东太平洋多金属结核区两个站位深海沉积物细菌多样性北大核心CSCD

【目的】为了解东太平洋中国多金属结核勘探合同区西区2个站位(WBC1305和WBC1316A)深海沉积物细菌群多样性。【方法】直接提取环境样品总基因组,通过PCR和TA克隆策略构建了2个站位6个层次16S r RNA基因文库,对2个站位沉积物表层泥样中细菌多样性和群落结构特征进行分析,并通过构建系统发育树,进行系统发育学分析。【结果】2个站位6个文库共获得有效克隆533个,其中472个克隆包括α-变形菌纲、β-变形菌纲、γ-变形菌纲、δ-变形菌纲、浮霉菌门、酸杆菌门、硝化螺旋菌门、放线菌门、绿弯菌门、厚壁菌门、拟杆菌门、迷踪菌门、芽单胞菌门、Hydrogenedentes、Chlorobi和Nitrospinae16个细菌类群,而另外61个克隆为不可分类细菌类群。【结论】结果表明γ-变形菌纲和厚壁菌门分别是WBC1305和WBC1316A站位的优势种群;WBC1316A站位细菌群落结构更加丰富和复杂。     

2005年夏季东太平洋中国多金属结核区小型底栖生物研究

“大洋一号”调查船于2005年7月在太平洋结核区中国合同区东、西小区调查中共进行了12个站位的小型底栖生物的取样.研究表明:调查区域小型底栖生物共有13个类群.东、西两小区小型底栖生物平均密度分别为(104.4±20.48)个/10 cm2,(40.26±25.84)个/10 cm2,线虫平均生物量分别为(5.25±0.99)(μg·干重)/10 cm2,(1.68±0.77)(μg·干重)/10 cm2,东小区小型底栖生物平均密度、线虫生物量明显高于西小区.线虫是绝对优势类群,分别占东、西小区小型底栖生物总密度的93.13％和91.36％,其它优势类群有桡足类,多毛类,介形类等.小型底栖生物密度随着沉积物深度的增加而减少,其数量的75％以上分布在0-2 cm层,东小区深层的小型底栖生物所占比例比西小区要大.与环境因子相关分析表明:调查区域的小型底栖生物密度,线虫密度,线虫生物量,桡足类密度,多毛类密度与经、纬度呈显著负相关,与脱镁叶绿素呈显著正相关,与沉积物微型生物生物量相关性不显著.小型底栖生物密度,线虫密度,线虫生物量,多毛类密度与叶绿素a呈显著正相关,桡足类与叶绿素a相关性不显著.脱镁叶绿素与沉积物微型生物生物量呈显著正相关.     

OBSERVATIONS OF AN UNIDENTIFIED BEAKED WHALE (MESOPLODON SP.) IN THE EASTERN TROPICAL PACIFIC

Multiple sightings of a distinctive but unidentified species of beaked whale have been made in the eastern tropical Pacific. The unidentified whale has two color morphs: a conspicuously marked black and white form (judged to be larger), and a uniformly gray-brown form. Maximum length estimates have been 5–5.5 m. Other features include a relatively flat head, with a small, distinct melon; a moderately long beak; and a low, wide-based, triangular dorsal fin. On most animals the trailing edge of the dorsal fin is only slightly falcate and often appears straight. On the black and white morph, a broad white or cream-colored swathe originates immediately posterior to the dorsal surface of the head and runs posterio-ventrally on either side of the animal. The prevalence of scarring on the black and white animals suggests sexual dimorphism and that these larger, more conspicuously marked animals are adult males, while the smaller, browner, unscarred animals are females and young. Possibilities for identification include: 1) a well-marked race of a known Mesoplodon sp., 2) Mesoplodon (Indopacetus) pacificus or 3) an undescribed species.     

BLUE WHALE (BALAENOPTERA MUSCULUS)DISTRIBUTION IN THE EASTERN TROPICAL PACIFIC

The distribution of blue whales, Balaenoptera musculus , in the eastern tropical Pacific (ETP) was analyzed from 211 sightings of 355 whales recorded during research vessel sighting surveys or by biologists aboard fishing vessels. Over 90% of the sightings were made in just two areas: along Baja California, and in the vicinity of the Costa Rica Dome (a large, stationary eddy centered near 9°N, 89°W), with the rest made along the equator near the Galapagos islands, the coasts of Ecuador and northern Peru. All sightings occurred in relatively cool, upwelling-modified waters. Because these areas are the most productive parts of the ETP, and have relatively large standing stocks of euphausiids, it seems possible that blue whales select low latitude habitats which permit foraging. The waters off western Baja California were occupied seasonally, with a peak in sightings coinciding with the spring peak in upwelling and biological production. The Costa Rica Dome area was occupied year round, suggesting either a resident population, or that both northern and southern hemisphere whales visit, with temporal overlap. The modal group size was one for all areas and seasons, but the frequency of groups with two or more whales was significantly higher in sightings made near the Galapagos Islands and the coast of Ecuador and northern Peru.     

