基于稳定同位素分析推定秋冬季南极半岛南极大磷虾营养变化

南极大磷虾（Euphausia superba）为南大洋生态系统中的关键种,也是南极生态系统食物网中的重要枢纽。该种秋冬季转换期的营养信息对于理解其知之甚少的越冬机制非常重要。但关于此方面的少数研究在时空变化上仍存在着差异。为此,我们调查了南极半岛秋季（4-5月）和冬季（6月）磷虾成体δ¹³C和δ¹⁵N值的个体、月份及区域性差异。我们的目标旨在检验该期间磷虾的营养变化以及磷虾与其在南极海洋生态系统中的摄食环境之间的关系。结果如下：（1）磷虾δ¹³C值与体长之间无显著关系,但δ¹⁵N值与体长之间则存在显著相关性;（2）秋季磷虾δ¹³C值呈现增长趋势,但冬初季节并无显著变化,此期间δ¹⁵N值无显著不同;（3）布兰斯菲尔德与南设得兰群岛之间的δ¹⁵N平均值显著不同。我们的数据表明南极半岛秋至初冬转换期间磷虾成体营养呈现个体、季节性及区域性变化。     

南极夏季南设德兰群岛东部海域南极大磷虾的摄食策略

Euphausia superba is a key species in the Southern Ocean that serves as a link between primary production and higher trophic levels. To investigate the feeding strategies of E. superba from the eastern South Shetland Islands,fatty acid biomarkers, stable isotope signatures, and an incubation experiment were conducted. The results of the incubation experiment proved that adult E. superba mainly fed on 2–20 μm particles, demonstrating the importance of nanoplankton in their diet. Moreover, significant positive relationships between δ15 N and body size demonstrated that size-related dietary shifts were present in E. superba. Evidence from principal component analysis and the C16:1ω7/C18:4ω3 ratio showed that juveniles preferentially fed on dinoflagellates and adults were more likely to feed on diatoms. Fatty acid profiles in adult E. superba roughly mirrored the different trophic conditions and feeding strategies between stations. Adult E. superba at Stas D2-07, D5-07, DA-01 and DA-02 exhibited elevated levels of C16:1ω7, C18:4ω3, C18:1ω9 and C18:1ω9/C18:1ω7, indicating higher levels of feeding on both phytoplankton and higher trophic diets. In contrast, adult E. superba at Stas D1-03 and D1-04 were characterized by high levels of polyunsaturated fatty acids/saturated fatty acids ratios and low levels of C16:1ω7,C18:1ω7, C18:4ω3, C18:1ω9 and total fatty acids. We inferred that adult krill at Stas D1-03 and D1-04 still suffered from difficult dietary conditions after overwintering. The different dietary conditions between stations suggest a highly plastic feeding strategy of E. superba in the eastern South Shetland Islands.     

Diet analysis of Antarctic krill Euphausia superba Dana

Sampling date and position are shown in Table 1.Complete E.superbasamples with fullstomach were usua1ly used.They were averagely 45 mm long and 1.5 g weight(wet).Beingconcentrated with filtered sea water,every food species from krill stomach was observed andidentified under an optical microscope,and their size was measured.     

南极大磷虾粉对点带石斑鱼幼鱼氟蓄积的影响

为研究南极大磷虾(Euphausia superba)粉对点带石斑鱼幼鱼氟蓄积和生长的影响,作者通过饲养点带石斑鱼(Epinephelus malabaricus)幼鱼(初始体质量为(3.50±0.30)g,体长(5.5±0.3)cm)100 d,在基础日粮中添加0%(对照组)、2%、4%和6%的南极大磷虾粉制成4组饲料,饲料中氟质量分数分别为145.81、202.71、257.53和317.60 mg/kg。结果显示:南极大磷虾粉中的氟在点带石斑鱼幼鱼组织中的分布程度,以脊椎骨和鳃中为最高,氟质量分数分别为(58.020~114.380)mg/kg和(46.029~123.874)mg/kg,其次是皮(含鳞片)((44.127~88.761)mg/kg),再次是肝((7.654~18.248)mg/kg),而肌肉中氟蓄积最低((3.352~3.999)mg/kg);脊椎骨、皮(含鳞片)和鳃中氟含量随饲养时间的延续而产生蓄积,且与饲料中南极大磷虾粉的水平呈正相关,肝中氟含量随饲养时间延续而产生蓄积,但与南极大磷虾粉的水平无相关性,肌肉中氟含量与饲养时间和南极大磷虾粉水平均无相关性;100 d时,4%组和6%组的特定生长率处于最高水平,且显著高于对照组(P0.05)。本研究表明在饲料中添加4%~6%南极大磷虾粉,对点带石斑鱼幼鱼生长具有明显的促进作用。     

