滇池入湖河流大清河河口段浮游藻类格局研究

2006年7月至2007年12月对大清河3个样点的浮游藻类组成及密度、浮游叶绿素a浓度等指标进行逐月监测.共观察到浮游藻类65个分类单元,计53个属.所有样点的平均藻类密度是1.23×10⁸ ind·L^-1,最高密度为1.39×10⁹ ind·L^-1,最低密度为3.21×10⁵ ind·L^-1.铜绿微囊藻(Microcystis aeruginosa)为绝对优势种,监测期间其平均相对丰度为92.23%.随着离湖距离的增加,浮游藻类总密度、铜绿微囊藻的百分含量明显降低,而香农-威纳(Shannon-Wiener)、辛普森(Simpson 1/Dominance)多样性指数和均匀度(Evenness)则呈现升高趋势.同时,样点2、3的铜绿微囊藻百分含量与滇池的极为相似,而样点1则距离滇池较远,其铜绿微囊藻的百分含量及生物多样性指数方面均不同于样点2、3,说明滇池水的倒灌已显著影响到样点2、3的藻类组成.通过比较各样点间的群落相似性指数发现:样点1、3间的相似性指数显著低于样点1、2和样点2、3间的相似性指数.样点2、3间的相似性指数除2007年4、5及7月外,均超过60%.通过对样点1、2和3的浮游藻类群落在工程运行前后进行"非度量多维标度"(NMS)分析,发现示范工程运行后的1年内还未对大清河监测河段水生生物群落的恢复有显著作用.     

惠州沙田水库浮游植物群落特征及演替研究

2009 年7 月(丰水期)和12 月(枯水期)分别对沙田水库4 个样点进行浮游植物采集。检测出浮游植物58 种(含变种), 隶属7 门8 纲18 目31 科46 属。丰、枯水期均出现的优势种分别为史氏棒胶藻(Rhabdogloea smithii)、铜绿微囊藻(Microcystis aeruginosa)、微小多甲藻(Peridinium pusillum)、小球藻(Chlorella vulgaris); 仅在丰水期形成的优势种分别为简单棕鞭藻(Ochromonas simplex)、梅尼小环藻(Cyclotella meneghiniana)、针形纤维藻(Ankistrodesmus aciculars)和柯氏并联藻(Quadrigula chodatii); 而枯水期形成的优势种分别为分歧锥囊藻(Dinobryon divergens)、水溪绿球藻(Chlorococcum infusionum)。丰、枯水期丰度分别为(8.36±1.37)×10⁵ cell·L^-1 和(3.60±1.81)×10⁵ cell·L^-1; 生物量分别为1.34±0.55 mm³·L^-1 和0.43±0.43 mm³·L^-1; Shannon-Weaver 多样性指数变化范围在1.25-2.75 之间, 丰、枯水期水质分别为中营养和富营养水平。与2000 年结果比较, 浮游植物群落的物种组成由绿藻型更替为绿硅藻型, 丰度组成由蓝-绿藻型更替为绿-蓝-甲藻型; 清洁水体的优势种消失/减少, 耐污种类优势种增加, 其中绿藻优势种存在向小型、单细胞种类更替的趋势。     

鹤地水库浮游生物与富营养化特征分析*

于2000年丰水期和枯水期调查分析了鹤地水库的营养状态及浮游生物特征。结果表明:鹤地水库营养盐含量很高,综合营养状态指数评价为中一富营养化水平。浮游植物丰水期和枯水期的细胞密度分别为1950.5～3509.7×10⁴cells·L^-1和130.5～231.3×10⁴cells·L^-1,蓝藻中的微囊藻和席藻数量占细胞总数的83%以上。在丰水期和枯水期,浮游植物的群落结构均为蓝藻-绿藻-硅藻型,优势种为微囊藻和席藻。次优势种由丰水期蓝藻中的粘球藻,颤藻,绿藻中的衣藻,和硅藻中的颗粒直链藻等转变为枯水期的蓝藻门的水华束丝藻和硅藻门的颗粒直链藻等富营养化指示种。鹤地水库的浮游动物种类不多,但数量很高。丰水期的无节幼体和桡足幼体数量很多,但从优势种类来说,轮虫以曲腿龟甲轮虫,纵长异尾轮虫,剪形臂尾轮虫为主,枝角类的优势种为长额象鼻蚤;枯水期时无节幼体的数量最多,桡足幼体数量急剧下降,优势种类则转变为枝角类的长额象鼻蚤和桡足类的广布中剑水蚤。两个水期浮游动物的优势种类均是以耐污种和广布性种类为主。     

