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1.
胡聪  胡刚  张忠华  李峰 《生态学报》2021,41(13):5300-5308
沉水植物是水生生态系统中重要的初级生产者。当前有关沉水植物生态化学计量特征的研究主要集中在非喀斯特区,而在喀斯特区的相关研究较为缺乏。因此,以广西澄江喀斯特典型湿地中的7种沉水植物为研究对象,分析沉水植物地上部分及底泥的碳(C)、氮(N)、磷(P)化学计量特征。结果显示,(1)7种沉水植物地上部分总碳、总氮和总磷平均含量最大值均出现在小茨藻(Najas minor)分别为(325.4±5.01) g/kg、(33.07±1.59) g/kg和(3.79±0.16) g/kg;C : N、C : P、N : P平均值分别为10.14±0.18、96.23±3.56和9.47±0.32,C : N最大值(11.89±0.54)出现在苦草(Vallisneria natans),C : P和N : P最大值(113.27±18.14和11.13±1.63)均出现在穗花狐尾藻(Myriophyllum spicatum)。(2)底泥有机碳、总氮、总磷、碱解氮和速效磷含量平均值分别为(15.05±0.56) g/kg、(2.06±0.08) g/kg、(0.58±0.01) g/kg、(162.53±9.16) mg/kg和(21.73±0.86) mg/kg,有机碳、总氮、总磷、碱解氮和速效磷的平均含量最大值均出现在小茨藻(N.minor)分别为(18.54±1.04) g/kg、(2.55±0.25) g/kg、(0.66±0.03) g/kg、(214.82±32.05) mg/kg和(26.37±3.31) mg/kg;底泥的C : N、C : P和N : P平均值分别是7.33±0.14、25.7±0.72和3.53±0.09,C : N、C : P和N : P最大值分别出现在金鱼藻(Ceratophyllum demersum)(7.45±0.32)、小茨藻(N. minor)(28.29±1.29)和黑藻(Hydrilla verticillata)(3.89±0.25)。(3)沉水植物的地上部分总碳与底泥的有机碳和总氮均呈显著负相关性;沉水植物的地上部分总氮与底泥有机碳、碱解氮、C : P均呈显著正相关性;沉水植物地上部分C : N、C : P均与底泥有机碳、总氮、总磷、碱解氮、C : P、N : P呈显著负相关,表明不同喀斯特湿地沉水植物和底泥之间的养分耦联性不同。本研究为喀斯特湿地生态系统生态化学计量学研究提供理论依据。  相似文献   

2.
太浦河水体叶绿素a纵向演变特征及主要影响因子   总被引:2,自引:0,他引:2  
刘毛亚  童春富  吴逢润 《生态学报》2020,40(19):7084-7092
叶绿素a作为重要的水质指标,可直观的描述水体的营养状态。在随水流输送过程中,受沿程环境条件的影响,水体叶绿素a浓度会发生相应改变。2017年11月-2018年10月,在东太湖及太浦河沿线设置了固定采样站点,开展了水体叶绿素a的月际取样调研与分析。结果表明:从东太湖至太浦河沿线叶绿素a浓度发生了明显的纵向演变,在东太湖叶绿素a浓度年平均为(15.341±2.329)μg/L,经过多个站点,到达金泽水文站时,浓度为(11.002±1.004)μg/L,整体上呈显著下降态势(P<0.05),但不同站点两两之间的对比特征存在差异,而且在不同月份其纵向演变特征也有所不同。聚类及非度量多维尺度分析也表明其在空间和时间上分布的差异性。非线性回归分析表明,在时间和空间上与叶绿素a浓度相关性最高的环境因子为水下0.5 m处的光照强度(P<0.01);在2018年10月,水体叶绿素a浓度与溶解氧也呈显著相关(P<0.05)。综合现有研究,水体叶绿素a的纵向演变受水质等多种因素的影响。未来需采用系统分析手段,探讨水质、降水、水力停留时间、流速和流量等多种因子对叶绿素a时空分布特征的综合作用,以期为水源地水质安全保障提供科学依据。  相似文献   

