Showing papers by "University of Rhode Island published in 1980"

Long-Range Atmospheric Transport of Soil Dust from Asia to the Tropical North Pacific: Temporal Variability

Abstract: The concentration of airborne soil dust at Enewetak Atoll(11°N, 162°E) in April 1979 was 2.3 micrograms per cubic meter but decreased steadily to 0.02 microgram per cubic meter over the next 5 months. The spring dust is probably derived from China; its deposition rate (∼0.3 millimeter per 1000 years) suggests that it may be a significant contributor to the deep-sea sediments of the North Pacific.

Between Coastal Marshes and Coastal Waters — A Review of Twenty Years of Speculation and Research on the Role of Salt Marshes in Estuarine Productivity and Water Chemistry

Abstract: It has been almost 20 years since John Teal (1962) published his well-known paper synthesizing a variety of independent studies of production, respiration, and animal abundances in the salt marsh ecosystem of Sapelo Island, Georgia. Teal’s work brought out a number of interesting points, but I think the reason the paper is most often cited is because of its last sentence. After discussing various trophic relationships in the marsh, the paper ended with the conclusion that “...the tides remove 45% of the production before the marsh consumers have a chance to use it and in so doing permit the estuaries to support an abundance of animals.”

Halogens in the Mantle Beneath the North Atlantic

Abstract: F, Cl and Br contents of tholeiitic volcanic glasses dredged along the Mid-Atlantic Ridge from 53 degrees to 28 degrees N, including the transect over the Azores Plateau, are reported. The halogen variations parallel those of $^{87}$Sr/$^{86}$Sr, La/Sm or other incompatible elements of varying volatility. The latitudinal halogen variation pattern is not obliterated if only Mg-rich lavas are considered. Variations in extent of low-pressure fractional crystallization or partial melting conditions do not appear to be the primary cause of the halogen variations. Instead, mantle-derived heterogeneities in halogens, with major enrichments in the mantle beneath the Azores, are suggested. The Azores platform is not only a 'hotspot' but also a 'wetspot', which may explain the unusually intense Azores volcanic activity. The magnitude of the halogen and incompatible element enrichments beneath the Azores appear strongly dependent on the size of these anions and cations, but independent of relative volatility at low pressure. The large anions Cl and Br behave similarly to large cations Rb, Cs and Ba, and the smaller anion F similarly to Sr and P. Processes involving crystal and liquid (fluid and/or melt), CO$\_{2}$ rahter than H$\_{2}$O dominated, seem to have produced these largescale mantle heterogeneities. Geochemical 'anomalies' beneath the Azores are no longer apparent for coherent element pair ratios of similar ionic size. Values of such 'unfractionated' coherent trace element ratios provide an indication of the mantle composition and its nature before fractionation event(s) which produced the inferred isotopic and trace element heterogeneities apparently present beneath the North Atlantic. The relative trace element composition of this precursor mantle does not resemble that of carbonaceous chondrites except for refractory trace element pairs of similar ionic size. It is strongly depleted in halogens, and to a lesser extent in large alkali ions Rb and Cs relative to refractory Ba. These relative depletions are comparable within a factor of 5 to Ganapathy & Anders's estimates for the bulk Earth, with the exception of Cs. There is also evidence for removal of phosphorus into the iron core during its formation. With the exception of San Miguel, alkali basalts from the Azores Islands appear to have been derived from the same mantle source as tholeiitic basalts from the ridge transect over the Azores Platform but by half as much degree of partial melting. The Azores subaerial basalts seem to have been partly degassed in Cl, Br and F, in decreasing order of intensity. A working model involving metasomatism from release of fluids at phase transformation during convective mantle overturns is proposed to explain the formation of mantle plumes or diapirs enriched in larger relative to smaller halogen and other incompatible trace elements. The model is ad hoc and needs testing. However, any other dynamical model accounting for the 400-1000 km long gradients in incompatible trace elements, halogens and radiogenic isotopes along the Mid-Atlantic Ridge should, at some stage, require either (1) some variable extent of mixing or (2) differential migration of liquid relative to crystals followed by re-equilibration (or both), as a diffusion controlled mechanism over such large distances is clearly ruled out, given the age of the Earth.

Analysis of organic carbon in marine sediments1

Abstract: A method is presented for measuring organic carbon in both carbonate-rich and carbonate-poor marine sediments. Samples are sonicated with phosphoric acid to remove carbonates. The spent acid supernatant is analyzed for dissolved organic carbon, the solid residue for total carbon; their sum yields the organic carbon content of the sample. The technique is free from carbonate interferences, involves no losses due to acid solubilization, and has excellent precision (better than ±0.02% Corg) and accuracy (better than ±2%).