MOLECULAR CHARACTERIZATION OF THE DIVERSITY AND POTENTIAL TOXICITY OF CYANOBACTERIAL MATS IN TWO TROPICAL LAGOONS IN THE SOUTH PACIFIC OCEAN1

Marine benthic cyanobacteria in tropical areas have recently been associated with several human poisoning events. To enhance the characterization of these microorganisms and their potential toxicity, benthic cyanobacterial communities were sampled in the lagoons of two islands (Raivavae and Rurutu) located in French Polynesia where human poisoning events by seafood had been reported. The morphological appearance of the mats was used to identify four types of cyanobacterial mat. By a 16S rRNA sequencing approach, it appeared that these mats were usually dominated by a restricted number of operational taxonomic units (OTUs), which were closely related to Leptolyngbya, Oscillatoria, Hydrocoleum, and Anabaena sequences, as previously reported in other tropical lagoons. Interestingly, we determined that these dominant filamentous OTUs were associated in the mats with other cyanobacteria, including unicellular species. By using a population genetic approach based on the sequencing of the internally transcribed spacer (ITS) of the rRNA operon, we found a very restricted genetic diversity in the most common OTU, which displayed a high sequence similarity with Leptolyngbya sp. In addition, there was no geographic differentiation at various spatial scales in the distribution of the different genotypes, suggesting that this species is able to spread over large distances. Finally, PCR screening of genes involved in the biosynthesis of known cyanotoxins revealed the presence of the saxitoxin gene (stxG) in two mats containing a mix of filamentous and unicellular cyanobacterial species.     

GEOGRAPHIC PATTERNS OF VARIATION IN OFFSHORE SPOTTED DOLPHINS (STENELLA ATTENUATA) OF THE EASTERN TROPICAL PACIFIC OCEAN

The spotted dolphin (Stenella attenuata), a species commonly associated with the tuna fishery, is widely distributed in the eastern tropical Pacific Ocean (ETP). Geographic patterns in morphological characteristics of this dolphin were evaluated for 36 skull measurements of 574 museum specimens allocated to 5° latitude-longitude blocks. A strong subdivision between northern and southern offshore populations was demonstrated using principal components, canonical variates and cluster (UPGMA and function-point) analyses of block means derived from standardized, sex-adjusted measurements. Classification functions derived from a stepwise multiple discriminant analysis correctly identified more than 87 percent of the specimens as being from either a northern or southern locality. These results support recognition of southern spotted dolphins as a separate management stock. Dolphins from a sample representing a far-western locality show similarities with those from the south. Patterns of geographic variation in morphology were evaluated using Mantel tests and matrix correlations; 17 of the 36 characters showed regional patterning and 18 exhibited local patterning. Morphological trends were also assessed with respect to 14 oceanographic measures that characterize environmental variability in the ETP. In general, clinal variation in morphology mirrors a north-south trend found in several environmental variables. Overall, the most striking associations between morphological and environmental variables involved Solar Insolation (Jan.). Sea surface temperatures also exhibited a strong association with morphological variables; the highest correspondence was found between width of the temporal fossa and sea surface temperature in July. In addition, the thickness of the oxygen minimum layer exhibited a pattern of variation that was statistically associated with 58 percent of the skull characters. The geographic patterns found for cranial morphology and environmental measures are strongly clinal and in general congruent, suggesting that oceanographic conditions in part determine trends in morphological characteristics of spotted dolphins.     

ACOUSTIC IDENTIFICATION OF NINE DELPHINID SPECIES IN THE EASTERN TROPICAL PACIFIC OCEAN

Acoustic methods may improve the ability to identify cetacean species during shipboard surveys. Whistles were recorded from nine odontocete species in the eastern tropical Pacific to determine how reliably these vocalizations can be classified to species based on simple spectrographic measurements. Twelve variables were measured from each whistle ( n = 908). Parametric multivariate discriminant function analysis (DFA) correctly classified 41.1% of whistles to species. Non-parametric classification and regression tree (CART) analysis resulted in 51.4% correct classification. Striped dolphin whistles were most difficult to classify. Whistles of bottlenose dolphins, false killer whales, and pilot whales were most distinctive. Correct classification scores may be improved by adding prior probabilities that reflect species distribution to classification models, by measuring alternative whistle variables, using alternative classification techniques, and by localizing vocalizing dolphins when collecting data for classification models.     

