Submarine ridges do not prevent large-scale dispersal of abyssal fauna: A case study of Mesocletodes (Crustacea, Copepoda, Harpacticoida)

We examined the large-scale distribution of deep-sea harpacticoid copepods at the species level, in order to clarify the underlying processes of copepod dispersal. The study was based on samples collected from 12 regions and a total of 113 stations: 57 stations at depths between 1107 and 5655 m on abyssal plains in the South and North Atlantic, Southern Ocean, southern Indian Ocean, and the Pacific Ocean, and 56 stations above 900 m in the North Atlantic and eastern Mediterranean Sea.We chose the genus Mesocletodes Sars, 1909 as an ideal group to study the large-scale distribution of harpacticoid copepods in the deep oceans. Clear apomorphies and a comparatively large body size of about 1 mm allow rapid recognition of allied species in meiofauna samples. In addition, Mesocletodes represents more than 50% of the family Argestidae Por, 1986, one of the most abundant harpacticoid families in the deep sea.The geographical distributions of 793 adult females of Mesocletodes belonging to 61 species throughout the South and North Atlantic, Southern Ocean, southern Indian Ocean, Pacific Ocean, and eastern Mediterranean Sea indicated that most species are cosmopolitan. Neither the topography of the sea bottom nor long distances seem to prevent species from dispersing. Passive transport by bottom currents after resuspension is likely the propulsive factor for the dispersal of Harpacticoida, while plate tectonics and movement of individuals in the sediment may play relatively minor roles.     

Reactive mercury in the eastern North Atlantic and southeast Atlantic

The vertical distribution of reactive mercury has been measured at two stations in the eastern North Atlantic and one station in the southeast Atlantic in conjunction with the IOC Open Ocean Baseline Survey. The average concentrations of reactive Hg in vertical profiles ranged from 0.70 to 1.07 pM with the highest values found at the northeast Atlantic stations and the lowest at the southeast station. No significant concentration gradients were found below the surface mixed layer at the two stations in the eastern North Atlantic. At station 7, in the southeast Atlantic, an increase in reactive Hg was noted in the water adjacent to the mixed layer (35–200 m) which was coincident with an oxygen depletion, down to 20% saturation at 200 m. The concentration of reactive Hg in the North Atlantic Deep Water (0.48–1.34 pM), the Antarctic Intermediate Water (0.47 pM), the Antarctic Bottom Water (0.67–1.25 pM), and the Mediterranean Outflow Water (0.83–1.06 pM) were noted. The trends in Hg concentration in the water masses between stations showed the concentration decreasing with distance from the water mass source except for Hg in the Antarctic Bottom Water. The increase noted in this water mass was attributed to mixing with North Atlantic Deep Water and or release from bottom sediments.     

Distribution of deep-water Scleractinian corals in the Atlantic Ocean

The distribution pattern of deep-water Scleractinian corals was studied in the Atlantic Ocean at a depth more than 2 km on the basis of our own and published data. It was shown that deep-water corals predominate (with respect to species diversity and number) in the eastern part of the ocean. In its western part, some species (Desmophyllum dianthus, Flabellum angulare, etc.) were not revealed. In the tropical zone of the North Atlantic, the distribution pattern of shallow- and deep-water corals differs. At the coast of South America, deepwater corals are absent, which is probably related to the deep part of the global oceanic conveyor belt.     

表层海水硅同位素的分布特征及其影响因素

本文分析了采集自太平洋、印度洋和大西洋的表层海水溶解硅酸盐的δ30Si值,结果表明,太平洋表层海水的δ30Si值为0.45‰～2.91‰,平均值为(1.52±0.59)‰;印度洋表层海水的δ30Si值为0.98‰～2.30‰,平均值为(1.52±0.36)‰;大西洋表层海水的δ30Si值为0.90‰～2.23‰,其平均...     

