Showing papers by "Woods Hole Oceanographic Institution published in 1986"

Oceanic Dimethylsulfide: Production During Zooplankton Grazing on Phytoplankton

Abstract: About half the biogenic sulfur flux to the earth's atmosphere each year arises from the oceans. Dimethylsulfide (DMS), which constitutes about 90% of this marine sulfur flux, is presumed to originate from the decomposition of dimethylsulfoniopropionate produced by marine organisms, particularly phytoplankton. The rate of DMS release by phytoplankton is greatly increased when the phytoplankton are subjected to grazing by zooplankton. DMS production associated with such grazing may be the major mechanism of DMS production in many marine settings.

Thecate heterotrophic dinoflagellates: feeding behavior and mechanisms

Abstract: The feeding of 18 species of thrcale hetrophi dinoflagellates from three genera (Protoperidininm, Oblea, Zygabikodinium) can all be described within one general framework These species engulf diatoms and other prey with a pseudopod (herein terned a “Pallium”)which originates at the flagellar pore in the sulcus The pallium is a highly plastic, membranous organ which rasily strethes to accommodate spines and many as 58 diatom cells in a chain The contents of the phytoplanklon prey are liquified and transporued throughthe pallioum typically within 7 to 30 minutes of capture (although feeding may last 2 h) teaving an intact but empty cell wall or frustule Thus far, with few exceptions, Protoperidinium specises have been observed feeding inly on diatoms, whereas two diplopsaloid species feed on dinoflagellates and prasinophytes as well In four species from the three genera studied a capture filament has been observed that connects the food to the dinoflagellate prior to extension of the pallium, sometimes allowing the cell to pull the food while swimming A distinctive precapture swimming behavior is also deseribed foe six species, suggesting that the dinoflagellates are selective grazers

Nitrospira marina gen. nov. sp. nov.: a chemolithotrophic nitrite-oxidizing bacterium

Abstract: A new chemolithotrophic nitrite-oxidizing bacterium, for which the name Nitrospira marina is proposed, was isolated from the Gulf of Maine N marina is a Gramnegative curved rod which may form spirals with 1 to 12 turns Cells have a unique periplasmic space and lack intracytoplasmic membranes and carboxysomes N marina is an obligate chemolithotroph, but best growth is obtained in a mixotrophic medium N marina may be one of the most prevalent nitrite-oxidizing bacteria in some oceanic environments Type strain is field with American Type Culture Collection (ATCC 43039)

Cosmogenic helium in a terrestrial igneous rock

Abstract: New helium isotopic measurements on samples from the Kula formation of Haleakala volcano of Hawaii are presented that are best explained by an in situ cosmogenic origin for a significant fraction of the He-3. Results from crushing and stepwise heating experiments, and consideration of the exposure age of the sample at the surface and the cosmic ray fluxes strongly support this hypothesis. Although crustal cosmogenic helium has been proposed previously, this represents its first unambiguous identification in a terrestrial sample.

Growth Pattern and Yield of a Chemoautotrophic Beggiatoa sp. in Oxygen-Sulfide Microgradients.

Abstract: Recently developed techniques involving opposed, gel-stabilized gradients of O2 and H2S permit cultivation of a marine Beggiatoa strain as a chemolithoautotroph which uses gliding motility to precisely track the interface between H2S and O2. In the current study with microelectrodes, vertical profiles of H2, O2, and pH were measured in replicate cultures grown for various intervals. After an initial period of exponential biomass increase (doubling time, 11 h), linear growth prevailed throughout much of the time course. This H2S-limited growth was followed by a transition to stationary phase when the declining H2S flux was sufficient only to supply maintenance energy. During late-exponential and linear growth phases, the Beggiatoa sp. consumed a constant 0.6 mol of H2S for each 1.0 mol of O2, the ratio anticipated for balanced lithoautotrophic growth at the expense of complete oxidation of H2S to SO42−. Over the entire range of conditions studied, this consumption ratio varied by approximately twofold. By measuring the extent to which the presence of the bacterial plate diminished the overlap of O2 and H2S, we demonstrated that oxidation of H2S by Beggiatoa sp. is approximately 3 orders of magnitude faster than spontaneous chemical oxidation. By integrating sulfide profiles and comparing sulfide consumed with biomass produced, a growth yield of 8.4 g (dry weight) mol−1 of H2S was computed. This is higher than that found for sulfide-grown thiobacilli, indicating very efficient growth of Beggiatoa sp. as a chemoautotroph. The methods used here offer a unique opportunity to determine the yield of H2S-oxidizing chemolithoautotrophs while avoiding several problems inherent in the use of homogeneous liquid culture. Finally, by monitoring time-dependent formation of H2S profiles under anoxic conditions, we demonstrate a method for calculating the molecular diffusion coefficient of soluble substrates in gel-stabilized media.

