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首页> 外文期刊>Estuarine Coastal and Shelf Science >Factors Influencing The Characteristics Of The Fish Faunas In Offshore, Deeper Waters Of Permanently-open, Seasonally-open And Normally-closed Estuaries
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Factors Influencing The Characteristics Of The Fish Faunas In Offshore, Deeper Waters Of Permanently-open, Seasonally-open And Normally-closed Estuaries

机译：永久开放，季节性开放和常闭河口近海，深水区鱼类动物特征的影响因素

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摘要

This study explored the ways in which various factors influence the species compositions, species richness and catch rates of fishes in offshore, deeper waters of the basin and river regions of five estuaries, which are located along ca 400 km of the southern coastline of Western Australia and differ markedly in their physico-chemical characteristics. Gill netting seasonally for two years at sites in the basin and saline lower reaches of the main tributary of the seasonally-open Broke, Irwin and Wilson inlets, the permanently-open Oyster Harbour and the normally-closed Wellstead Estuary yielded 22,329 fishes representing 58 species. Overall, and irrespective of estuary type, the species compositions of the basins and rivers differed markedly. This was attributable to consistently greater abundances of Mugil cephalus, and usually also of Acanthopagrus butcheri, in the rivers of each estuary and to the restriction of a range of species largely to the basins. However, the compositions in the basins of the five estuaries varied markedly, reflecting differences in the extent and duration of the opening of the estuary mouth and/or whether extensive growths of macrophytes were present. Changes in the ichthyofaunal composition of the normally-closed Wellstead Estuary between the first and second years of the study were attributable, in particular, to the movement of two mugilid species into offshore waters as they increased in size. Cyclical changes in ichthyofaunal composition were conspicuous in both regions of the estuary that underwent the most pronounced seasonal variations in environmental conditions. In each estuary, species richness was greater in the basin than river, where salinities were more variable and fell to lower levels and were thus less conducive to the immigration of most marine species. Catch rates were least in Broke Inlet, which had the lowest primary productivity, and were particularly high in Wellstead Estuary, which is highly eutrophic. The results of this study emphasise that ichthyofaunal composition can vary greatly with region (basin vs river) in microtidal estuaries, a finding that is of direct relevance to managers as these systems are becoming increasingly degraded and yet still constitute important nursery areas for certain fish species and often support recreational and commercial fisheries.
机译：这项研究探索了各种因素如何影响位于西澳大利亚州南部海岸线约400公里处的五个河口近海，盆地深处和河流区域的鱼类的物种组成，物种丰富度和捕获率并且其理化特性明显不同。在流域和季节性开放的Broke，Irwin和Wilson进水口，永久开放的牡蛎港和常闭的Wellstead河口主要支流的下游含盐度为两年的net网季节性捕捞，共产生58种共22,329条鱼。总体而言，不论河口类型如何，流域和河流的物种组成都存在显着差异。这是由于每个河口河中的头尾藻（Mugil cephalus）的丰度一直较高，通常还包括黑棘叶棘（Acanthopagrus butcheri）的丰度，并且该种类的种类主要限制在盆地内。然而，五个河口盆地的组成变化很大，反映出河口张开的程度和持续时间的不同和/或是否存在大型植物的生长。在研究的第一年和第二年之间，常闭的韦斯特德河口的鱼喙的组成发生了变化，这尤其是由于两个乌贼种类随着大小的增加而移入了近海。在环境条件最明显的季节变化的两个河口区域，鱼鳞au组成的周期性变化非常明显。在每个河口，盆地中的物种丰富度都比河流要大，河流中的盐度变化更大，下降到较低水平，因此不利于大多数海洋物种的迁移。在初生生产力最低的Broke Inlet中，捕获率最低，而在富营养化程度很高的Wellstead河口中，捕获率特别高。这项研究的结果强调，在潮汐河口，鱼of的组成可能随地区（流域与河流）而变化很大，这一发现与管理者直接相关，因为这些系统正日益退化，但仍构成某些鱼类的重要育苗区。并经常支持娱乐性和商业性渔业。

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