Growth of bivalves at deep-sea hydrothermal vents along the galapagos rift

Direct measurements of shell growth of an unclassified mussel from active hydrothermal vents along the Galápagos Rift reveal growth rates of approxmately 1 centimeter per year for mature specimens. The largest mussel collected (with shell length of 18.4 centimeters) was estimated to be 19 +/- 7 years old at the time of sampling. Recorded growth rates are among the highest documented for deep-sea species.     

Surface-generated mesoscale eddies transport deep-sea products from hydrothermal vents

Atmospheric forcing, which is known to have a strong influence on surface ocean dynamics and production, is typically not considered in studies of the deep sea. Our observations and models demonstrate an unexpected influence of surface-generated mesoscale eddies in the transport of hydrothermal vent efflux and of vent larvae away from the northern East Pacific Rise. Transport by these deep-reaching eddies provides a mechanism for spreading the hydrothermal chemical and heat flux into the deep-ocean interior and for dispersing propagules hundreds of kilometers between isolated and ephemeral communities. Because the eddies interacting with the East Pacific Rise are formed seasonally and are sensitive to phenomena such as El Ni?o, they have the potential to introduce seasonal to interannual atmospheric variations into the deep sea.     

Larval dispersal and species longevity in lower tertiary gastropods

Species longevity in Lower Tertiary volutids (Gastropoda) is primarily controlled by a combination of developmental type and environmental tolerance. Larval dispersal may be an important factor in molluskan evolutionary rates.     

Subtidal gastropods consume sulfur-oxidizing bacteria: evidence from coastal hydrothermal vents

The black abalone (Haliotis cracherodii), a commercially important shallow-water gastropod common off White Point, Southern California, is found frequently at subtidal hydrothermal vents within mats of filamentous sulfur-oxidizing bacteria. Foraging vent abalones actively consume the bacteria and confine their nightly feeding forays to bacterial mats surrounding the vents. The growth of abalones consuming the sulfur bacteria exceeds that of control individuals consuming microalgae and is comparable to reported growth rates of abalones consuming macroalgae. Thus, off White Point, the black abalone may derive a portion of its nutrition from the subsidy of geothermal energy.     

Galapagos hydrothermal mounds: stratigraphy and chemistry revealed by deep-sea drilling

The Galápagos mounds sea-floor hydrothermal system is at least 300,000 years old and once produced manganese-poor sediments, which nearly blanketed the area of the present mounds field. Present-day mound deposits are limited manganese-rich exposures, suggesting that the system has changed from rock-to water-dominated and has diminished in intensity with time.     

In situ measurements of chemical distributions in a deep-sea hydrothermal vent field

Large changes in the concentration of sulfide around a hydrothermal vent in the Galápagos Rift provide direct evidence for the consumption of sulfide by the organisms of the vent community. These changes were detected with a new chemical analyzer capable of measuring silicate, sulfide, oxygen, and temperature on the sea floor at depths of 2500 meters. More than 10,000 measurements showed systematic variations in the sulfide and oxygen concentrations due to biogenic oxidation of sulfide in the hydrothermal solutions. Silicate concentration was highly correlated with temperature, but different trends were observed at different locations.     

一株深海热液口超嗜热古菌的分类鉴定及高温酶活性研究

对一株分离自深海热液口古菌HJ21进行了分类鉴定及高温酶活性的研究.该菌株是极端嗜热的厌氧球菌,直径为1.0～1.2 靘.菌株最适生长温度88 ℃;菌株生长pH为5.0～9.0,最适pH为6.5～7.0;菌株生长NaCl质量浓度为10～50 g·L-1,最适为20 g·L-1.根据其形态特征、生理生化特性以及16S rRNA基因序列分析结果,确定HJ21菌株为热球菌属(Thermococcus).该菌株能产生高热稳定的高温α-淀粉酶、普鲁兰酶、α-葡萄糖苷酶和蛋白酶,这些酶的最适作用温度分别为95、95、100和100 ℃,α-淀粉酶、普鲁兰酶和α-葡萄糖苷酶在90 ℃的半衰期分别为5、5和2 h;蛋白酶在100 ℃保温2.5 h后仍具有84%的酶活性.     

Membrane lipid from deep-sea hydrothermal vent methanogen: a new macrocyclic glycerol diether

The membrane lipid of a new deep-sea hydrothermal vent methanogen, Methanococcus jannaschii, has been structurally characterized. The hydrolyzed polar lipid of this archaebacterium is primarily (95 percent) a macrocyclic glycerol diether, which has not been described previously. The structure was elucidated by a combination of chemical and spectroscopic techniques. An initial survey of selected methanogens failed to indicate the presence of this membrane lipid in any microorganism other than Methanococcus jannaschii.     