Seasonal fluxes of pelagic diatoms in the subarctic Pacific, 1982–1983

Abstract: An assessment of the vertical flux of pelagic diatoms was conducted on PARFLUX sediment trap samples collected during September 1982–September 1983 at subarctic Pacific Station PAPA (50°N, 145°W; water depth 4200 m). A total of 24 time-series sediment trap samples were collected for 11- to 16-day periods during the year. Seasonal fluxes of 18 encountered taxa are reported. All of the taxa fall into one of five different types of seasonal flux patterns. Generally, taxa in Types 1–3 are indicators for high mass, opal, and organic carbon fluxes based on correlation analysis with mass and opal fluxes. Among them, Chaetoceros atlanticum, Rhizosolenia styliformis and Asteromphalus robustus are the best indicators for production. Unique signals from Coscinodiscus marginatus are present in the October–December high flux season and the January–March high percentage values. Based on flux maxima and minima and species components, samples from 1000 and 3800 m were cross-correlated. The correlations show that the two samples are generally offset by one sample interval of 2 weeks. The sinking speeds of diatoms are thus estimated to be approximately 175 m d−1 regardless of taxa, size, or morphology, invoking the necessity of aggregated and accelerated sinking. Diatom fluxes of various taxa measured at 1000 and 3800 m with one sample offset are generally nearly equal, implying that no significant dissolution takes place en route to the sea floor. A marked change was noted in the relative abundance of diatom species composition from the flux to surface sediment assemblages. For example, Denticulopsis seminae represents 87% in the flux of total diatoms compared to 30% in surface sediments. A significant alteration in percentages of diatom taxa place on the sea floor, with only 2% of the diatom flux being preserved in the surface sediments.

Whistle repertoires of two bottlenosed dolphins, Tursiops truncatus: Mimicry of signature whistles?

Abstract: The whistle vocalizations of two bottlenosed dolphins, Tursiops truncatus, were recorded at the Sealand Aquarium in Brewster, Massachusetts. The identification of which dolphin within the group produced a vocalization was made possible by a telemetry device attached to the dolphin's head with a suction cup. 77% of the identified whistles (219 our of 284) fell into two primary categories, type 1 and type 2 (Table 1). The remaining 23% of whistles fell into five secondary categories. Of the primary whistles produced by one dolphin, 78% were of type 1 (22% type 2), while 69% of primary whistles from the other dolphin were of type 2 (31% type 1). The result that each of the dolphins favored a different primary whistle supports the findings of Caldwell and Caldwell (1965), that each dolphin produces an individually distinctive whistle. But in the present study, both dolphins produced both primary whistle types. This may represent mimicry of signature whistles.

Controlled-source electromagnetic sounding of the oceanic lithosphere

Abstract: The attenuation of ionospheric signals in the frequency range 0.06–24 Hz by sea water effectively precludes using the magnetotel-luric method to study the electrical structure of the upper oceanic lithosphere. We have carried out a dipole–dipole electromagnetic sounding in the North Pacific by injecting electromagnetic signals into the ocean and sea bed. The crust at the site is 25 Myr old and has a thin sediment cover. The technique, similar to that used in earlier work1,2, involves dragging a horizontal dipole antenna along the sea floor. The electric fields that propagated through the resistive basement were detected by seafloor receivers at ranges of 10–65 km. As the ambient electric field is very small (varying from 10−18 V2 m−2 Hz−1 at 0.1 Hz to 10−24 V2 m2 Hz−1 above 1 Hz; ref. 3), the controlled-source signals could be easily monitored. Our data are consistent with a simple one-dimensional Earth model consisting of a 3–7-km-thick crustal layer of moderate conductivity (∼0.001 S m−1) underlain by a thicker region of very low conductivity (<2 × 10−5 S m−1). The results suggest an upper mantle water content of at most 0.1% by volume.