Deep-sea pycnogonids from the North Atlantic and their distribution in the World Ocean

The information on the composition and distribution of present-day pycnogonids in different regions of the World Ocean and, especially, in the northern part of the Atlantic Ocean acquired during the past decades allowed us to perform a biogeographical analysis of these animals, which represent a permanent component of bottom communities. For 34 species of sea spiders (Pycnogonida) found in the North Atlantic deeper than 2 km, ten types of geographical distribution were recognized. Half of the species identified represent Atlantic forms, and 41% of them are endemic forms with West-Atlantic, East-Atlantic, amphi-Atlantic, and central-Atlantic distributions. The other half of the deep-sea Atlantic species have broad geographical ranges. Among them, 11.7% are Atlantic-Pacific species, 14.7% dwell in the Atlantic and West Pacific, 8.9% are low-latitudinal panocaanic species, and 14.7% are panoceanic species able to penetrate to higher latitudes. The zoogeographical species composition shows a significant independence of this fauna in the northern Atlantic Ocean and its relation to the Pacific and Indian oceans. At present, these relations are probably maintained via the temperate latitudes of the Southern Hemisphere and via the Drake Passage; meanwhile, it seems that, previously, they were realized possibly via the ancient Tethys Ocean.     

First record of a Vestimentifera (Polychaeta: Siboglinidae) from chemosynthetic habitats in the western Mediterranean Sea—Biogeographical implications and future exploration

A new population of vestimentiferan tubeworms was discovered during a recent expedition to a mud volcano field in the Alboran Sea, western Mediterranean Sea. Morphological data and mitochondrial cytochrome-c-oxidase subunit 1 (COI) sequences show that the Alboran tubeworm is essentially identical to Lamellibrachia sp. found in the eastern Mediterranean. This is the first record of a vestimentiferan species in the western basin of the Mediterranean, an area with direct connection to the Atlantic via the Strait of Gibraltar and therefore of great importance to the study of distributional patterns and evolution of Mediterranean species. We examine the current hypotheses on the biogeographic distribution of vestimentiferan species in the eastern Atlantic and Mediterranean Sea and conclude that independently of when Lamellibrachia colonized the Mediterranean, neither the present hydrological settings of both Mediterranean Sea and Atlantic Ocean, nor vestimentiferans reproductive biology are impeditive to the presence of the Mediterranean species of Lamellibrachia in the NE Atlantic. The West African and Lusitanian margins are the most likely places to find living populations of this species in the NE Atlantic.     

Paleo-bathymetry of the northern North Atlantic and consequences for the opening of the Fram Strait

In the past decade, the geophysical database in the northern North Atlantic and central Arctic Ocean constantly grew. Though far from being complete, the information from new aeromagnetic and seismic data north of the Jan Mayen Fracture Zone and in the Arctic Ocean, in combination with existing compiled geological and geophysical data, is used to produce paleo-bathymetric maps for several Cenozoic time intervals. This paleo-bathymetric model provides evidence for an initial deep-water exchange through the Fram Strait starting around 17 Ma. Furthermore, the model suggests that crustal rifting prior to initial seafloor spreading might have facilitated an earlier deep-water connection. This confirms that the paleo-topography of the Yermak Plateau played an important role in allowing at least the exchange of shallow water between the northern North Atlantic and the Arctic Ocean before the opening of the deep-water Fram Strait gateway. In the south of the research area the paleo-bathymetric model indicates that the first possibility for a deep-water overflow from the Norwegian-Greenland Sea to the North Atlantic could have been between 15 and 20 Ma.     

Geodynamics and plume tectonics of the Azore-Gibraltar fault zone (North Atlantic)

Maps of the principal structures and geological-geophysical knowledge for the Azores-Gibraltar and Icelandic regions have been made. The geodynamic conditions of the Azores archipelago formation have been analyzed. It has been noted that the uplifting of the Azores plume (as well as the Icelandic one) might have been triggered by near-surface tectonic processes. The computer modeling has been performed with respect to the coefficients of the geodynamic sinking rates for the Azores fragment of the Mid-Atlantic Ridge. Based on the modeling results, this rate was ∼1.5 times higher than the average sinking rate for the mid-ocean ridges of the World Ocean in general. The high sinking rate of the Azores fragment is caused by the influence of the plume material on the sinking process. Based on the complex analysis of the seismicity, thermal flow, and seismic tomography data distribution, as well as the implemented numerical calculations, the European (northern) part of the diffuse boundary between the Eurasian and African plates has been identified for the first time. Along with the African (southern) boundary, it outlines the identified by the authors West Mediterranean plate.     

