2004年秋季南海北部浮游植物组成及其数量分布特征   总被引：5，自引：1，他引：4       下载免费PDF全文

李涛  刘胜  王桂芬  曹文熙  黄良民  林秋艳 《热带海洋学报》2010,29(2):65-73

根据2004年9月18日—10月2日南海北部航次所获得的表层浮游植物群数据, 对其组成及数量分布进行了探讨分析。该次调查鉴定浮游植物共53属152种(含变种和变型), 分别属于硅藻门35属88种、甲藻门15属60种、蓝藻门1属2种及金藻门1属1种等; 优势种中分布较广泛的有柔弱伪菱形藻Pseudo-nitzschia delicatissima、反曲原甲藻Prorocentrum sigmoides、微小原甲藻P. mininum、锥状施克里普藻Scrippsiella trochoidea和红海束毛藻Trichodesmium erythraeum等; 浮游植物细胞丰度的数量范围为(0.11—23.61)×106cells•m-3, 呈现近岸区域高于远岸区域的平面分布格局, 最大值和最小值分别出现在海南岛东北部海域的E506站和海南岛东南部海域的B3站; 浮游植物物种丰富度也是近岸的站点较高, 以靠近珠江口E708站的51种为最多。硅藻类细胞丰度范围为(0.02—8.13)×106cells•m-3, 主要分布在高盐的外海水域, 其中产二甲基磺酸丙酯(DMSP)的小环藻Cyclotella spp.在多个站点出现; 甲藻类以近岸水域居多, 细胞丰度最高达15.67×106cells•m-3(E506站), 其中数量较多的赤潮种类主要有锥状施克里普藻、反曲原甲藻、微小原甲藻、环沟藻Gyrodinium spp.等; 固氮的红海束毛藻在调查海域广泛分布, 但主要集中于东部, 以E206站最多, 高达1.8×107cells•m-3。结合水文资料和其他层次的浮游植物资料进行对比分析, 结果表明, 红海束毛藻的分布与黑潮水的入侵存在一定关系, 其分布受水团和海流的影响。  相似文献   

海南昌江沿岸海域石珊瑚的物种多样性及其分布     

牛文涛  张潇娴  林荣澄  王初升 《台湾海峡》2010,29(3):389-393

2009年3月,采用水下照相及摄像方法,对海南昌江沿岸海域的石珊瑚物种多样性、分布及覆盖度进行了调查.结合历史资料,共发现石珊瑚10科15属28种和1未定种.其中鹿角珊瑚属（Acropora）、角蜂巢珊瑚属（Favites）、叶状珊瑚属（Lobophyllia）等为优势类群,常见分布珊瑚种类有角孔珊瑚（Gonioporasp.）、标准蜂巢珊瑚（Favia speciosa）、五边角蜂巢珊瑚（Favites pentagona）、多孔鹿角珊瑚（Acropora millepora）、十字牡丹珊瑚（Pavona decussata）、伞房叶状珊瑚（Lobophyllia corymbosa）等.石珊瑚主要分布于海尾镇三联村以南海域,覆盖率最高为12%.本次调查在海南昌江沿岸海域记录的珊瑚种类数多于以前的记录,但少于海南南岸的三亚鹿回头,也少于北部的广西涠洲岛、广东徐闻、香港等海域,随着调查次数的增加,预计会有更多的种类被发现.该海域是北部湾珊瑚幼虫交流的中间过渡区,对珊瑚礁的保护与恢复具有重要意义.  相似文献   

Changes in survivorship,behavior, and morphology in native soft‐shell clams induced by invasive green crab predators     

W. Lindsay Whitlow 《Marine Ecology》2010,31(3):418-430

Many studies on invasive species show reduced native densities, but few studies measure trait‐mediated effects as mechanisms for changes in native growth rates and population dynamics. Where native prey face invasive predators, mechanisms for phenotypic change include selective predation, or induced behavioral or morphological plasticity. Invasive green crabs, Carcinus maenas, have contributed to declines in native soft‐shell clams, Mya arenaria, in coastal New England, USA. We tested the hypothesis that clam ability to detect chemical cues from predators or damaged conspecifics would induce greater burrowing depth as a refuge from invasive crabs, and greater burrowing would require increased siphon growth. To determine how crab predation affected clam survivorship and phenotypic traits in the field, clams in exclosure, open, and crab enclosure plots were compared. Crab predation reduced clam density, and surviving clams were deeper and larger, with longer siphons. To determine whether the mechanism for these results was selective predation or induced plasticity, phenotypes were compared between clams exposed to chemical cues from crab predation and clams exposed to seawater in laboratory and field experiments. In response to crab predation cues, clams burrowed deeper, with longer siphons and greater siphon mass. Overall, crab predation removed clams with shorter siphons at shallow depths, and crab predation cues induced greater burrowing depths and longer siphons. Longer siphons and greater siphon mass of deeper clams suggests clams may allocate energy to siphon growth in response to crabs. By determining native behavior and morphological changes in response to an invasive predator, this study adds to our understanding of mechanisms for invasive impacts and illustrates the utility of measuring trait‐mediated effects to investigate predator–prey dynamics.  相似文献   

