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1.
几种环境因子对墨氏胸刺水蚤摄食的影响 总被引：6，自引：0，他引：6
研究了不同藻类、藻细胞密度、温度、盐度、容器容积、昼夜变化等环境因子对浮游桡足类墨氏胸刺水蚤(Centropagesmcmurrichi)的摄食关系。结果表明:1)藻种类、藻细胞密度对墨氏胸刺水蚤的清滤率和滤食率都有显著影响;2)墨氏胸刺水蚤对4种藻的摄食顺序为球等鞭金藻(摄食率I=12.418μgC/ind穐)>角毛藻(I=9.824μgC/ind穐)>异胶藻(I=6.683μgC/ind穐)>小球藻(I=5.229μgC/ind穐);3)温度在6~20℃范围内变化对墨氏胸刺水蚤的清滤率和滤食率无显著影响,但以10~15℃为佳。盐度对墨氏胸刺水蚤的清滤率和滤食率有显著影响,最适摄食盐度为20~27;4)容器容积和昼夜变化对墨氏胸刺水蚤的摄食影响不显著。 相似文献
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采用饵料浓度差减法,在实验条件下研究了不同细胞密度的中肋骨条藻和东海原甲藻对海月水母水螅体、碟状体和水母体摄食活动的影响。结果表明,不同种类和密度的微藻细胞密度对水螅体、碟状体和水母体的摄食有显著影响。在实验的藻细胞密度范围内,随藻细胞密度的增加,水螅体和碟状体对中肋骨条藻和东海原甲藻的摄食率一直升高。水螅体对中肋骨条藻和东海原甲藻的最大摄食率均发生在藻细胞密度最高处,分别为4623cells/(ind.h)和4118cells/(ind.h)。碟状体对中肋骨条藻和东海原甲藻的最大摄食率也是发生在藻细胞密度最高处,分别为174671cells/(ind.h)和47218cells/(ind.h)。清滤率随着藻细胞密度增加而降低。在相似细胞密度下,碟状体对中肋骨条藻的摄食率高于东海原甲藻。水螅体和碟状体对同种藻的摄食情况不同,在相似藻细胞密度下,碟状体的摄食率比水螅体高。经过藻类饵料适应处理的水螅体对藻类的摄食率会有显著增加,约为未经饵料适应处理的10倍。水母体对中肋骨条藻和东海原甲藻未发生摄食。 相似文献
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微型浮游动物在抑食金球藻(Aureococcus anophagefferens)引发褐潮时表现的摄食压力可潜在控制褐潮的爆发和消亡。本研究就三种海洋常见原生动物——海洋尖尾藻(Oxyrrhis marina)、海洋尾丝虫(Uronema marinum)和扇形游仆虫(Euplotes vannus)——对单种饵料及混合饵料中抑食金球藻中国株的摄食进行了研究。单种抑食金球藻指数期细胞喂食的三种原生动物的生长率和摄食率呈现米氏方程变化趋势。比较三种原生动物摄食抑食金球藻的最大摄食率, 发现其随动物粒径的增大而增大, 但仅为摄食球等鞭金藻(Isochrysis galbana)的30%~59%。海洋尖尾藻和海洋尾丝虫的最大生长率(μmax)与饵料种类无关, 扇形游仆虫摄食抑食金球藻时的μmax值小于摄食球等鞭金藻的个体。海洋尖尾藻、海洋尾丝虫和扇形游仆虫摄食抑食金球藻时的毛生长率(gross growth efficiency, GGE)分别为65.8%、35.2%和49.1%。三种原生动物摄食抑食金球藻指数期细胞和球等鞭金藻以不同比例混合的饵料时表现出对抑食金球藻的选择倾向; 在含有抑食金球藻稳定期细胞的混合饵料喂食的情况下, 三种原生动物避食抑食金球藻或不表现明显摄食倾向性。抑食金球藻释放胞外聚合物(extracellular polymeric substance, EPS)的测定结果显示, 细胞从指数期生长至稳定期释放出的EPS的水平显著上升(P<0.05), 可能与原生动物对不同生长期藻细胞具有不同选择偏好有关。 相似文献
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四种淡水贝的摄食率和耗氧率的实验研究 总被引：1，自引：0，他引：1
研究了4种淡水贝褶纹冠蚌、背角无齿蚌、河蚬、铜锈环棱螺的摄食率和耗氧率.摄食率的测定采用血球计数板直接计数法,耗氧率的测定采用winkler碘量法.结果表明:温度对4种贝摄食率均有显著影响,在一定的适宜温度范围内,摄食率随温度的升高而加大,到一定温度时达到最大值;以单一藻类为食时,铜锈环棱螺的摄食率最大,4种贝对栅藻和微囊藻均无选择性,其摄食率无显著性差异;当以混合藻类为食时,褶纹冠蚌、背角无齿蚌和河蚬的摄食率均大于以单一藻类为食时的摄食率,而铜锈环棱螺对微囊藻的摄食则受到了抑制.用双曲线模型OC=DO/(K1 K2×DO)评估贝类对低溶氧环境的适应能力,结果表明,铜锈环棱螺的控氧能力较强. 相似文献
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从微藻粒径大小、饵料密度以及营养价值角度，选取牟氏角毛藻（Chaetoceros muelleri）、亚心形扁藻（Platymonas subcordiformis）、球等鞭金藻（Isochrysis galbana）分别作为硅藻、绿藻和金藻的代表，开展了不同规格的香港巨牡蛎对3种微藻在同等密度、同等生物量混合条件下的摄食选择性研究。结果显示，香港巨牡蛎在两种不同混合藻条件下对3种不同微藻摄食选择性有显著性差异（P<0.01）。3种藻相同密度混合条件下，大、中、小3种规格香港巨牡蛎更倾向摄食粒径较大的亚心形扁藻，且贝类规格越大选择倾向性越低，摄食选择效率分别为0.32、0.35、0.48，对球等鞭金藻无明显选择性。3种藻等生物量混合条件下，香港巨牡蛎对亚心形扁藻和球等鞭金藻的摄食有选择性，且规格大小对选择效率影响显著（P<0.01），个体越小选择性越强，小规格香港巨牡蛎倾向滤食亚心形扁藻（P<0.01），大、中规格更倾向摄食粒径较小的球等鞭金藻。两种混合条件下，香港巨牡蛎都对牟氏角毛藻都有负的选择效率，而且牟氏角毛藻密度越高负值绝对值越大。微藻的细胞大小、形状、营养价值以及香港巨牡蛎的个体大小都对摄食选择性有着明显的影响，香港巨牡蛎的摄食选择性在现场海区中还明显受到生境及食物条件的限制。 相似文献
7.
人工育苗是我国培育中间球海胆养殖业种苗的主要手段,然而传统的海胆附着基的人工育苗效果不尽如人意,尤其是在控制稚胆剥离损伤方面。目前,海上吊笼养殖是中间球海胆人工养殖最主要的养成方式之一,而随着室内工厂化养殖技术的更新和优化,海胆的室内工厂化养殖产业发展迅速并受到广泛关注。为探明以软质塑料膜作为中间球海胆附着基的育苗效果以及不同规格种苗养殖的效果,分别使用硬质波纹板和软质塑料膜作附着基进行中间球海胆人工育苗,并开展了大、小两种规格（壳径分别为0.5 cm和2.0 cm）的海胆种苗室内工厂化养殖和海区养殖研究,旨在明确软质塑料膜替代传统硬质波纹板作海胆育苗附着基的可行性以及中间球海胆室内工厂化养殖和海区养殖效果的优劣。实验结果表明：软质塑料膜在采苗效率方面与波纹板无异,但在促进稚胆生长和提高存活率方面优势显著（p<0.05）;在不同规格中间球海胆种苗的工厂化养殖和海上养成研究中,相同养殖条件下,养殖12月龄的大规格种苗相较于小规格种苗在生长和存活方面优势显著（p<0.05）,同时工厂化养殖能确保更高的养殖成活率和更优的生长性能（p<0.05）,然而中间球海胆的工厂化养殖在... 相似文献
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《海洋湖沼通报》2020,(2)
