中华哲水蚤卵密度及其沉降速率

中华哲水蚤是中国全球海洋生态系统动力学（China-GLOBEC）研究中的关键次级生产者,是浮游植物与高营养级生物之间的中间纽带。为了阐明中华哲水蚤的卵沉降动力学,采用密度梯度离心法研究了中华哲水蚤的卵密度,研究结果表明：在厦门湾中华哲水蚤平均卵密度为1．0733gcm^-3。按照斯托克斯定律,中华哲水蚤卵的沉降速率为43．9～67．5md^-1。对中华哲水蚤卵沉降时间与孵化时间的比较表明,在厦门湾中华哲水蚤卵能够在孵化之前就沉降到海底。并对中华哲水蚤卵快速沉降的生态学意义展开了讨论。     

脂肪酸对中华哲水蚤摄食两种海洋微藻的指示作用

在室内以饥饿培养为对照,以海洋原甲藻(Prorocentrum micans)和中肋骨条藻(Skeletonema costatum)培养中华哲水蚤(Calanus sinicus),研究了各脂肪酸标记对中华哲水蚤摄食不同饵料的指示作用。结果显示,海洋原甲藻中18 ∶ 4ω3、22 ∶ 6ω3含量较高,中肋骨条藻中16 ∶ 1ω7、20 ∶ 5ω3的含量较高。二者分别表现出典型的甲藻门和硅藻门的脂肪酸组成特征。中华哲水蚤的脂肪酸组成有两个特点:(1)20 ∶ 5ω3和22 ∶ 6ω3的含量均较高;(2)其体内表征桡足类浮游植物食性、由桡足类自身合成的20 ∶ 1和22 ∶ 1脂肪酸占有相当的比例。虽然中华哲水蚤对不同脂肪酸的吸收和转化效率不同,但以脂肪酸作为标记还是成功的指示了中华哲水蚤对微藻的摄食。在饥饿培养中,首先消耗的是那些浮游动物自身不能合成的多不饱和脂肪酸,而结构脂肪酸都表现出了较高的保守性。结合各脂肪酸标记变化趋势和Pearson相关性分析的结果认为,18 ∶ 4ω3、18 ∶ 4ω3/16 ∶ 1ω7、∑18/∑16能较好的指示中华哲水蚤对海洋原甲藻的摄食,仅16 ∶ 1ω7/18 ∶ 4ω3能指示中华哲水蚤对中肋骨条藻的摄食。     

藻类种类和浓度对中华哲水蚤(Calanus sinicus)摄食和消化酶活性的影响

通过饵料浓度差法在实验条件下研究了不同浓度的金藻、三角褐指藻和巴夫藻对中华哲水蚤(Calanus sinicus)摄食和消化酶活性的影响,结果表明:不同藻类和浓度对中华哲水蚤的摄食有明显的影响.(1)中华哲水蚤对3种饵料藻的摄食存在一饱和浓度,低于饱和浓度,摄食率随着食物浓度的增加而增加;高于饱和浓度,摄食率呈下降趋势.实验浓度下,中华哲水蚤对金藻、三角褐指藻和巴夫藻的最大摄食率分别为4664、6021 cells ml-1和4524 cells ml-1.滤水率随着食物浓度的增加而呈单一性的下降.(2)中华哲水蚤消化酶活性随藻类种类和浓度的变化而变化.不同藻类和浓度下,昆布多糖酶活性都明显高于麦芽糖酶和纤维二糖酶的活性,而麦芽糖酶活性又稍高于纤维二糖酶的活性.不同藻类喂养条件下,中华哲水蚤3种消化酶的活性发生了不同程度的变化,以巴夫藻喂养时酶活性稍高.     