Paleoceanographic events and deep-sea ostracodes

Eight recognized or theorized paleoceanographic events during the past 70 million years were tested against changes in the global deep-sea benthic ostracode fauna. Two events, the sudden Cretaceous-Tertiary boundary event at 66 million years ago and the more gradual 40-million-year event (formation of the psychrosphere), show up most dramatically. Before the 40-million-year event, ostracodes freely radiated into the deeper water regions but were provincial. The development of thermal stratification isolated these deep-water taxa, mostly the survivors of the Cretaceous-Tertiary boundary event, which adapted to a new, free-flowing but more frigid ecosystem and spread rapidly throughout the world.     

Zodiacal dust and deep-sea sediments

The recent detection of radioactive Al(26) in marine sediments has led to the conclusion that it is brought into the earth's atmosphere by micrometeorites which have been exposed, in interplanetary space, to solar high-energy protons. The Al(26) method is not precise enough to yield directly a reliable value for the mass accretion rate to the earth to better than about 3 orders of magnitude, but is sufficiently accurate to allow a crucial decision between two widely differing of interplanetary dust which have been proposed to explain observations of the zodiacal light. The two models lead to Al(26) concentrations which would differ by about 5 orders of magnitude. Thus, the presence of Al(26) is consistent with the zodiacal dust model with particles of some tens of microns rather then with submicron particles. From this model a mass accretion to the earth then be calculated which is set at 1250 (upper limit, 2500; lower limit, 250) tons per day, or 2.8 x 10(-15) g/cm(2) sec, or 4.5 x 10(11) g over the earth per This value does not depend on the flux of the solar high-energy particles, which may be uncertain by an order of magnitude or more. The presence of Al(26) supports the idea that an important fraction of the dust is stony in composition material density, and thus eliminates some more exotic dust models, as such one consisting entirely of carbon grains. We may also conclude that the accreted dust particles have been in the solar system and exposed to protons from solar high-energy particles for a time interval which is greater than a significant of the Al(26) half-life (0.74 x 10(6) years).     

Biological communities at the Florida escarpment resemble hydrothermal vent taxa

Dense biological communities of large epifaunal taxa similar to those found along ridge crest vents at the East Pacific Rise were discovered in the abyssal Gulf of Mexico. These assemblages occur on a passive continental margin at the base of the Florida Escarpment, the interface between the relatively impermeable hemipelagic clays of the distal Mississippi Fan and the jointed Cretaceous limestone of the Florida Platform. The fauna apparently is nourished by sulfide rich hypersaline waters seeping out at near ambient temperatures onto the sea floor.     

Sea-level fluctuations and deep-sea sedimentation rates

Sediment accumulation rate curves from 95 drilled cores from the Pacific basin and sea-level curves derived from continental margin seismic stratigraphy show that high biogenous sediment accumulation rates correspond to low eustatic sea levels for at least the last 48 million years. This relationship fits a simple model of high sea levels producing lower land/sea ratios and hence slower chemical erosion of the continents, and vice versa.     

Nitrogen fixation at 92 degrees C by a hydrothermal vent archaeon

A methanogenic archaeon isolated from deep-sea hydrothermal vent fluid was found to reduce N(2) to NH(3) at up to 92 degrees C, which is 28 degrees C higher than the current upper temperature limit of biological nitrogen fixation. The 16S ribosomal RNA gene of the hyperthermophilic nitrogen fixer, designated FS406-22, was 99% similar to that of non-nitrogen fixing Methanocaldococcus jannaschii DSM 2661. At its optimal growth temperature of 90 degrees C, FS406-22 incorporated (15)N(2) and expressed nifH messenger RNA. This increase in the temperature limit of nitrogen fixation could reveal a broader range of conditions for life in the subseafloor biosphere and other nitrogen-limited ecosystems than previously estimated.     

沙塘鳢胚胎和仔鱼发育的初步研究

对沙塘鳢（Odontobutis obscura）胚胎和仔鱼的发育进行了观察,描述了各发育阶段的形态特征。在22℃恒定条件下,沙塘鳢的胚胎发育历时528h,可分为28个发育分期。在整个发育过程中,各个器官如眼、耳囊、心脏、肾脏、肝脏、消化道、鳔、胸鳍和尾鳍等得到优先发育。     

Migrations and growth of deep-sea lobsters, Homarus americanus

In distinct contrast to the restricted movements of coastal stocks of lobsters (Homarus americanus), those inhabiting the outer continental shelf undertake extensive seasonal migrations. Of 5710 tagged lobsters released on the outer continental shelf off New England from April 1968 to June 1969, 400 had been recaptured by April 1970. The distribution of the recoveries demonstrated shoalward migration in spring and summer and a return to the edge of the shelf in fall and winter. Deep-sea lobsters have a faster rate of growth than coastal lobsters; growth increments at molting and the frequency of molting are greater.     

Manganese and biotic debris associations in some deep-sea sediments

Incipient manganese concretions occur in microcavities of planktonic skeletal debris (especially diatom frustules) in some Pacific Basin deep-sea sediments. These concretions contain over 50 percent manganese and very little iron (< 1 percent). There is a continuum of growth stages in the concretions having a diameter between 0 and approximately 2 millimeters, and a genetic relationship is suggested between the very small and the centimeter sized concretions.