大眼金枪鱼的资源现状

大眼金枪鱼的分布很广 ,在南、北纬 4 0°以内的太平洋、印度洋和大西洋均有分布 ,是金枪鱼渔业的重要捕捞种类之一。本文分别论述了大眼金枪鱼在大西洋、印度洋和太平洋的渔业概况、生物学特性、资源状况和管理对策。     

北冰洋水体对格陵兰海混合增密对流的可能影响分析

格陵兰海内发生的等密度混合后产生的增密对流是重要的对流现象之一。北冰洋正在发生快速变化,其内水团变性以及环流系统的改变都将使格陵兰海等密度混合对流发生明显变化,继而对全球气候变化产生影响。以往关于等密度混合对流的研究很少,大都集中在对流发生海域。由于等密度混合的主体是大西洋回流水与北冰洋流出水体,本文目的是探讨北极内部不同海域的水体会对混合增密对流造成的可能影响。文中定义了有效对流速度,强调水平温度梯度和垂向层化强度是影响有效对流速度的决定性因素;水平温度差越大,垂向层化越弱,产生的对流越强。发生在东格陵兰极锋处的有效对流都是大西洋的水体,一部分是在格陵兰海回流的大西洋回流水;一部分是在北冰洋潜沉并回流的北极大西洋水,该水体在北冰洋循环的时间越长,温度差越大,产生的有效对流越强。而横越北冰洋的太平洋水因密度过低而不能参与等密度混合对流,加拿大海盆主盐跃层之上的水体也都不能参与对流。北冰洋几个海盆深层水的温度差异明显,有可能与格陵兰海深层水形成有效对流;但是,由于深层水流速低、湍流混合弱、水平温度梯度小,是否可以产生有效对流尚不清楚。     

The distribution of particulate organic carbon and nitrogen in some surface waters of the World Ocean

Data is presented for the concentrations of organic carbon and nitrogen, and C:N ratios, in marine particulate matter, and for POC and PN, from surface waters collected in the northeastern Atlantic, South Atlantic, Indian Ocean and China Sea.The organic carbon content of this particulate matter varies between 4.6% and 29.9%, and has an average of 17.8%. The average organic carbon content of particulate matter from the various oceans decreases in the order: Northeastern Atlantic > South Atlantic > Indian Ocean > China Sea.The nitrogen content of the particulate matter varies between 1.0% and 3.9%, with an average of 2.2%, and in general follows the same trend as that of organic carbon.C:N ratios vary between 5.1 and 10.6, and have an average of 7.9.The POC contents of the oceanic waters vary between 6.6 and 211 μg/l, with an average of 52 μg/l. The concentrations in the surface waters decrease in the following order: Northeastern Atlantic τ China Sea > South Atlantic > Indian Ocean.The concentrations, and compositions, of particulate matter from various coastal localities are given for comparison with the oceanic values.     

Early Turonian global warming in the Atlantic and Indian Oceans according to the data of the Foraminifera analysis

In the article, my own data on the species composition of the shells of planktonic Foraminifera (PF) from the Early Turonian sediments of the Atlantic and Indian Ocean and from a number of the cross sections of Australia have been analyzed. In addition, literature materials on the epicontinental basins of the northern hemisphere were also studied. The foraminifera species (PF) are grouped, and four types of thanatocoenoses are distinguished according to their relationship. A climatic zonality map for the early Turonian was constructed on the basis of the spatial distribution of these types. The reconstruction obtained was compared with the climatic maps compiled earlier for the later time intervals of the Late Cretaceous. It was established that the Turonian was characterized by the warmest climate. The tendency for global warming was the most clearly manifested in the Early Turonian.     

Ontogenetic and gender-modulated behavioural rhythms in the deep-water decapods Liocarcinus depurator (Brachyura: Portunidae), Munida tenuimana and Munida intermedia (Anomura: Galatheidae)

The regulation and expression of biological rhythms with respect to sex and ontogeny in deep-water benthic decapod crustaceans constitutes an exciting field in marine biology that is far from understood. Liocarcinus depurator , Munida intermedia and Munida tenuimana are ecologically key crustacean decapod species of the Atlantic and Mediterranean shelves and slopes, and their activity rhythms in the field are poorly known. Our aim was to measure the behavioural rhythms of these species, while at the same time defining their type of displacement ( i.e. endobenthic, nektobenthic or benthopelagic). Whether gender and ontogeny modulate the rhythmic behaviour of these decapods is unknown, and we sought to clarify this issue. A temporally scheduled series of trawl hauls and light intensity measures was performed on the western Mediterranean shelf (100–110 m depth) and slope (400–430 m), close to the autumn equinox and the summer solstice. The sex and the size of animals in the catches were analysed. Catch patterns were evaluated through waveform and periodogram analyses. Liocarcinus depurator was captured at night on the shelf, whereas on the slope, animals displayed peaks both in the middle of the day and night. Size-related differences (but no gender differences) were found in its rhythmic behaviour, possibly due to intra-specific competition ( e.g. fighting) between juveniles and adults. Munida intermedia were weakly diurnal in October and both diurnal and nocturnal in June. Munida tenuimana presented no discernible rhythmicity in October, but was nocturnal in June. Both species showed no evident sex or size modulation of their behaviour. Data were interpreted assuming that all tested species present an endobenthic behaviour ( i.e. animals emerge from the substrate during the active phase of their behavioural cycle).     