福建九龙江北溪浮游植物群落分布特征及其影响因子

分别于2011年枯水期(2月)、丰水期(5月)和平水期(10月),系统调查研究了福建九龙江北溪浮游植物群落组成、丰度的分布特征及其与环境因子的关系.共鉴定浮游植物107种,隶属于7门64属.不同水文期浮游植物主要优势种类不同,枯水期为马索隐藻和梅尼小环藻,丰水期为四尾栅藻和四角十字藻,平水期则演替为微小平裂藻.不同水文期浮游植物丰度变化明显,其平均值依次为枯水期(154.77×10⁴ cells·L^-1)>平水期(76.40×10⁴ cells·L^-1)>丰水期(45.40×10⁴ cells·L^-1).相关分析表明, 枯水期和平水期浮游植物丰度与铵态氮(NH₄⁺-N)呈显著正相关,丰水期浮游植物丰度与温度呈极显著正相关.典范对应分析(CCA)表明,水体温度是影响该水域浮游植物分布格局的重要因子,溶解态活性磷浓度也对浮游植物的分布有较大的影响.CCA排序图较好显示了浮游植物物种分布和环境因子之间的关系.     

嘉陵江南充段硅藻群落结构及水环境分析

为了揭示嘉陵江流经南充A段5县（市）受到的污染及水质状况,按枯水期、平水期和丰水期采集研究15个采样点的硅藻样品,分析其群落结构的物种组成、细胞密度、多样性指数和均匀度指数等,并结合化学指标对水质状况进行评价。结果表明：（1）嘉陵江南充段共有硅藻136种（含变种和变型）;细胞密度介于4500--39000ind／L之间,总平均18213ind／L;（2）硅藻物种数、细胞密度、均匀度指数及多样性指数等呈现出显著季节性和水平分布上的差异;（3）嘉陵江南充“段水质总体上属于β-中污水体,具有一定的自净能力。其中,阆中水质最好,属清洁水体;南部、仪陇和蓬安水质有所下降,介于β-中污与清洁水体之间;南充水质较差,属α-中污水体。     

汤溪水库的富营养化现状研究

为了解汤溪水库的富营养化现状,于2000年丰水期和枯水期对该水库的水质和浮游生物分布进行了调查。结果表明,汤溪水库综合营养状态指数(TLI)在30～50之间,属中营养水平。浮游植物丰度为0.81×10⁶～6.57×10⁶cells·L^-1,丰水期高于枯水期。浮游植物以蓝藻、绿藻和硅藻为主,其优势种主要为水华微囊藻(Microcystis flos-aquae)、颗粒直链藻(Melosira granulata)、极小直链藻(Melosira minmum)和衣藻(Chlamydomonas sp.)等富营养化指示种。浮游动物丰度为43.25～812.2ind.·L^-1,其优势种也多为富营养化指示种,如:螺形龟甲轮虫(Keratella cochlearis)、角突臂尾轮虫(Brachionus angularis)、前节晶囊轮虫(Asplanchna priodonta)和广布中剑水蚤(Mesocyclops leuckarti)。与1984年相比,该水库由硅藻型变为蓝藻型,其营养水平与浮游植物丰度都显著增加。在2000年一次微囊藻水华发生时,水体表层浮游植物丰度高达11.97×10⁶cells·L^-1。     

