Mary McGann
Research Geologist at the USGS Pacific Coastal and Marine Science Center
Science and Products
What determines the downstream evolution of turbidity currents?
Shallow-water foraminifera and other microscopic biota of Clipperton Island, tropical eastern Pacific
A ship's ballasting history as an indicator of foraminiferal invasion potential--An example from Prince William Sound, Alaska, USA
We investigated the potential role of ballast sediment from coastal and transoceanic oil tankers arriving and de-ballasting in Port Valdez as a vector for the introduction of invasive benthic foraminifera in Prince William Sound, Alaska. Forty-one ballast sediment samples were obtained in 1998-1999 from 11 oil tankers that routinely discharged their ballast in Prince William Sound after sailing fr
Sediment and organic carbon transport and deposition driven by internal tides along Monterey Canyon, offshore California
Linking direct measurements of turbidity currents to submarine canyon-floor deposits
Submarine canyons are conduits for episodic and powerful sediment density flows (commonly called turbidity currents) that move globally significant amounts of terrestrial sediment and organic carbon into the deep sea, forming some of the largest sedimentary deposits on Earth. The only record available for most turbidity currents is the deposit they leave behind. Therefore, to understand turbidity
Discovery of an extensive deep-sea fossil serpulid reef associated with a cold seep, Santa Monica Basin, California
Initial dispersal (1986-1987) of the invasive foraminifera Trochammina hadai Uchio in San Francisco Bay, California, USA
A time series of three closely-spaced data sets are used to track the early expansion of the invasive Japanese benthic foraminifera Trochammina hadai in the southern portion of San Francisco Bay known as South Bay. The species initially appeared in 1983, comprising only 1.5% of the assemblage in one of four samples that were dominated by the native species Ammonia tepida and Cribroelphidium excava
The occurrence of the invasive foraminifera Trochammina hadai Uchio in Flamengo Inlet, Ubatuba, São Paulo State, Brazil
Powerful turbidity currents driven by dense basal layers
Faunal and stable isotopic analyses of benthic foraminifera from the Southeast Seep on Kimki Ridge offshore southern California, USA
Developing Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories
Seafloor fluid seeps on Kimki Ridge, offshore southern California: Links to active strike-slip faulting
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What determines the downstream evolution of turbidity currents?
Seabed sediment flows called turbidity currents form some of the largest sediment accumulations, deepest canyons and longest channel systems on Earth. Only rivers transport comparable sediment volumes over such large areas; but there are far fewer measurements from turbidity currents, ensuring they are much more poorly understood. Turbidity currents differ fundamentally from rivers, as turbidity cAuthorsCatharina Heerema, Peter J. Talling, Matthieu J.B. Cartigny, Charles K. Paull, Lewis Bailey, Stephen Simmons, Daniel Parsons, Michael Clare, Roberto Gwiazda, Eve M. Lundsten, Krystle Anderson, Katherine L. Maier, Jingping Xu, Esther J. Sumner, Kurt J. Rosenberger, Jenny Gales, Mary McGann, Lionel Carter, Ed PopeShallow-water foraminifera and other microscopic biota of Clipperton Island, tropical eastern Pacific
The recent foraminiferal fauna and associated microbiota of Clipperton Island (10.2833°N, 109.2167°W) were investigated at 20 sites collected in the intertidal zone around the perimeter of the island and from the edge of the inner brackish-water lagoon. Due to the island’s geographic location in a low productivity zone, a lack of variable habitats on and surrounding the island, and heavy surf thatAuthorsMary McGann, Robert W Schmieder, Louis-Philippe LonckeA ship's ballasting history as an indicator of foraminiferal invasion potential--An example from Prince William Sound, Alaska, USA
We investigated the potential role of ballast sediment from coastal and transoceanic oil tankers arriving and de-ballasting in Port Valdez as a vector for the introduction of invasive benthic foraminifera in Prince William Sound, Alaska. Forty-one ballast sediment samples were obtained in 1998-1999 from 11 oil tankers that routinely discharged their ballast in Prince William Sound after sailing fr
AuthorsMary McGann, Gregory M. Ruiz, Anson H. Hines, George D. SmithSediment and organic carbon transport and deposition driven by internal tides along Monterey Canyon, offshore California
Submarine canyons provide globally important conduits for sediment and organic carbon transport into the deep-sea. Using a novel dataset from Monterey Canyon, offshore central California, that includes an extensive array of water column sampling devices, we address how fine-grained sediment and organic carbon are transported, mixed, fractionated, and buried along a submarine canyon. Anderson-typeAuthorsKatherine L. Maier, Kurt J. Rosenberger, Charles K. Paull, Roberto Gwiazda, Jenny Gales, Thomas Lorenson, James P. Barry, Peter J. Talling, Mary McGann, Jingping Xu, Eve M. Lundsten, Krystle Anderson, Steven Litvin, Daniel Parsons, Michael Clare, Stephen Simmons, Esther J. Sumner, Matthieu J.B. CartignyLinking direct measurements of turbidity currents to submarine canyon-floor deposits