Community structure of infaunal macrobenthos around vestimentiferan thickets at the San Clemente cold seep,NE Pacific     

Angelo F. Bernardino  Craig. R. Smith 《Marine Ecology》2010,31(4):608-621

The San Clemente cold seep lies within 100–200 km of other reducing habitats in the NE Pacific, offering an opportunity to compare diversity and species overlap among reducing habitats (i.e. whale‐, kelp‐, and wood‐falls) at similar depths within a single region. Video observations from the research submersible Alvin at the San Clemente seep (1800 m depth) indicated clumps (‘thickets’) of vestimentiferans distributed as meter‐scale patches interspersed with vesicomyid clam beds and black sediments. Sediment‐core samples were collected at distances of 0 to 80–200 m along randomly oriented transects radiating outward from vestimentiferan thickets to evaluate changes in macrofaunal community structure from thickets into the background community. Macrofaunal abundance was elevated at distances of 0–1 m compared to 80–200 m (i.e. the ‘background’ community). The tube‐building frenulate worms Siboglinum spp., along with peracarid crustaceans, dominated sediments within 1 m of vestimentiferan thickets. Species diversity was depressed within 1 m of thickets but with high rates of species accumulation, suggesting that seep sites greatly increase sediment heterogeneity and facilitate colonization by non‐background macrofaunal species. Stable isotope data indicate chemosynthetic nutrition for some dominant macrofaunal species within 1 m of tubeworm thickets. The macrofaunal community near vestimentiferan thickets in San Clemente seep contains intermediate levels of species richness and diversity compared to other deep‐sea seep areas in the northeast Pacific. There was low species overlap between the San Clemente seep macrofauna and communities in reducing habitats near wood‐, whale‐, and kelp‐falls at similar depths within the region, suggesting that seeps harbor a distinct infaunal community.  相似文献   

Diel and seasonal variability in the fish community structure of a mud‐bottom estuarine habitat in the Gulf of Mexico     

Manuel Castillo‐Rivera  Rocío Zárate‐Hernández  Selene Ortiz‐Burgos  José Zavala‐Hurtado 《Marine Ecology》2010,31(4):633-642

We hypothesized that temporal variation in fish species composition and community structure in a low complexity habitat in the Pueblo Viejo Lagoon, Mexico, is influenced by diel light/dark cycles and tidal stage, and by seasonal changes in salinity and temperature. We collected a total of 17,661 individuals during 2‐h interval sampling over six bi‐monthly 24‐h sampling cycles representing 53 species, of which 11 (～20%) were previously unknown in the system. Diel variation indicated that significantly higher numbers of individuals and species were caught at night, whereas diversity and evenness were higher during the day. Species richness was significantly higher in July and January, whereas diversity and evenness peaked around May; both were correlated with temperature. Diel variation in species composition was influenced primarily by the light/dark cycle. Cluster analyses of each diel cycle separated fish assemblages from midday samples from those of nocturnal samples, separated by an extended wide transition period as fish moved at dawn and during the late afternoon/dusk. Significant shifts (as determined by MANOVA) in assemblage structure occurred between months. Canonical correspondence analysis showed that temperature and day/night effects were the most important environmental variables structuring the fish community. This constrained ordination also defined species with specific habitat preferences as follows: (i) diurnal, warm temperature species (mainly planktivores) (Brevoortia gunteri, Cetengraulis edentulus, Diapterus auratus, and Membras martinica); (ii) nocturnal, warm temperature species (mainly predators) (Citharichthys spilopterus, Cathorops melanopus, and Bairdiella spp.); and (iii) low temperature, diurnal species (Brevoortia patronus and Mugil curema) or those with twilight and nocturnal distributions (Anchoa mitchilli, the most numerically abundant species). Our results indicate that diel and seasonal changes in fish community structure were mainly related to day/night cycles and temperature regimes.  相似文献   

胶州湾中部海域秋、冬季大型无脊椎动物群落结构及多样性研究   总被引：4，自引：1，他引：3  

陈晓娟  薛莹  徐宾铎  任一平  昝肖肖 《中国海洋大学学报(自然科学版)》2010,40(3)