Large Diurnal Sea Surface Temperature Variability: Satellite and In Situ Measurements

Abstract: Data from a surface mooring located in the Sargasso Sea at 34°N, 70°W between May 1982 and May 1984 were compared with satellite data to investigate large diurnal sea surface temperature changes. Mooring and satellite measurements are in excellent agreement for those days on which no clouds covered the site at the time of the satellite pass. During the summer half-year at this site, there is a 20% charm of diurnal warming of more than 0.5°C, with values of up to 3.5°C observed in the two-year period. Diurnal warming observed at the mooring has been simulated well by a one-dimensional model driven by local beat and momentum fluxes. Under the conditions of very light wind and strong insolation that produce the Largest surface warming, the surface mixed-layer depth reduces to the convection depth, and wind-mixing becomes unimportant. The thermal response is then limited to depths between 1 and 2 m, making it likely that such events have been underreported in routine ship observations. In all cases observed, the spatial extent of warming events as determined by satellite data are well correlated with the corresponding atmospheric pressure patterns. Conditions giving rise to the largest diurnal warming events are often associated with a westward-extending ridge of the Bermuda high. In the region studied, 57°–75°W and 29°–43°N, diurnal warming of more than 1°C was found on occasion to cover areas in excess of 300 000 km2, with warming of more than 2°C coveting areas in excess of 130 000 km2.

Structure and function of a benthic invertebrate stream community as influenced by beaver (Castor canadensis)

Abstract: Beaver (Castor canadensis) affect the benthic invertebrate community of small woodland streams in Quebec through habitat modifications Their activities influence community structure through the replacement of lotic taxa by lentic forms and community function by increasing the absolute importance of collectors and predators while decreasing the relative importance of shredders and scrapers in impounded sites At our study site during the 1983 ice-free season, standing stocks of coarse particulate organic matter (>1 mm) were 2–5 times greater (P<005) in impounded sites than riffle sites in spring and summer Fine (212 μm–1 mm) and very fine (05 μm–212 μm) particulate organic matter were 3–10 times greater (P<005) in impounded sites in all seasons Chlorophyll a standing stocks did not differ statistically among sites Total density and biomass of invertebrates in impoundments were 2–5 times greater (P<005) than riffle sites in spring and summer, but statistically similar in autumn Generic diversity (H′) was greater (P<005) in unaltered sites in autumn Non-impounded sites were dominated by Simuliidae, Tanytarsini chironomids, scraping mayflies and net spinning caddisflies while impounded sites were characterized by Tanypodinae and Chironomini chironomids, predacious odonates, Tubificidae, and filtering pelycopods Our results suggest that current paradigms applied to lotic ecosystems need to be reevaluated to incorporate the influence of beaver upon invertebrate communities

A new sulfur-reducing, extremely thermophilic eubacterium from a submarine thermal vent.

Abstract: A newly described bacterial isolate, designated strain NS-E, differs from presently known extremely thermophilic bacteria in various characteristics. It is a strictly heterotrophic eubacterium of marine origin and has a temperature range for growth of 50 to 95 degrees C with an optimum at 77 degrees C and a pH of 7.5. Its DNA base composition is 41.3 mol% guanine + cytosine. It is obligately anaerobic, utilizes various sugars as well as yeast extract, and reduces elemental sulfur facultatively to hydrogen sulfide. In 24-h cultures cell densities are up to fourfold higher in the presence than in the absence of elemental sulfur. Sulfide concentrations of 1.0 and 10.0 mM limit growth by 65 and 95%, respectively. Oxygen sensitivity is apparent only at or above that range of temperature at which growth occurs.

Whale reactions to human activities in cape cod waters

Abstract: A review of our whale observations of more than 25 years indicated that each of the species commonly observed within 35 km of Cape Cod reacted differently to stimuli from human activities, and that these responses have gradually changed with time. Over the years of exposure to ships, for example, minke whales (Balaenoptera acutorostrata) have changed from frequent positive interest to generally uninterested reactions, finback whales (B. physalus) have changed from mostly negative to uninterested reactions, right whales (Eubalaena glacialis) have apparently continued the same variety of responses with little change, and humpbacks (Megaptera novaeangliae) have dramatically changed from mixed responses that were often negative to often strongly positive reactions. These reactions appeared to result mostly from three types of stimuli: primarily underwater sound, then light reflectivity, and tactile sensation. The whale reactions were related to their assessment of the stimuli as attractive, uninteresting or disturbing, their assessment of the movements of the sources of the stimuli relative to their own positions, and their assessment of the occurrence of stimuli as expected or unexpected. Whale reactions were modified by their previous experience and current activity: habituation often occurred rapidly, attention to other stimuli or preoccupation with other activities sometimes overcame their interest or wariness of stimuli, and inactivity seemed to allow whales to notice and react to stimuli that otherwise might have been ignored. The changes over time in the reactions of whales to stimuli from human activities were gradual and constantly varying with increased exposure to these activities.

