东太平洋公海茎柔鱼饵料中鱼类和头足类组成初步分析

茎柔鱼(Dosidicus gigas)广泛分布于东太平洋海域,在海洋生态系统中扮演着重要角色。本研究根据2019年6—12月我国鱿钓生产船在东太平洋公海采集的62尾茎柔鱼样本,对其胃含物残留的4131个耳石和75个角质颚样本进行鉴定分析。结果表明: 茎柔鱼主要摄食鱼类10种、头足类4种。从摄食饵料的出现频率和数量百分比来看,主要摄食的鱼类饵料为荧串光鱼、朗明灯鱼和墨西哥尾灯鱼,荧串光鱼在不同胴长组的茎柔鱼胃内均有出现,是茎柔鱼最重要的饵料;摄食的头足类主要有茎柔鱼、鸢乌贼和爪乌贼。随着胴长的增大,茎柔鱼摄食的饵料种类不断增加,头足类和灯笼鱼饵料比例增加,且摄食的饵料尺寸增大,摄食营养结构发生改变,摄食营养水平随之提高。研究结果可为评估不同饵料生物在茎柔鱼食性转变过程中的食物贡献提供基础资料。     

秘鲁外海茎柔鱼摄食洄游的稳定同位素研究

茎柔鱼是具有高度洄游性的中上层头足类,是生态系统中的关键物种,也是我国远洋渔业重要捕捞对象之一.了解掌握茎柔鱼摄食及洄游信息有助于对其资源进行更合理利用.头足类内壳是一良好的信息载体,其生长发育具有不可逆性且生长贯穿整个生活史过程,包含了头足类生活史过程中的全部信息.本研究通过对秘鲁外海茎柔鱼耳石日龄进行鉴定,建立其内壳叶轴生长方程,根据该生长方程对内壳叶轴进行连续切割,测定其碳、氮稳定同位素比值,并初步分析了其在生长发育过程中的食性转换和洄游习性.结果表明: 茎柔鱼个体在出生180 d后开始洄游活动,且营养层次存在下降趋势.证明了内壳连续取样分析茎柔鱼个体摄食习性和栖息地变化的可行性.     

南海中西部海域鸢乌贼中型群和微型群的营养生态位

为了深入了解南海鸢乌贼不同种群的碳氮稳定同位素特征及营养生态位之间的关系,于2017年8月在南海中西部海域采集其中型群和微型群样品,分析不同胴长组的碳氮稳定同位素值和营养级变化,并比较其营养生态位差异.结果表明:中型群鸢乌贼的δ^13C范围在-19.54‰^-18.10‰,δ^15N范围在7.79‰~9.45‰,营养级范围在2.72~3.21,平均营养级为2.90;微型群鸢乌贼的δ^13C范围为-19.69‰^-18.43‰,δ^15N范围为8.02‰~8.99‰,营养级范围为2.79~3.08,平均营养级为2.91.两个鸢乌贼种群间δ^13C差异不显著,δ^15N差异显著.胴长显著影响了鸢乌贼的δ^13C和δ^15N值,且随着胴长的增大,δ^15N值有增大的趋势.中型群鸢乌贼的营养生态位宽幅和营养级的多样性程度都大于微型群.     

脂类抽提对北太平洋柔鱼肌肉碳、氮稳定同位素测定结果的影响

稳定同位素技术可深层次地分析头足类的摄食习性和栖息地等方面的重要信息.稳定同位素分析多选取动物肌肉为研究组织,然而,肌肉中的脂类含量会影响对其稳定同位素信息的准确解析.北太平洋柔鱼是重要的大洋经济性头足类,在海洋生态系统中具有重要的生态地位.本研究选取了53尾北太平洋柔鱼,通过分析脂类抽提对胴体肌肉稳定同位素比值的影响,探讨脂类物质对稳定同位素比值的干扰机制,对比不同碳稳定同位素比值校正模型的适用性,并提出适用于北太平洋柔鱼胴体肌肉δ¹³-C校正模型.结果表明： 北太平洋柔鱼肌肉的脂类抽提会引起稳定同位素测定结果的显著变化,δ¹³-C和δ¹⁵-N分别平均升高0.71‰和0.47‰,在分析组织碳稳定同位素比值时,脂类抽提在样品预处理过程中十分必要,其能消除脂类对样品稳定同位素分析的干扰,从而更加准确地分析研究对象食性与栖息地的变化.在单独进行氮稳定同位素比值分析时,则不需要进行脂类抽提.     