Eolian dust from the lower atmosphere of the eastern Atlantic and Indian Oceans,China Sea and Sea of Japan

Dust-loadings in the lower atmosphere of the Atlantic and Indian Oceans and the China Sea and Sea of Japan are given. Average dust-loadings decrease in the following order: North Atlantic (northeast trades, ～ 7.7 μg/m³ of air) > northern Indian Ocean (～ 1.2 μg/m³ of air) > South Atlantic (southeast trades, ～ 0.78 μg/m³ of air) = southern Indian Ocean (～ 0.68 μg/m³ of air) > China Sea (～ 0.21 μg/m³ of air).There are differences in the clay mineralogies of dusts transported in similar latitudes in the North Atlantic and northern Indian Oceans. Dusts in the Atlantic northeast trades are dominated by kaolinite from the soils of equatorial Africa; dusts in the northeast monsoons of the northern Indian Ocean have a source in the arid regions of the Rajasthan desert where illite is the principal clay mineral.In the regions investigated quartz occurs in larger amounts in the dusts of the Northern Hemisphere (～ 7% quartz) than those of the Southern Hemisphere (～ 3% quartz) over both the Atlantic and Indian Oceans.From the results given in the present paper and those reported in the literature a map is presented illustrating the order of magnitude of lower atmospheric dust-loadings in part of the world ocean.     

Argo资料的全球上层海温年和半年周期振荡的空间分布特征

利用小波分析方法,对2003-2008年周平均的Argo(地转海洋学实时观测阵)海温资料进行了分析,给出了全球上层海温年周期和半年周期振荡的空间分布特征.结果表明,南北半球中高纬地区以表层海温的年周期变化为主,在低纬度地区,表层海温以半年周期为主,而温跃层附近海温既有年周期也有半年周期(赤道太平洋、东南印度洋和赤道西大西洋以年周期为主;赤道东、西印度洋以半年周期为主).南北半球中高纬的年周期海温和北半球中纬度的半年周期海温在表层范围最大,显著性最高,强度最强,位相最前.随深度的增加,范围减小,显著性降低,强度减弱,位相滞后.信号主要集中在水深50 m以上,影响深度在150m以浅;赤道附近的太平洋和热带东南印度洋的年周期海温以及赤道东、西印度洋的半年周期海温在水深100m范围最大,显著性最高,强度最强,位相最前,信号主要集中在温跃层附近,影响深度均可达500m.     

印度洋浮游生态系统的特点及其对全球变暖的响应

与太平洋和大西洋相比,印度洋有独特的季风和洋流系统和由此驱动的浮游生物分布及生产规律.在全球变暖的背景下,印度洋的变暖趋势比太平洋和大西洋更为显著,是研究变暖对海洋浮游生态系统影响的热点海区之一.文章结合国内外文献,评述印度洋浮游生态系统的现状、特点及对全球变暖的响应,包括印度洋的浮游生物地理分布、南北印度洋浮游生态系...     

The influence of light availability and predatory behavior of the decapod crustacean Nephrops norvegicus on the activity rhythms of continental margin prey decapods