太平洋牡蛎人工培育群体的繁殖习性初探

作者对太平洋牡蛎(Crassostrea gigas)人工培育群体的繁殖习性进行了初步探讨。经室内升温人工育苗培育的牡蛎性成熟年龄缩短,受精135d后性腺发育成熟;雌雄性比随着年龄而变化,4.5月龄的牡蛎群体中,雄性占优势(68.93%),雌雄性比为1∶2.73;1龄群体中,雌雄两性比例接近,性比为1∶1.07;2龄群体中雌性(63.69%)明显多于雄性,雌雄性比为1∶0.599。群体中存在雌雄同体现象,雌雄同体率随着年龄的增长而降低,4.5月龄的牡蛎群体中,雌雄同体高达1.94%,1龄群体中雌雄同体比例降低为0.35%,而2龄牡蛎群体中,雌雄同体率仅为0.12%;雌雄同体者能够自体受精。怀卵量随年龄的增长而增大,1龄牡蛎的平均怀卵量在800万粒～856.8万粒,而2龄牡蛎的平均怀卵量在2333.80万粒～2900万粒之间,明显多于1龄群体;怀卵量的多少也与亲贝的营养条件和性腺的发育程度有关。雌体的壳高、壳宽、体质量和软体部质量都明显大于雄体(P<0.05),但雌雄两性在壳长方面差异不显著。     

Predicting suitable habitat for the cold-water coral Lophelia pertusa (Scleractinia)

Ecological-niche factor analysis (ENFA) was applied to the reef framework-forming cold-water coral Lophelia pertusa. The environmental tolerances of this species were assessed using readily available oceanographic data, including physical, chemical, and biological variables. L. pertusa was found at mean depths of 468 and 480 m on the regional and global scales and occupied a niche that included higher than average current speed and productivity, supporting the theory that their limited food supply is locally enhanced by currents. Most records occurred in areas with a salinity of 35, mean temperatures of 6.2–6.7  °C and dissolved oxygen levels of 6.0–6.2 ml l⁻¹. The majority of records were found in areas that were saturated with aragonite but had low concentration of nutrients (silicate, phosphate, and nitrate). Suitable habitat for L. pertusa was predicted using ENFA on a global and a regional scale that incorporated the north-east Atlantic Ocean. Regional prediction was reliable due to numerous presence points throughout the area, whereas global prediction was less reliable due to the paucity of presence data outside of the north-east Atlantic. However, the species niche was supported at each spatial scale. Predicted maps at the global scale reinforced the general consensus that the North Atlantic Ocean is a key region in the worldwide distribution of L. pertusa. Predictive modelling is an approach that can be applied to cold-water coral species to locate areas of suitable habitat for further study. It may also prove a useful tool to assist spatial planning of offshore marine protected areas. However, issues with eco-geographical datasets, including their coarse resolution and limited geographical coverage, currently restrict the scope of this approach.     

The impact of intrapopulation variability in reproductive traits on population reproductive potential of Grand Bank American plaice (Hippoglossoides platessoides) and yellowtail flounder (Limanda ferruginea)

In geographically extensive fish populations the potential exists for reproductive traits to vary over the population’s range but, the impact that such intrapopulation variability has on overall population reproductive potential has not been formally assessed. Here intrapopulation spatial variability in size at maturity and fecundity are demonstrated for Grand Bank American plaice (Hippoglossoides platessoides) and yellowtail flounder (Limanda ferruginea). Recognition of intrapopulation variability in these reproductive traits coupled with spatial variability in abundance resulted in an increase in estimated population total egg production (TEP) by as much as 10¹⁴ eggs for American plaice and 10¹⁵ eggs for yellowtail flounder as compared to assessment of TEP for the population as a whole. Results highlight the need to explore variability in life history traits not only between but, also within populations and emphasizes the need for sufficient spatial coverage during sampling in order to assess the reproductive potential of fish populations.     