基于稳定同位素技术的北太平洋柔鱼角质颚信息

根据2012年7—10月中国鱿钓船在42°N—45°N、153°E—157°E海域采集的柔鱼样本,测定20对北太平洋柔鱼上、下角质颚的碳、氮稳定同位素比值,分析其碳、氮稳定同位素比值与柔鱼性别、个体大小和色素沉着等级之间的关系。结果表明:角质颚的碳、氮稳定同位素值在雌雄个体间均未发现显著差异;角质颚的碳稳定同位素值与个体大小呈显著负相关,而氮稳定同位素值与其呈显著正相关;随着柔鱼个体的生长,其角质颚的色素沉着等级逐渐增大,角质颚的氮稳定同位素比值也随之升高,而色素沉着等级与儿茶酚类物质的含量有关,儿茶酚类物质含量的增大使柔鱼角质颚强度增大,从而更有利于柔鱼摄食高营养级生物。     

东太平洋赤道海域茎柔鱼的营养生态位和肠道微生物组成

掌握海洋生物的营养生态位特征及其应对环境变化的响应机制,对于评估渔业和气候变化对海洋生态系统功能的影响至关重要。茎柔鱼(Dosidicus gigas)是东太平洋重要的渔业经济物种,在生态系统中具有承上启下的重要生态作用。在气候变化的大背景下,掌握茎柔鱼应对气候变化的响应过程将有利于合理把控其资源状况。本研究采用稳定同位素和高通量技术手段,分别从宏观和微观角度量化比较分析了正常时期和厄尔尼诺时期赤道海域的茎柔鱼营养生态位、肠道长度及肠道微生物组成。结果表明: 不同气候时期茎柔鱼的δ¹³C值存在显著差异,说明食物来源具有差异性;其肠道微生物主要由放线菌门、拟杆菌门、蓝细菌门、厚壁菌门、变形菌门和软壁菌门组成,不同时期微生物群落组成无显著差异,但多样性和相对丰度差异显著。在厄尔尼诺时期,茎柔鱼个体具有较小的营养生态位、较长的肠道、更高的肠道微生物群落多样性及丰富度;肠道微生物的差异主要体现在厚壁菌门、拟杆菌门、螺旋体门、WPS-2和Kiritimatiellaeota,样本距离更为集中。这表明由厄尔尼诺事件导致的栖息地环境及食物变化可能限制茎柔鱼的活动,改变其肠道微生物的结构和功能,有利于其适应环境及食性的变化。     

大洋性头足类胃和肠道中的微塑料——以秘鲁外海茎柔鱼为例

海洋动物摄入微塑料已得到广泛证实,但对于大洋性头足类动物仍存在较大空白.茎柔鱼是头足类商业捕捞中产量最高的物种,在东太平洋生态系统占主导地位.本研究以秘鲁外海茎柔鱼成体为对象,定量分析胃和肠道内微塑料的丰度与组成,并探究微塑料在组织和性别间的潜在差异.结果 表明:茎柔鱼雌、雄个体相同组织内存在相似的微塑料丰度与组成.组...     

稳定同位素技术在头足类摄食生态学研究中的应用

头足类在海洋食物网营养关系中占有重要地位,然而对其复杂的生活史过程,尤其是摄食生态学信息仍知之甚少.稳定同位素技术作为传统食物网科学研究方法的有力补充,可更深层次地分析头足类的摄食习性和栖息地等方面的重要信息.本文在比较分析国内外头足类摄食生态学研究方法的基础上,系统归纳总结了稳定同位素技术在头足类摄食生态学研究中的发展现状并介绍最新进展情况,着重分析稳定同位素技术在头足类生活史信息,尤其是在摄食生态学研究中的应用现状及发展前景,包括测定样品标准化、头足类生长发育过程中的食性转换和洄游分布等核心问题,以促进其在头足类生物学研究中的应用.     