在2016年进行了基于人工育苗的海黍子增殖研究。在烟台长岛挑选生殖托刚生成的种藻,平挂于近海暂养,待生殖托成熟时,运输到青岛崂山育苗场在硬质藻礁上培育幼苗,培育光照控制在水表面9000lx以下,流水培育15d后,幼苗平均密度是20.4株/cm~2。幼苗长至0.4～0.6m时,产生1～3条分蘖,幼苗附着较为牢固时,将附有幼苗的组装型藻礁投放至青岛崂山青山湾,此区域的水文条件无剧烈变化,砂泥底质,无人工底播动物,投放水深为3.5m左右,37d后发现平均附着密度为157株/个藻礁,平均长度1.50cm,6个月后,藻体已长至0.8m左右,并且藻礁上已经附着了石莼、蜈蚣藻等其他藻类。本研究建立了一种幼苗成活率较高和藻体附着牢固的海黍子藻礁增殖方法,获得了良好的增殖效果,可为海黍子藻场构建提供技术支撑。 相似文献
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通过单因子实验,研究了短角异剑水蚤(Apocyclops royi)在不同温度、光照、pH 值、饵料密度以及单性条件下对盐生杜氏藻的滤水率(F)和滤食率(G),及其对3种常见饵料微藻(盐生杜氏藻、球等边金藻和海水小球藻)摄食的选择性,旨在为该物种的人工高效可控培养提供实验和技术基础.结果表明,实验温度范围内(20,25和30℃),短角异剑水蚤对盐生杜氏藻的滤水率和滤食率差异不显著,其中25℃时 F和 G 较高,分别为(0.049±0.014)mL/(个?h)和(1.393±0.369)×104个/(个?h);滤水率和滤食率随光照强度的增加而升高,光照强度为9800 lx 时 F 和 G 最高,分别为(0.053±0.012)mL/(个?h)和(1.295±0.303)×104个/(个?h); pH 值为9.0时,滤水率和滤食率显著高于其他实验组(7.0、8.0、10.0);滤水率随饵料密度的增加呈现先增加后降低的趋势,滤食率随饵料密度的增大而升高;滤水率和滤食率存在性别差异,雌性的 F 和 G 均比雄性约高16%.实验的3种微藻中,球等鞭金藻的选择性指数最高. 相似文献
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环境因子对三种常见微藻细胞中二甲基硫丙酸含量影响的初步研究 总被引：2，自引：0，他引：2
以3种常见的海洋浮游藻类──扁藻、杜氏藻和牟氏角刺藻作为实验材料,采用正交方法设计实验条件,研究盐度、温度和光强的变化对藻类细胞内二甲基硫丙酸（DMSP）含量的影响。结果表明,3种藻类细胞DMP含量相差很大。扁藻DMSP含量最高,其次为杜氏藻,牟氏角刺藻含量最低。种间差别的影响明显高于环境条件的变化对藻细胞DMSP含量的影响。3种环境因子对藻细胞DMSP含量的影响效果不同,盐度变化引起藻细胞DMP含量的变化最为显著,其次为温度和光强。随着盐度的增加,扁藻、杜氏藻和牟氏角刺藻细胞内DMSP含量均呈上升趋势。 相似文献
11.
Mark J. A. Vermeij Meghan L. Dailer Sheila M. Walsh Mary K. Donovan Celia M. Smith 《Marine Ecology》2010,31(2):291-299
Much of coral reef ecology has focused on how human impacts change coral reefs to macroalgal reefs. However, macroalgae may not always be a good indicator of reef decline, especially on reefs with significant sea urchin populations, as found in Kenya and Hawaii. This study tests the effects of trophic interactions (i.e. herbivory by fishes and sea urchins) and spatial competition (between algae and coral) on algal community structure of reefs surrounding two Hawaiian Islands that vary in their level of human impacts. Reef‐building organisms (corals and crustose coralline algae) were less abundant and turf algae were more abundant on Maui as compared to Lanai, where human impacts are lower. In contrast to previous studies, we found no evidence that macroalgae increased with human impacts. Instead, low turf and macroalgal abundance were best explained by the interactive effects of coral cover and sea urchin abundance. Fishing sea urchin predators appeared to have cascading effects on the benthic community. The absence of sea urchin predators and high sea urchin densities correspond to a disproportionately high abundance of turf and crustose coralline algae. We propose that high turf algal abundance is a better indicator of reef decline in Hawaii than high macroalgal abundance because turf abundance was highest on reefs with low coral cover and few fish. The results of this study emphasize that understanding changes in community composition are context‐dependent and that not all degraded reefs look the same. 相似文献