CETACEANS OF THE WESTERN TROPICAL INDIAN OCEAN: DISTRIBUTION, RELATIVE ABUNDANCE, AND COMPARISONS WITH CETACEAN COMMUNITIES OF TWO OTHER TROPICAL ECOSYSTEMS

We conducted a cetacean survey in the pelagic western tropical Indian Ocean (WTIO) aboard an 85-m research vessel from March to July 1995, covering 9,784 linear km. Using 25 × binoculars and line-transect methods, we recorded 589 sightings of 21 species. Stenella longirostris was the most abundant cetacean, in terms of number of individuals sighted, by an order of magnitude above any other species, while Physeter macrocephalus was the most frequently sighted, in terms of number of schools. Twelve species were widespread, seven were rare, and two were localized; our sightings include new distributional records for 12 species. Significant observations included the following: (1) Delphinus cf. tropicalis was abundant off the coast of Oman (16 sightings) and readily distinguishable in the field from D. delphis and D. capensis, (2) Balaenoptera musculus was fairly common and localized in the area of the Maldives (17 sightings), and (3) three sightings were made of an unidentified bottlenose whale tentatively referred to as Indopacetus (i. e., Mesoplodon) pacificus. We recorded 26 mixed-species cetacean schools, 43 schools with which seabirds associated, and 17 schools associated with tuna. Notable among these were mixed aggregations of Stenella attenuata, S. longirostris, yellowfin tuna, and seabirds. The cetacean community of the WTIO was similar to that of the eastern tropical Pacific (ETP) and the Gulf of Mexico (GM) in several respects. First, differences in abundance rank of individual species were small, with the result that common species were common and rare species were rare, regardless of ocean. Second, these differences in abundance were due primarily to differences in encounter rate, which varied with ocean by as much as 3,000%, and less so to school size, which generally varied less than 100%. Third, regardless of ocean, three species comprised the majority of cetaceans in the community, Stenella attenuata, S. longirostris, and S. coeruleoalba, representing 62%-82% of all individuals for all species. However, the rank order of abundance for these three species differed with ocean. Most notably, S. attenuata was abundant in the ETP and GM (abundance rank = 2 and 1, respectively) but much less common in the WTIO (abundance rank = 6). Although habitat preferences for S. attenuata appear to overlap considerably with those of S. longirostris in the ETP, our results suggest there may actually be significant differences between these two species. Detailed analysis of oceanographic correlates of distribution will be necessary in order to understand fully the habitat requirements of these pelagic dolphins, often the most conspicuous elements of tropical cetacean communities around the world.     

热带西太平洋浮游有孔虫Globigerinoides ruber(白色)的基因型研究及其古海洋学意义

Globigerinoides ruber是最常见的热带-亚热带浮游有孔虫种类,被广泛地应用于古环境重建。本实验通过浮游生物垂直拖网采集热带西太平洋海区目标站位表层200 m以浅水体中的浮游有孔虫,在体视显微镜下挑选出单个活体G.ruber(白色)个体,采用DOC法提取虫体的总DNA,利用有孔虫特异性引物扩增SSU rDNA目的片段。我们通过构建系统发育树研究了G.ruber(白色)基因型多样性,并比较了不同基因型G.ruber(白色)的形态差异和分布特点。ML/BI树显示:在热带西太平洋海区获得的G.ruber(白色)样本中,有两大基因型Type I和Type II,Type I又包括Type Ia、Type Ib2两种类型。Type I和Type II个体的形态特征和栖息环境存在明显差异:Type I个体的三个房室呈显著的球状,主要分布在表层30 m以浅的水体中;Type II个体的三个房室呈扁平的近似球状,主要分布在水深30 m以下的水体中。本工作是对热带西太平洋浮游有孔虫DNA分子数据的重要补充,旨在为古海洋学重建提供更加精确的替代性指标。     

ASSESSING PRIMARY PRODUCTION VARIABILITY IN THE NORTH PACIFIC SUBTROPICAL GYRE: A COMPARISON OF FAST REPETITION RATE FLUOROMETRY AND 14C MEASUREMENTS1