On the origin and transport of the winter arctic aerosol

Abstract: Results of a systematic study of the winter aerosol at Barrow, Alaska, are presented which show that the atmosphere of arctic Alaska contains an abundance of pollution-derived aerosol, particularly during the winter half-year, and that Europe, rather than the US, appears to be primarily responsible for the winter arctic aerosol It is found that the aerosol is an order of magnitude more concentrated in winter than in summer throughout most of the troposphere, is gray in winter but colorless in summer, is much more enriched in pollution-derived constituents (such as V, Mu, and SO/sub 4/) in winter than in summer, and appears to be highly secondary in nature A simple transport model is described, and it is demonstrated that the actual concentrations of V, SO/sub 4/, and Pb-210 at Barrow are quantitatively consistent with polluted European air masses as the source, followed by transport over the European USSR and then to the north

The relation between pore water chemistry and benthic fluxes of nutrients and manganese in Narragansett Bay, Rhode Island

Abstract: Ahs tract Benthic fluxes of dissolved nutrients and manganese from biologically disturbed, relatively unpolluted sediment in Narragansett Bay, Rhode Island, have been measured. Analyses of the vertical gradients of chemical species dissolved in port waters and the uptake of 22Na from the overlying water permits evaluation of the contribution of biological advection and molecular diffusion to the transport of dissolved materials across the sediment-water interface. The activity of bottom-dwelling organisms appears to be about as important as molecular diffusion in most cases. The sum of the independently estimated contributions by both mechanisms is in good agreement with integrated benthic fluxes measured in situ. Sulfate and oxygen oxidize comparable amounts of organic matter in these sediments.

Population genetics of skeletonema costatum (bacillariophyceae) in narragansett bay1

Abstract: During a two year period 457 clones of the diatom Skeletonema costatum were isolated prior to and during the summer-fall and winter-spring blooms of this species in Narragansett Bay, R.I. Their allozyme banding patterns were examined for 5 enzyme loci. Genotypic frequencies indicated that the winter bloom populations were genetically different from the prevalent summer bloom populations of the same species. Genetic differences between seasonal blooms are as great as those found between species of terrestrial organisms, but are not accompanied by morphological variation. Although blooms have distinct prevalent forms, they are not genetically homogeneous. No single clone is ever representative of all populations of S. costatum. The dynamics of these allochronic populations appear to be governed by a form of cyclic natural selection, and are probably a regular feature of the cycles of abundance of this species in this area. These results cast doubt on some of the assumptions often made in the “autecological approach” to phytoplankton ecology. This study comprises the first quantitative examination of the population genetics of a microalga.

Palaeoceanographic change in the Pacific at the Eocene-Oligocene boundary

Abstract: Oxygen isotopic studies both of benthic formanifera1–5 and shallow-marine carbonates6–8 have provided a useful monitor of marine palaeotemperatures. The Deep Sea Drilling Project (DSDP) has provided cores from many ocean basins to conduct detailed stable isotopic and palaeoceanographic studies of the Cenozoic and late Mesozoic. DSDP Sites 277 and 292, separated by ∼60° latitude in Palaeogene times, each record an 18O enrichment in benthic foraminifera of nearly 1‰ beginning at the Eocene–Oligocene boundary. Planktonic foraminiferal trends are similar to benthic trends in the high latitude southwest Pacific Ocean, but tropical planktonics show only a minor (∼0.3‰) increase which may reflect a change in seawater composition. These results suggest a sudden cooling of Pacific deep waters and high latitude surface waters forms a useful stratigraphic marker for the Eocene–Oligocene boundary. This boundary is particularly important because of its association with several worldwide palaeo-oceanographic and biogeographic changes. These include a sudden drop in the calcite compensation depth of 1–2 km (refs 9, 10); a decrease in planktonic microfossil diversity11–13; a change in planktonic biogeographic patterns12–14; and increased erosion of deep-sea sediments over wide areas15,16.

Allelopathic inhibition of nitrification and nitrifying bacteria in a ponderosa pine (Pinus ponderosa Dougl.) community.