西北太平洋柔鱼耳石微量元素

耳石是头足类重要的硬组织之一,其微化学被用于头足类生活史的重建、群体划分等渔业生态学领域.本文根据我国鱿钓船2007年在西北太平洋海域生产期间采集的柔鱼样本,利用激光剥蚀电感等离子质谱法(laser ablation inductively coupled plasma mass spectrometry, LA-ICP-MS)分析了18枚柔鱼耳石的微量元素组成及其分布特性.结果表明： 柔鱼耳石主要由55种元素组成,含量最多的前10位元素分别为钙(Ca)、锶(Sr)、钠(Na)、磷(P)、钾(K)、硅(Si)、镁(Mg)、硼(B)、铁(Fe)和钡(Ba).方差分析表明,不同性别间柔鱼的Ca、Sr、Na、K、Mg、Fe、Ba的含量不存在显著性差异,但P、Si和B含量差异性明显;不同孵化期的群体间Sr和Na含量存在显著性差异,Ca、P、K、Si、Mg、B、Fe和Ba不存在显著性差异;不同耳石部位的Ca、Sr、Na、P、Mg和Ba含量存在显著性差异,而K、Fe、B和Si则不存在显著性差异.研究表明微量元素Sr和Na比较适合用于研究柔鱼的群体划分、洄游史推测等渔业生态学.
     

东太平洋中部中上层鲨鱼群落营养生态位分化

鲨鱼在大洋生态系统中占据着重要的生态地位,其作为顶级捕食者,通过下行效应直接影响生态系统的稳定.稳定同位素技术是目前研究摄食生态学强有力的手段之一,可利用碳氮稳定同位素在食物网中的特性分别指示鲨鱼的食物来源和营养级.本研究选取8种130尾采集自东太平洋中部的中上层鲨鱼,应用稳定同位素绘制其种群生态位图谱,比较不同种群间的生态地位及资源分配方式上的差异.结果表明:不同鲨鱼种群碳、氮稳定同位素比值存在显著差异;8种鲨鱼在东太平洋生态系统中的营养级为4.3~5.4,大青鲨、尖吻鲭鲨与其他6种鲨鱼存在摄食隔离,表现出独特的营养生态地位.这些结果充分证明大洋性中上层鲨鱼并非生态系统的冗余种,其营养生态位的独特性不会被其他捕食者简单地替代和弥补.     

Trophic interactions between two introduced suspension-feeders, Crepidula fornicata and Crassostrea gigas, are influenced by seasonal effects and qualitative selection capacity

The effects of season and qualitative selection capacity on trophic relationships between two sympatric invasive suspension-feeders, Crepidula fornicata and Crassostrea gigas, were investigated in Bourgneuf Bay (France) from January 2003 to June 2004. Carbon and nitrogen stable isotopic deviations, δ¹³C and δ¹⁵N, of common Atlantic slippersnails and Pacific oysters were analysed relative to isotopic composition and availability of end-members.Slippersnail deviations were less variable over the sampling period compared with those of oysters. Significant differences between δ¹³C and δ¹⁵N of C. fornicata and C. gigas were found from winter to early summer, and linked to major isotopic changes in oysters. We identified three distinct seasonal periods: January to March when oysters were ¹⁵N-enriched compared to slippersnails and to themselves at other times of the year, April to June-July when oysters showed a ¹⁵N-depletion and a more marked ¹³C-depletion compared to slippersnails and to themselves at other times of the year, and July-August to December when both species presented similar carbon and nitrogen deviations. Species-specific differences in qualitative selection capability may explain these seasonal differences in isotopic deviations. Whereas the isotopic composition of the indiscriminate suspension-feeding slippersnails reflects the composition of the seston throughout the year, the oyster is capable of qualitative selection. The oyster isotopic compositions are consistent with a facultative activation of selection mechanisms under conditions of qualitative and quantitative food limitation, notably the preferential ingestion and assimilation of the dominant organic source in the suspended pool.We conclude that C. fornicata and C. gigas are trophic competitors only in winter and spring at this site, where detrital end-members are major POM components. These results underscore (1) the importance of long-term (annual) studies in the evaluation of potential trophic competition, and (2) the necessity to include the qualitative selection capacities of suspension-feeders in future interpretations of trophic relationships in marine coastal ecosystems.     