Influence of environmental data of different sources on marine species habitat modeling: A case study for Ommastrephes bartramii in the Northwest Pacific Ocean

The quality of environmental data and its possible impact on the marine species habitat modelling are often overlooked while the sources for these data are increasing. This study selected sea surface temperature(SST) from two commonly used sources, the NOAA Ocean Watch and IRI/LDEO Climate Data Library, and then constructed habitat suitability index model to evaluate the influences of SST from the two sources on the outcomes of Ommastrephes bartramii habitat models for the months of July–October...     

Interannual and geographical variability of the brood size of the euphausiids Euphausia pacifica and Thysanoessa spinifera along the Oregon coast (1999–2004)

Brood sizes of 1259 adult female Euphausia pacifica and Thysanoessa spinifera were measured during 48 h incubations (10 °C, ±0.5 °C) on 27 oceanographic cruises between July 1999 and September 2004. The data set includes measurements from several stations off Newport, Oregon (Newport Hydrographic line, 44°39′N) made over a 5-year period and measurements from 14 more extensive cruises at stations representative of continental shelf, slope, and oceanic waters off Oregon and California, USA. E. pacifica had similar brood sizes at inshore (<200 m) and offshore (>200 m) stations with an average of 151 and 139 eggs brood⁻¹ fem⁻¹, respectively. T. spinifera brood sizes were considerably higher at inshore stations—particularly at Heceta Bank (44°N) and south of Cape Blanco (42°50′N)—than at offshore stations, 155 and 107 eggs brood⁻¹ fem⁻¹, respectively. Average brood sizes of E. pacifica increased during the study period, from 125 (in 2000) to 171 eggs brood⁻¹ fem⁻¹ (in 2003). Average percentage of carbon weight invested in spawning (reproductive effort) was higher in E. pacifica (14%) than in T. spinifera (6%), because both species have similar brood size but T. spinifera females are larger than E. pacifica females and produce smaller eggs. Reproductive effort for both species was higher during summer 2002, probably associated with anomalous cool subarctic waters and high chl-a concentration observed during that summer. Brood sizes and chl-a values remained relatively high in 2003–2004 compared to the 1999–2001 period. Geographical and temporal variability in brood sizes for both species were significantly correlated with in situ measurements of chl-a concentration but not with sea surface temperature. No gravid females were collected during late autumn and winter cruises, thus the spawning season along the Oregon coast appears to extend from March through September for both species. However, T. spinifera usually starts reproductive activity earlier in the spring (March) than E. pacifica. Both species had their highest brood sizes in summer during the period of most intense upwelling, which is associated with an increase in regional phytoplankton standing stock.     

糖原含量与糖原磷酸化酶基因(GPH)和己糖激酶基因(HK)的表达在福建牡蛎生殖周期中的相关性分析

Glycogen, a polymer of glucose, is an important means of storing energy. It is degraded by glycogen phosphorylase (GPH) and hexokinase (HK), glycogen phosphorylase, and hexokinase cDNAs (Ca-GPH andCa-H...     

南极红藻Iridaea cordata和Curdiea racovitzae转录组分析及其极端光环境适应相关基因的挖掘

南极红藻具有重要的生态学功能和开发利用价值。南极极端环境赋予了其独特的生理耐受机制,也是发现新基因和代谢途径的理想材料。我们测序分析了南极产胶红藻Iridaea cordata (Turner) Bory和Curdiea racovitzae Hariot的转录组序列,并与其常温近缘种进行了比较,同时挖掘了其与光限制和强紫外线辐射等光环境适应相关的基因。I. cordata和C. racovitzae的转录组序列分别拼接成了14 055条和12 006条非冗余基因,平均长度分别为1 473 bp和1 448 bp。在I. cordata转录组中发现多条与绿藻基因同源的捕光复合物LHC基因Lhca2、Lhca6和Lhcb,并且在两种南极红藻中都各发现了1条编码结合岩藻黄质和Chl a/c蛋白的Lhcf基因,目前尚未在其他红藻中发现这类基因。光裂解酶修复紫外线诱导DNA损伤,在I. cordata的转录组序列中发现了6-4光裂解酶,光裂解酶CPD Ⅰ和CPD Ⅱ基因,而C. racovitzae转录组序列中仅找到了光裂解酶CPD Ⅱ基因。尽管南极红藻中这些特有基因的功能有待进一步的验证,但...     