Abstract: The dynamics of ponderosa pine (Pinus ponderosa Dougl.) stands in western North Dakota were studied to determine the influence of plant-produced chemicals on nitrification rates and competitive interactions within the stands. Ponderosa pine accounted for more than 98% of all tree and shrub stratum stems in this climax community. Low levels of nitrate-nitrogen relative to ammonium-nitrogen and low numbers of Nitrosomonas and Nitrobacter in the soils indicated that nitrification rates were low. Inhibition of nitrification is often attributed to low soil pH in coniferous forests, but the slightly alkaline soils in this study (pH 7.25-7.75) suggested that another factor caused the low nitrification. Evidence obtained suggested that the reduction in nitrate synthesis was due to the production and subsequent transfer to the soil of secondary plant chemicals that were toxic to Nitrosomonas. Chemical inhibitors of nitrification, including caffeic acid, chlorogenic acid, quercitin, and condensed tannins, were found in extracts from ponderosa pine needles, bark, and A horizon soils. These extracts proved to be toxic to soil suspensions of Nitrosomonas causing reductions of from 68-93% of the control. These findings indicate that climax ponderosa pine communities minimize the conversion of ammonia-nitrogen to nitrate-nitrogen by chemically inhibiting nitrification. NITRIFICATION is the microorganism-mediated oxidation of ammonia to nitrate. Since nitrate-nitrogen (NO3-N) and ammonium-nitrogen (NH4-N) are the only inorganic forms of nitrogen known to be readily assimilated and utilized by plants, and since all plant species are not equal in their abilities to absorb and/or utilize nitrate-nitrogen and ammonium-nitrogen (Bigg and Daniel, 1978; Gigon and Rorison, 1972; Krajina, Madoc-Jones, and Mellor, 1973; Van Den Driessche, 1978), the absolute quantity of each form of nitrogen available to plants is of utmost importance to the mineral nutrition of those plants. The differential fitness among certain forest species may in part be directly related to their nitrogen uptake abilities in soils with a predominance of one or the other form of available inorganic nitrogen. Therefore, the presence or absence of appreciable nitrification is an important community 1 Received for publication 28 November 1979; revision accepted 21 January 1980. We are indebted to Elmer Finck, Lloyd Hulbert, Elroy Rice, Chris Smith, Peter Wong, and two anonymous reviewers for their invaluable critiques of various drafts of this manuscript. We would also like to convey our thanks to Dick Bares and Jim Crompton for assistance with the field work. Partial funding was provided by a grant from the North Dakota Regional Environmental Assessment Program and laboratory facilities were provided by Project Reclamation at the University of North Dakota. 2 Present address: Sec. of Ecology and Systematics, Langmuir Lab., Cornell University, Ithaca, New York 14850. characteristic which can influence the predominant mode of nitrogen uptake by plants. Recent research indicates that nitrification sometimes is inhibited by plant-produced chemicals which are toxic to one or both of the microorganisms (Nitrobacter and Nitrosomonas) responsible for nitrate production in soils (Basaraba, 1964; Lodhi, 1977, 1978b; Munro, 1966a, b; Rice, 1964, 1974; Rice and Pancholy, 1972, 1973, 1974). The concomitant decreases in NO3-N that result from the curtailment of nitrification can have a significant positive impact on the mineral budget of an ecosystem because, as Likens, Bormann, and Johnson (1969) have shown, high nitrification rates can initiate large scale losses of anions and cations from forest communities. Rice and Pancholy (1972, 1973, 1974) have suggested that nitrification rates decrease along successional clines until they reach a minimum in climax communities. This minimum was shown to be related to plant-produced chemicals which inhibited nitrification in tallgrass prairie and deciduous forest climax communities. Additional information from other climax communities, which is needed to bolster or reject this hypothesis, has been lacking. Much confusion exists as to the relationship between soil pH and nitrification rate. Alexander (1961) and Brady (1974) indicate that nitrification is severely suppressed in acid soils (below pH 6.0), yet others (Likens, Bormann, and Johnson, 1969; Smith, Bormann, and Li-

Late Miocene marine carbon-isotopic shift and synchroneity of some phytoplanktonic biostratigraphic events

Abstract: A search for stable-isotopic signals and biostratigraphic events in Deep Sea Drilling Project (DSDP) cores to improve chronologic resolution with an aim to reconstruct the paleoenvironment of the preglacial and postglacial Miocene oceans has led to the recognition of an apparently global decrease in the benthic foraminiferal δ 13 C in the latest Miocene. This carbon-isotopic shift is consistently bracketed by the first evolutionary appearances of several taxa of phytoplankton the ages of which have been accurately estimated from paleomagnetically dated piston cores. The first appearance of nannofossils Amaurolithus primus and A. delicatus at 6.25 m.y. B.P. and the diatoms Thalassiosira praeconvexa and Nitzschia miocenica elongata at 6.10 and 6.00 m.y. B.P., respectively, and the carbon-isotopic shift itself (dated between 6.10 and 5.90 m.y. B.P.) provide convenient synchronous events to aid in the reconstruction of the late Miocene world ocean. Magnetostratigraphically estimated ages of other useful late Miocene nannofossil events include first appearances of Discoaster quinqueramus at 8.00 m.y. B.P., D. surculus at 6.40 m.y. B.P., Amaurolithus tricorniculatus s.s. at 5.70 m.y. B.P., A. amplificus at 5.65 m.y. B.P., and Ceratolithus acutus at 5.20 m.y. B.P., and the last appearances of D. quinqueramus at 5.45 m.y. B.P. and A. amplificus at 5.30 m.y. B.P.