Submarine canyons are conduits for episodic and powerful sediment density flows (commonly called turbidity currents) that move globally significant amounts of terrestrial sediment and organic carbon into the deep sea, forming some of the largest sedimentary deposits on Earth. The only record available for most turbidity currents is the deposit they leave behind. Therefore, to understand turbidity
AuthorsKatherine L. Maier, Jenny Gales, Charles K. Paull, Kurt J. Rosenberger, Peter J. Talling, Stephen Simmons, Roberto Gwiazda, Mary McGann, Matthieu J.B. Cartigny, Eve M. Lundsten, Krystle Anderson, Michael Clare, Jingping Xu, Daniel Parsons, James P. Barry, Monica Wolfson-Schwher, Nora M. Nieminski, Esther J. SumnerDiscovery of an extensive deep-sea fossil serpulid reef associated with a cold seep, Santa Monica Basin, California
Multi-beam mapping of the Santa Monica Basin in the eastern Pacific has revealed the existence of a number of elevated bathymetric features, or mounds, harboring cold seep communities. During 2013-2014, mounds at ~600 m water depth were observed for the first time and sampled by Monterey Bay Aquarium Research Institute’s ROV Doc Ricketts. Active cold seeps were found, but surprisingly one of theseAuthorsMagdalena N Georgieva, Charles K. Paull, Crispin TS Little, Mary McGann, Diana Sahy, Daniel Condon, Lonny Lundsten, Jack Pewsey, David W Caress, Robert C VrijenhoekInitial dispersal (1986-1987) of the invasive foraminifera Trochammina hadai Uchio in San Francisco Bay, California, USA
A time series of three closely-spaced data sets are used to track the early expansion of the invasive Japanese benthic foraminifera Trochammina hadai in the southern portion of San Francisco Bay known as South Bay. The species initially appeared in 1983, comprising only 1.5% of the assemblage in one of four samples that were dominated by the native species Ammonia tepida and Cribroelphidium excava
AuthorsMary McGannThe occurrence of the invasive foraminifera Trochammina hadai Uchio in Flamengo Inlet, Ubatuba, São Paulo State, Brazil
The agglutinated foraminifera Trochammina hadai Uchio (1962), a dominant species in Japan, first appeared as an invasive species in San Francisco Bay, US, in 1983. Trochammina hadai's first appearance in the Brazilian coastal waters of Flamengo Inlet, Ubatuba, Sao Paulo State, is recorded nearly three decades later, in two of thirty-four sediment samples collected in the western portion known as "AuthorsPatricia P. B. Eichler, Mary McGann, Andre R. Rodrigues, Alison Mendonca, Audrey Amorim, Carla Bonetti, Cristiane Cordeito de Farias, Silvia H. Mello e Sousa, Helenice Vital, Moab Praxedes GomesPowerful turbidity currents driven by dense basal layers
Seafloor sediment flows (turbidity currents) are among the volumetrically most important yet least documented sediment transport processes on Earth. A scarcity of direct observations means that basic characteristics, such as whether flows are entirely dilute or driven by a dense basal layer, remain equivocal. Here we present the most detailed direct observations yet from oceanic turbidity currentsAuthorsC. K. Paull, P. J. Talling, Katherine L. Maier, Daniel Parsons, Jingping Xu, D. W. Caress, R. Gwiazda, E. Lundsten, K. Anderson, James P. Barry, M. Chaffey, T. O'Reilly, Kurt J. Rosenberger, Jenny Gales, Brian Kieft, Mary McGann, Samantha E. Simmons, M. McCann, Esther J. Sumner, M. A. Clare, M. J. CartignyFaunal and stable isotopic analyses of benthic foraminifera from the Southeast Seep on Kimki Ridge offshore southern California, USA
We investigated the benthic foraminiferal faunal and stable carbon and oxygen isotopic composition of a 15-cm push core (NA075-092b) obtained on a Telepresence-Enabled cruise to the Southeast Seep on Kimki Ridge offshore southern California. The seep core was taken at a depth of 973 m in the vicinity of a Beggiatoa bacterial mat and vesicomyid clams (Calyptogena) and compared to previously publishAuthorsMary McGann, James E. ConradDeveloping Foram-AMBI for biomonitoring in the Mediterranean: Species assignments to ecological categories
Most environmental bio-monitoring methods using the species composition of marine faunas define the Ecological Quality Status of soft bottom ecosystems based on the relative proportions of species assigned to a limited number of ecological categories. In this study we analyse the distribution patterns of benthic foraminifera in the Mediterranean as a function of organic carbon gradients on the basAuthorsFrans Jorissen, Maria P. Nardelli, Ahuva Almogi-Labin, Christine Barras, Luisa Bergamin, Erica Bicchi, Akram El Kateb, Luciana Ferraro, Mary McGann, Caterina Morigi, Elena Romano, Anna Sabattini, Magali Schweizer, Silvia SpezzaferriSeafloor fluid seeps on Kimki Ridge, offshore southern California: Links to active strike-slip faulting
The Kimki Ridge fluid seeps are located in western Catalina Basin about 60 km southwest of the southern California mainland and at a water depth of approximately 1100 m. Multichannel seismic reflection profiles collected by the U.S. Geological Survey (USGS) in 2014 show acoustic transparency within the Kimki Ridge, suggesting the possibility of fluid seeps and possible sub-seafloor fluid pathways.AuthorsJames E. Conrad, Nancy G. Prouty, Maureen A. L. Walton, Jared W. Kluesner, Katherine L. Maier, Mary McGann, Daniel S. Brothers, Emily C. Roland, Peter Dartnell - News