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The impact of nonnative species on river otters and aquatic-terrestrial linkages in Yellowstone National Park.

机译：黄石国家公园中外来物种对水獭和水生陆地联系的影响。

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摘要

River otters (Lontra canadensis) in Yellowstone Lake, Yellowstone National Park, depend on native cutthroat trout (Oncorhynchus clarki bouvieri) as prey, especially during summer when the fish migrate from the lake into its tributary streams to spawn. As part of their social behavior, otters deposit excreta at latrine (scent-marking) sites along these spawning streams and fertilize riparian plants with aquatically-derived nutrients such as nitrogen (N). Over the last two decades, however, nonnative lake trout trout (Salvelinus namaycush) and whirling disease (caused by the parasite Myxobolus cerebralis), have contributed to a dramatic decline in the lake's cutthroat trout population. Declines in cutthroat trout could reduce the abundance and distribution of otters, and sever the nutrient link they provide. This dissertation describes aspects of the biology of river otters in Yellowstone Lake in the context of these changes to the lake's food web.;This dissertation is presented in four journal-formatted chapters. Chapter 1 compares the hematology of high elevation Yellowstone otters with a sea level population. Comparisons of oxygen dissociation curves revealed no significant difference in hemoglobin-oxygen binding affinity between the two populations. Instead, high elevation otters had greater hemoglobin concentrations than their sea level conspecifics. Yellowstone otters displayed higher levels of the vasodilator nitric oxide, and half the concentration of the serum protein albumin, possibly to compensate for increased blood viscosity. Theoretical aerobic dive limits were similar between high elevation and sea level otters due to the lower availability of oxygen at altitude.;Chapter 2 presents the first estimates of population size and survival for river otters in Yellowstone National Park. Although the cutthroat trout population continued to decline during the study, there was no significant change in otter population size. However, overall densities (1 otter/9.91 km of shoreline) were lower than reported for most river otter populations, and evidence of a recent genetic bottleneck suggested the population may have already declined by the onset of the study. Annual survival for otters was 0.67 and correlated with cutthroat trout abundance in some models. Otters primarily responded to reductions in cutthroat trout via behavioral shifts in their spatial distribution and prey consumption. Activity at latrine sites decreased with declines in cutthroat trout on several tributary streams. Cutthroat trout remained the dominant prey item in otter scats throughout the study, but showed a declining trend from a frequency of occurrence of 73% in 2003 to 54% in 2008.;Chapter 3 documents the effects of otter-derived N fertilization on trees at latrine sites. Stable N isotope (15N) values were higher in needles of Engelmann spruce (Picea engelmannii) and lodgepole pine (Pinus contorta) on otter latrines than at reference sites. However, tree growth was greater on reference sites. No relationship existed between cutthroat trout abundance and tree ring 15N, precluding the ability to detect whether the trout-otter-excreta link has changed with the cutthroat trout population.;Chapter 4 is a note on seasonal breeding in Yellowstone otters. Although river otters in temperate regions typically breed in March and April, Yellowstone otters showed evidence of late seasonal breeding in June. This observation suggests otters in Yellowstone Lake have a relatively long breeding season, or their breeding schedule is delayed so that energetically-demanding lactation coincides with spawning runs of Yellowstone cutthroat trout. (Abstract shortened by UMI.).
机译：黄石国家公园黄石湖中的水獭（Lontra canadensis）依靠本地的凶猛鳟鱼（Oncorhynchus clarki bouvieri）作为猎物，特别是在夏季，当鱼从湖中迁移到其支流中繁殖时。作为其社会行为的一部分，水獭会沿着这些产卵流在厕所（气味标记）处沉积粪便，并用水生养分（例如氮）为河岸植物施肥。然而，在过去的二十年中，外来湖鳟鳟鱼（Salvelinus namaycush）和旋转疾病（由寄生性脑粘虫）引起了湖鳟鳟鱼种群的急剧下降。凶猛的鳟鱼数量下降可能会减少水獭的数量和分布，并切断它们提供的营养。本文在对黄石湖食物网的这些变化的背景下，描述了黄石湖水獭的生物学方面。本文在四个期刊格式的章节中进行介绍。第1章比较了高海拔黄石水獭和海平面种群的血液学。氧解离曲线的比较显示两个人群之间的血红蛋白-氧结合亲和力没有显着差异。相反，高海拔水獭的血红蛋白浓度高于其海平面的血红蛋白浓度。黄石水獭显示出较高水平的血管扩张剂一氧化氮，而血清蛋白白蛋白的浓度为一半，可能是为了弥补血液粘度的增加。由于海拔高度上氧气的可用性较低，因此高海拔水獭和有氧水獭的理论有氧潜水极限是相似的。第2章介绍了黄石国家公园水獭的种群大小和生存率的第一个估计值。尽管在研究过程中，喉咙鳟鱼的数量持续下降，但是水獭的种群数量并没有显着变化。但是，总体密度（1獭/9.91 km的海岸线）低于大多数水獭种群的报告，最近的遗传瓶颈证据表明，该种群可能在研究开始时就已经减少了。在某些模型中，水獭的年生存率为0.67，与喉咙鳟鱼的丰度相关。水獭主要通过减少空间分布和猎物消费的行为来应对凶猛鳟鱼的减少。随着一些支流溪流鳟鱼的减少，厕所位置的活动减少。在整个研究中，残酷的鳟鱼仍然是水獭的主要猎物，但呈下降趋势，从2003年的73％下降到2008年的54％。；第3章记录了水獭衍生的氮肥对水獭树木的影响。厕所地点。水獭厕所上的恩格尔曼云杉（Picea engelmannii）和黑松（Pinus contorta）的针头中的稳定N同位素（15N）值高于参考位置。但是，参考站点上的树木生长更大。尖嘴鳟鱼的丰度与15N年轮之间没有关系，因此无法检测出鳟鱼-獭-粪便之间的联系是否随着尖嘴鳟鱼种群的变化而改变。;第4章是关于黄石水獭季节性繁殖的注释。尽管温带地区的水獭通常在3月和4月繁殖，但黄石水獭显示出6月后期季节性繁殖的证据。该观察结果表明，黄石湖中的水獭繁殖季节相对较长，或者它们的繁殖计划被推迟，因此精力旺盛的泌乳与黄石stone鱼鳟鱼的产卵期相吻合。 （摘要由UMI缩短。）。

著录项

  • 作者

    Crait, Jamie R.;

  • 作者单位

    University of Wyoming.;

  • 授予单位 University of Wyoming.;
  • 学科 Agriculture Wildlife Conservation.;Biology Ecology.;Biology Zoology.
  • 学位 Ph.D.
  • 年度 2013
  • 页码 191 p.
  • 总页数 191
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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