3.
Blood serum selenium levels were measured in 891 healthy children and adolescents (aged 11–18 yr, 450 girls and 441 boys) residing in both rural and urban areas from eight regions of Slovakia. Subjects were divided into four age groups (11–12 y, 13–14 y, 15–16 y, and 17–18 y). Serum selenium concentration was determined by the electrothermal atomic absorption spectrometric method. The mean (±SD) serum selenium concentrations were 0.750 ±0.255 μmol/L in girls and 0.773 ±0.235 μmol/L in boys. A large proportion of the individuals (25.7% in girls, 18.1% in boys) exhibited serum selenium levels under 0.57 μmol/L (45 μg/L). An increasing trend of the serum selenium values with age has been observed in both boys (p < 0.01) and girls (p < 0.05). Boys had higher serum selenium levels in the all age groups but the differences were not statistically significant.  相似文献   

4.
袁博  郭梦京  郑兴  周孝德 《生态学杂志》2018,29(11):3773-3782
溶解性有机质是水体中有机质分解与营养盐再生的核心载体之一,是碳、氮等生源要素生物地球化学循环的重要环节,也是水环境科学研究的重点内容.本研究应用液相-有机碳-有机氮检测(LC-OCD-OND)技术研究了西安市灞河流域水体中溶解性有机质(DOM)不同分子量组分特征,分析其与河水水质的相关性.结果表明: 河水DOM按照分子量分布,主要由生物大分子、腐殖质类物质、腐殖质降解产物、低分子中性物质和低分子酸组成,各组分平均浓度分别为0.15、1.75、0.48、0.36和0.002 mg·L-1,河水中DOM总体含量水平由高到低的顺序为城市河段>城镇河段>源区河段.组分中分子量介于1000~20000 Da的腐殖质类物质占DOM总量的49.0%,含量及丰度从高到低依次为中游城镇段>污水厂出口段>污水厂下游河口段>上游源头段;分子量>20000 Da的生物大分子约占DOM总量的5.1%,丰度由高到低依次为污水厂出口>污水厂下游河口>上游源头>中游城镇段,污水处理厂出水所产生的外生源有机质对河流DOM的贡献最大.DOM不同分子量组分与水质的相关性明显,表明基于LC-OCD-OND分级表征的DOM各分子量组分和丰度不仅可以作为水质监测的一个综合性指标,也可以用来表征河流水质的空间异质性,并能对污染物各组分进行定量化判别和来源解析.  相似文献   

5.
可溶性有机质(DOM)的生物降解性影响着土壤有机质的存留和释放,对深入认识森林土壤养分循环意义重大。为探究森林更新对土壤DOM降解特征的影响,选取亚热带地区米槠天然林(NF)、米槠次生林(SF)和米槠人工促进天然更新林(AR)土壤DOM溶液为研究对象,进行室内降解(42 d)试验。结果表明: 1)3种林分土壤可溶性有机碳(DOC)的降解率和易降解DOC的比例均为SF>AR>NF;可溶性有机氮(DON)和微生物生物量碳(MBC)是显著影响易降解DOC比例的因子;2)难降解组分占3种林分土壤DOC的大部分(72.3%~94.6%),其周转时间长,有利于稳定土壤有机质(SOC)的形成;3)土壤DOM最初的腐殖化指数(HIXem)会影响易降解DOC的周转时间。DOM光谱结构随降解过程呈现动态变化,说明DOM中易降解组分被消耗完后,微生物会转而降解芳香类和疏水性物质以获取碳源。综上,米槠天然林更新为次生林和人促林后增加了易降解DOC的比例,提高了土壤DOM生物可降解性,不利于SOC的积累。  相似文献   