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The common tropical sea urchin Diadema antillarum Philippi is the dominant herbivore on fringing coral reefs in Barbados, West Indies. The biological importance of Diadema as an agent of energy transfer was evaluated from energy budgets constructed for the population and for individuals of 10 size groups. Monthly energy budgets for urchins of various size groups balance within 1 kcal except for urchins of the largest size group examined. Approximately 20% of the monthly net benthic primary production of the fringing coral reef is consumed by Diadema. This percentage is considerably larger than the 7% reported for the consumption of benthic algal production by a population of the temperate water sea urchin, Strongylocentrotus droebachiensis, feeding in kelp beds but is lower than the 47% reported for the consumption of sea grass by the tropical urchin Lytechinus variegatus. Higher rates of secondary production of Diadema compared to that of Strongylocentrotus may be in part due to higher net and gross growth efficiencies exhibited by Diadema. It is apparent that Diadema is more efficient at converting its algal food resources into urchin biomass than is Strongylocentrotus of similar size. In comparison to Strongylocentrotus and Lytechinus, Diadema releases as much energy to the benthos in the form of fecal pellet detritus as do the other two species. The production of fecal pellet detritus is the most important pathway of energy transfer on the fringing coral reef. Fecal pellet detritus contributes approximately 26 kcal m−2 month−1 to the benthic community. This amount is equivalent to 7·4% of the monthly net primary production of the benthic algae or approximately 37% of the caloric intake of the urchin population. In addition fecal pellet detritus produced by Diadema contains about 10 times the caloric content of surface sediments found to the north and south of the fringing reef and approximately 1·7 times the caloric content of sediments within the reef. The utilization of this energy-rich fecal pellet detritus by other reef organisms is discussed briefly. 相似文献
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《African Journal of Marine Science》2013,35(1):145-156
Previous field observations have suggested an association between the urchin Parechinus angulosus and juveniles of the abalone Haliotis midae. To test the generality and nature of this association, surveys were carried out at five sites between Cape Point and Danger Point in the kelp beds of the South-Western Cape, South Africa. These showed that both species occupy primarily hard substrata, showing preferences for encrusting coralline algae. They also confirmed a strong, positive relationship between urchins and juvenile abalone. Of the juvenile abalone sampled, more than 98% were found beneath sea urchins. All small (3–10 mm) and medium-sized(11–20 mm) juvenile abalone were under urchins, whether on flat or vertical reef, or in crevices. A small proportion (～10%) of larger juveniles(21–35 mm) was not found under urchins, and in these instances they occupied crevices instead. These findings are of particular importance in terms of their implications for the lucrative commercial abalone fishery in South Africa, indicating that urchins are of critical importance to the continued survival of viable abalone populations. There has been a dramatic decrease in natural populations of sea urchins over the past five years in the heart of the abalone fishing grounds, and the present findings suggest that this will lead to recruitment failure of abalone, because juvenile abalone seem dependent on the urchins. The long-term consequences for the industry may be crucial. 相似文献