紧水滩水库浮游轮虫群落与水质生态学评价

2010年5月-2011年3月,调查了紧水滩水库(Ⅰ-Ⅵ站)浮游轮虫的群落及与水质之间的关系.共鉴定轮虫45种,污染指标种37种,其中寡污-β中污带、β中污带和β-α中污带污染指示种类分别占总指示轮虫的32.4%、35.1%和24.3%.优势种为螺形龟甲轮虫(Keratella cochlearis)、针簇多肢轮虫(Polyarthra trigla)和等刺异尾轮虫(Trichocerca stylata).轮虫群落密度变幅为4.8～542.5ind.·L^-1,平均135.7ind.·L^-1;Shannon-Wiener多样性指数H′变幅为2.60～3.65,平均3.20:Q_B/T值变幅为0.83～2.50,平均1.39.Ⅰ-Ⅱ站的群落密度和多样性指数较低,Q_B/T值较大;而Ⅲ-Ⅵ站的群落密度和多样性指数均较高,Q_B/T值较小.Q_B/T值随着水体透明度的增大而明显下降.紧水滩水库属于寡污-中污(贫-中营养型)水体,其中Ⅰ-Ⅱ站为中污(中营养型),Ⅲ-Ⅵ站为寡污-β中污(贫营养型)水体.     

飞来峡水库蓄水初期营养状态及浮游生物分布特征

于2000年丰水期和枯水期调查分析了新建河流型水库-飞来峡水库在蓄水初期的营养状态及浮游生物特征。结果表明:水库处于营养累积高峰期,已开始回落,但流域上游大量含磷废水使水库中磷含量继续上升,目前属于中营养型。共记录到浮游植物29种(属),以蓝藻门、绿藻门、硅藻门种类较多,其中丰水期以蓝藻和绿藻为主,枯水期是硅藻占优势,除大坝附近外,浮游植物两个季节密度变化不大,为0.39×10⁶cells·L^-1.浮游动物53种(属),其中包括僧帽溞和透明薄皮溞两种嗜寒性种类,丰度为52ind.·L^-1,枯水期高于丰水期,数量以轮虫和无节幼体为多。     

嘉陵江浮游生物群落结构研究

为揭示嘉陵江梯级水库浮游生物群落结构特征,按枯水期和丰水期对嘉陵江12个梯级水库24个样点进行浮游生物的野外采集,分析其群落结构的物种组成,并采用Shannon-wiener指数、Margalef指数和Pielou均匀度指数进行分析.结果表明:嘉陵江四川段浮游植物共8门42科95属171种,浮游动物的组成共有4纲9目21科30属62种;浮游动物优势种类有21种.浮游生物评价结果表明梯级库区水质处于中度污染状态.     

浙江横山水库浮游植物群落结构特征及其影响因子

为揭示横山水库浮游植物群落结构特征及其与水质环境因子的关系, 于2011年3月至2012年2月, 逐月对横山水库4个站点浮游植物种类组成、丰度与生物量以及12项水质理化指标进行了调查分析.结果表明： 共鉴定出浮游植物246种, 隶属于7门78属, 主要优势种有变异直链藻、颗粒直链藻、梅尼小环藻、美丽星杆藻、尖针杆藻、短小曲壳藻、镰形纤维藻、湖生颤藻、啮蚀隐藻、尖尾蓝隐藻、细胶鞘藻和铜绿微囊藻等, 优势种的季节更替明显. 全年浮游植物丰度及生物量分别为0.51×10⁵～14.22×10⁵ ind·L^-1及0.07～1.27 mg·L^-1; 全年Margalef指数、Pielou指数及Shannon指数分别为1.10～3.33、0.26～0.81及0.51～2.38. 横山水库浮游植物群落结构变化规律为春季硅-隐藻型、夏季蓝-绿藻型、秋季硅藻型、冬季硅-隐藻型.典范对应分析(CCA)表明, 温度、透明度、化学需氧量和pH与横山水库浮游植物群落结构关系最为密切.水质评价显示, 横山水库水质处于α中污, 营养水平为中营养.     