The day–night cycle is one of the strongest geophysical cycles modulating species' behavioral rhythms. However, in deep-water continental margins, where light intensity decreases over depth, interspecific competition may alter behavioral responses to day–night cycles. The burrowing decapod crustacean Nephrops norvegicus is a large-size predator in benthic communities, exerting despotic territorial behavior. In this study, we analysed how the effect of light intensity cycles on decapod behavioral rhythms is reduced as one moves from shelves to slopes. In the Western Mediterranean, the predatory behavior and interspecific competition for substrate use of Nephrops increases moving from the shelf (100–110 m) to the slope (400–430 m). Vector fitting and generalized additive models were used to assess the effect of light intensity and behavioral rhythms of N. norvegicus on the temporal variation of prey decapods co-occurring in trawl tow catches carried out on the shelf and the slope during October 1999 and June 2000. The combination of diel variations in light intensity and N. norvegicus abundance influences the activity rhythms of prey decapods in a depth- and seasonal-dependent manner. Light modulation is stronger on the shelf and weaker on the slope, where Nephrops population size is greater. Although present regression analysis does not necessarily imply a direct cause–effect relationship between rhythms of predators and prey, we suggest that Nephrops alters the temporal patterning in the behavior of its prey on the slope, where light intensity is reduced. This alteration is stronger in endobenthic species than in benthopelagic species; the former rely on bottom substrate for the expression of behavioral rhythms, experiencing stronger interspecific competitions with Nephrops at time of activity.     

High resolution gravimetric geoid heights and gravimetric vertical deflections of Europe including marine areas

Gravimetric geoid heights and gravimetric vertical deflections have been detemined for Europe including the Mediterranean Sea, North Sea, Norwegian Sea, Baltic Sea and parts of the North Atlantic Ocean in a 12′×20′ grid. The computation has been carried out by least squares spectral combination using closed integral formulas, combining 104 000 mean free air gravity anomalies in 6′×10′ blocks, 12 000 mean free air gravity anomalies in 1⁰×1⁰ blocks and the sherical harmonic model GEM9. The precision of the computed geoid heights has been estimated to ±1 m, the precision of the computed vertical deflections has been estimated to ±2″. Comparisons of the gravimetric geoid heights and vertical deflections with a number of other solutions have been carried out, confirming the precision estimation.     

2013年夏季西南印度洋表层浮游动物群落分布格局

本研究基于2013年夏季“大洋一号”船大洋第30航次西南印度洋海区科学考察走航线路,对西南印度洋21°S到38°S海域表层浮游动物群落进行连续采样调查,研究了该海域表层中型浮游动物群落结构和物种多样性及空间分布格局。结果显示,研究海域表层中型浮游动物群落组成包括:桡足类、磷虾类、端足类、十足类、介形类、毛颚动物、被囊类、异足类、翼足类、刺胞动物及多毛类等11大类,总计50属69种;优势类群为桡足类(69%)和磷虾类(27%)。多样性指数随经度和纬度的变化特征:H′、D多样性指数及J均匀度指数随纬度的升高均呈下降趋势;在经度梯度上,几种多样性指数也大致呈现出东高西低的趋势。聚类分析表明,研究区可大致以36°S附近为界划分为南部和北部两大类群,分别以北部桡足类(平均粒径小),南部磷虾类(平均粒径大)Euphausia属为优势群落。群落相似性结果反映出,南部类群与南极克罗克海峡和南极长城湾水域群落,北部类群与西北印度洋海域群落的联通性不高。     

Environmental setting of deep-water oysters in the Bay of Biscay

We report the northernmost and deepest known occurrence of deep-water pycnodontine oysters, based on two surveys along the French Atlantic continental margin to the La Chapelle continental slope (2006) and the Guilvinec Canyon (2008). The combined use of multibeam bathymetry, seismic profiling, CTD casts and a remotely operated vehicle (ROV) made it possible to describe the physical habitat and to assess the oceanographic control for the recently described species Neopycnodonte zibrowii. These oysters have been observed in vivo in depths from 540 to 846 m, colonizing overhanging banks or escarpments protruding from steep canyon flanks. Especially in the Bay of Biscay, such physical habitats may only be observed within canyons, where they are created by both long-term turbiditic and contouritic processes. Frequent observations of sand ripples on the seabed indicate the presence of a steady, but enhanced bottom current of about 40 cm/s. The occurrence of oysters also coincides with the interface between the Eastern North Atlantic Water and the Mediterranean Outflow Water. A combination of this water mass mixing, internal tide generation and a strong primary surface productivity may generate an enhanced nutrient flux, which is funnelled through the canyon. When the ideal environmental conditions are met, up to 100 individuals per m² may be observed. These deep-water oysters require a vertical habitat, which is often incompatible with the requirements of other sessile organisms, and are only sparsely distributed along the continental margins. The discovery of these giant oyster banks illustrates the rich biodiversity of deep-sea canyons and their underestimation as true ecosystem hotspots.