Observations of solitary waves in a viscously deformable pipe

Abstract: We have made simple observations of the ascent of a buoyant fluid through a pipe formed in a denser and more viscous fluid that can deform viscously and allow the pipe radius to change. There is no wall between the two fluids, and the Reynolds number is small in both fluids. If the buoyant fluid is supplied at a uniform rate, the system exhibits uniform Poiseuille flow. The response of the system to fluctuations in the rate of supply of the buoyant fluid is to form local maxima in the pipe radius that ascend as solitary waves. Larger-amplitude waves can catch up and collide with smaller waves and, to a good approximation, both waves recover their original form and amplitude after such a collision. Periodic wavetrains are formed when the supply of fluid to the pipe is increased and sustained at a higher rate. These observations gain significance because the system is analogous to that of one-dimensional buoyancy-driven porous flow in a viscous matrix. The experiment may be regarded as a laboratory analogue for studying some aspects of the equations governing porous flow. The observed behaviour is consistent with recent theoretical and computational studies, which have focused on the problem of magma migration in the Earth. The behaviour we observe will, however, arise in other systems governed by the same mechanics. The existence of solitary waves in such systems means that the responses to transient changes in the porosity or the supply of fluid could be long-lived.

Monooxygenase Induction and Chlorobiphenyls in the Deep-Sea Fish Coryphaenoides armatus

Abstract: Inhibition of liver microsomal ethoxyresorufin O-deethylase and aryl hydrocarbon hydroxylase activities by α-naphthoflavone and by polyclonal antibodies to hydrocarbon-inducible cytochrome P-450E from teleost liver indicated a xenobiotic-induced origin of these activities in the deep-sea fish Coryphaenoides armatus. Specific recognition of a protein by antibodies to P-450E in an immunoblot assay further indicated xenobiotic-induced cytochrome P-450 in these animals. Levels of apparently induced cytochrome P-450 and monooxygenase activity correlated positively with the tissue content of chlorobiphenyls of known inducing activity, implicating such compounds in biochemical effects occurring in the deep ocean.

Input of excess CO2 to the surface ocean based on 13C/12C ratios in a banded Jamaican sclerosponge

Abstract: The CO2 content of the atmosphere has increased during the past two centuries as a result of the combustion of fossil fuels for energy1 and the reduction of forest and soil carbon reservoirs on land2. The amount of CO2 added to the atmosphere from fossil-fuel burning is known from historical records1 (±10%), but the contribution from reduction of the terrestrial biosphere is far less certain. Several authors have estimated the relative contributions from the two sources by measuring the change in the 13C/12C ratio in atmospheric CO2 as revealed in tree rings3–8 (CO2 derived from these two sources is depleted in 13C with respect to that in the atmosphere). Using trees in the Northern Hemisphere, recent estimates of the integrated CO2 release from the terrestrial biosphere since AD 1800 ranged from 70% (ref. 5) to 90% (ref. 9) of that released from fossil fuels. Here we present surface ocean δ13C and δ18O records measured in the skeleton of a living sclerosponge (Ceratoporella nicholsoni), which accretes aragonite in isotopic equilibrium with the surrounding sea water/dissolved inorganic carbon (DIC) system. The δ13C record reveals a decrease of 0.50‰ from 1820 to 1972. Using a model of the world carbon cycle and a deconvolution of our δ13C data, we estimate that the amount of excess CO2 derived from the terrestrial biosphere is ∼38% of that from fossil-fuel sources. Our model calculations support a preindustrial CO2 concentration in the atmosphere of 280 p.p.m.v. (parts per million by volume), in agreement with direct measurements of air occluded in Antarctic ice cores10.