6.
为探究毛竹林下种植茶树对土壤有机碳储量与碳组分的影响,该研究以毛竹纯林、竹茶混交林和常绿阔叶林为研究对象,采集这3种林分类型的表层(0~10 cm)土壤,测定土壤有机碳(SOC)、碳组分、生物与非生物因素指标。结果表明:(1)竹茶混交林林下植物多样性相较于毛竹纯林显著降低,但其土壤有机碳密度(22.54±2.09)t·hm-2、碳组分与毛竹纯林无显著差异(P>0.05)。竹茶混交林的矿物结合态有机碳(MOC)为(20.13±1.83)g·kg-1,占总有机碳的92.66%。常绿阔叶林土壤有机碳密度比竹茶混交林和毛竹纯林高土壤有机碳密度分别高41.15%和41.00%(P<0.05)。(2)3种林分类型土壤微生物量碳(MBC)含量范围为0.58~3.08 g·kg-1,土壤16S rRNA丰度范围为2.18×1010 ~5.65×1010copies·g-1,固碳基因cbbL丰度范围为0.37×108 1.10 ×108 copies·g-1,土壤微生物碳利用效率范围为0.03~0.28; 3种林分类型之间微生物相关指标不存在显著差异(P>0.05)。(3)3种林分类型SOC与土壤pH、砂粒含量和地上凋落物生物量呈显著负相关,与土壤黏粒含量、粉粒含量、总氮、C:N、总磷和铵态氮含量呈显著正相关(P<0.05)。(4)就不同碳组分而言,颗粒有机碳(POC)和MOC均与土壤pH、砂粒含量和根系生物量呈显著负相关,与土壤含水量、黏粒含量、粉粒含量、总氮、C:N、总磷和铵态氮含量呈显著正相关(P<0.05)。综上表明,竹茶混交改造会造成原生毛竹纯林林下植被多样性下降,但并未造成土壤碳储量下降; 而相较于常绿阔叶林,毛竹经营措施需要改进,以提升其碳汇效益。  相似文献   

7.
Fan P  Li L  Liu ZJ  Si JQ  Zhang ZQ  Zhao L  Ma KT 《生理学报》2007,59(3):331-338
本文旨在探讨大鼠新鲜离体输精管平滑肌细胞中乙酰胆碱(acetylcholine,ACh)引起超极化反应的机制,采用细胞内微电极记录技术和细胞内荧光标记技术研究ACh对大鼠输精管不同走行方向平滑肌细胞的作用。用尖端含0.1%碘化吡啶(propidium iodide,PI)的记录电极标记电生理记录后的平滑肌细胞,其中37个为外层纵行细胞,17个为内层环行细胞。它们的平均静息膜电位分别为(-53.56±3.88)mV和(-51.62±4.27)mV,膜输入阻抗分别为(2245.60±372.50)MQ和(2101.50±513.50)MQ。ACh引起的膜超极化反应是浓度依赖性的,EC50为36 μmol/L。ACh引起的超极化反应可被非选择性的毒草碱(muscarinic receptor,M)受体阻断剂阿托品(atropine,1 μmol/L)和选择性的M3受体阻断剂diphenylacetoxy-N-methylpiperidine-methiodide(DAMP,100nmol/L)阻断。ACh引起的超极化还能被一氧化氮合酶抑制剂L-硝基-精氨酸甲酯(N-nitro-L-arginine methylester,L.NAME,300μmol/L)阻断,并可被ATP敏感的钾通道阻断剂glipizide(5μmol/L)或内向整流钾通道阻断剂钡离子(50μmol/L)部分阻断。Glipizide和钡离子联合使用可完全阻断ACh引起的超极化反应。上述结果表明:ACh通过作用于大鼠输精管平滑肌细胞膜上的M3受体引起超极化反应,一氧化氮、ATP敏感性钾通道和内向整流钾通道参与了ACh引起的超极化反应。  相似文献   