根据2008年9月~2009年2月在胶州湾中部海域进行的逐月定点底拖网调查,对该海域秋、冬季大型无脊椎动物群落结构及多样性变化进行了初步研究.结果表明,胶州湾秋、冬季共捕获大型无脊椎动物60种,其中甲壳动物和软体动物是主要的无脊椎动物类群;优势种组成具有较明显的月间变化,主要为口虾蛄Oratosquilla oratoria、短蛸Octopus ocellatus、脊腹褐虾Crangon affinis等湾内定居性种类及洄游性较小的种类.Margalef种类丰富度指数范围为1.998~4.669,自9月起逐月递减,11月达到最低值,随后又逐月升高,2月达到最高值;Shannon-Wiener多样性指数和Pielou均匀度指数范围分别为1.325~2.500和0.422~0.693,逐月变化趋势与物种丰富度指数基本一致.多样性指数与海域温度、盐度和深度等环境因子均无显著性相关.多元统计分析表明,胶州湾中部海域秋、冬季大型无脊椎动物群落可划分为2个时间组群;组群间群落种类组成结构差异不显著.  相似文献   

Riparian vegetation dynamics across two different landscapes along the river Cauvery in the Kodagu region of Western Ghats     

C. SUNIL  R.K. SOMASHEKAR  B.C. NAGARAJA 《山地科学学报》2012,9(3):351-361

Decades of commercial planting and other anthropogenic processes are posing a threat to the riparian landscapes of the Cauvery river basin, which supports a high floral diversity. Despite this, the habitats in the upstream sections of the River Cauvery are still intact, as they are located in sacred groves. To understand the dynamism of riparian forests exposed to anthropogenic pressures, the upstream stretch of Cauvery extending from Kushalanagara to Talacauvery (~102 km) was categorized into two landscapes: agro ecosystem and sacred (i.e. preserved). The tree species were sampled using belt transects at 5 km intervals and the regeneration status of endemic species assessed using quadrats. A total of 128 species belonging to 47 families, and representing 1,590 individuals, was observed. Amongst them, 65% of unique species were exclusive to sacred landscapes. A rarefaction plot confirmed higher species richness for the sacred compared to the agro ecosystem landscapes, and diversity indices with more evenness in distribution were evident in sacred landscapes. A significant loss of endemic tree species in the agro ecosystem landscapes was found. Overall, this study demonstrates that an intense biotic pressure in terms of plantations and other anthropogenic activities have altered the species composition of the riparian zone in non-sacred areas. A permanent policy implication is required for the conservation of riparian buffers to avoid further ecosystem degradation and loss of biodiversity.  相似文献   

Seasonal Dynamics of Rhizosphere Soil Microbial Abundances and Enzyme Activities under Different Vegetation Types in the Coastal Zone,Shandong, China          下载免费PDF全文

Gang Xu  Peng Chen  Jun‐Na Sun  Hong‐Bo Shao 《洁净——土壤、空气、水》2014,42(8):1115-1120

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One‐Pot Polyvinyl Alcohol‐Assisted Hydrothermal Synthesis of Hierarchical Flower‐Like BiOCl Nanoplates with Enhancement of Photocatalytic Activity for Degradation of Rhodamine B          下载免费PDF全文

Yunchao Xie  Fei Chang  Chenlu Li  Juan Chen  Jieru Luo  Liang Li  Xuefeng Hu 《洁净——土壤、空气、水》2014,42(4):521-527

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Changes in the small-jellyfish community in recent decades in Jiaozhou Bay, China   总被引：1，自引：0，他引：1  

孙松  李颖虹  孙晓霞 《中国海洋湖沼学报》2012,30(4):507-518

We used long term monitoring data to evaluate changes in abundance and species dominance of small-jellyfish (collected with zooplankton net whose bell diameter was less than 5 cm) between 1991 and 2009 in the Jiaozhou Bay, China. Zooplankton samples were vertically towed with conical plankton net from near-bottom to surface, identified microscopically, and mapped in time-space using Grapher 7.0 and Surfer 8.0. Results show that the abundance of small-jellyfish throughout the bay had been increasing during 2001-2009 on average of 15.2 ind./m 3 , almost 5 times higher than that between 1991 and 2000. The occurrence of peak abundance shifted from spring to summer after 2000, and two peaks appeared in spring and summer, respectively, after 2005. Both the abundance and the frequency of blooms of small-jellyfish increased after 2000 in the bay. In addition, the biodiversity of jellyfish has increased significantly in recent years with a change in dominant species. Several new dominant species appeared after 2000, including Rathkae octopunctata in winter, Phialidium hemisphaericum in spring, summer, and autumn, Phialucium carolinae in spring, and Pleurobrachia globosa in summer and autumn, while some previous dominant species throughout the 1990s (Eirene ceylonensis, Zanclea costata, Lovenella assimilis, and Muggiaea atlantica) were no longer dominant after 2000. The abundance of small-jellyfish was positively correlated with the density of dinoflagellates, and the abundance of zooplankton. We believe that the changes in smalljellyfish abundance and species composition were the result of eutrophication, aquaculture and coastal construction activities around the bay. Concurrently, seawater warming and salinity decrease in recent decades promoted the growth and reproduction of small-jellyfish in the bay.  相似文献