Acoustic properties of fine‐grained sediments from Emerald Basin: Toward an inversion for physical properties using the Biot–Stoll model

Acoustic data from two long cores, comprising marine clays and silts taken from Emerald Basin off Nova Scotia, are presented. High‐resolution measurements of compressional wavevelocity,attenuation, and power law exponent are made using ultrasonic frequencies between 100 to 1000 kHz. The observed values of the frequency dependence of attenuation suggest that a nonconstant Q mechanism is needed to explain these data, and Biot–Stoll theory is used to model the experimental results. An inversion scheme is used to constrain physical parameters in the Biot–Stoll dispersion relation. The inversion shows that there is a restricted range of permeability and grain size. By assigning reasonable values for grain size in the inversion, the Biot–Stoll model predicts unique values for the permeability and frame bulk modulus that agree well with estimates made by other means

Calculation of acoustic parameters by a filter-correlation method

This paper presents the filter correlation method, a technique for extracting consistent and accurate estimates of attenuation parameters from acoustic waveform data. The method minimizes problems associated with short time windows and multipath secondary arrivals. The method comprises two stages: a causal passband filter stage followed by a cross-correlation step. The results of the filter-correlation estimator are compared to those of the spectral difference approach for short time series with and without a secondary multipath arrival. Preliminary analyses of acoustic data collected on cored marine silts and clays show the attenuation properties of these materials cannot be described by a constant Q mechanism. The filter correlation method refines estimates of frequency-dependent velocity, revealing a small but systematic anisotropy between measurements made parallel and transverse to the sediments\u27 bedding plane. The observed velocity anisotropy can be modeled by assuming layered porosity variations in the cored sediments. No systematic anisotropy in attenuation was observed

Canada GEESE 2: Visualization of Integrated Marine Geoscience Data for Canadian and Proximal Waters

The Geological Survey of Canada has made most of its holdings of marine geoscience data available online with unrestricted access. These holdings constitute the premier collections of geological and geophysical source data for Canadian and proximal waters. Multibeam bathymetric imagery, analog high resolution seismic and sidescan sonar data, seabed photographs, grain size analyses, and radiocarbon dates can be directly downloaded from NRCan’s Geogratis (http://geogratis.cgdi.gc.ca) servers. KML files allow the user to discover and explore these collections, highlighting the building blocks of marine data downloadable from ftp/http servers.SOMMAIRELa Commission géologique du Canada a mis en ligne la plupart de ses fonds de données géoscientifiques marines et y donne accès sans restriction. Ces fonds constituent des collections de premier choix de données géologiques et géophysiques de base des eaux canadiennes ou proximales. On peut ainsi télécharger des serveurs Géogratis de RNCan (http://geogratis.cgdi.gc.ca) des données d’imagerie bathymétrique par secteurs, des données analogiques séismiques haute résolution et de levé de sonar à balayage latéral, des photographies du fond marin, des analyses granulométriques, et des datations au radiocarbone. Le format KML des fichiers permet aux utilisateurs d’exploiter facilement le contenu de ces collections, en mettant en relief les données marines de base téléchargeables depuis les serveurs FTP/HTTP