氨基酸在黄东海食物网关键种——鯷鱼（Engraulis japonicus）食物链中的传递

采用活体饵料对黄东海生态系统食物网关键种食物链的中下营养层次"浮游植物-中华哲水蚤(Calanus sinicus)-鯷鱼(Engraulis japonicus)"进行了室内模拟实验研究,以了解氨基酸在该食物链中的传递过程.通过76 d的培养实验,对采集样品做了14种氨基酸含量的定量分析.结果表明,在3个营养层次中中华哲水蚤起着十分关键的承上启下作用,它不仅将小球藻的植物性蛋白转化为动物性蛋白,大幅度地提高了赖氨酸的含量,而且将氨基酸总含量从小球藻的6.10%提高到24.16%.作为该食物网主要经济鱼类重要饵料的鯷鱼则进一步将氨基酸含量提高到27.06%.中华哲水蚤的氨基酸相对组成与小球藻有明显的相关性(r=0.606,p＜0.05),其中7种必需氨基酸的相关性相对较弱,而非必需氨基酸的相关性明显较强.鯷鱼的食性由合成饵料转变为活体中华哲水蚤时,其氨基酸量也随饵料的改变而有所变化,从与合成饵料相关转为与中华哲水蚤有更紧密的相关.鯷鱼排泄粪便中的氨基酸含量主要由新陈代谢的生理过程所决定.     

春季东海中华哲水蚤对有害藻华物种的选择性摄食

2005年4月27日—6月5日在东海有害藻华高发区的6个典型站位采样,分析了浮游植物的群落结构,并采用现场实验研究了中华哲水蚤(Calanus sinicus)的选择性摄食.结果表明,中华哲水蚤对浮游植物的选择性摄食具有食物密度依赖性.低浮游植物细胞丰度下中华哲水蚤具有明显的选择性摄食行为,高浮游植物细胞丰度下中华哲水蚤摄食选择性由偏好转变为排斥,浮游植物细胞丰度329 cells·ml^-1是中华哲水蚤由偏好趋于排斥摄食的阈值.中华哲水蚤的选择性摄食还与食物组成有关,对于食物中的微型浮游动物,中华哲水蚤无选择性或排斥摄食.有害藻华发生区中华哲水蚤对具齿原甲藻(Prorocentrum dentatum)的偏好摄食以及对米氏凯伦藻(Karenia mikimotoi)的排斥摄食,促使藻华的物种演替最终向米氏凯伦藻水华方向发展.     

长江口北港和北支浮游动物群落比较

根据2004年5、8、11月和2005年2月在长江口4个航次的海洋综合调查,通过物种多样性、累积优势度曲线等群落水平指标和相似性检验分析(ANOSIM),对长江口北港和北支浮游动物群落及其主要优势种的差异,以及主要生态因子对浮游动物群落的影响进行了分析.结果表明：北港主要由潮汐影响的淡水和低盐水组成,北支由中、高盐水组成.春季,北港浮游动物丰度和多样性均低于北支,主要优势种为中华华哲水蚤;北支浮游动物优势种数较多,主要优势种为真刺唇角水蚤.夏季,北港和北支的多样性较接近,但种类组成差别较大,北港以中华华哲水蚤为主;北支由火腿许水蚤、虫肢歪水蚤和太平洋纺锤水蚤等构成河口和近岸群落.秋季,北港的丰度和多样性均低于北支,且两个水域的浮游动物群落差异明显,北港以中华华哲水蚤为主,北支则由小拟哲水蚤、针刺拟哲水蚤、真刺唇角水蚤和中华哲水蚤等组成.冬季,两个水域种数和多样性均较低,群落差别在四季中最小,均以中华华哲水蚤占绝对优势.温度和盐度及其相互作用是决定长江口浮游动物群落特征的最主要因素.其中温度是研究水域浮游动物群落季节变化的主要因素,而由径流和外海水之间的消长引起的盐度变化是北港和北支浮游动物群落区域变化的决定因素.     

