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Research and Discoveries: The Revolution of Science through Scuba
Michael A. Lang, Roberta L. Marinelli, Susan J. Roberts, and Phillip R. Taylor, editors
vi + 258 pages, 111 figures
2013 (Date of Issue: 21 October 2013)
Number 39, Smithsonian Contributions to the Marine Sciences
DOI: 10.5479/si.1943667X.39
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Abstract
The Smithsonian Institution, the National Science Foundation, and the Ocean Studies Board of the National Research Council convened the “Research and Discoveries: The Revolution of Science through Scuba” symposium on 24–25 May 2010 in Washington, D.C., to celebrate the advances and scientific contributions of research using self-contained underwater breathing apparatus (scuba). This volume presents 19 papers by 60 scholars of research findings, with particular focus on the scientific contributions accomplished using scuba. It is the first major effort to highlight and validate the use of scuba in science by evaluating the output of scientific research in high-impact journal publications. Thirteen papers report research findings and discoveries from around the world in environments such as coral reefs, oceanic blue water, under-ice polar habitats, and temperate kelp forests, providing perspectives on ecological scales and function, physiology, symbiosis and chemistry, biodiversity and behavior, and structured populations. The final six papers are illustrative of underwater research that was not only greatly facilitated by scuba, but could perhaps not have been accomplished without it. Topics range from biological studies on the coral holobiont to ecological roles of major algal groups on reefs and the functional role of small and cryptic metazoans. The research facilitated by scuba and reported in these papers focuses on the scientific results, not necessarily on the research methodologies using scuba to obtain those data and observations, and includes several case studies. Where appropriate, laboratory studies complementary to underwater field observations are referenced. The symposium showed the strong integration and validation of scientific diving within the overall science domain since the introduction of scuba to the science community in 1951. Overarching symposium themes celebrated past, present, and future scientific diving contributions, and evaluated the accomplishments and impact of underwater research on the overall understanding of nature and its processes. Enduring materials from the symposium, including abstracts, speaker biographies, and webcast videos of presentations, have been posted at www.si.edu/sds.

The Saint-Antonin Conglomerate in the Maritime Alps: A Model for Coarse Sedimentation on a Submarine Slope
Daniel Jean Stanley
25 pages, 12 figures, 1 table
1980 (Date of Issue: 23 July 1980)
Number 5, Smithsonian Contributions to the Marine Sciences
DOI: 10.5479/si.01960768.5
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Abstract

The Upper Eocene to Lower Oligocene Saint-Antonin Conglomerate, a formation more than 1000 m thick well exposed in the French Maritime Alps, about 30 km north of the Mediterranean coast, comprises coarsening-upward successions, or megasequences, of silty shale-siltstone, sandstone and conglomerate sections. The megasequences include coarse channelized deposits associated with coarse lenticular and fine-grained sheet facies that are identified as migrating channels and lobe and channel overflow deposits. Microfossils in the finer-grained units indicate dispersal in an open marine, outer shelf to upper bathyal environment where minimal depths ranged from 100 to 200 m. The spatial and temporal distribution patterns of facies successions, assemblage of stratification types and sedimentary structures, and petrology of the various textural grades indicate submarine progradation on a slope, or in a slope basin, seaward of a fan delta system. The Saint-Antonin Conglomerate is more similar to alluvial fans than to some of the gravel-rich submarine fan deposits that accumulate on a gentle gradient at the base of a slope. The coarsening-upward megasequences record a strong tectonic overprint, including a northward shift of the basin margin on which these strata were deposited, concurrent andesitic flows and structurally-induced fan delta switching on the adjacent land. This latter phenomenon was largely responsible for the irregular back-and-forth migration of the sandstone and gravel-rich tongues on the upper slope. Emplacement of poorly sorted (disorganized) conglomerates and pebbly sandstones, and of strata displaying crudely stratified inverse grading or preferred clast fabric, was largely by debris flow and associated high-concentration dispersions. Slumping, turbulent flows with some bed-load traction and turbidity currents also were effective mechanisms for the transport of sediment to proximal depositional sites on the slope. Modern counterparts of the Saint-Antonin Conglomerate are probably to be found on the leading edge of plates, rift margins and other tectonically-active coastal chain-bounded margins where coarse terrigenous sediments bypass narrow shelves and are transported directly on steep mobile slopes.