8.
太湖典型草、藻型湖区紫外辐射的衰减及影响因素分析   总被引:2,自引:0,他引:2  
2004年4月通过野外原位观测和实验室测定相结合的方法对东太湖和梅梁湾典型草、藻型湖区紫外辐射光谱衰减及影响因素进行了研究。结果表明,320nm(UV-B)、380nm(UV-A)的衰减系数在6.33~19.59m-1、3.41~13.64m-1间变化,对应的1%表面光强穿透深度分别为0.24~0.73m、0.35~1.35m,到达湖面的99%UV-B辐射在0.5m左右表层水就衰减完毕,东太湖和梅梁湾紫外辐射衰减系数存在明显的湖区差异;溶解性有机碳(DOC)的浓度在6.60~17.17mg/L间变化,其均值为(9.99±2.48)mg/L;375nm波长处CDOM吸收系数为1.78~6.25m-1,均值为(3.70±1.10)m-1;在短波部分CDOM吸收与DOC浓度存在显著性相关,相关性大致随波长降低而增加,320nm处的线性关系式:ad320=0.885DOC 2.182;紫外辐射衰减主要受制于水体中的CDOM浓度,衰减系数与DOC浓度、CDOM吸收系数存在显著性相关,340nm处的关系式分别为:Kd340=0.82 1.05DOC、Kd340=1.98 1.49ad340。在太湖紫外辐射衰减还要受悬浮物和叶绿素a浓度的影响,衰减系数与DOC、叶绿素a和悬浮物浓度多元回归的结果明显要高于单独与DOC浓度或CDOM吸收系数的回归结果。  相似文献   

9.
【目的】探究湖泊沉积物中有机碳组分构成及其对湖泊微生物群落结构的影响。【方法】本研究采集了青藏高原29个湖泊共81个沉积物样品,通过硫酸水解法分析样品中易降解和难降解有机碳含量及其与环境变量之间的相关性;同时使用高通量测序技术分析样品中原核微生物和真菌群落的多样性和组成及其与易降解和难降解有机碳含量的相关关系。【结果】本研究的青藏高原湖泊沉积物中易降解有机碳Ⅰ(labile organic carbon Ⅰ, LOCⅠ)、易降解有机碳Ⅱ(labile organic carbon Ⅱ, LOCⅡ)和难降解有机碳(recalcitrant organic carbon, ROC)的含量分别为0.03–29.62 mg/g、0.02–23.38 mg/g和0.64–75.72 mg/g,ROC是沉积物有机碳的主要组分(占比为54.97%±19.50%)。LOCⅠ含量与海拔、总氮、总磷、钙离子、活性钙和活性铁含量显著相关(P<0.05);LOCⅡ含量与总氮、钙离子和活性钙含量显著相关;而ROC含量与海拔、总氮、总磷、钙离子和活性钙含量显著相关。其中,钙离子和活性钙的浓度与3种有机碳组分...  相似文献   

10.
本研究旨在观察氯离子通道阻断剂尼氟灭酸(niflumic acid,NFA)引起豚鼠耳蜗螺旋动脉平滑肌细胞产生超极化的机制。以豚鼠为实验动物,运用细胞内微电极和全细胞膜片钳记录技术,观察NFA和其它药物对急性分离的耳蜗螺旋动脉平滑肌细胞的作用。结果显示:NFA、indanyloxyacetic acid94(LAh-94)和diSOdium4,4’-diisothiocyanatostilbene-2,2’-disulfonate(DIDS)可使低静息膜电位的细胞产生超极化,但对高静息膜电位的细胞无明显作用。低静息膜电位细胞的平均静息电位为(-42.47&#177;1.38)mV(n=24),100μmol/LNFA、10μmol/LIAA-94和200μmol/LDIDS分别使细胞超极化至(13.7&#177;4.3)mV=9,P〈0.01),(11.4&#177;4.2)mV(n=7,P〈0.01)和(12.3&#177;3.7)mV(n=8,P〈0.01),这种氯离子通道阻断剂引起细胞超极化反应的效应呈浓度依赖性。NFA引起的超极化和外向电流几乎完全被100nmol/L iberiotoxin、100nmol/L charybdotoxin、10mmol/L tetraethylammonium、50μmol/LBAPTA—AM、10μmol/Lryanodine和0.1-10mmol/Lcaffeine阻断,但不能被100μmol/Lnifedipine、100μmol/LCdCI,和无Ca^2+灌流外液阻断。结果捉示:氯离_了通道的阻断剂NFA可通过平滑肌细胞内钙库的钙释放增加细胞内钙,进而激活钙依赖的钾通道,产生耳蜗螺旋动脉平滑肌细胞的超极化反应。  相似文献   

