comparisons to test whether competition resulted in smaller values of isotopic niche size and overlap within each depth assemblage compared to those obtained by chance. We found that several species with similar isotopic niches were segregated based on depth. The comparison with null models showed that competition drove species to reduce niche size and specialize to avoid strong interspecific competition in the epi- to bathypelagic layers. Utilizing isotopic diversity indices weighted by biomass, our calculation showed significant divergence within the community, indicating that species with the highest biomass had extreme isotopic values. The high degree of specialization of species raises concerns about their vulnerability to various pressures, including climate change and exploitation. At the community level, this vulnerability is also a concern in maintaining the integrity of ecological processes.

比斯开湾表层至深海鱼类群落的高度营养专业化结构
深海生态系统具有明显的环境梯度,尤其是在食物资源方面。上深海区以下缺乏初级生产,导致食物资源随深度增加而减少。针对食物资源的减少,该群落有两种截然相反的摄食策略:一种是随机性策略,即物种采取机会主义摄食策略,以通才为食;另一种是决定性策略,即物种通过生态位分区进行隔离和专化,以缓解强烈的种间竞争。为了检验这些方面,我们利用对肌肉样本进行的碳和氮稳定同位素分析,分析了 16 种鱼类的同位素生态位。我们的主要目标是识别同位素生态位的隔离或重叠,并通过将物种划分为营养行会并将其深度分布与拖网数据进行比较,确定具有相似同位素生态位的物种是否表现出基于深度的隔离。然后,我们使用无效模型比较法来检验竞争是否会导致每个深度集合内的同位素生态位大小和重叠值小于偶然得到的数值。我们发现,一些具有相似同位素生态位的物种根据深度被分隔开来。与空模型的比较结果表明,竞争促使物种缩小生态位大小并进行专化,以避免在上深海层至深海层出现强烈的种间竞争。利用按生物量加权的同位素多样性指数,我们的计算显示群落内部存在显著的分化,表明生物量最高的物种具有极端的同位素值。物种的高度专业化使人们担心它们在气候变化和开发等各种压力下的脆弱性。在群落层面,这种脆弱性也是维持生态过程完整性的一个问题。
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来源期刊
CiteScore
4.60
自引率
4.20%
发文量
144
审稿时长
18.3 weeks
期刊介绍: Deep-Sea Research Part I: Oceanographic Research Papers is devoted to the publication of the results of original scientific research, including theoretical work of evident oceanographic applicability; and the solution of instrumental or methodological problems with evidence of successful use. The journal is distinguished by its interdisciplinary nature and its breadth, covering the geological, physical, chemical and biological aspects of the ocean and its boundaries with the sea floor and the atmosphere. In addition to regular "Research Papers" and "Instruments and Methods" papers, briefer communications may be published as "Notes". Supplemental matter, such as extensive data tables or graphs and multimedia content, may be published as electronic appendices.
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