Salt Tectonics and Basement Fractures: Key Controls of Recent Sediment Distribution on the Balearic Rise, Western Mediterranean
Gilbert Kelling, Andrés Maldonado and Daniel Jean Stanley
52 pages, 19 figures, 9 tables
1979 (Date of Issue: 19 October 1979)
Number 3, Smithsonian Contributions to the Marine Sciences
DOI: 10.5479/si.01960768.3
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Abstract

The Balearic Rise is a morphologically and structurally complex feature on the southern margin of the Balearic Platform, in the western Mediterranean. Originating as a foundered block in Late Miocene time, the rise has acquired a sedimentologically diverse cover of Plio-Quaternary sediments. A study by means of high-resolution reflection profiling (3.5 kHz) and gravity/piston cores emphasizes the effects of a variety of sedimentary processes and of structural controls in the genesis of these Plio-Quaternary sequences. During this geologically recent time interval the Menorca Canyon-Valley-Fan system has exerted an important influence on the sedimentary development of this marginal feature.

On the basis of the 3.5kHz profiles, eight categories of acoustic response of the seafloor and shallow subbottom sediments have been defined and can be linked to distinctive sub-environments of the rise that are characterized by specific sedimentary and structural attributes. Abrupt variations in thickness of the Plio-Quaternary sequence attest to the continuing activity of faulting, which has generated a horst-and-graben morphology across most of the rise. More continuous subsidence is evident below the Menorca Fan but even here subrecent fracturing, accompanied by salt-diapirism, has produced a physiographic and sedimentologic complexity which differs significantly from most of the currently accepted submarine fan models.

The cored sediments fall into five main types: bioclastic (and terrigenous) sand, silt, turbidite mud, hemipelagic mud, and calcareous ooze. Combinations of these sediment types form three principal associations or sequences: channel sands, turbiditic sequences, and hemipelagic sequences. Four distinct core assemblages are also recognized, on the basis of predominant sediment type and sequence: channel sand assemblage, proximal turbiditic/hemipelagic assemblage, hemipelagic/turbiditic mud assemblage, and basin plain assemblage.

Radiocarbon dating of core samples yields average sedimentation rates of 6 to 7 cm per thousand years, the highest rates being encountered on the Balearic Basin plain and in the main Menorca Fan channel while the lowest rates occur in the hemipelagic muds of the elevated regions of the rise. Most of the thick channel sands were deposited between 23,000 and 16,000 years BP, during the last major lowering of sea level.

The Menorca Fan differs significantly in physiography and sediment distribution from most other modern submarine fans, mainly because of the reduced importance of overbank flow and channel migration, which results from the activity of shallow fractures and the blocking effects of salt-diapirs, together with the exceptionally coarse grade of material supplied to the fan.


Seagrasses
Ronald C. Phillips and Ernani G. Menez
104 pages, 57 figures, 39 maps, 4 tables
1988 (Date of Issue: 29 December 1988)
Number 34, Smithsonian Contributions to the Marine Sciences
DOI: 10.5479/si.01960768.34
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This work presents general and current information on seagrass ecology, physiology, biology, distribution and evolution. Additionally, all known taxa of seagrasses are keyed to recognized species. Forty-eight species are described and illustrated, with accompanying maps to indicate their world distribution.