Ichthyofauna from wetlands of San Pedro, Balancán, Tabasco, México

San Pedro River's wetlands sustain trophic nets in the fluvial system, due to the high habitat availability, and space and temporal variations. In order to describe the relationship between environmental parameters and ichthyofauna, this study evaluated fish assemblages composition, distribution, abundance, density, biomass, richness species, diversity and equitability in the wetlands. Sampling considered three different sites and climatic seasons (dry, rainy and cold fronts). The physical and chemical parameters considered were dissolved oxygen, temperature, pH, water transparency and the depth. Fishes were caught with a shrimp net, after six minutes towings and were identified afterwards. A total of 1 049 organisms of 25 fish species were caught, two of which were exotic species: Oreochromis niloticus and Parachromis managuense. A total of 23 species were found at site I (with the highest density 0.23 ind./m2), 17 at site II (0.23 ind./m2) and 14 at site III (0.12 ind./m2). The dry season had the highest species number with 21 species, followed by the rainy season with 17 species, and the cold season with five species. Similarly, the highest biomass (8.30 g/m2) was found in dry season, followed by the rainy (2.16 g/m2) and the cold seasons (0.03 g/m2). Considering seasons, highest density was found during the dry (0.436 ind./m2), followed by the rainy (0.213 ind./m2) and the cold (0.023 ind./m2) seasons. The dominant density species during the study period, according to the quadrants graphic of Olmstead-Tukey were: Petenia splendida, Vieja heterospila, Vieja synspila, Dorosoma petenense and Astyanax aeneus. There were significant differences in the species richness among sites. Temperature, depth and transparency showed differences among the seasons. The canonical correspondence analysis indicated that fish distribution was governed by environmental parameters during all seasons. In terms of fish abundance and composition, environmental parameters play an important role showing spatial and temporal differences in the ecosystem, this could be explained with the fact that most of young fishes have a movement behavior to the wetlands, searching refuge and feed during the dry season. Considering the diversity indexes variation, it may be concluded that San Pedro River's wetlands correspond to a system where the ichthyofauna composition fluctuates spatial and seasonally.     

The efficacy of performing field surveys during the dry and rainy seasons to estimate species richness and composition of local bat assemblages

Here we assessed the efficacy of performing field surveys during both dry and rainy seasons to estimate species richness and composition of phyllostomid bats in 12 sites of the Brazilian Atlantic Forest. Our goal was to elucidate two opposite scenarios. If bat species compositions differ between the dry and rainy seasons, then field surveys in both seasons will be considered complementary for estimating local bat assemblages. In contrast, if bat species compositions in the dry season are a nested subset of the species present in the rainy season, then field surveys in both seasons will be considered redundant. Our results showed that field surveys performed only during the rainy season exhibited the same efficacy in recording bat species as field surveys considering both dry and rainy seasons combined. Consequently, the rare species sampled in the rainy season contributed to the uniqueness of communities in terms of species composition. Considering that time, funding, and the number of field personnel available for work are important factors when determining the sampling effort in highly biodiverse regions like the tropics, our results can be useful in establishing protocols for research projects with limited resources aiming to create a comprehensive list of species.     

Influence of season on leaf litter ant (Hymenoptera: Formicidae) diversity in the locality of Minko'o (Southern,Cameroon)

Seasonality is known to influence ant activity in many tropical rain forests in the world such as South America and Africa. We surveyed ant fauna in the leaf litter in the locality of Minko'o. The work aimed to evaluate the effect of seasonal variation on the diversity and composition of litter ants. Ants were sampled from November 2015 to June 2017, using four sampling methods: visual capture, bait, pitfall trap and extraction. Species richness, Shannon diversity index and analysis of similarities were used to characterise diversity of ant communities between seasons. We collected 306 ant species, shared out between 56 genera and 11 subfamilies. Subfamilies Myrmicinae, Ponerinae, Dolichoderinae, Formicinae, Dorylinae, Cerapachyinae and Pseudomyrmecinae occurred in all the seasons. Species richness was highest in major dry season with 243 species followed by minor rainy season with 188, major rainy season with 177 species and finally minor dry season that recorded the lowest with 155 species. Kruskal–Wallis test showed that ant species richness did not differ between seasons (p > 0.05). Species diversity index indicated that diversity was the highest during minor dry season (H′ = 4.24), followed by the major dry season (H′ = 4.23), minor rainy season (H′ = 4.21) and lowest during major rainy season (H′ = 4.06). Eight most frequents ants have been recorded: Axinidris sp.1, Camponotus flavomarginatus, Monomorium guineense, Myrmicaria opaciventris, Odontomachus troglodytes, Carebara perpusilla, Paltothyreus tarsatus and Pheidole megacephala. Assessment of the seasonal effect on diversity reveals that dry season is richer and more diverse than rainy season and the season significantly influence the diversity of litter ants.     