Note on the occurrence of Pseudo-nitzschia australis and domoic acid in squid from Monterey Bay, CA (USA)

Over the past decade diatom blooms of domoic acid (DA)-producing Pseudo-nitzschia spp. have been responsible for numerous marine mammal and bird mortalities in Monterey Bay, CA. One possible toxin vector is the market squid, Loligo opalescens, a small pelagic mollusk that plays an important role in the near-shore food web of the California Current ecosystem as a favored vertebrate prey species. This study examined the trophic link between toxic Pseudo-nitzschia and L. opalescens using toxin and stomach content analyses of animals collected from Monterey Bay, CA in 2000. Receptor binding assay data (confirmed by tandem mass spectrometry), demonstrated the presence of DA in squid during a toxic Pseudo-nitzschia event, with P. australis frustules observed in stomach samples. Though DA levels were low (<0.5 μg DA g⁻¹ tissue) in L. opalescens during the study period, it is now clear that this potent neurotoxin can occur in squid and is likely delivered through its krill prey species, which are known to retain DA after feeding on toxic Pseudo-nitzschia. Our findings suggest that further study of the relationship between Pseudo-nitzschia blooms and DA contamination of squid is warranted to better evaluate the potential health risk to humans and wildlife associated with this major commercial seafood species and important prey item.     

盐度对长牡蛎和近江牡蛎及其杂交稚贝生长和存活的影响

2011年8月以长牡蛎自繁组GG(Crassostrea gigas♀×C.gigas♂),近江牡蛎自繁组AA(C.ariakensis♀×C.ariakensis♂)、正交组GA(Crassostrea gigas♀×C.ariakensis♂)、反交组AG(C.ariakensis♀×C.gigas♂)为实验材料,开展了稚贝对盐度的适应性研究。结果发现长牡蛎的最适生存盐度为15—35,最适生长盐度为25—35;近江牡蛎的最适生存盐度为10—25,最适生长盐度为20—25;GA的最适生存盐度为15—30,最适生长盐度为15—30,AG的最适生存盐度为20—30,最适生长盐度为20—25。GG对低盐度敏感,AA对高盐度敏感,AG具有高盐度存活的杂种优势,在盐度30时,中亲杂种优势HG×A为13.32,单亲杂种优势HGA和HAG分别为1.89和27.88,在盐度40时,HAG上升到400,GA和AG都不具有生长优势。杂种稚贝对盐度适应介于双亲之间,且表现出一定程度的父系遗传特点。     

Niche partitioning in orbweaving spiders Meta menardi and Metellina merianae (Tetragnathidae)

Hypogean habitats are relatively simple exhibiting low diversity, low production and relative constancy of environmental factors, and are therefore appropriate for studying species coexistence in situ. We investigated the coexistence of two closely related, similarly sized orb-weaving spider species, Meta menardi and Metellina merianae, living syntopically in a Slovenian cave. We studied the annual dynamics of both species within a mixed population, and the impact of the ambient temperature, relative humidity, airflow and illumination, and compared their trophic niches to legacy data on prey of both species from 55 caves in Slovenia. We predicted a large overlap in their spatial niches and substantial differences in their temporal and trophic niches. We found that their spatial niches overlap greatly with few exceptions, mostly on the dates of notable meteorological changes in the cave but that their temporal niches differ significantly with r-strategy resembling epigean annual dynamic in M. merianae and a steady low abundance course in M. menardi within the cave. We also found that different predatory strategies significantly segregate their trophic niches: M. merianae uses a typical orb-weaving hunting strategy, while M. menardi combines web hunting with off-web hunting. Our findings suggest that both the diverse dynamics and trophic niches enable the coexistence of M. menardi and M. merianae despite their similar spatial niches, and that M. menardi, in particular, is optimally adapted to the epigean/hypogean ecotone.     

Paralarvae of the jumbo squid,Dosidicus gigas

Abstract. The rhynchoteuthion stage of the jumbo squid, Dosidicus gigas, has morphological characteristics similar to the paralarvae of the purpleback squid, Sthenoteuthis oualaniensis, making it difficult to determine the locations, seasons, and conditions where spawning of jumbo squid occurs. In this study, 180 paralarvae of D. gigas were collected off the west coast of the Baja California peninsula and identified by sequencing a 369-bp fragment of the cytochrome oxidase I gene. Of these, 77 specimens, 0.8–6.0 mm in mantle length, were described. Indices based on morphometric ratios were used to determine whether the shapes of different body structures were reliable for identifying the paralarvae. For two ratios, the results appear to discriminate members of D. gigas from those of S. oualaniensis. Additionally, eye or intestinal photophores were not observed in any paralarvae of D. gigas. Morphological and morphometric information provided a valuable basis for the discrimination and identification of these two species.     