渤海浮游动物群落生态特点Ⅰ.种类组成与群落结构

以1959年全国海洋普查浮游动物中网周年标本为材料,对渤海浮游动物的群落结构进行分析.渤海浮游动物群落以近岸广温种为主,主要优势种包括小拟哲水蚤(Paracalanus parvus)、双毛纺锤水蚤(Acartia bifilosa)、强额拟哲水蚤(Paracalanus crassirostris)、拟长腹剑水蚤(Oithona similis)、墨氏胸刺水蚤(Centropages mcmurrichi)、中华哲水蚤(Calanus sinicus)、真刺唇角水蚤(Labidocera enchaeta)、强壮箭虫(Sagitta crassa)等.由于受海流影响,渤海中也有少量暖水性种类出现,包括Euchaeta rimana Bradford 1974、精致真刺水蚤(Euchaeta concinna)、刺尾角水蚤(Pontella spinicauda)、羽环纽鳃樽(Cyclosalpa pinnata)、长吻纽鳃樽(Brooksia rostrata)、锯齿海樽(Doliolum denticulatum)、肥胖箭虫(Sagitta enflata)和介形类.聚类分析和主要成分分析的结果表明:受海流影响,春季(5月份)渤海浮游动物群落可以划分成近岸型、受黄海海流影响的外海型以及过渡类型.夏季(8月份)由于水文条件的差异,群落结构比较复杂.秋、冬季(11月份、2月份)主要是以近岸类型为主,这可能同该海区盛行东北风有关.     

黄海中华哲水蚤度夏区大型底栖动物的次级生产力

本文根据2001年8月和2002年8-10月在黄海中华哲水蚤度夏区4个航次调查中设置的大面调查站中的9个重合站所采集的大型底栖动物样品,统计了其平均栖息密度、平均生物量,利用Brey (1990)的经验公式进行了次级生产力和P/B值的计算.结果表明,该海域大型底栖动物在2001年8月和2002年8-10月这两个期间内,平均栖息密度分别为379.44 ind./m2和156.67 ind./m2,平均生物量[以去灰干重(AFDW)计]分别为9.44 g(AFDW)/m2和7.36 g (AFDW)/m2,据之计算出2001和2002年大型底栖动物的次级生产力(以去灰干重计)分别为9.64 g(AFDW)/(m2·a)和6.42 g (AFDW)/(m2· a),P/B值分别为1.20和0.98.同相关研究结果的比较显示,黄海中华哲水蚤度夏区内大型底栖动物次级生产力高于渤海、东海,也高于黄海其它调查区已有报道结果;而P/ B值则高于渤海,低于东海,与黄海其它调查区报道结果接近[动物学报 54(3):436-441 ,2008].     

中华哲水蚤(Calanus sinicus)对浮游植物和微型浮游动物的摄食速率估算

2005年4月27日至5月30日在东海有害藻华高发区的6个典型站位采样,结合稀释法实验和Frost的直接计量法研究了中型浮游动物对浮游植物和微型浮游动物群落的现场摄食速率,并对中华哲水蚤(Calanus sinicus)的食物组成、中型浮游动物和微型浮游动物对浮游植物群落的摄食压力进行了估算。研究结果表明春季调查区:中华哲水蚤对浮游植物的物种比摄食率介于0.01~8.43d-1,平均值为(2.72±2.14)d-1。中华哲水蚤对浮游植物的物种摄食速率介于0.05~838.23cells ind.-1d-1,平均值为(52.72±154.21)cells ind.-1d-1,对几种有害藻华原因生物的摄食速率较高。中华哲水蚤对浮游植物物种摄食速率具有食物密度依赖性,在低浮游植物丰度下,其摄食速率会随着浮游植物丰度的增加而增加,达到一定阈值后随着浮游植物丰度增加而逐渐降低。中型浮游动物群落对浮游植物群落碳摄食速率介于0.53~4.97ngC L-1d-1,平均值为(2.16±1.63)ngC L-1d-1。微型浮游动物对浮游植物群落物种平均碳摄食速率介于0.04~13.20ngC ind.-1d-1,平均值为(2.91±5.22)ngCind.-1d-1。微型浮游动物群落对浮游植物群落碳摄食速率介于61.07~8632.85ngC L-1d-1,平均值为(2801.01±4198.46)ngC L-1d-1。分析比较中型浮游动物和微型浮游动物对浮游植物现存量摄食压力表明,海区中微型浮游动物的摄食压力要远高于中型浮游动物,介于95.59%~99.98%,平均值为97.88%±2.33%。调查海区中型浮游动物还通过对微型浮游动物的摄食影响浮游植物生长。     