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《African Journal of Marine Science》2013,35(4):395-406
Kelp forests along South Africa's southwest coast occur in a region of biogeographical overlap. Commonly referred to as transition-zone kelp forests, these dynamic ecosystems are particularly susceptible to grazing from species such as urchins. This study explores relationships between urchins and macroalgae in transition-zone kelp forests along the western side of False Bay. Six kelp forests in this region were sampled. At each site, the urchin Parechinus angulosus and kelp Ecklonia maxima were counted, percentage cover of understorey algae was recorded, and drift algae were collected. Despite variability in urchin and algal cover across sites, kelps generally increased from north to south, while urchins did the opposite. Urchins were negatively associated with macroalgae, although this relationship was weak. A localised threshold of 50 urchins m–2 was identified, above which kelp density failed to increase above 10 m–2 and percentage cover of understorey algae usually remained below 20%. Surprisingly, no relationship was discovered between drift algae and attached algae. The findings highlight the complexity of these cool-water environments. To better understand the role of urchins in this system, particularly under changing climate trends, experimental research into the feeding behaviour and possible effects of urchins on attached algae in the presence/absence of drift algae is advised. 相似文献
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Cruz Palacín Gonzalo Giribet Susanna Carner Luis Dantart Xavier Turon 《Journal of Sea Research》1998,39(3-4)
Numerous studies of interactions between urchins and algae in temperate areas have shown an important structuring effect of sea urchin populations. These studies focused almost wholly on the effect of high urchin densities on laminarian forests. In contrast, algal communities below 5–6 m depth in the northwestern Mediterranean are characterised by low sea urchin densities (<5 ind m−2) and the absence of laminarian forests. No previous research has addressed sea urchin/algal interactions in this type of community. To determine the effect of the most abundant echinoid species, Paracentrotus lividus, on well-established algal communities in this area, we performed a removal–reintroduction experiment in rocky patches located between 13 and 16 m depth in the northwestern Mediterranean, where sea urchin densities ranged between 0.9 and 3.4 ind m−2. After 6 months, the cover of non-crustose algae was significantly higher in the plots from which sea urchins had been removed than in control plots (84 vs 67% cover). These removal plots reverted to their original state upon reintroduction of sea urchins. The non-crustose algae consisted of turfing and frondose forms, with the former representing some 70% of the non-crustose algal cover. Change in the cover of turfing algae was responsible for the significant increase in algal development in the sea urchin removal plots. The response of frondose algae to the treatment varied between algal species. It is concluded that grazing by P. lividus exerts a significant effect on habitat structure, even in communities with low sea urchin densities, such as those found in vast areas of the Mediterranean sublittoral. 相似文献
16.