The sibling species Drosophila melanogaster and Drosophila simulans differ in the expression profile of glutathione S-transferases

Two major forms of glutathione S-transferase are known in Drosophila melanogaster: GST D and GST 2. In the present paper we report the existence of a third major form of glutathione S-transferase in Drosophila simulans. Induction with phenobarbital revealed a different regulation of GST between these species. Despite the fact that these two species are closely related, there was a difference in the expression profile of the enzyme implicated in the detoxification system, suggesting variations in capacity to suit their environment.     

Evolution and phylogenetic relationships within Porinaceae (Ostropomycetidae), focusing on foliicolous species

A phylogeny of the lichen family Porinaceae using mitochondrial SSU rDNA sequences is presented, with special focus on foliicolous taxa. Fifty specimens of 28 mostly tropical species, representing eight species groups of Porina as well as the genus Trichothelium, were analysed together with species of other members of Ostropomycetidae, and using Agyriaceae as outgroup. We performed the phylogenetic analyses with a Bayesian approach and under the criterion of maximum parsimony. Four main clades can be distinguished: the P. nitidula-group s. lat. (including Trichothelium, P. papillifera and P. rubescens), the Porina epiphylla-group s. lat. (including the P. radiata-, the P. nucula-, the P. imitatrix- and the P. epiphylla-group s. str.) and two clades of the P. rufula-group. The genus Porina as understood by all recent concepts is paraphyletic, and Trichothelium is nested within the Porina nitidula-group. The non-setose P. repanda forms a monophyletic clade with Trichothelium. The tree does not support a monophyletic origin of substrate preferences or photobiont selection. Species-specific associations with morphologically different trentepohlioid photobionts mapped on the tree suggest that closely related mycobiont species switch between different types of algae.     

中国石蕊科地衣研究之五中国石蕊属地衣一新种

本文报道了产于中国西南地区的石蕊属地衣一新种:亚厚叶石蕊(Cladoniasubincrassata S.Y.Guo),其主要的次生代谢产物为松萝酸和泽屋菇.文中还从形态、化学和地理分布方面将新种和邻近种厚叶石蕊(Cladonia incrassata)进行了比较.     

Prosthecium species with Stegonsporium anamorphs on Acer

Data from microscopic morphology, single-spore cultures, and DNA analyses of teleomorphs and anamorphs support the recognition of five species of Prosthecium with Stegonsporium anamorphs on Acer: P. acerinum sp. nov., the teleomorph of S. acerinum; P. acerophilum comb. nov., formerly known as Dictyoporthe acerophila; P. galeatum comb. nov., originally described as Massaria galeata; P. opalus sp. nov.; and P. pyriforme sp. nov., the teleomorph of S. pyriforme s. str. The morphology of both type specimens and freshly collected material was investigated. The teleomorphs have brown ellipsoidal ascospores with five distosepta and often a longitudinal distoseptum. The anamorphs of all species described here belong to Stegonsporium; their connection to the Prosthecium teleomorphs was demonstrated by morphology and DNA sequences of single spore cultures derived from both ascospores and conidia. The anamorphs and teleomorphs of all five Prosthecium species are described and illustrated by LM images, and a key to these species is provided. As perceived from this work, S. pyriforme is restricted to Europe and does not occur in North America, whereas S. acerinum is restricted to North America, not found in Europe. The host associations given in the literature are revised and evidence is provided that only A. opalus, A. pseudoplatanus, and A. saccharum are confirmed hosts of Prosthecium with Stegonsporium anamorphs. Molecular phylogenetic analyses of tef1, ITS rDNA, and partial nuLSU rDNA sequences confirm that the species with Stegonsporium anamorphs are closely related to P. ellipsosporum, the generic type species. Stilbospora macrosperma is confirmed as the anamorph of P. ellipsosporum by DNA data of single spore isolates obtained from both ascospores and conidia.