Grazing of Acartia hudsonica (A. clausi) on Skeletonema costatum in Narragansett Bay (USA): Influence of food concentration and temperature

Abstract: Grazing experiments were performed with temperatureacclimated Acartia hudsonica fed the diatom Skeletonema costatum in concentrations ranging from 50 to 3×104 cell ml-1 at 5°, 10° and 15°C. The ingestion data were best fit by an Ivlev equation. Feeding threshold values of 39 and 59 cells ml-1 were not significantly different from zero; however, filtration rates were depressed at low food concentrations. Maximum filtration rates increased exponentially with temperature, reaching a maximum with copepods collected at 14°–15°C, and then declining. Both the increase in ingestion rate with increasing food concentration and the maximum ingestion rate were significantly greater as experimental temperature was increased. Maximum ingestion rates were reached at concentrations greater than 6×103 cells ml-1. Percent of body carbon ingested per day at 5 μg C L-1 increased from 1.5% at 5°C to 6.7% at 15°C. At 500 μg C L-1, the ingestion increased from 84% (5°C) to 660% (15°C). Percent of body nitrogen at 0.5 μg N L-1 increased from 0.6% per day at 5°C to 2.5% per day at 15°C. At 50 μg N L-1, the ingestion was 42% body nitrogen at 5°C and 250% at 15°C. The influence of grazing by A. hudsonica on phytoplankton in Narragansett Bay, USA was estimated for 1972–1977. The percent of standing stock removed by grazing rarely exceeded 5% per day except during the late spring when S. costatum growth becomes nutrient limited and higher temperatures favor the rapid population growth of A. hudsonica.

Geostrophic fronts, bores, breaking and blocking waves

Abstract: An undisturbed geostrophic density current flows along a vertical wall (the coast) with the free streamline (the front) located at a distance L from the wall which is comparable to the Rossby radius of deformation. Finite amplitude perturbations with downstream wavelengths much larger than L are discussed, and it is shown that the slope of the front in the horizontal plane increases with time. Some perturbations tend to ‘break’ seaward by developing large transverse velocities away from the coast. The temporal evolution of some perturbations is such as to completely ‘block’ the upstream flow, but the subsequent behaviour is beyond the scope of the theory. We also discuss the propagation of the nose of the intrusion when a density current debouches from a coastal source and then flows along the coastal boundary.

Factors influencing infanticidal behavior in wild male house mice (Mus musculus)

Abstract: 1. Infanticidal behavior was examined in wild-strain male house mice (Mus musculus). Preliminary studies established that male house mice killed significantly more unrelated than related pups. Several factors influencing a male's tendency to kill unrelated young were then systematically investigated. Independent variables included the length of time a male cohabited with a pregnant female (10, 6, 3, or 1 days), the phenotype of the unrelated offspring (wild or albino), and whether the male copulated with an estrous female before cohabiting with a pregnant female. In the latter case, the estrous female was ‘painted’ with urine from the pregnant female with which the male was later paired. The dependent variable in all cases was pup survival to five days postpartum. 2. Males which copulated before cohabitation killed significantly fewer young than males which did not mate. Increased length of cohabitation significantly reduced infanticide by males which mated, but did not affect the number of pups killed by males which did not copulate. Offspring phenotype was not an important factor in preventing infanticide.

Diel variation in chlorophyll a , carbohydrate and protein content of the marine diatom Skeletonema costatum

Abstract: Skeletonema costatum (Greville) Cleve isolated from Narragansett Bay, USA, was incubated at 3 light intensities (ca. 0.008, 0.040 and 0.075 ly min-1) under a 12 h light: 12 h dark (12L:12D) photoperiod at 2°, 10° and 20°C. Cellular chlorophyll a increased at intensities less than ca. 0.040 ly min-1; increases occured within one photoperiod at temperatures above 10°C. Cellular carbohydrate increased with light intensity at all temperatures; increases during the photophase were due to net production of the dilute acid-soluble fraction. Cellular protein increased during the photoperiod at 10° and 20°C; there was little difference in cellular protein among all cultures after one photoperiod. The rate at which cellular chlorophyll a increased in response to a decrease in light suggests that diel variation in cellular chlorophyll a is temperature-dependent in S. costatum. Protein: carbohydrate ratios ranged from ca. 0.5 to 2.0 over a diel cycle; ratios increased at lower intensities and higher temperatures. The diel range in protein:carbohydrate ratios equals that in cultures developing nitrogen deficiency; thus, use of this ratio as an index to phytoplankton physiological state must account for diel light effects.