Early succession of micro‐periphyton communities in kelp bed and barren ground ecological systems 
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下载免费PDF全文 In shallow sublittoral rocky habitats of the Southeast Pacific, two conspicuous ecological systems exist; kelp beds dominated by large Laminariales algae, and barren grounds dominated by crustose coralline algae and sea urchins. The aim of this study was to examine the successional development of micro‐periphyton communities in both ecological systems using a colonization experiment conducted in Northern Chile. In both ecological systems, we installed replicated ceramic plates at 10 m depth and samples were taken after 1, 2, 4, 6, 8 and 14 days of exposure. Bacteria, diatoms, protozoans and small eukaryotes were identified, quantified and analysed. The succession of micro‐periphyton communities in both ecological systems followed a common pattern consisting of a net accumulation of functional groups and taxa over time; however, the total density of all groups was significantly higher in the kelp beds. In addition, the community structure of the developing micro‐periphytons was different and specific for each ecological system. Although previous studies have suggested that kelp beds and barren grounds are capable of switching from one state to the other without substantial changes in biodiversity, our results show that each of these ecological systems promotes its own successional development, suggesting that they are unique, self‐organized entities. This study is the first step towards an understanding of these ecological systems operating independently at this scale of organization. 相似文献
17.
By the consumption of algae, parrotfishes open space for young coral settlement and growth, thus playing a central role on the maintenance of coral reefs. However, juvenile parrotfish ecology is often overlooked due to the difficulty discerning species during this phase. Herein, we present the first attempt to investigate changes in habitat use and diet that happen to juveniles of the Redeye parrotfish Sparisoma axillare, focusing on four zones within an algal‐dominated reef: the macroalgal beds, back reef, reef flat, and fore reef. Smaller S. axillare juveniles (<5 cm) preferred to inhabit the macroalgal beds and the reef flat, whereas juveniles larger than 5 cm were more abundant in the back and fore reefs due to distinct post‐settlement habitat conditions. Aggressive interactions with the territorial damselfish Stegastes fuscus were the primary driving factor of juvenile distribution and feeding rates. Attack rates increased with juvenile size and the lowest bite rates were observed in zones with higher densities of territorial damselfish. In previous studies, the persistence of parrotfish recruits in habitats dominated by damselfish was reduced, but newly settled parrotfish occurred more densely within the damselfish domain by behaving as a cryptic reef fish. As these juveniles grew, their bite rates increased, a change associated with a shift from cryptic to roving behavior. Feeding preferences were determined by substrate cover, where juveniles fed on available food sources in each habitat. Juveniles relied on jointed calcareous algae in habitats dominated by these algae, a pattern not observed for thick leathery algae. Filamentous algae were the preferred food for smaller fish; for individuals greater than 10 cm, a higher ingestion of sand was observed. Most studies evaluating the functional role of parrotfish do not consider species feeding preferences. However, the potential for a species to turn an impacted reef back to a coral‐dominated phase is influenced by their food selection, which is dependent on the algal species composition. 相似文献
18.