Distribution, population parameters, and diet of Astropecten marginatus (Asteroidea: Astropectinidae) in the Venezuelan Atlantic coast

Astropecten marginatus is a sea star widely distributed in Northern and Eastern South America, found on sandy and muddy bottoms, in shallow and deep waters. To describe some of its ecological characteristics, we calculated it spatial-temporal distribution, population parameters (based on size and weight) and diet in the Orinoco Delta ecoregion (Venezuela). The ecoregion was divided in three sections: Golfo de Paria, Boca de Serpiente and Plataforma Deltana. Samples for the rainy and dry seasons came from megabenthos surveys of the "Línea Base Ambiental Plataforma Deltana (LBAPD)" and "Corocoro Fase I (CFI)" projects. The collected sea stars were measured, weighted and dissected by the oral side to extract their stomach and identify the preys consumed. A total of 570 sea stars were collected in LBAPD project and 306 in CFI one. The highest densities were found during the dry season in almost all sections. In LBAPD project the highest density was in "Plataforma Deltana" section (0.007 +/- 0.022 ind/m2 in dry season and 0.014 +/- 0.06 ind/m2 in rainy season) and in the CFI project the densities in "Golfo de Paria" section were 0.705 +/- 0.829 ind/m2 in rainy season and 1.027 +/- 1.107 ind/m2 in dry season. The most frequent size range was 3.1-4.6cm. The highest biomass was found in "Golfo de Paria" section (7.581 +/- 0.018 mg/m2 in dry season and 0.005 +/- 6.542 x 10(-06) mg/m2 in rainy season for 2004-2005 and 3.979 +/- 4.024 mg/m2 in dry season; and 3.117 +/- 3.137 mg/m2 in rainy season for 2006). A linear relationship was found between the sea star size and its weight but no relationship was observed between its size and the depth where it was collected. Mollusks are dominant in the sea star diet (47.4% in abundance). The diet in any of the sections, seasons or between projects or size class was heterogeneous, using multivariate ordinations (MDS) and SIMPER analysis and there was no difference in the prey number or food elements that a sea star can eat. Although A. marginatus has been described as a predator, in this study were also inferred scavenger and detritivorous habits.     

引种植物定植区近地层光合有效辐射特征

为了探讨西双版纳热带植物园引种植物主要定植区近地层的光合有效辐射特征及其变化规律,利用2008—2009年不同季节的小气候观测资料,分析了西双版纳热带植物园引种植物主要定植区近地层的光合有效辐射的季节和日变化特征。结果表明:西双版纳热带植物园区域的光合有效辐射具有明显的日变化和季节差异,雨季最强,旷地的光合有效辐射日总量可达406.6mol·m-2·d-1,雾凉季最弱,旷地光合有效辐射日总量为236.0mol·m-2·d-1;由于受高大树木遮蔽的影响,在沟谷林、龙脑香林和树木园的光合有效辐射数值较低;受太阳高度角变化和林冠林隙的影响,在雨季近地层光合有效辐射会出现突跃现象。各引种植物定植区近地层的光合有效辐射的数值也不同,存在地域差异和季节差异。在具有高大树木、遮蔽较大的定植区,近地层光合有效辐射的数值较小;而遮蔽较小的定植区,情况则反之,近地层光合有效辐射的季节差异与旷地相似,雨季较大,雾凉季较小。在具有高大树木、遮蔽较大的定植区,近地层光合有效辐射与旷地的比值较小,不足旷地的10%,其中在具有多层多种森林群落结构的沟谷林,其最小比值(雾凉季)仅为1.6%;而遮蔽较小的定植区比值较大(>55%)在干热季其数...     