11.
渗滤液溶解性有机物对土壤Cd、Pb有效性的影响   总被引:1,自引:0,他引:1  
在Cd、Pb污染土壤中,通过生物盆栽试验,研究了2种不同填埋年龄的垃圾渗滤液溶解性有机物(DOM)对黑麦草生长的影响及其对重金属Cd、Pb吸收的影响.鲜样、水阁样分别为填埋年龄0和12年的垃圾渗滤液.结果表明,垃圾渗滤液DOM施入土壤,残留在土壤中的DOM平均浓度为对照的1.39倍(鲜样)和1.47倍(水阁样).2种垃圾渗滤液DOM处理的土壤水溶态Cd、Pb和交换态Cd、Pb均在前期呈波动变化,到后期则上升.在Cd污染土壤中,鲜样和水阁样垃圾渗滤液DOM处理土壤水溶态Cd、交换态Cd分别高出对照37.44%、4.81%,48.97%、14.94%;在Pb污染土壤中,鲜样和水阁样垃圾渗滤液DOM处理土壤水溶态Pb、交换态Pb分别高出对照8.56%、7.22%,18.99%、11.47%.鲜样和水阁样垃圾渗滤液DOM处理黑麦草总Cd浓度分别高于对照19.59%和104.4%,总Pb浓度分别高36.03%和44.66%;但两处理的黑麦草总生物量下降14.03%~52.24%.因此,垃圾渗滤液DOM进入污染土壤后,有利于土壤重金属生物有效性的提高和植物体内重金属的累积,却抑制植物的生长, 尤以填埋年龄长的垃圾渗滤液DOM影响更大.  相似文献   

12.
The transformation of native Cerrado into Pinus caribaea Morelet plantations changes the DOM dynamics including changed rates of mineralisation, denitrification, and C export to the groundwater. To examine the differences in quantity, temporal dynamics, and quality of DOM between Cerrado and Pine plantations we collected rainfall, throughfall, stemflow, litter leachate (under pine only) and soil solution at 15, 80, and 200 cm depth in weekly intervals during the rainy seasons 1997/98 and 1998/99. We determined total dissolved organic carbon (DOC) concentrations and assessed DOM quality by separating hydrophilic and hydrophobic fractions and by NMR analysis of organic layer extracts. The rainfall had a mean DOC concentration of 2.6 mg L–1. The mean concentrations of DOC in the throughfall of the pine plantations (5.0–10.5 mg L–1) were significantly above those of Cerrado (2.6–4.9 mg L–1). During the first part of the rainy seasons (October–December), the concentrations of DOC in the soil solution (15–200 cm depth) under Cerrado and pine did not differ significantly. During the second part of both rainy seasons (January–April), the concentrations of DOC in the soil solution under Cerrado (4.4–5.1 mg L–1) exceeded those under PI (1.4–2.7 mg L–1). Possible explanations of the latter include higher DOM input into the Cerrado soil and a stronger retention and/or faster mineralisation of the pine DOM than of the Cerrado DOM in the mineral soil. As the structural composition of DOM extracted from the organic layer under Cerrado and pine did not differ significantly, faster mineralisation was the most likely explanation for partly lower DOC concentrations in the soil solution under pine than under Cerrado. This assumption was supported by increasing contributions of hydrophobic DOM to total DOM with increasing depth under pine while, under Cerrado, the DOM composition did not change with depth. The reason for DOM mineralisation under pine was probably the higher N availability because total N concentrations were 11–23 times higher under pine than under Cerrado.  相似文献   