Late Quaternary deep-ocean circulation

Abstract: A review of paleoceanographic studies dealing with late Quaternary deep-water circulation in the oceans is presented. These studies, which are based on the analysis of deep-sea benthic foraminiferal faunal and geochemical data and sedimentological data, are discussed in light of physical oceanographic conditions in the modern ocean. We include in this review a re-evaluation of benthic foraminiferal data from North Atlantic and Southern Ocean piston cores and suggest that the dominance of Uvigerina during glacial intervals reflects increased amounts of organic carbon at the sea floor compared to modern values. A number of geochemical studies have suggested that the production or characteristics of North Atlantic Deep Water (NADW) changed during glacial times. Although these changes have been thought to result from a cessation of overflow water from the Norwegian-Greenland Seas, it is suggested here that seasonal sea-ice cover was possible over southern portions of the Norwegian Sea during glacial intervals. The presence of seasonally open water would have allowed Norwegian Sea Overflow Water to have been produced, although perhaps at lower volumes and with different hydrographic properties than at present. The record of Antarctic Bottom Water (AABW) circulation does not show a simple relationship with paleoclimatic oscillations, indicating that changes in oceanographic conditions in the Southern Ocean had little effect on AABW formation. The AABW record contrasts with the glacial-interglacial cycles of NADW, suggesting no direct link between AABW and NADW circulation. A variety of data suggests that changes in Pacific Deep Water circulation occurred as a result of glacial production of North Pacific deep water or from an increased flux of Southern Ocean water.

On the continuity of mean flow between the Scotian Shelf and the Middle Atlantic Bight

Abstract: Oxygen-isotope tracer data combined with results from two linear barotropic coastal models are used to argue that the observed equatorward mean alongshelf flow in the Middle Atlantic Bight is a downstream extension of the mean alongshelf flow over the Scotian Shelf. Qualitative agreement between model results and observations supports the concept that the alongshelf pressure gradient associated with the mean alongshelf flow in the Middle Atlantic Bight has an upstream or downstream and not an offshelf origin. The role of the local large-scale general circulation is apparently to help keep the shelf water on the shelf rather than to drive the shelf mean flow.

Microoxic-Anoxic Niche of Beggiatoa spp.: Microelectrode Survey of Marine and Freshwater Strains

Abstract: Beggiatoa spp. grow optimally in media containing opposed gradients of oxygen and soluble sulfide, although some strains also require an organic substrate. By using microelectrodes, we characterized oxygen and sulfide gradients during their initial development in uninoculated media and in cultures of marine and freshwater strains. In gradient media, Beggiatoa strains always grew some distance below the air/agar interface as a dense “plate” of constantly gliding filaments with sharply demarcated upper and lower boundaries. Within established plates, the maximum oxygen partial pressure was 0.6 to 6.0% of air saturation and not significantly lower if filaments were fixing nitrogen. Oxygen penetrated only 100 to 300 μm into the plate, and the anoxic fraction increased from less than 10% to approximately 90% during later stages of growth. For lithoautotrophically grown marine strains, the linearity of the oxygen profile above the plate plus its drop to zero therein indicated that oxygen uptake for the entire tube occurred only within the Beggiatoa plate. Consequently, oxygen consumption could be predicted solely from the distance between the air/agar interface and the top of a plate, given the diffusion coefficient for oxygen. By contrast, for freshwater strains grown heterotrophically (with sulfide also in the medium), oxygen profiles were frequently nonlinear because of nonbiological reaction with sulfide which had diffused past the aggregated filaments. For all strains tested, microoxic aggregation also occurred in the absence of sulfide, apparently reflecting a step-up phobic response to oxygen.

On phytoplankton growth rates and particulate C: N: P ratios at low light1

Abstract: In a series of continuous culture experiments involving N-limited growth of the chrysophyte Pavlova lutheri (Mono) I found that large deviations in cellular C: N: P ratios from the Redfield ratio of 106 : 16 : 1 occurred only as a function of low relative growth rate and not of low light intensity. By contrast, light-limited phytoplankton in continuous culture can attain the Redfield chemical proportions at all combinations of light intensity and dilution rate. Because the absolute magnitude of the maximum growth rate is variable with respect to light intensity and other abiotic factors, the chemical composition of particulate matter can be used as a diagnostic tool to estimate the degree of nutrient deficiency of both laboratory-grown and natural phytoplankton populations at all light intensities. There is an abundance of data from recent oceanic studies to substantiate the possibility that the chemical composition of oceanic phytoplankton typically is in the Redfield proportions. These results support the hypothesis that oceanic phytoplankters are growing at relative growth rates close to unity.