Marine Biology Department (MARB)

Permanent URI for this collectionhttps://hdl.handle.net/1969.3/28243

The focus of this department is biological science with an ocean or estuarine emphasis

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Now showing 1 - 20 of 53
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    Feeding in Aquatic Mammals: An Evolutionary and Functional Approach
    (Cham, Springer, 2019) Marshall, C.D.; Pyenson, N.D.
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    Environmental Drivers of Habitat Use by Hawksbill Turtles (Eretmochelys imbricata) in the Arabian Gulf (Qatar)
    (2020-12-01) Marshall, Christopher
    Understanding the environmental drivers of movement patterns are critical to the protection, management and recovery of endangered species. The Arabian Gulf is considered to be the hottest marine system in the world and is known for its extreme environmental conditions that pose substantial physiological stress on marine organisms living there. Satellite tags were deployed on hawksbill turtles in the Arabian Gulf and quantitative ecological modeling (i.e., Bayesian state-space models and GAMMs) was used to provide new insights into the ecological basis of observed hawksbill movement and behavior. Hawksbills used a relatively large core area in the southeast Arabian Gulf when transit and area-restricted search behaviors were included. The numerous hotspots identified suggest that important habitat occurs along a large area of the Qatari eastern coastline and into Saudi Arabia. Offshore islands with fringing reef habitat and deep-water habitats near the 30-50 m isobaths were intensely used. Hawksbills made seasonal migrations to deep-water habitat during summer months, typically once SST reached ~33°C and bottom temperature reached ~32°C. These data provide valuable information to managers seeking to conserve hawksbills in the region. Our data also provide a context to understand the underlying physiological, energetic and behavioral drivers of hawksbill movement in the Arabian Gulf. Future studies should include the use of biologging devices, benthic surveys, and dietary biomarkers to better understand the seasonal migrations of Arabian Gulf hawksbills to this deep-water region.
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    Comparative Analysis of the Flexural Stiffness of Pinniped Vibrissae
    (PLOS ONE, 2015-07-06) Ginter Summarell, Carly; Ingole, Sudeep; Fish, Frank; Marshall, Christopher
    Vibrissae are important components of the mammalian tactile sensory system and are used to detect vibrotactile stimuli in the environment. Pinnipeds have the largest and most highly innervated vibrissae among mammals, and the hair shafts function as a biomechanical filter spanning the environmental stimuli and the neural mechanoreceptors deep in the follicle-sinus complex. Therefore, the material properties of these structures are critical in transferring vibrotactile information to the peripheral nervous system. Vibrissae were tested as cantilever beams and their flexural stiffness (EI) was measured to test the hypotheses that the shape of beaded vibrissae reduces EI and that vibrissae are anisotropic. EI was measured at two locations on each vibrissa, 25% and 50% of the overall length, and at two orientations to the point force. EI differed in orientations that were normal to each other, indicating a functional anisotropy. Since vibrissae taper from base to tip, the second moment of area (I) was lower at 50% than 25% of total length. The anterior orientation exhibited greater EI values at both locations compared to the dorsal orientation for all species. Smooth vibrissae were generally stiffer than beaded vibrissae. The profiles of beaded vibrissae are known to decrease the amplitude of vibrations when protruded into a flow field. The lower EI values of beaded vibrissae, along with the reduced vibrations, may function to enhance the sensitivity of mechanoreceptors to detection of small changes in flow from swimming prey by increasing the signal to noise ratio. This study builds upon previous morphological and hydrodynamic analyses of vibrissae and is the first comparative study of the mechanical properties of pinniped vibrissae.
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    Comparative analysis of the flexural stiffness of pinniped vibrissae
    (PLOS ONE, 2015-05)
    Vibrissae are important components of the mammalian tactile sensory system and are used to detect vibrotactile stimuli in the environment. Pinnipeds have the largest and most highly innervated vibrissae among mammals, and the hair shafts function as a biomechanical filter spanning the environmental stimuli and the neural mechanoreceptors deep in the follicle-sinus complex. Therefore, the material properties of these structures are critical in transferring vibrotactile information to the peripheral nervous system. Vibrissae were tested as cantilever beams and their flexural stiffness (EI) was measured to test the hypotheses that the shape of beaded vibrissae reduces EI and that vibrissae are anisotropic. EI was measured at two locations on each vibrissa, 25% and 50% of the overall length, and at two orientations to the point force. EI differed in orientations that were normal to each other, indicating a functional anisotropy. Since vibrissae taper from base to tip, the second moment of area (I) was lower at 50% than 25% of total length. The anterior orientation exhibited greater EI values at both locations compared to the dorsal orientation for all species. Smooth vibrissae were generally stiffer than beaded vibrissae. The profiles of beaded vibrissae are known to decrease the amplitude of vibrations when protruded into a flow field. The lower EI values of beaded vibrissae, along with the reduced vibrations, may function to enhance the sensitivity of mechanoreceptors to detection of small changes in flow from swimming prey by increasing the signal to noise ratio. This study builds upon previous morphological and hydrodynamic analyses of vibrissae and is the first comparative study of the mechanical properties of pinniped vibrissae.
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    Early diagenesis of organic matter in sediments off the coast of Peru
    (1985) Rowe, Gilbert T.; Howarth, Robert
