Recovery of three arctic stream reaches from experimental nutrient enrichment
Recovery of three arctic stream reaches from experimental nutrient enrichment
复制标题
通过营养富集实验恢复三个北极河流的河段
DOI：
10.1111/j.1365-2427.2007.01723.x
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发表时间：
2005
影响因子：
2.7
通讯作者：
A. Hershey
中科院分区：
文献类型：
--
作者：
J. Benstead;A. Green;L. Deegan;B. Peterson;K. Slavik;W. Bowden;A. Hershey
摘要
1.营养丰富和由此引起的富营养化是对淡水生态系统广泛的人为影响，但对营养丰富的恢复知之甚少，特别是在河流环境中。我们研究了阿拉斯加北坡两条北极苔原小溪(库帕鲁克河和奥克斯鲁库伊克溪)三个河段的实验低浓度营养丰富(仅限N+P或P)的多年群落恢复模式。
2.不同群落组成部分的恢复速度不同，并取决于丰产的持续时间(连续2-13个生长季)。附生藻类的生物量迅速恢复到参考水平(在2年内)，无论营养物质的添加或富集持续时间如何。库帕鲁克河的水生苔藓覆盖率只有在长期富集期(8年)后才大幅增加，在风暴冲刷了正在恢复的河段的大部分残留苔藓后，花了8年的时间才恢复到接近基准水平。
3.库帕鲁克河苔藓植物的多年持续似乎阻碍了受这一主要初级生产者转变影响的昆虫种群的恢复，这些昆虫种群要么受到积极影响(例如，大多数摇蚊分类群)，要么受到负面影响(例如，管状摇蚊Orthocladius riverorum)。这些恢复滞后的原因可能是苔藓植物对自然底栖动物栖息地的持续影响。
4.奥克斯鲁库伊克河(Oksrukuyi Creek)北极灰熊(包括成年和幼年)的夏季生长速度(经过6年的施肥，没有苔藓植物定居)一直通过添加营养物质而提高，在1-2年内恢复到参考水平。
5.这些几乎纯净的北极河流生态系统从低水平的营养丰富中恢复的速度似乎在很大程度上受到丰富的持续时间的控制，而丰富的持续时间是由最终的苔藓植物殖民引起的物理生境变化以及随后的物理干扰造成的，这种变化导致苔藓植物消失。气候变化或当地人为活动造成的营养贫乏的北极河流生态系统的营养丰富，如果导致长期生存的初级生产者被殖民，从而改变自然生境，可能会产生戏剧性和持续性的后果。
Summary
1. Nutrient enrichment and resulting eutrophication is a widespread anthropogenic influence on freshwater ecosystems, but recovery from nutrient enrichment is poorly understood, especially in stream environments. We examined multi-year patterns in community recovery from experimental low-concentration nutrient enrichment (N + P or P only) in three reaches of two Arctic tundra streams (Kuparuk River and Oksrukuyik Creek) on the North Slope of Alaska (U.S.A.).
2. Rates of recovery varied among community components and depended on duration of enrichment (2–13 consecutive growing seasons). Biomass of epilithic algae returned to reference levels rapidly (within 2 years), regardless of nutrients added or enrichment duration. Aquatic bryophyte cover, which increased greatly in the Kuparuk River only after long-term enrichment (8 years), took 8 years of recovery to approach reference levels, after storms had scoured most remnant moss in the recovering reach.
3. Multi-year persistence of bryophytes in the Kuparuk River appeared to prevent recovery of insect populations that had either been positively (e.g. the mayfly Ephemerella, most chironomid midge taxa) or negatively (e.g. the tube-building chironomid Orthocladius rivulorum) affected by this shift in dominant primary producer. These lags in recovery (of >3 years) were probably driven by the persistent effect of bryophytes on physical benthic habitat.
4. Summer growth rates of Arctic grayling (both adults and young-of-year) in Oksrukuyik Creek (fertilised for 6 years with no bryophyte colonisation), which were consistently increased by nutrient addition, returned to reference rates within 1–2 years.
5. Rates of recovery of these virtually pristine Arctic stream ecosystems from low-level nutrient enrichment appeared to be controlled largely by duration of enrichment, mediated through physical habitat shifts caused by eventual bryophyte colonisation, and subsequent physical disturbance that removed bryophytes. Nutrient enrichment of oligotrophic Arctic stream ecosystems caused by climate change or local anthropogenic activity may have dramatic and persistent consequences if it results in the colonisation of long-lived primary producers that alter physical habitat.