Coastal hypoxia reduces trophic resource coupling and alters niche characteristics of an ecologically dominant omnivore
Coastal hypoxia reduces trophic resource coupling and alters niche characteristics of an ecologically dominant omnivore
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DOI：
10.1016/j.fooweb.2022.e00252
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发表时间：
2022-09-12
期刊：
影响因子：
1.7
通讯作者：
Woodland，Ryan J.
中科院分区：
文献类型：
--
作者：
Quillen，Kennedy;Santos，Nina;Woodland，Ryan J.
在沿海生态系统中，能量和生物量通过各种营养途径移动，其中中上层和底栖途径往往主导着食物网动态。耦合这些途径的消费者在这些食物网中发挥重要的结构化作用，通过整合空间上断开或异步的生产途径。本研究的目的是量化的底栖和浮游营养途径的饮食的Myodysisamericanain的Choptank和Patuxent河（切萨皮克湾的支流）的贡献，并确定这两个营养途径的相对贡献不同的生态系统具有不同的环境，物理和流域特征。这种糠虾每天在整个水柱中进行垂直迁移，据推测，帕塔克森特河（但不是Choptank河）深水生境中的缺氧（< 2毫克/升）可能会降低帕塔克森特河相对于Choptank河的糠虾底栖路径的重要性。在2018年和2019年夏天，在每条河流中收集了糠虾和营养资源，并分析了碳和氮稳定同位素组成和组织化学计量（C：N）。基于稳定同位素的底栖营养途径贡献、营养位置和同位素生态位面积（营养生态位的代理）以及N的C：N组成的估计。在支流内部和支流之间进行了比较。总体而言，糠虾在Patuxent河同化底栖动物的材料，实现较低的营养地位，并有较低的C：N比（代理脂质含量）比Choptank河糠虾。没有一致的模式在营养生态位面积的观察，虽然生态位面积（和浮游营养途径的贡献）的Choptank河糠虾增加在高流量的河流事件。这项研究提供的证据表明，缺氧条件下的Patuxent降低了底栖-浮游耦合的强度由N。此外，与较低的营养地位和减少的脂质储存的化学计量标志物有关。除了作为杂食性消费者的角色，N。美洲大蠊是许多掠食者的主要猎物分类群，这突出表明该物种对当地食物网的重要性，以及对沿海生态系统的营养生态变化产生自下而上影响的潜力。
Energy and biomass move through a variety of trophic pathways in coastal ecosystems, with pelagic and benthic pathways often dominating food web dynamics. Consumers that couple these pathways play important structuring roles in these food webs by integrating spatially disconnected or asynchronous production pathways. The objective of this study was to quantify benthic and pelagic trophic pathway contributions to the diet of the mysidNeomysisamericanain the Choptank and Patuxent rivers (tributaries of Chesapeake Bay) and determine if the relative contribution of these two trophic pathways differs between ecosystems with different environmental, physical, and watershed features. This mysid species undergoes daily vertical migrations throughout the water column and it was hypothesized that hypoxia (< 2 mg/L) in deep-water habitats of the Patuxent River (but not the Choptank) could reduce the importance of the benthic pathway for mysids in the Patuxent River relative to the Choptank River. Mysids and trophic resources were collected in each river during the summers of 2018 and 2019 and analyzed for carbon and nitrogen stable isotope composition and tissue stoichiometry (C:N). Stable-isotope based estimates of benthic trophic pathway contribution, trophic position, and isotopic niche area (proxy for trophic niche) and C:N composition ofN. americanawere compared within and between tributaries. Overall, mysids in the Patuxent River assimilated less benthic material, realized lower trophic positions, and had lower C:N ratios (proxy for lipid content) than Choptank River mysids. No consistent pattern in trophic niche area was observed although niche area (and pelagic trophic pathway contribution) of Choptank River mysids increased during a high river discharge event. This study provides evidence that hypoxic conditions in the Patuxent reduced the strength of benthic-pelagic coupling byN. americanaand, further, is associated with lower trophic position and a reduced stoichiometric marker of lipid storage. In addition to their role as omnivorous consumers,N. americanaare a dominant prey taxon for many predators, underscoring the importance of this species to local food webs and the potential for bottom-up effects on the dynamics of coastal ecosystems in response to changes in their trophic ecology.