Seagrasses from the Philippines
Ernani G. Menez, Ronald C. Phillips and Hilconida P. Calumpong
40 pages, 26 figures
1983 (Date of Issue: 1 December 1983)
Number 21, Smithsonian Contributions to the Marine Sciences
DOI: 10.5479/si.01960768.21
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Seagrasses were collected from various islands in the Philippines during 1978-1982. A total of 12 species in seven genera are recorded. Generic and specific keys, based on vegetative characters, are provided for easier differentiation of the seagrasses. General discussions of seagrass biology, ecology, collection and preservation are presented. Local and world distribution of Philippine seagrasses are also included.


Sohm Abyssal Plain: Evaluating Proximal Sediment Provenance
Daniel Jean Stanley, Patrick T. Taylor, Harrison Sheng and Robert Stuckenrath
48 pages, 23 figures, 5 tables
1981 (Date of Issue: 23 October 1981)
Number 11, Smithsonian Contributions to the Marine Sciences
DOI: 10.5479/si.01960768.11
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The southernmost part of the Sohm Abyssal Plain in the Northwest Atlantic Basin is geographically distal with respect to the major source of Quaternary terrigenous material transported from the Canadian Maritime Provinces. An assessment of the proportion of more locally introduced sediment relative to that derived from distal sources is based largely on size and compositional analyses of Quaternary piston core samples. These data are supplemented by radiocarbon dating of selected core samples, bottom photographs, conductivity-temperature-depth profiles, and seismic records.

The premises of the study are that (a) locally derived sediment should be most abundant near high-relief bathymetric features such as seamounts and abyssal hills, and (b) such material should contain enhanced proportions of reworked volcanic debris and alteration products. Core analyses reveal that the amounts of these are directly related to proximity of volcanic ocean-bottom features, and that a significant, although not total, amount of such volcanic materials recovered from cores are derived from submarine weathering of basalt. Associated with this assemblage are nannofossils, dating from the Quaternary to the Upper Cretaceous, reworked from older strata. This increased proportion of volcanic and related products and reworked faunas near seamounts and basement rises strongly implies that such topographic features continue to serve as major source terrains. Locally derived volcanic materials, however, are usually disseminated and masked on the Sohm Abyssal Plain, particularly in sectors receiving large amounts of terrigenous turbidites and biogenic suspensates, and/or undergoing reworking by bottom currents.

We propose that the volcanic fraction can serve as a useful index, or “yardstick,” to interpret the role of locally derived material in abyssal plain sedimentation. A sedimentation model is developed to illustrate the premise that as access to land-derived sources diminishes, the proportion of terrigenous components is reduced while pelagic and volcanic fractions are enhanced. Thus, sediment accumulating in abyssal plains almost totally isolated from terrigenous sources would comprise significant amounts of pelagic (including wind-blown) and volcanic components. Our model illustrates that even in an abyssal plain, such as the Sohm, which has had an important and direct access to abundant distally derived terrigenous sources, particularly during the Pliocene and Quaternary, the locally supplied reworked volcanic products account for a significant fraction of the total abyssal plain sediment fill.


Submarine Canyon Wall Sedimentation and Lateral Infill: Some Ancient Examples
Daniel Jean Stanley
32 pages, 17 figures
1980 (Date of Issue: 13 February 1980)
Number 4, Smithsonian Contributions to the Marine Sciences
DOI: 10.5479/si.01960768.4
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Abstract