夏季南黄海冷水团及其周边海域小型底栖动物类群组成与分布

对2011年6月南黄海冷水团及其周边海域23个站位的小型底栖动物类群组成、丰度、生物量和空间分布及其与环境因子的关系进行了研究。结果表明,调查海域共鉴定出小型底栖动物20个类群,平均丰度为(1194±873)个/10 cm~2,平均生物量为(881±669)μg干重/10 cm~2,其中自由生活海洋线虫是绝对优势类群,占小型底栖动物总丰度的89.7%,其次为底栖桡足类(5.5%)、甲壳类幼体(1.8%)、多毛类(1.2%);对生物量的贡献上依次为海洋线虫(49.0%)、多毛类(22.9%)、桡足类(13.9%)、介形类(7.8%)、涡虫(2.0%)。在垂直分布上,79.1%的小型底栖动物分布在沉积物0—2 cm的表层,16.4%分布在2—5 cm的次表层,4.5%的小型底栖动物分布在5—8 cm的下层。与环境因子的相关性分析表明,小型底栖动物的总丰度和总生物量与沉积物叶绿素a含量显著正相关;小型底栖动物的生物量和沉积物中部分重金属(Pb、Cu、Fe、Ni、Co)含量呈显著负相关,但与Cd含量呈极显著正相关。BIOENV分析结果表明,沉积物含水量、有机质含量和分选系数组合最能解释小型底栖动物类群组成分布差异。根据小型底栖动物的类群组成可将研究海域划分为3个区域,包括:冷水团中央区域,冷水团边缘区和近岸区,其中冷水团边缘区丰度和生物量最高,冷水团区域次之,近岸区最低;整个冷水团海域小型底栖动物丰度和生物量分别是非冷水团海域的2.3倍和2.1倍。     

Molecular analysis of green-tide-forming macroalgae in the Yellow Sea

In the summer of 2008, free-floating green algae bloomed in the Yellow Sea. Samples were collected in a wide area (119°32′-122°00′E, 32°25′-36°49′N). We calculated the sequence divergences of nuclear ITS, chloroplast rbcL, and psbA data of free-floating samples collected from the Yellow Sea and Ulvaceae from Europe and Japan. In the ITS sequence, 19 out of the 21 Yellow Sea samples of 2008 were identical to those of a sample taken at Qingdao in 2007. A low divergence (0.2%) was found in remaining two samples. Similar evidence was shown by pairwise distances of rbcL and psbA gene sequence data, implying the uniformity of the Yellow Sea blooms in 2007 and 2008. The ITS sequence of the Yellow Sea samples differed 8.1-10.8% from free-floating Enteromorpha or Ulva reported worldwide. ITS-based molecular phylogenetic results and rbcL sequence data grouped the free-floating alga in the Yellow Sea into one clade with Enteromorpha procera, Enteromorpha linza and Enteromorpha prolifera. Furthermore, both morphological characteristics and ribotype network of the ITS sequences imply that the blooming algae in 2007 and 2008 were E. prolifera. The haplotypes of the Yellow Sea free-floating E. prolifera are closely related to those from the Japanese coast but less to European and American algae.     

Anisakis pegreffii Larvae in Sea Eels (Astroconger myriaster) from the South Sea,Republic of Korea

Anisakis simplex sensu stricto (s.s.), Anisakis pegreffii, Anisakis berlandi (=A. simplex sp. C), and Anisakis typica are the 4 major species of Anisakis type I larvae. In the Republic of Korea (Korea), A. pegreffii, A. berlandi, and A. typica larvae in fish hosts has seldom been documented. In this study, molecular analysis was performed on Anisakis larvae from the sea eels (Astroconger myriaster), the major source of human anisakiasis in Korea, collected from Tongyeong City, a southern coastal area of Korea. All 20 sea eels examined were infected with Anisakis type I larvae (160 larvae; 8 per fish). Their species were analyzed using PCR-RFLP patterns and nucleotide sequences of internal transcribed spacers (ITS1, 5.8 subunit gene, and ITS2) and mitochondrial cytochrome c oxidase 2 (cox2). Most (86.8%; 112/129) of the Anisakis type I larvae were A. pegreffii, and 7.8% (10/129) were A. typica. The remaining 5.4% (7/129) was not identified. Thus, A. pegreffii is the major species of anisakid larvae in sea eels of the southern coast of Korea.     

