Aquatic food-web structure along a salinized dryland river.
Aquatic food-web structure along a salinized dryland river.
复制标题
盐化旱地河流沿岸的水生食物网结构。
DOI：
10.1111/fwb.12893
复制
发表时间：
2017
影响因子：
2.7
通讯作者：
Allison A. Pease
中科院分区：
文献类型：
--
作者：
J. East;Christopher Wilcut;Allison A. Pease
总结
尽管预计随着用水需求的增加和气候变化，全球盐碱化将会加剧，但人们对河流盐碱化对生态系统的影响知之甚少。在美国西南部的一些河流中，由于水流变化和其他人为影响而加剧了天然盐水输入，导致盐碱化。佩科斯河的盐化与鱼类多样性下降有关，但对水生食物网结构的影响尚未得到调查。
我们利用稳定同位素分析（δ13C 和 δ15N）估算了 12 个地点水生消费者的碳源、营养位置和组合范围的营养结构，从而评估了沿佩科斯河干流纵向梯度的当地食物网的变化。还检查了部分地点常见鱼类的跨季节时间变化。
消费者丰富度、食物链长度和组合范围的生态位宽度与比电导率成反比。混合模型揭示了沿纵向河流梯度支持鱼类生产的膳食碳来源的差异，并转向依赖河流盐化河段的藻类生产。在退化程度较轻且鱼类丰富度较高的地点，营养生态位宽度最大。盐化地区的当地食物网以广盐物种为主，食物链较短，群落生态位宽度较窄。跨季节，五种常见鱼类的 δ13C 和 δ15N 特征保持相当稳定。
我们的结果表明，佩科斯河部分地区的盐化限制了当地食物网中消费者和营养资源的多样性。描述与盐化和其他环境变化相关的食物网结构变化对于栖息地评估、河流恢复和其他保护策略非常重要。
Summary
Very little is known about the ecosystem impacts of river salinization despite expectations for global increases in salinization with growing water demand and climate change. In some rivers in the southwestern United States, salinization has occurred as a result of natural saline inputs exacerbated by flow alteration and other anthropogenic impacts. Salinization in the Pecos River has been linked to declines in fish diversity, but impacts on the structure of aquatic food webs have not been investigated.
We assessed variation in local food webs along the longitudinal gradient of the main stem Pecos River by estimating carbon sources, trophic positions and assemblage-wide trophic structure for aquatic consumers at 12 sites using stable isotope analysis (δ13C and δ15N). Temporal variation across seasons was also examined for common fish species at a subset of sites.
Consumer richness, food-chain length and assemblage-wide niche breadth were inversely related to specific conductivity. Mixing models revealed differences in sources of dietary carbon supporting fish production along the longitudinal fluvial gradient, with a shift towards reliance on algal production in the salinized reaches of the river. Trophic niche breadth was greatest for assemblages in less degraded sites with higher fish species richness. Local food webs in salinized sites were dominated by euryhaline species and had shorter food chains and narrower assemblage-wide niche breadths. Across seasons, δ13C and δ15N signatures remained fairly constant for five common fish species.
Our results suggest that salinization in portions of the Pecos River constrains the diversity of consumers and trophic resources in local food webs. Characterising changes in food-web structure in relation to salinization and other environmental changes is important for habitat assessment, stream restoration and other conservation strategies.