The Gravity Signature of a Large Quaternary Depocentre off Southeastern Canada

New bathymetry, gravity and Pliocene - Quaternary sediment isopach maps have been compiled and gridded for the Scotian margin. A large positive gravity anomaly exists over the Laurentian Fan, which is the major Pliocene - Quaternary depocentre on the Scotian margin. This gravity anomaly is not related to deep structure but can be largely explained by considering the Pliocene-Quaternary sediments as isostatically uncompensated. This implies that the underlying continental margin lithosphère has had considerable strength for at least 3 Ma. Some residual anomalies not accounted for by Pliocene-Quaternary sediment thickness may represent thicker Miocene depocentres, but improved seismic and stratigraphie data are required to assess this possibility. The technique of gravity identification of major sediment depocentres is a useful reconnaissance tool in certain circumstances, such as where there is a topographic expression and the deposit is thick and of major areal extent.On a procédé à la compilation des cartes bathymétrique, de gravité marine et des cartes isopaques des sédiments pliocènes/quaternaires de la marge continentale de Scotian. Il existe une importante anomalie gravimetrique au-dessus du cône Laurentien, principale zone d'accumulation pliocène/quaternaire de la marge continentale de Scotian. L'anomalie gravimetrique n'est pas reliée à la tectonique de fond, mais peut en bonne partie s'expliquer si l'on considère que les sédiments pliocenes/ quaternaires n'ont subi aucune compensation isostatique. Ceci implique que la lithosphère de la marge continentale sous-jacente offre une grande résistance depuis au moins 3 Ma. Certaines anomalies résiduelles non imputables à l'épaisseur de la couverture sédimentaire pliocène/quaternaire pourraient être attribuées aux épaisses zones d'accumulation du Miocène; de meilleures connaissances de la sismicité et de la stratigraphie sont nécessaires pour confirmer cette hypothèse. La technique permettant de déterminer la gravité des zones de grande accumulation est un bon outil de reconnaissance en certains cas, c'est-à-dire lorsqu'il y a un relief d'importance et que le dépôt est épais et d'une grande superficie.Neue Karten der Tiefseelotung, der Tiefsee-Schwere und "isopache" Karten der Pliozân/Quaternàr-Sedimente wurden fur den Konti-nentalsaum von Nova Scotia kompiliert. Eine breite, positive Schwereanomalie besteht ûber dem laurentidischen Fâcher, welcher die Hauptablagerungszone im Pliozân-Quaternâr am Kontinentalsaum von Nova Scotia ist. Dièse Schwereanomalie beruht nicht auf der Tiefenstruktur, sondern kann weitgehend dadurch erklàrt werden, daB die Pliozàn-Quatemàr-Sedimente isostatisch nicht kompensiert waren. Dies bedeutet, dafî die Erdkruste des darunterliegenden Kon-tinentalsaums seit mindestens 3 Ma eine betràchtliche Widerstandsfàhigkeit aufweist. Einige Rest-Anomalien, die nicht auf die Dicke des Pliozàn-Quaternâr-Sediments zurùckgefùhrt werden kônnen, kônnten mit dickeren Ablagerungszonen aus dem Miozân erklàrt werden; doch um dièse Môglichkeit zu bestàtigen, sind verbesserte seismische und stratigraphische Messungen nôtig. DieTechnik, die Schwere von bedeutenden Sedimentablagerungs zonen zu bestimmen, ist unter bestimmten Voraussetzungen ein nùtzliches Erkennungs instrument, wie z.B. wenn ein wichtiges Relief vorhanden ist, und die Ablagerung dick und von grôBeren AusmaBen ist

Environmental drivers of the occurrence and abundance of the Irukandji jellyfish (Carukia barnesi)

Understanding the links between species and their environment is critical for species management. This is particularly true for organisms of medical and/or economic significance. The 'Irukandji' jellyfish (Carukia barnesi) is well known for its small size, cryptic nature, and highly venomous sting. Being the namesake of the Irukandji syndrome, contact with this marine stinger often leads to hospitalization and can be fatal. Consequently, the annual occurrence of this organism is believed to cost the Australian government an estimated $AUD3 billion annually in medical costs and losses for tourism. Despite its economic importance the logistical difficulties related to surveying C. barnesi in situ has led to a paucity of knowledge regarding its ecology and significantly impeded management strategies to date. In this study, we use six years of direct C. barnesicapture data to explore patterns pertaining to the annual occurrence and abundance of this species in the nearshore waters of the Cairns coast. We provide novel insights into trends in medusae aggregations and size distribution and primarily focus on the potential role of environmental drivers for annual C. barnesi occurrence patterns. Using a two-part hurdle model, eight environmental parameters were investigated over four time periods for associations with records of medusa presence and abundance. Final models showed a small amount of variation in medusa presence and abundance patterns could be accounted for by long-term trends pertaining to rainfall and wind direction. However, the assessed environmental parameters could not explain high annual variation or site location effects. Ultimately best-fit models had very low statistical inference power explaining between 16 and 20% of the variance in the data, leaving approximately 80% of all variation in medusa presence and abundance unexplained