In situ ¹⁴C uptake (dawn to dusk) and fast repetition rate fluorometry (FRRF) measurements at nearly monthly intervals were compared at Station ALOHA (22°45′N, 158°00′W) between August 2002 and September 2003 in order to determine the feasibility of using FRRF profiling as a means for estimating primary production (PP). The FRRF and ¹⁴C rates were significantly correlated (r²=0.906, P value <0.05, n=70) with slopes of 2.00 and 1.90 for chl a and light normalized data, respectively. However, the relationship between ¹⁴C‐ and FRRF‐derived carbon fixation varied vertically and temporally. The FRRF: ¹⁴C ratio was >1.5 in near‐surface water (5–25 m depth) and approached 1.0 deeper in the euphotic zone. Vertical variations probably reflected the effect of different physiological processes (i.e. Mehler reaction, dark respiration, and excretion) on overall photoautotrophic respiration. In particular, the decrease in Mehler reaction rates with increasing water depth may have accounted for the decrease in difference between ¹⁴C and FRRF measurements with depth. The influence of in situ light field variability in controlling the absorption cross‐section of photosystem II (PSII) (σ_PSII′) may also have been responsible for some of this difference. When compared with total community respiration (R), the derived light‐driven photoautotrophic respiration (reported here as the difference between FRRF and ¹⁴C measurements) represented approximately 50% of R integrated over the euphotic zone. Our results show that FRRF and ¹⁴C measurements were well correlated in oligotrophic waters but the exact relationship between the two processes varies both temporally and vertically, such that a unique relationship between these two techniques could not be derived from first‐order principles.     

KILLER WHALES, WHALING, AND SEQUENTIAL MEGAFAUNAL COLLAPSE IN THE NORTH PACIFIC: A COMPARATIVE ANALYSIS OF THE DYNAMICS OF MARINE MAMMALS IN ALASKA AND BRITISH COLUMBIA FOLLOWING COMMERCIAL WHALING

The hypothesis that commercial whaling caused a sequential megafaunal collapse in the North Pacific Ocean by forcing killer whales to eat progressively smaller species of marine mammals is not supported by what is known about the biology of large whales, the ecology of killer whales, and the patterns of ecosystem change that took place in Alaska, British Columbia, and elsewhere in the world following whaling. A comparative analysis shows that populations of seals, sea lions, and sea otters increased in British Columbia following commercial whaling, unlike the declines noted in the Gulf of Alaska and Aleutian Islands. The declines of seals and sea lions that began in western Alaska around 1977 were mirrored by increases in numbers of these species in British Columbia. A more likely explanation is that the seal and sea lion declines and other ecosystem changes in Alaska stem from a major oceanic regime shift that occurred in 1977. Killer whales are unquestionably a significant predator of seals, sea lions, and sea otters—but not because of commercial whaling.     

CLASSIFICATION OF THE GENUS ISHIGE (ISHIGEALES,PHAEOPHYCEAE) IN THE NORTH PACIFIC OCEAN WITH RECOGNITION OF ISHIGE FOLIACEA BASED ON PLASTID rbcl AND MITOCHONDRIAL cox3 GENE SEQUENCES1

The taxonomy and biogeography of a genus with species that occur in geographically isolated regions is interesting. The brown algal genus Ishige Yendo is a good example, with species that apparently inhabit warm regions of both the northwestern and northeastern Pacific Ocean. We determined the sequences of mitochondrial cox3 and plastid rbcL genes from specimens of the genus collected over its distributional range. Analyses of the 86 cox3 and 97 rbcL sequences resulted in congruent trees in which Ishige sinicola (Setch. et N. L. Gardner) Chihara consisted of two distinct clades: one comprising samples from Korea and Japan, and the other comprising samples from the Gulf of California. Additional observations of the morphology and anatomy of the specimens agree with the molecular data. On the basis of results, we reinstated Ishige foliacea S. Okamura (considered a synonym of I. sinicola from the Gulf of California) for plants from the northwest Pacific region and designated a specimen in the Yendo Herbarium (SAP) as the lectotype. I. foliacea is distinguished by large (up to 20 cm) and wide (up to 20 mm) thalli, with a cortex of 4–7 cells, and a medulla composed of long, tangled hyphal cells. Both cox3 and rbcL sequence data strongly support the sister‐area relationship between the northwest Pacific region and the Gulf of California. A likely explanation for this pattern would be the presence of a species ancestral to contemporary species of Ishige in both regions during the paleogeological period, with descendants later isolated by distance.