Effects of impoundments on stream crayfish assemblages

IF 1.7 4区 环境科学与生态学 Q3 ECOLOGY
Freshwater Science Pub Date : 2022-01-24 DOI:10.1086/719051
Zanethia C. Barnett, S. Adams, J. Hoeksema, G. Easson, Clifford A. Ochs
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引用次数: 2

Abstract

Life-history timing, trophic interactions, and colonization potential of stream benthos are linked to a stream’s flow regime. Modifications to flow regimes often alter the composition of benthic assemblages. We assessed the impacts of relatively large storage dams (>15 m in height, >400-ha impoundments) on crayfish assemblages in southern Appalachian Mountain streams, Alabama, USA. We sampled crayfishes at multiple sites in flowing sections upstream and downstream of dams in 3 impounded streams and along similar lengths of 2 unimpounded streams in the Bear Creek and Cahaba River drainages. We analyzed at 2 scales: within and between drainages. This multi-scale approach allowed us to assess the effects of impoundments on crayfish assemblages in 1 drainage and then assess whether impoundment effects could be generalized across drainages. We compared crayfish assemblages between impounded and unimpounded streams and examined changes in crayfish assemblages with distance from impoundments, considering land-use history as a potential confounding factor. Adult densities averaged 45% higher, and sizes 10% smaller, in downstream sections of unimpounded streams compared with impounded streams. Densities and sizes of adults in upstream sections did not differ between unimpounded and impounded streams. In both drainages, unimpounded stream crayfish assemblage structure gradually shifted along the stream length, with species present upstream differing from those present downstream. Conversely, in all impounded streams, species assemblages did not differ between upstream and downstream sections, illustrating that dams diminish crayfish diversity. Nonetheless, finer-scale assessments showed that crayfish density and richness increased with distance downstream of impoundments. This suggests that assemblage recovery is possible with increasing distance downstream of impoundments. Additionally, we detected fewer crayfish assemblage differences between impounded and unimpounded streams in the Cahaba River drainage than the Bear Creek drainage. In the Cahaba River drainage, urbanization and the presence of an invasive crayfish species in both streams may have hindered our ability to distinguish impoundment effects on crayfishes. Our results show that large dams negatively affect crayfishes and may affect hundreds of crayfish species in thousands of stream km, possibly altering stream systems by interfering with the numerous ecosystem functions influenced by crayfishes.
水库对溪流小龙虾群落的影响
河流底栖生物的生活史时间、营养相互作用和定殖潜力与河流的流量状态有关。流动状态的改变经常改变底栖生物群落的组成。我们评估了美国阿拉巴马州阿巴拉契亚山脉南部河流中相对较大的蓄水坝(高度为15米,蓄水面积为400公顷)对小龙虾种群的影响。我们在3条被截流的河流和2条未截流的河流的上游和下游的多个地点取样了小龙虾。我们在两个尺度上进行了分析:排水系统内部和排水系统之间。这种多尺度方法使我们能够评估1个流域的蓄水对小龙虾种群的影响,然后评估蓄水效应是否可以推广到各个流域。考虑到土地利用历史是一个潜在的混杂因素,我们比较了蓄水和未蓄水河流的小龙虾组合,并研究了小龙虾组合随距离水库的变化。与蓄水的河流相比,未蓄水的河流下游的成虫密度平均高45%,体型平均小10%。上游区段成虫密度和大小在未蓄水和蓄水的河流之间没有差异。在这两个流域中,未蓄水的溪流小龙虾组合结构沿河流长度逐渐移动,上游和下游的种类有所不同。相反,在所有被截流的河流中,上游和下游的物种组合没有差异,说明水坝减少了小龙虾的多样性。小龙虾密度和丰富度随水库下游距离的增加而增加。这表明,随着水库下游距离的增加,组合恢复是可能的。此外,我们发现Cahaba河流域的蓄水和未蓄水溪流之间的小龙虾组合差异小于Bear Creek流域。在卡哈巴河流域,城市化和入侵小龙虾物种的存在可能阻碍了我们区分蓄水对小龙虾的影响的能力。我们的研究结果表明,大型水坝对小龙虾产生负面影响,可能影响数千公里河流中的数百种小龙虾,可能通过干扰小龙虾影响的众多生态系统功能来改变河流系统。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Freshwater Science
Freshwater Science ECOLOGY-MARINE & FRESHWATER BIOLOGY
CiteScore
4.10
自引率
0.00%
发文量
49
审稿时长
6-12 weeks
期刊介绍: Freshwater Science (FWS) publishes articles that advance understanding and environmental stewardship of all types of inland aquatic ecosystems (lakes, rivers, streams, reservoirs, subterranean, and estuaries) and ecosystems at the interface between aquatic and terrestrial habitats (wetlands, riparian areas, and floodplains). The journal regularly features papers on a wide range of topics, including physical, chemical, and biological properties of lentic and lotic habitats; ecosystem processes; structure and dynamics of populations, communities, and ecosystems; ecology, systematics, and genetics of freshwater organisms, from bacteria to vertebrates; linkages between freshwater and other ecosystems and between freshwater ecology and other aquatic sciences; bioassessment, conservation, and restoration; environmental management; and new or novel methods for basic or applied research.
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