Juan José Alvarado Jorge Cortés Hector Guzman Héctor Reyes‐Bonilla 《Marine Ecology》2016,37(5):1088-1102
Bioerosion is a natural process in coral reefs. It is fundamental to the health of these ecosystems. In the Eastern Tropical Pacific (ETP) coral reefs, the most important bioeroders are sponges, bivalves, sea urchins and the fish Arothron meleagris. In the 1980s, El Niño caused high coral mortality and an increase in macroalgal growth. As a result, greater sea urchin bioerosion occurred. This weakened the reef framework. Considering the high vulnerability of the ETP coral reefs, the goal of this study was to determine the current bioerosion impact of the sea urchin Diadema mexicanum along the western coasts of Mexico, El Salvador, Costa Rica and Panamá. The balance between coral bioaccretion and sea urchin bioerosion was also calculated. Between 2009 and 2010, in 12 coral reefs localities, D. mexicanum density, bottom cover and rugosity were quantified along band transects. The daily bioerosion rate was obtained from the amount of carbonates evacuated by sea urchins per unit time. The rate of coral accretion was calculated by multiplying the coral growth rate of the dominant genus by the density of their skeleton and by their specific coral cover. The localities were dissimilar (R = 0.765, P < 0.001) in terms of live coral cover, crustose calcareous algae, turf cover, rugosity index, and density and size of D. mexicanum. At all sites, with the exception of Bahía Culebra (Costa Rica), coral bioerosion was less than coral bioaccretion. Diadema mexicanum plays a dominant role in the balance of carbonates in the ETP, but this depends on reef condition (protection, overfishing, eutrophication) and so the impacts can be either positive or negative. 相似文献
19.
Stanislas Dubois John A. Commito Frdric Olivier Christian Retire 《Estuarine, Coastal and Shelf Science》2006,68(3-4):635
Biogenic structures built by ecosystem engineers such as corals, bivalves, polychaetes, and sea grasses provide habitat for benthic vertebrates and invertebrates. The polychaete Sabellaria alveolata is an important foundation species whose reef structure adds topographic complexity and high levels of biodiversity to the otherwise low-relief, low diversity, soft-bottom environments in the Bay of Mont Saint-Michel, France, where the largest such reef formations in Europe are found. In this bay, reefs are being increasingly colonised by oysters (Crassostrea gigas) from local aquaculture operations and by green algae (Ulva sp.) due to the increasing inputs of nitrates from terrestrial origin. The purpose of this study was to investigate the possible impacts of epibiotic oysters and green algae on the S. alveolata population and reef community structure in the Bay of Mont Saint-Michel, France. Univariate and multivariate comparisons of macrofauna were conducted for five reef types: controls (no epibionts), low oyster density, high oyster density, green algae, and oyster and green algae. Results showed that all the three reef types with oysters had significantly higher species richness and diversity values than control and algae-only reef types. Pairwise ANOSIM and SIMPER comparisons of controls versus the four reef types with epibionts revealed that all three of the reef types with oysters were significantly different from controls, but there was no significant difference between controls and algae-only reef types. A striking feature of the reef comparisons is that no single species in this species-rich system contributed more than 8.86% to the dissimilarity between the reef types. Thus, k-dominance curves for species abundances were not effective in revealing differences among the reef types. Our results demonstrate that recent anthropogenic inputs of oysters affect the reef species assemblage more strongly than algal epibionts. In addition, epibionts, especially green algae, alter S. alveolata population structure, causing a reduction in new recruits that over the long run may cause significant damage to the reef structure itself. These results are a first step towards understanding anthropogenic threats to S. alveolata reefs and may be useful in the development of strategies for their protection and management. 相似文献
20.
《African Journal of Marine Science》2013,35(1):137-144
In kelp beds of the South-Western Cape, South Africa, a strong positive relationship exists between the sea urchin Parechinus angulosus and juveniles of the abalone Haliotis midae. Field surveys reported here revealed a positive, but weak, association between this urchin and H. midae recruits (i.e. individuals <3 mm shell length). Selectivity indices showed that recruits occurred exclusively on encrusting coralline algae and showed preferences for strongly textured corallines, rather than those with smooth texture. On smooth corallines, around 80% of recruits were under urchins, compared with about 25% on textured corallines, suggesting that any need for shelter beneath urchins is greatest on smooth surfaces. 相似文献