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首页> 外文期刊>european journal of phycology >Determining the environmental preferences of four estuarine epipelic diatom taxa: growth across a range of salinity, nitrate and ammonium conditions
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Determining the environmental preferences of four estuarine epipelic diatom taxa: growth across a range of salinity, nitrate and ammonium conditions

机译：确定四个河口上层硅藻类群的环境偏好：在一系列盐度、硝酸盐和铵条件下的生长

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Intertidal cohesive estuarine sediments frequently support extensive microphytobenthic biofilms, which are usually dominated by epipelic (motile) diatoms. The distribution of different diatom taxa varies along estuarine gradients, but it is not clear what the causative factors are in determining these patterns. In many estuaries, salinity covaries with other environmental gradients, particularly with nutrient concentrations when the river is the main nutrient source. Autecological information is required to aid interpretation of these field distributions. In this study the maximum specific growth rate (#x3BC;) and stationary phase biomass of four common taxa of estuarine epipelic diatoms (Navicula phyllepta, N. perminuta, N. salinarum and Cylindrotheca closterium) were measured in axenic unialgal cultures grown under a range of nitrogen and salinity regimes. All threeNaviculaspecies and two different clones ofC. closteriumshowed significant differences in their response to a range of ammonium (10#x2013;4000 #xB5;M) and nitrate (10#x2013;2000 #xB5;M) concentrations across a salinity range of 10#x2013;35#x2030;. Growth rates ofN. phylleptawere significantly lower at ammonium concentrations 400 #xB5;M, but the other three taxa showed little evidence of ammonium toxicity, even at concentrations 1 mM. On the basis of the response of each species, the following putative ranking of preferences for inorganic nitrogen concentrations (lowest to highest, with salinity optima in parentheses) was constructed:N. phyllepta(10#x2013;20#x2030;) #x2013;N. perminuta(10#x2013;30 #x2030;) #x2013;N. salinarum(20#x2013;35#x2030;)/C. closterium(clone 1, 10#x2013;25#x2030;, clone 2, 25#x2013;35#x2030;). Such a ranking should be interpreted cautiously, as interclonal differences and adaptation to local environmental conditions can alter the preferences of taxa. These autecological data are partially supported by previously published data on field distribution, and suggest that certain taxa may have value as trophic indicator species.
机译：潮间带粘性河口沉积物经常支持广泛的微底栖植物生物膜，这些生物膜通常以上层（运动）硅藻为主。不同硅藻类群的分布沿河口梯度变化，但尚不清楚决定这些模式的致病因素是什么。在许多河口，盐度与其他环境梯度相等，特别是当河流是主要营养来源时，盐度与营养浓度一致。需要自生态学信息来帮助解释这些田间分布。本研究在一系列氮和盐度条件下生长的 axenic unialgal 培养物中测量了河口外层硅藻 4 个常见分类群（Navicula phyllepta、N. perminuta、N. salinarum 和 Cylindrotheca closterium）的最大比生长速率 （μ） 和固定相生物量。所有三个Naviculaspecies和两个不同的克隆C。在10-35‰的盐度范围内，氯铵对铵（10-4000μM）和硝酸盐（10-2000μM）浓度范围的响应存在显著差异。增长率为N。在铵浓度>400 μM时，phyllepta显著降低，但其他三个分类群几乎没有铵毒性的证据，即使在浓度>1 mM下也是如此。根据各物种的响应，构建了以下对无机氮浓度偏好的假定排序（从低到高，括号内为盐度最优）：N。phyllepta（10–20‰） –N. perminuta（10–30 ‰） –N. salinarum（20–35‰）/C. closterium（克隆 1， 10–25‰， 克隆 2， 25–35‰）。这种排名应谨慎解释，因为克隆间差异和对当地环境条件的适应可以改变分类群的偏好。这些自生态学数据得到了先前发表的田间分布数据的部分支持，并表明某些分类群可能具有作为营养指示物种的价值。

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