Submarine canyon wall and tributary sequences at three Annot Sandstone localities in the French Maritime Alps record early-stage resedimentation events in proximal sectors of the Tertiary Annot Basin. Canyon margin lithofacies are distinctive in that they comprise a more variable suite of stratal types than intracanyon slope, canyon axis, distal fan and basin series of the same formation. Characteristic criteria include the highly variable geometry and spatial distribution of the series of strata, irregular bedding thickness, paleocurrent directions that diverge from the predominant regional patterns, and discontinuities within the formation and between the Annot Sandstone and the older marine shale series (Eocene Marnes bleues) forming the canyon margins. Three distinctive sandstone stratification types dominate the “grès d'Annot” canyon wall association: type 1 units, moderately to well-stratified and massive (often amalgamated), emplaced by debris flow and a continuum of sediment-fluid flow mechanism, not specifically identifiable in the field; some thick sand layers may represent deposition as ‘quick’ beds from high-concentration underflows, possibly gradational between liquified and turbidity current flows; type 2 units, displaying slightly to extensive deformed horizons within but not throughout the beds, probably are related to liquefied flow and post-depositional liquefaction processes; and type 3 units, emplaced ‘en masse’ and in some cases showing complete disruption of primary stratification (chaotic bedding), are identified as slides and slumps. In addition to the three above types, lower proportions of graded, generally thin ‘classic’ sandstone turbidites (Ta-b, Tb-c, and Tb-e) and mudstone turbidites are recognized.

Although they appear as distinctly different entities in the field, a genetic relation between some depositional types is suggested. The mapped facies diversity is interpreted in terms of flow transformation, that is, the release of different sediment types along the dispersal path from a single sediment gravity flow as it evolves during its progression downslope. The diversity of mass flow products at the three canyon margin localities records a variable succession of transformation phases on the relatively steep slopes (locally in excess of 10°) within a short distance from the point of initial failure. The distinctive aspect of “grès d'Annot” canyon margin sedimentation is the repetitive erosion→transport→deposition pattern of lateral infill. Definition of these proximal lithofacies serves to better understand the origin of the more distal marine fan and Annot Basin plain sequences seaward of the three canyon localities examined and also can be applicable to the study of modern canyon-fan settings.


Swimming Sea Cucumbers (Echinodermata: Holothuroidea): A Survey, with Analysis of Swimming Behavior in Four Bathyal Species
John E. Miller and David L. Pawson
18 pages, 4 figures
1990 (Date of Issue: 1 June 1990)
Number 35, Smithsonian Contributions to the Marine Sciences
DOI: 10.5479/si.01960768.35.1
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New information on swimming behavior of four species of deep-sea holothurians has been obtained using the research submersibles Johnson-Sea-Link (Harbor Branch Oceanographic Institution) and Pisces V (University of Hawaii, HURL Program). Hansenothuria benti Miller and Pawson and Enypniastes eximia Theel were studied off the Bahama Islands, Paelopatides retifer Fisher off the Hawaiian Islands, and Pelagothuria natatrix Ludwig off the Galapagos Islands. Video recordings were made of swimming behavior, and individuals of all species were collected at the time of observation. Four contrasting life modes are represented: H. benti lives and feeds on the seafloor, but when disturbed it can swim vigorously for several minutes by rapidly flexing the anterior and posterior ends of the body into S curves. Enypniastes eximia swims almost continuously, briefly settling to the seafloor to ingest surface sediments. The bulbous body is propelled upwards by rhythmic pulsation of a webbed anterodorsal veil; stability during swimming is maintained by counteractive flexing of posterolateral veils. Paelopatides retifer lives on or near the seafloor and has been found up to 300 meters above the seafloor. The swimming behavior of this species combines locomotory movements of the two preceding species. An anterior veil pulsates, and the posterior half of the body flexes into S curves. Pelagothuria natatrix is truly pelagic, floating or drifting near the seafloor or high in the water column. Swimming is effected by infrequent and irregular pulsation of an enormous anterior veil. There is no evidence to suggest that P. natatrix descends to feed on the seafloor.

Published data on the approximately 25 known species of swimming holothurians are summarized. Probable reasons for swimming behavior are discussed. Swimming appears to be most useful in predator avoidance, escape from physical hazards, locomotion, seeking out suitable substrata for feeding, and dispersal of juveniles or adults.