Seasonal contrasts in the response of coffee ants to agroforestry shade-tree management

In many tropical landscapes, agroforestry systems are the last forested ecosystems, providing shade, having higher humidity, mitigating potential droughts, and possessing more species than any other crop system. Here, we tested the hypothesis that higher levels of shade and associated humidity in agroforestry enhance coffee ant richness more during the dry than rainy season, comparing ant richness in 22 plots of three coffee agroforestry types in coastal Ecuador: simple-shade agroforests (intensively managed with low tree species diversity), complex-shade agroforests (extensively managed with intermediate tree species diversity) and abandoned coffee agroforests (abandoned for 10-15 yr and resembling secondary forests). Seasonality affected responses of ant richness but not composition to agroforestry management, in that most species were observed in abandoned coffee agroforests in the dry season. In the rainy season, however, most species were found in simple-shade agroforests, and complex agroforestry being intermediate. Foraging coffee ants species composition did not change differently according to agroforestry type and season. Results show that shade appears to be most important in the dry seasons, while a mosaic of different land-use types may provide adequate environmental conditions to ant species, maximizing landscape-wide richness throughout the year.     

刘家峡水库浮游植物群落结构与环境因子的关系

研究分析刘家峡水库浮游植物群落结构的变化, 探讨西北地区河道型水库环境因素对浮游植物群落结构的影响, 为刘家峡水库增殖渔业提供科学依据。2020年3—10月, 在刘家峡水库设置11个采样点, 每月对浮游植物进行定性和定量采集, 同时采集水样监测总氮、总磷和高锰酸盐指数等水环境指标, 分析水质变化规律, 及浮游植物的优势种、多样性和群落结构的季节变化特征。结果表明: 刘家峡水库共检测到浮游植物7门35属63种, 其中硅藻门种类最多, 共17属40种; 其次为绿藻门8属12种; 蓝藻门4属4种, 裸藻门1属2种, 黄藻门2属2种, 甲藻门2属2种, 金藻门1属1种。浮游植物密度在(3.17—59.09)×104个/L, 平均密度为13.54×104个/L。浮游植物生物量在0.0370—0.5004 mg/L, 平均生物量为0.2137 mg/L。浮游植物密度和生物量均有在4、5月份上升和6月份骤然下降的趋势, 最高值均出现在5月份。多样性指数H′值在1.16—2.43, 平均值为1.84; 丰富度指数D值在1.22—1.57, 平均值为1.42; 均匀度指数J值在0.23—0.51, 平均值为0.38。丰富度指数D值变化趋势与均匀度指数J值刚好相反。RDA分析显示, 对浮游植物影响最强的环境因子是总氮和透明度, 其次为溶解氧和水温。综合浮游植物和水质指标评价刘家峡水库处于Ⅰ或Ⅱ类水, 是极贫营养至贫营养类型。研究可为刘家峡水库水生态保护和渔业资源的可持续利用提供科学依据。     

Seed bank dynamics and tree‐fall gaps in a northwestern Mexican Quercus‐Pinus forest

Questions: How does the seed bank respond to different types of tree‐fall gaps and seasonal variations? How does the soil seed bank influence recovery of the standing vegetation in the mature forest and tree‐fall gaps? Location: 1800 — 2020 m a.s.l., Quercus‐Pinus forest, Baja California Sur, Mexico. Methods: Seed size, species composition and germination were estimated under different environmental conditions during dry and rainy seasons: a mature forest plot and gaps created by dead standing trees, snapped‐of f trees and uprooted trees. The soil seed bank was investigated using direct propagule emergence under laboratory conditions, from soil cores obtained during both seasons. Results: 21 species, 20 genera and 14 families constitute the seed bank of this forest community. Fabaceae, Asteraceae, Euphorbiaceae and Lamiaceae were the most frequently represented families in the seed bank. Floristic composition and species richness varied according to the different modes of tree death. Species composition of seed banks and standing vegetation had very low similarity coefficients and were statistically different. Seed bank sizes varied between 164 and 362 ind.m^‐2 in the mature forest plot for the dry and rainy seasons, respectively, while soil seed bank sizes for gaps ranged between 23–208 ind.m^‐2 forthe dry season and between 81–282 ind.m^‐2 for the rainy season. Conclusions: Seed bank sizes and germination response were always higher in the rainy season under all the environmental conditions analysed. Results suggest that timing responses to gap formation of the soil seed bank could be more delayed in this temperate forest than expected.