Study on bioactivity of extracts from marine sponges in Chinese Sea

The bioactivity screening of fractions from two inter-tidal sponges collected from the north of China Yellow Sea and one sponge collected from the South Chinese Sea was reported in this study. In sponge Hymeniacidon perleve there were 9 fractions out of 15 from CHCl₃ extract with anti Staphylococcus aureus activity, 9 fractions out of 19 from BuOH extract with anti Escherichia coli activity, and three fractions from CHCl₃ extract which had moderate to strong activity in inhibiting Bacillus subtilis, Candida albicans, and Aspergilus niger. The fractions of Reniochalina sp. showed bioactivity against bacteria and fungi. The fractions of Acanthella acuta Schmidt showed bioactivity against S. aureus and fungi. One compound from H. perleve obtained by the bioactively directing isolation was tested for bioactivity against the human hepatoma cell line Qgy7701 (IC₅₀ 10.1 μg/ml), Burkitt's lymphoma cell line Raji (IC₅₀ 9.76 μg/ml) and chronic myelogenous leukemia K562 (IC₅₀ 1.90 μg/ml).     

Diketopiperazines from two strains of South China Sea sponge-associated microorganisms

The paper reports the isolation and structural elucidation of seven diketopiperazines from the title microorganisms. Although all isolates are known, three of which were isolated from the actinomycetes for the first time. And this is also the first report to isolate four DKPs from the D. avara-associated microorganism.     

Posidonia oceanica in the Marmara Sea

The seagrass Posidonia oceanica is a stenohaline species endemic to the Mediterranean Sea, where it normally lives at a salinity of between 36.5 and 39.5 ppt. Surveys carried out at the North-eastern distribution limits revealed large beds in the Dardanelles Strait and isolated beds in the Marmara Sea, where the salinity ranges between 21.5 and 28 ppt. Microsatellite analysis of these low-salinity tolerant P. oceanica beds, show different signs of genetic isolation: excess of heterozygosity and a presence of fixed alleles. These particularities are rarely found in the whole distributional range of the species. Moreover, all the populations considered in the analysis have a very low genetic diversity in comparison with most of the meadows sampled throughout the Mediterranean Sea. Taking into consideration the genetic data, rhizome expansion rate and the actual extent of the isolated beds in the Marmara Sea and knowing the reproductive rate and dissemination characteristics of P. oceanica, we hypothesize that the isolated population of the Marmara Sea has been established since the Middle Holocene, before the catastrophic intrusion of brackish water into the Marmara Sea and the strong and persistent flow coming from the Black Sea.     

Sea lice escape predation on their host

Parasites seldom have predators but often fall victim to those of their hosts. How parasites respond to host predation can have important consequences for both hosts and parasites, though empirical investigations are rare. The exposure of wild juvenile salmon to sea lice (Lepeophtheirus salmonis) from salmon farms allowed us to study a novel ecological interaction: the response of sea lice to predation on their juvenile pink and chum salmon hosts by two salmonid predators-coho smolts and cut-throat trout. In approximately 70% of trials in which a predator consumed a parasitized prey, lice escaped predation by swimming or moving directly onto the predator. This trophic transmission is strongly male biased, probably because behaviour and morphology constrain female movement and transmission. These findings highlight the potential for sea lice to be transmitted up marine food webs in areas of intensive salmon aquaculture, with implications for louse population dynamics and predatory salmonid health.     

Warm-water decapods and the trophic amplification of climate in the North Sea

A long-term time series of plankton and benthic records in the North Sea indicates an increase in decapods and a decline in their prey species that include bivalves and flatfish recruits. Here, we show that in the southern North Sea the proportion of decapods to bivalves doubled following a temperature-driven, abrupt ecosystem shift during the 1980s. Analysis of decapod larvae in the plankton reveals a greater presence and spatial extent of warm-water species where the increase in decapods is greatest. These changes paralleled the arrival of new species such as the warm-water swimming crab Polybius henslowii now found in the southern North Sea. We suggest that climate-induced changes among North Sea decapods have played an important role in the trophic amplification of a climate signal and in the development of the new North Sea dynamic regime.     