Systematics and Ecology of the Sea-Urchin Genus Centrostephanus (Echinodermata: Echinoidea) from the Atlantic and Eastern Pacific Oceans
David L. Pawson and John E. Miller
15 pages, 5 figures, 5 tables
1983 (Date of Issue: 26 September 1983)
Number 20, Smithsonian Contributions to the Marine Sciences
DOI: 10.5479/si.01960768.20.1
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Surveys by the Johnson-Sea-Link submersibles have revealed the presence of large populations of black Centrostephanus, superficially resembling Diadema antillarum Philippi, along the shelf edge prominences off the east coast of Florida in depths of 48-80 meters. Typical habitats are aggregations of dead coral rubble, with seasonal growths of leafy red algae. Some aspects of the biology of these echinoids are described.

We affirm that only a single species of the genus, Centrostephanus longispinus (Philippi), occurs in the Atlantic Ocean. As Fell (1975) and Serafy (1979) have shown, western Atlantic populations can be referred to the subspecies Centrostephanus longispinus rubicingulus H.L. Clark, which usually differs from the typical subspecies in possessing uniformly black spines rather than banded purple and yellowish white spines when fully grown. C. besnardi Bernasconi from Isla Trindade, Brazil, is herein synonymized with C. longispinus rubicingulus. C. coronatus (Verrill) from California and the Galapagos Islands differs little from C. longispinus and the two species may yet prove to be subjective synonyms. There is some evidence to suggest that Gulf of California populations of C. coronatus differs from California populations at the subspecies level.


Turbidites Reworked by Bottom Currents: Upper Cretaceous Examples from St. Croix, U.S. Virgin Islands
Daniel Jean Stanley
79 pages, 63 figures, 3 tables
1988 (Date of Issue: 2 June 1988)
Number 33, Smithsonian Contributions to the Marine Sciences
DOI: 10.5479/si.01960768.33
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Sedimentological study of the Late Cretaceous volcaniclastic deposits in St. Croix, U.S. Virgin Islands, emphasizing primary structures and bedforms, reveals a remarkable suite of sandy lithofacies. An inventory of the different sand types in several formations shows that a natural continuum of deposits exists between downslope-directed gravity flow and bottom current-tractive “end-member” deposits. Most sandy strata, herein termed “intermediate variants,” record primary emplacement by turbidity currents, probably from the north, and a subsequent reworking of these layers by bottom currents flowing toward the west. The sand layers accumulated in a proximal setting, perhaps slope aprons, and these were then reworked along bathymetric contours. The lower portion of sand layers typically displays the original graded (A) turbidite division, while the texturally cleaner mid and upper parts of such strata usually show structures more typically associated with tractive transport. Photographs of polished slabs and large thin sections of the diverse Cretaceous sand layer types on St. Croix, reproduced at a 1:1 scale, may serve as a basis for comparison with other deep-water formations in the modern and ancient record. They may be most useful in interpreting sequences such as those on St. Croix where a solely turbidite or gravity-emplaced interpretation is inadequate.

This petrologic investigation also sheds further light on the paleogeography of the region. Examination of the sandy volcaniclastic sequences supports earlier hypotheses that they accumulated in a tectonically active island-arc setting. A strong tectonic and volcanic imprint is displayed by the syndepositional deformation of fabric, bedforms, and primary structures. Paleocurrent analyses indicate that, in what was to become the northeastern part of the Caribbean, the predominant bottom-current trend during Late Cretaceous time was roughly parallel to the surface circulation pattern, i.e., directed toward the west. The vigorous reworking of coarse sand and granule turbidites, and the development of bioturbation structures in tractive deposits indicate that, although the paleo-Atlantic was geographically much narrower, bottom-water circulation in this region was not restricted nor were bottom waters anoxic. Recognition here of the diverse suite of reworked sandy turbidite lithofacies, poorly documented to date, can hopefully serve to clarify other cases in both the modern and rock record where there has been interaction between bottom currents and turbidity currents.


Displaying 31 - 40 from the 41 total records