Seasonal dynamics, environmental preferences and habitat selection of John Dory (Zeus faber)

Spatial distribution patterns of John Dory (Zeus faber, L.) were examined in relation to sea bottom temperature, bathymetry, locational covariates and season. Data were collected during a 2-year period (1996–1997) of seasonal sampling using demersal trawl surveys in the Aegean Sea (eastern Mediterranean). The ecological preferences of the species throughout four seasons were elucidated and the degree in which these environmental relationships might be modulated by the different hydrographic and topographic regime was also considered. Key determinants of the species' spatial aggregation in all four seasons were the water depth, the sea bottom temperature and the latitude. The sea bottom temperature had a significant effect on seasonal John Dory abundance both directly, as a main effect, and indirectly, through its interactive effect with the water depth. John Dory seasonal abundance was consistently greater in the shallower regions of the area having warmer bottom waters. Results indicated a distinct southward shift as progressing through the year, with peak abundances being observed in gradually lower latitudes of shallow areas as seasons evolved. John Dory appeared to avoid the deeper waters regardless of their bottom temperature and geographic position. The present results also suggested a seasonal pattern of habitat associations for specific locations characterised by weak hydrographic activity. John Dory preferences for certain water depth zones, sea bottom temperatures and substrate types are hypothesized to modulate the seasonal spatial aggregation of the species to preferred grounds.     

不同环境因子权重对东海鲐鱼栖息地模型的影响研究

鲐鱼（Scomber japonicus）是栖息在西太平洋沿岸的中上层鱼类,了解其栖息地分布及其与海洋环境因子的关系有助于合理开发和管理该资源。本文根据2003-2011年7-9月中国东海鲐鱼的生产数据,采用正态分布函数分别构建海表面温度（sea surface temperature,SST）、海表温梯度（gradient of sea surface temperature,GSST）和海表面高度（sea surface height,SSH）与作业次数的适应性指数（suitability index,SI）,基于不同权重的算术平均法（arithmetic weighted model,AWM）分别建立栖息地指数（habitat suitability index,HSI）模型,并用2012年7-9月生产数据进行验证。结果显示,7、8、9月各月最佳HSI模型的SST、STG和SSH的权重分别为0.5、0.25、0.25,0.8、0.1、0.1和0、1.0、0,利用2012年7-9月生产数据与环境数据对各月份最佳权重HSI模型进行验证,在HSI>0.6的海域,7、8、9月各月作业次数比重和产量比重分别为85.87%和92.55%,76.74%和86.69%,51.83%和56.11%。研究表明,不同月份的环境因子对鲐鱼渔场分布的影响程度不同,本研究为更好地预测鲐鱼栖息地奠定了基础。     

Development of habitat models for Nephtys species (Polychaeta: Nephtyidae) in the German Bight (North Sea)

The aim of the study was the development of habitat models for Nephtys species (Polychaeta: Nephtyidae). The investigation area was the German Bight, the southeastern part of the North Sea. Models were developed based on field data collected between 2000 and 2006. In addition, data on environmental variables were retrieved from long-term monitoring data sets and from the sediment map by Figge [Figge, K., 1981. Nordsee. Sedimentverteilung in der Deutschen Bucht. Map No. 2900. Publisher: Deutsches Hydrographisches Institut, Hamburg]. The statistical modelling technique used was multivariate adaptive regression splines (MARS). Models were fitted individually for each species. Evaluation of predictive discrimination and predictive accuracy of the developed models was by calculation of the area under the receiver operating curve (AUC) or sensitivity and specificity, respectively. Habitat models with best predictive fit were selected for the presentation of habitat suitability maps.Six Nepthys species were found: Nephtys assimilis, N. caeca, N. cirrosa, N. hombergii, N. incisa and N. longosetosa. N. hombergii was most common whereas N. incisa and N. longosetosa were rare. Habitat preferences varied considerably among the species. For all investigated Nephtys species except N. longosetosa a habitat model could be developed based on four predictor variables. The habitat models with best predictive fit were those for N. cirrosa and N. hombergii. The N. caeca habitat model was of limited predictive accuracy and only accept predictive discrimination. The number of predictors as well as the relative importance of the respective predictors in the model varied among the different species. Direct comparison of most suitable habitats for the different species based on modelling revealed that in the mostly sandy regions parallel to the German coast in water depths up to 20 m an overlap between N. caeca, N. hombergii and N. cirrosa exists. In the deeper central German Bight with mostly fine sands with increased mud contents N. hombergii, N. assimilis and, at least partially and rare in numbers, N. incisa co-occur. It can be concluded that important sediment characteristics like grain size median and mud content as well as water depth and mean salinity are useful parameters to describe the habitat requirements of most Nepthys species in the German Bight. However, additional variables need to be incorporated into such analyses.     