Merging ancient and modern DNA: extinct seabird taxon rediscovered in the North Tasman Sea

Ancient DNA has revolutionized the way in which evolutionary biologists research both extinct and extant taxa, from the inference of evolutionary history to the resolution of taxonomy. Here, we present, to our knowledge, the first study to report the rediscovery of an ‘extinct’ avian taxon, the Tasman booby (Sula tasmani), using classical palaeontological data combined with ancient and modern DNA data. Contrary to earlier work, we show an overlap in size between fossil and modern birds in the North Tasman Sea (classified currently as S. tasmani and Sula dactylatra fullagari, respectively). In addition, we show that Holocene fossil birds have mitochondrial control region sequences that are identical to those found in modern birds. These results indicate that the Tasman booby is not an extinct taxon: S. dactylatra fullagari O''Brien & Davies, 1990 is therefore a junior synonym of Sula tasmani van Tets, Meredith, Fullagar & Davidson, 1988 and all North Tasman Sea boobies should be known as S. d. tasmani. In addition to reporting the rediscovery of an extinct avian taxon, our study highlights the need for researchers to be cognizant of multidisciplinary approaches to understanding taxonomy and past biodiversity.     

A First Record of Obligate Halophilic Aspergilli from the Dead Sea

The isolation of obligate halophilic aspergilli from the Dead Sea and the range of salt tolerance of halophilic fungi isolated, are reported here for the first time. The mycobiota of the Dead Sea isolated in this study, was dominated by Aspergillus and Penicillium species; Cladosporium were found in lesser numbers. All three genera were obtained from the water sample; however, Aspergillus was the only genus obtained from the sediment. There was significant difference in growth of each isolate at different salt concentrations and intraspecies analysis revealed dissimilarity in response of strains to different salt concentrations in the growth medium The isolates were euryhaline, with halotolerance up to 20–25% solar salt, Aspergillus and Penicillium species showing a higher level of halotolerance, as compared to that of Cladosporium. Halophilic fungi were found in greater numbers in the sediment sample as compared to that in the water sample. Penicillium and Cladosporium species were exclusively facultative halophiles, while some species of Aspergillus were facultative halophiles. All the obligate halophiles isolated, belonged to the genus Aspergillus and were identified as A. penicillioides and A unguis, the latter being a first record of the species from the Dead Sea.     

Species- and site-specific bacterial communities associated with four encrusting bryozoans from the North Sea, Germany

Epi- and endozoic bacterial communities associated with four bryozoan species from the Jade (North Sea, Germany) were investigated by the combined application of molecular tools and electron microscopic visualisation of zooids. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments of associated bacteria displayed specific bacterial community profiles in the examined species Aspidelectra melolontha, Conopeum reticulum, Electra monostachys and Electra pilosa. Actual bacterial epibiosis was only observed on C. reticulum whilst the other bryozoans under investigation were largely free of microbial epibionts. These observations indicated that bryozoan-associated bacteria identified by molecular methods originated from internal cavities of bryozoan zooids. Cluster analysis of DGGE band patterns revealed species-specific bacterial communities in A. melolontha, E. monostachys and E. pilosa. Bacteria associated with C. reticulum were seemingly influenced by site-specific parameters. A comparison of bacterial community profiles between reference and invertebrate surfaces allowed for an interpretation of conspicuous group-specific differences. Operational taxonomic units (OTUs) obtained from a single set of bryozoan replicates that were absent on the inorganic reference samples (mussel shells) were hypothesized to be favourable endobionts. Contrary, OTUs present in the references but absent in bryozoan samples could be assumed to stem from bryozoan-specific defenses against ubiquitous bacterial colonizers. Although there was no experimental evidence for a mutual relationship between prokaryotes and their eukaryotic bryozoan hosts, this study demonstrated that in three out of four bryozoans under investigation associated bacterial communities were characteristically shaped by host attributes.