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首页> 外文期刊>Estuarine Coastal and Shelf Science >Artificial mouth opening fosters anoxic conditions that kill small estuarine fish
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Artificial mouth opening fosters anoxic conditions that kill small estuarine fish

机译：人工张口助长缺氧条件，杀死河口小鱼

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摘要

Fish kills are not uncommon within estuaries in many regions of the world. In seasonally open systems, which are common in temperate areas, they are often associated with mouth openings. Such a kill occurred in July 2005 in the Surrey Estuary following a closed mouth period of seven months resulting in the loss of many thousands of fish. At the time the fish community within the estuary was under investigation which provided comprehensive data of this population prior to the kill. Monthly water quality monitoring was also being conducted prior to the kill and also carried out on a daily basis following the mouth opening. The Surrey was stratified during the closed mouth phase, isolated waters below the halocline had stagnated and become anoxic. As a result only waters above the halocline contained oxygen concentrations capable of sustaining most fish. It appears that if a mouth opening happens under low flow conditions, a shearing effect occurs within the water column where surface waters flow out to sea leaving deeper waters behind. This resulted in only anoxic waters being present for in excess of six days and was responsible for the fish kill. Fish sampling of the Surrey Estuary was conducted three and six months following the kill and those data were compared to that collected in the 12 months prior to the event. Three months after the kill few fish were collected within the estuary and included marine opportunists near the mouth and estuarine resident species in the far upper reaches of the system. However six months following the kill large numbers of estuarine resident species were collected throughout the Surrey Estuary. As many species were euryhaline, it is believed that some individuals migrated into freshwater reaches of the Surrey to escape the anoxic conditions within the estuary. As conditions improved they recolonised the Surrey Estuary. The high fecundity and rapid growth of these small, short lived species probably aided in their re-establishing populations within the estuary. It is clear from this research that artificial openings of estuaries should be avoided during low flow periods when oxygen concentrations are low. It also appears that many of the small estuarine resident species common in seasonally open estuaries are capable of recolonising estuaries following fish kills. The effects on larger, longer lived resident species are not known but likely to be more detrimental due to longer time required for them to reach sexual maturity.
机译：在世界许多地区的河口，杀死鱼类的情况并不少见。在温带地区常见的季节性开放系统中，它们通常与张口有关。 2005年7月，在萨里河口封闭七个月后，造成了数千头鱼的损失。当时，河口内的鱼类群落正在调查中，该数据提供了在杀死之前该种群的全面数据。在杀人之前还进行了每月水质监测，并且在张开嘴后每天进行水质监测。萨里河在闭口阶段被分层，盐湖以下的孤立水停滞并缺氧。结果，仅盐卤上方的水所含的氧气浓度能够维持大多数鱼类的生长。看来，如果在低流量条件下发生开嘴，在水柱内会产生剪切作用，地表水会流到海洋，而留下深水。这导致仅缺氧水存在超过六天，并导致鱼类死亡。萨里河口被杀后三个月和六个月对鱼进行采样，并将这些数据与事件发生前12个月收集的数据进行了比较。杀死三个月后，河口内几乎没有收集到任何鱼类，其中包括靠近港口的海洋机会主义者和该系统上游的河口常驻物种。然而，在杀死六个月后，整个萨里河口收集了大量河口常驻物种。由于许多种是鱼腥藻，据信有些人迁移到萨里的淡水河段以逃避河口内的缺氧条件。随着条件的改善，他们重新定居了萨里河口。这些小型，短命物种的高繁殖力和快速生长可能有助于它们在河口内重新建立种群。从这项研究中可以明显看出，在氧气浓度低的低流量时期，应避免人工开河。看来，在季节性开放河口中常见的许多小河口常驻物种能够在杀死鱼类后重新定殖河口。对较大，寿命更长的常驻物种的影响尚不明确，但由于它们达到性成熟所需的时间较长，因此可能更加有害。

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  • 来源
    《Estuarine Coastal and Shelf Science》 |2009年第4期|566-572|共7页
  • 作者

    Alistair Becker; Laurie J.B. Laurenson; Kylie Bishop;

  • 作者单位

    School of Life and Environmental Science, Deakin University, P.O. Box 423, Warmambool, Victoria 3280, Australia South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown 6140, South Africa;

    School of Life and Environmental Science, Deakin University, P.O. Box 423, Warmambool, Victoria 3280, Australia;

    School of Life and Environmental Science, Deakin University, P.O. Box 423, Warmambool, Victoria 3280, Australia South Coast Natural Resource Management, P.O. Box 1801, Esperance, Western Australia 6450, Australia;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    dissolved oxygen; stratification; Australia; seasonally open estuary;

    机译：溶解氧分层;澳大利亚;季节性开放的河口;

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