13.
Substantial evidence exists that allochthonous dissolved organic matter (DOM) can provide an important carbon source for pelagic bacteria. On the other hand, it is implicit in the concept of the ‘microbial loop’ that the degradation of recalcitrant, allochthonous DOM should be retarded in the pelagic environment, as bacteria able to utilize recalcitrant DOM compounds for slow growth would be outcompeted by faster-growing bacteria utilizing more labile DOM compounds. Several possible solutions of this apparent paradox are suggested in this paper, including formation of labile DOM from recalcitrant DOM by e.g. photochemical reactions, and mechanisms enabling the maintenance of a metabolically diverse bacterioplankton. These mechanisms include an explanation analogous to Hutchinson's classical solution to the ‘paradox of plankton’, and differential mortality of different populations within the bacterioplankton enabled by selective grazing, infections by bacteriophages and predatory bacteria, and spatial micropatchiness.  相似文献   

14.
陆地生态系统中人为因素对DOM影响研究进展   总被引:3,自引:2,他引:1  
卢萍  杨林章 《生态学杂志》2005,24(11):1308-1313
尽管DOM和WEOM只占土壤有机质的一小部分,却是土壤溶液的重要组成部分,参与众多土壤过程。本文着重介绍DOM和WEOM的定义、研究方法及森林和农田两种不同生态系统中DOM和WEOM的研究现状及耕作、施肥等农业措施对DOM和WEOM的影响。已有研究主要集中于DOC,而缺乏对DON、DOP的研究,且研究方法间差异较大。森林生态系统DOM/WEOM含量要高于草地和耕地。土地利用方式变化对DOM的影响主要取决于改变后的土地利用方式。管理措施对DOM/WEOM通常只有短暂的影响.且不同因素作用结果不一。  相似文献   

15.
Growth and survival of tadpoles (Bufo americanus) were used to assess the food value of three types of amorphous detritus thought to be derived from dissolved organic matter (DOM) transported in river water or groundwater: 1. Flocculent organic aggregates suspended at the mouth of a humic stained river which drains into Lake Superior; 2. Precipitates formed directly from humic stained river water; 3. The < 35 m fraction of littoral lake sediment. Tadpoles were unable to grow when fed the amorphous detritus, but experienced lower mortality than unfed animals. Although the food quality of certain types of detritus derived from DOM may be inadequate to support the growth of aquatic fine particle feeders it may contribute to the nutrition of facultative detritivores.  相似文献   

16.
Lennon JT 《Oecologia》2004,138(4):584-591
Subsidies are donor-controlled inputs of nutrients and energy that can affect ecosystem-level processes in a recipient environment. Lake ecosystems receive large inputs of terrestrial carbon (C) in the form of dissolved organic matter (DOM). DOM inputs may energetically subsidize heterotrophic bacteria and determine whether lakes function as sources or sinks of atmospheric CO2. I experimentally tested this hypothesis using a series of mesocosm experiments in New England lakes. In the first experiment, I observed that CO2 flux increased by 160% 4 days following a 1,000 m C addition in the form of DOM. However, this response was relatively short lived, as there was no effect of DOM enrichment on CO2 flux beyond 8 days. In a second experiment, I demonstrated that peak CO2 flux from mesocosms in two lakes increased linearly over a broad DOM gradient (slope for both lakes=0.02±0.001 mm CO2·m–2 day–1 per m DOC, mean±SE). Concomitant changes in bacterial productivity and dissolved oxygen strengthen the inference that increasing CO2 flux resulted from the metabolism of DOM. I conducted two additional studies to test whether DOM-correlated attributes were responsible for the observed change in plankton metabolism along the subsidy gradient. First, terrestrial DOM reduced light transmittance, but experimental shading revealed that this was not responsible for the observed patterns of CO2 flux. Second, organically bound nitrogen (N) and phosphorus (P) accompanied DOM inputs, but experimental nutrient additions (without organic C) caused mesocosms to be satuated with CO2. Together, these results suggest that C content of terrestrial DOM may be an important subsidy for freshwater bacteria that can influence whether recipient aquatic ecosystems are sources or sinks of atmospheric CO2.  相似文献   