Transport of Antarctic krill (Euphausia superba) across the Scotia Sea. Part I: Circulation and particle tracking simulations

The Harvard Ocean Prediction System (HOPS) is configured to simulate the circulation of the Scotia Sea and environs. This is part of a study designed to test the hypothesis that Antarctic krill (Euphausia superba) populations at South Georgia in the eastern Scotia Sea are sustained by import of individuals from upstream regions, such as the western Antarctic Peninsula. Comparison of the simulated circulation fields obtained from HOPS with observations showed good agreement. The surface circulation, particularly through the Drake Passage and across the Scotia Sea, matches observations, with its northeastward flow characterized by three high-speed fronts. Also, the Weddell Sea and the Brazil Current, and their associated transports match observations. In addition, mesoscale variability, an important component of the flow in this region, is found in the simulated circulation and the model is overall well suited to model krill transport. Drifter simulations conducted with HOPS showed that krill spawned in areas coinciding with known krill spawning sites along the west Antarctic Peninsula continental shelf can be entrained into the Southern Antarctic Circumpolar Current Front (SACCF). They are transported across the Scotia Sea to South Georgia in 10 months or less. Drifters originating on the continental shelf of the Weddell Sea can reach South Georgia as well; however, transport from this region averages about 20 months. Additional simulations show that such transport is sensitive to changes in wind stress and the location of the SACCF. The results of this study show that krill populations along the Antarctic Peninsula and the Weddell Sea are possible source populations that can provide krill to the South Georgia population. However, successful transport of krill to South Georgia is shown to depend on a multitude of factors, such as the location of the spawning area and timing of spawning, and variations in the location of the SACCF. Therefore, this study provides insight into which environmental factors control the successful transport of krill across the Scotia Sea and with it a better understanding of krill distribution in the region.     

Circumpolar connections between Antarctic krill (Euphausia superba Dana) populations: Investigating the roles of ocean and sea ice transport

Antarctic krill, Euphausia superba Dana, has a heterogeneous circumpolar distribution in the Southern Ocean. Krill have a close association with sea ice which provides access to a critical food source and shelter, particularly in the early life stages. Advective modelling of transport pathways of krill have until now been on regional scales and have not taken explicit account of sea ice. Here we present Lagrangian modelling studies at the circumpolar scale that include interaction with sea ice. The advection scheme uses ocean velocity output from the Ocean Circulation and Climate Advanced Modelling (OCCAM) project model together with satellite-derived sea ice motion vectors to examine the potential roles of the ocean and sea ice in maintaining the observed circumpolar krill distribution. We show that the Antarctic Coastal Current is likely to be important in generating the large-scale distribution and that sea ice motion can substantially modify the ocean transport pathways, enhancing retention or dispersal depending upon location. Within the major krill region of the Scotia Sea, the effect of temporal variability in both the ocean and sea ice velocity fields is examined. Variability in sea ice motion increases variability of influx to South Georgia, at times concentrating the influx into pulses of arrival. This variability has implications for the ecosystem around the island. The inclusion of sea ice motion leads to the identification of source regions for the South Georgia krill populations additional to those identified when only ocean motion is considered. This study indicates that the circumpolar oceanic circulation and interaction with sea ice is important in determining the large-scale distribution of krill and its associated variability.     

孔鳐雄性生殖系统解剖学与组织学观察

本研究对成年雄性孔鳐(Okamejei kenojei)的生殖系统进行解剖学和组织学观察,结果表明,孔鳐的生殖系统主要由精巢、附睾、输精管、储精囊、间质腺、鳍脚腺和鳍脚组成。其中孔鳐的精巢中的精小囊,按照成熟度依次由中心向小叶外周辐射状排列,其精子发育成熟过程根据精巢支持细胞的位置、精小囊的大小和精小囊中的生精细胞所处的状态可划分为7个时期:精巢支持细胞未迁移期、精巢支持细胞迁移期、精巢支持细胞定植早期、精巢支持细胞定植晚期、精子变形期、精子迁移期、精子聚拢期。变态成熟的精子最终每59~64根精子组成精子束进入附睾。精子束在附睾中经历“游离-聚拢-游离”3个过程后,最终储存在储精囊中。鳍脚是孔鳐的外生殖器,主要有鳍扇、扇盾等结构组成,它与储精囊相连,是将精液输送至体外的器官。