A multibeam bathymetric survey of Bay of Islands, Newfoundland: new evidence of late-glacial and Holocene geological processes

Multibeam bathymetric imagery of Ray of Islands, Newfoundland, is interpreted within the context of late-glacial and post-glacial processes- West of Humber Arm, the fiord floor is irregular and deep. Humber Arm has steep sidewalls and a flat floor. It contains glaciomarine mud. capped by a layer of red mud probably derived from the Deer Lake Basin, which was connected to the ocean ca. 12.2 ka. In the early postglacial period, sediments on the fiord sidewalls slid into deep water, forming erosional channels. Depositional lobes, stacked in many areas, overlie glaciomarine sediments in deep water. The glaciomarine and submarine slide sediments are overlain by postglacial mud that is imprinted by elongate, ovoid, and circular fluid-escape trenches, and sedimentary furrows. The natural morphology of the fiord has been modified by anthropogenic activity at Comer Brook. Effects include an apron of bark offshore from the paper mill, dredge spoil, and a sunken vessel at the mouth of Humber River. Large submarine slides, probably triggered by wharf construction at Seal Head, formed deep channels on the fiord sidewalls and overlapping depositional lobes on the fiord floor. They are morphologically similar to the lateglacial slide failures in the fund. RÉSUMÉ Les images bathymétriques multifaisceaux de Bay of Islands, Terre-Neuve, sont interprétées dans le contexte des processus tardiglaciaires et post-glaciaires. À I'ouest de Humber Arm. Ie fond du l’jord est irrégulier et profond. Humber Arm est doté de parois abruptes et d'un fond plat. Il renferme de la boue glaciomarine recouverte d'une couche de boue rouge provenant probablemenl du bassin du lac Deer, qui était relié à l'océan il y a environ 12.2 millies d'années avant nos jours. Au début de la période post-glaciaire, Ies sediments sur Ies parois du l’jord ont glissé a l’intérieur de I'eau profonde en formant des chenaux d'érosion. Des lobes sédimentaires s'empilant en de nombreux endroits recouvrent les sédiments glaciomarins en eaux profondes. Les sédiments de glissement glaciomarins et sous-marins sont recouverts d'une boue post-glaciaire marquée de tranchées allongées, ovoides et circulaires d'évacuation des liquides et de silions sédimentaires. L'activité anthropique a modi fié la morphologic naturelle du l’jord a Corner Brook. Les effets de cette activité comprennent un tablier d'écorce au large de la papeterie, des matériaux de dragage et un navire ayant coulé à I'embouchure dc la riviére Humber. D'importants éboulements sous-marins, probablement causés par la construction du quai de Seal Head, ont formé des chenaux profonds dans les parois du l’jord et des lobes sédimentaires qui se superposcnt sur Ic fond du l’jord Ceux-ci sont morphologiquemcnt analogues aux fractures de glissement tardiglaciaires dans le l’jord. Traduit par la rédactio

Genome-wide linkage scan for genes affecting longitudinal trends in systolic blood pressure

Only one genome scan to date has attempted to make use of the longitudinal data available in the Framingham Heart Study, and this attempt yielded evidence of linkage to a gene for mean systolic blood pressure. We show how the additional information available in these longitudinal data can be utilized to examine linkages for not only mean systolic blood pressure (SBP), but also for its trend with age and its variability. Prior to linkage analysis, individuals treated for hypertension were adjusted to account for right-censoring of SBP. Regressions on age were fitted to obtain orthogonal measures of slope, curvature, and residual variance of SBP that were then used as dependent variables in the model-free linkage program SIBPAL. We included mean age, gender, and cohort as covariates in the analysis. To improve power, sibling pairs were weighted for informativity using weights derived from both the marker and trait. The most significant results from our analyses were found on chromosomes 12, 15, and 17 for mean SBP, and chromosome 20 for both SBP slope and curvature