17.
18.
Experiments using a plexiglass Y -maze fluviarium showed that nymphs of Parameletus chelifer and Parameletus minor each used different environmental cues to orient. P. chelifer nymphs reacted to pH while nymphs of P. minor were very sensitive to concentration of dissolved organic matter. The capacity to detect these water quality differences was lost as soon as the nymphs reached seasonally submerged areas suitable for growth at the margin of the river. When nymphs of both species had reached their growing areas, water temperature became the crucial cue for orientation.  相似文献   

19.
While changes in dissolved organic matter (DOM) concentrations are expected to affect zooplankton species through attenuation of potentially damaging ultraviolet (UV) radiation, generation of potentially beneficial or harmful photoproducts, pH alteration, and microbial food web stimulation, the combined effects of such changes on zooplankton community structure have not been studied previously. Our purpose was to determine how an increase in allochthonous DOM and associated changes in pH in an initially transparent lake may affect zooplankton community structure, and how exposure to solar UV may alter these DOM and pH effects. We ran microcosm experiments manipulating UV, DOM, and pH near the surface of Lake Giles in northeastern Pennsylvania. We found that when DOM was added in the presence of ambient UV, Daphnia and copepod UV-mortality was reduced by approximately three and two times compared to UV exposure without extra DOM. When DOM was added in the absence of UV, adult Daphnia and copepods were reduced compared to no DOM addition in the absence of UV. Daphnia and cyclopoid egg production and rotifer abundance were generally higher in the presence of DOM, regardless of UV treatment. The lower abundance yet high egg production in the presence of DOM and absence of UV may be explained by higher abundance of egg-bearing adults compared to non-egg-bearers. We conclude that allochthonous DOM benefits some zooplankton in a high-UV environment, but may be detrimental under low-UV conditions. Overall, Daphnia abundance and egg production were higher than that of calanoid copepods in the DOM additions, indicating that in some lakes an increase in allochthonous DOM may lead to a zooplankton community shift favoring Daphnia over calanoid copepods.  相似文献   

20.
Studies on spatial subsidies have overwhelmingly addressed their trophic nature. However, certain subsidies might affect recipient communities beyond the feeding pathway. Terrestrial colored dissolved organic matter (DOM) is such a subsidy providing a carbon source for bacteria and heterotrophic nanoflagellates which zooplankton can consume (trophic pathway), but also protecting zooplankton against damaging UV radiation through its color (non-trophic pathway). These mechanisms have been quantified separately, but few studies have attempted to decouple them and evaluate their effects in the context of subsidies. In this study, I experimentally isolated the trophic and non-trophic pathways by which DOM (as maple leaf leachate) affects zooplankton, and also addressed how local food resources (i.e., phytoplankton) could mediate the response of zooplankton to DOM subsidies. Terrestrial subsidies (DOM) effectively shielded zooplankton against damaging UV radiation. Local resources (i.e., phytoplankton), however, did not seem to mediate the fitness response of zooplankton to UV radiation. This study also suggested that the carbon in DOM might be slightly detrimental to zooplankton independent of the UV protection effect. High levels of local resources combined with carbon subsidies from DOM did not translate into higher zooplankton survival, presumably because of the detrimental effects of DOM on zooplankton. This study provides further support for the importance of terrestrial subsidies in affecting communities through non-trophic pathways (UV attenuation) and documents that the trophic pathway might be strongly dependent on subsidy quality. Further studies on the role of subsidies that include the less documented non-trophic pathways are needed to improve our mechanistic understanding of how communities and ecosystems respond to spatial subsidies. Handling editor: D. Bade  相似文献   

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