    Measured rates of SO4 and NH4 were used to estimate organic matter regeneration from the sediments in an area of intense upwelling and high primary production off Peru. While the estimated rates of remineralization were high compared to other ecosystems at comparable water depths, this source of nutrients appeared to be on the order of 10% of the phytoplankton demand. Disparities between measured vs modelled estimates of sulfate reduction appear to be a function of the concentration gradients across the sediment-water interface and mixing by biological and physical processes. The suite of measurements allowed estimation of 'irrigation' and an 'irrigation' coefficient at the nearshore station where measured rates were considerably above those estimated from the pore water sulfate gradient.
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    Benthic production and processes off Baja California, Northwest Africa and Peru: a classification of benthic subsystems in upwelling ecosystems
    (Instituto de Investigaciones Pesqueras., 1985) Rowe, Gilbert T.
    Estimates of the standing stocks, secondary production and metabolism of the benthos have been compared in the coastal upwelling ecosystems off northwest Africa, Baja California, and southern Peru. Northwest Africa is characterized by shelf break upwelling and as a result standing stocks, macrobenthic production and sediment organic matter are highest out at the shelf-slope boundary. Sediment microbial activity and biomass on the other hand are highest nearshore in the dynamic zone where aeolian silt and sand are being blown into the sea from the Sahara Desert. Baja California is dominatd by the red crab Pleuroncodes planipes, having high rates of growth and metabolic utilization of organic matter, both on bottom and in the water. Peru benthos and metabolism are very different from the above areas because of the low oxygen concentrations in the bottom water. Organic matter is far higher in the sediment and heterotrophic metabolism is principally anaerobic rather than aerobic. A normal offshore benthic fauna is replaced by a mat of sulfur bacteria with unknown production and metabolic rates. Benthic subsystems in upwelling ecosystems can be placed in two categories: those overloaded with organic matter, depleted of oxygen and dominated by sulfate reduction and those that are are not overloaded and remain aerobic. Peru and southwest Africa typify overloaded systems whereas NW Africa and Baja California are examples of aerobic systems. Although benthic metabolism and inorganic nutrient regeneration are high in both types of subsystems, all upwelling ecosystems, with their dynamic open boundaries, export organic particulate matter and import inorganic nutrients at rates that are far in excess of that consumed or produced by benthic metabolism.
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    Benthic biomass in the Pisco, Peru upwelling
    (1971-02) Rowe, Gilbert T.
    Quantitative benthic samples were taken off Peru in and adjacent to the Pisco upwelling in an attempt to assess the effects of extremes in productivity and dissolved oxygen on the distribution of biomass (organic cabon). The macrofauna was combused to organic carbon (less the carbonate fraction) to allow direct comparisons with the production of organic carbon at the surface and its distribution in the water column and sediments. Similar techniques were employed in the Gulf of Mexico previously (Rowe and Menzel, 1970), and it is hoped comparisons of the two sets of data contrasting regions of low and high proudctivity will give some insights into the nature of the movement of organic energy from its source through the water column to the bottom.
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    Renowned Texas A&M University at Galveston oyster expert comments on red tide near Texas shores
    (Texas A&M University at Galveston, 2011-10-28) Texas A&M University at Galveston, Media Relations and Communications
    Media release. Contact is Cathy Cashio. Discusses impact of red tide on Texas per Dr. Sammy Ray.
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    Publications of Sammy Ray after 2001
    (2011-08-24T15:25:09Z) Ray, Sammy M
    List of peer- reviewed publications of Dr. Ray after 2001
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    Testimony before the Committee on Resources, United States House of Representatives
    (U.S. House of Representatives, 2005-07-19) Ray, Sammy M
    Text presented as testimony before the U.S. House of Representatives on July 19, 2005 in opposition to "Endangered species" designation for the Eastern oyster, Crassostrea virginica.
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    Publications
    (2011-08-22) Ray, Sammy M
    List of publications by Dr. Sammy M. Ray from 1948 through 2001.
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    DermoWatch : Gulf-Wide Coverage for Dermo Disease in Oysters
    (2011-08-18T15:18:14Z) Robinson, Lance; Kortright, Enrique V; Soniat, Thomas M; Ray, Sammy M
    DermoWatch is a web site (www.dermowatch.org), a monitoring program, and an online community for the management of the oyster parasite, Perkinsus marinus, and monitoring freshwater inflows
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    Oyster Biology
    (2008-05-08) Ray, Sammy M
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    Monthly Summary of Perkinsus marinus (Dermo) Data for Texas Oysters
    (2010) Ray, Sammy M
    Excel spreadsheets of datasets for dermo disease prevalence in Texas oysters.
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    Dermo log 2009-2010
    (2010-11-18) Culbert, Jan; Ray, Sammy M
    Spreadsheet of data for dermocystidian marinum incidence in oysters on reefs along the coast of Texas.
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    Monthly Summary of Perkinsus marinus (Dermo) Data for Texas Oysters
    (2008) Ray, Sammy M
    Excel spreadsheets of monthly data on extent of dermo disease in Texas oysters.
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    Tube identification sheets
    (2011-05-05) Ray, Sammy M
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    Preparing and filling test tubes
    (2011) Ray, Sammy M
    Procedure for preparing and filling test tubes for the analysis of dermocystidian marinum disease in oysters.
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    Procedures for mixing antibiotics for dermo tests
    (2011) Ray, Sammy M
    Instructions for combining chloromycetin and mycostatin antibiotics in culturing and analysis of dermocystidian marinum disease in oysters
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    Stain process
    (2011) Ray, Sammy M
    Description of how to stain medium for the cells of dermocystidian marinum in analysis of disease extent in oysters.