DISTRIBUTION AND MOVEMENTS OF BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) ALONG THE NORTHERN SOUTH CAROLINA COAST: A RESEARCH PARTNERSHIP WITH ECOTOURISM

Assessments of bottlenose dolphin stocks rely on current information about the distribution and abundance of specific populations. We partnered with two ecotourism dolphin watch businesses to investigate bottlenose dolphins along the northern South Carolina coast. The temporal and spatial distribution of dolphins was examined by comparing dorsal fin images from research-based surveys with photo-identification efforts from commercial dolphin watch groups. Matches between survey locations and times revealed patterns of seasonal residency, potential migratory dispersal between seasons, and variable patterns for home range size. An enhanced understanding of the structure of local populations will contribute to the management of local fisheries, ecotour operations, and coastal ocean health

Bay watch: using unmanned aerial vehicles (UAV’s) to survey the box jellyfish Chironex fleckeri

Biological investigations on free ranging marine species are regarded as challenging throughout the scientific community. This is particularly true for ‘logistically difficult species’ where their cryptic natures, low abundance, patchy distributions and difficult and/or dangerous sampling environments, make traditional surveys near impossible. What results is a lack of ecological knowledge on such marine species. However, advances in UAV technology holds potential for overcoming these logistical difficulties and filling this knowledge gap. Our research focused on one such logistically difficult species, the Australian box Jellyfish (Chironex fleckeri), and we investigated the capacity of consumer grade UAV technology to detect this, highly venomous, target species in the inshore waters of Northern Queensland Australia. At two sites in the Weipa area, we utilized video analysis, visual count comparisons with a netted animal tally, and evaluated the role of associated environmental conditions, such as wind speed, water visibility and cloud cover on jellyfish detection rates. In total fifteen, 70 meter transects were completed between two sites, with 107 individuals captured. Drone success varied between the two sites with a significant difference between field and post-field (laboratory) counts. Animal size and cloud cover also had significant effects on detection rates with an increase in cloud cover and animal size enhancing detection probability. This study provides evidence to suggest drone surveys overcome obstacles that traditional surveys can’t, with respect to species deemed logistically difficult and open scope for further ecological investigations on such species

Physiological and morphological responses of 'Irukandji' polyps to thermal and osmotic conditions: consequences for niche profiling

The Irukandji jellyfish (Carukia barnesi) is a medically important species. While the medusa stage of this species is well known, due to its highly venomous sting, the benthic polyp has core roles in regulating both the timing and abundance of medusa making it a research priority. However, due to their small size, Carukia barnesi polyps have never been found in situ and, basic ecological knowledge surrounding this life stage is limited. In this study we adopt a lab-based approach, utilizing physiological tolerance as a functional tool, to gain new insights into the in situ location for Carukia barnesi polyps. The physiological tolerance of Carukia barnesi polyps was characterized by measuring the oxygen consumption rates of polyps exposed to different salinity/temperature combinations. A total of nine salinities and seven temperatures were investigated, ranging from 11 °C/16‰ to 34 °C/42.5‰, encompassing the spectrum of environments experienced on the Great Barrier Reef. Polyps were also monitored for morphological changes such as asexual reproduction, polyp deterioration, and mortality. Salinity did not have a significant effect on oxygen consumption rates, with Carukia barnesi polyps displaying a significant tolerance to a wide range of salinities. The effect of temperature, however, was statistically significant with oxygen °consumption rates increasing alongside water temperature. There was no statistical evidence to support an interactive effect between salinity and temperature. Based on these results, we conclude that the polyp stage of this species is likely located in an environment with stable temperatures and fluctuating salinities and, consequently, future endeavors aimed at locating this life stage should expand targeted survey areas outside stable oceanic environments, typical of medusa, and encompass dynamic environments such as estuaries and submarine freshwater upwellings