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Monica Orellana

Research Scientist/Engineer - Principal & Principal Oceanographer

Email

morellan@uw.edu

Phone

206-685-5422

Department Affiliation

Polar Science Center

Education

B.S. Biology, Concepcion (Chile), 1980

M.S. Biological Oceanography, University of Washington, 1985

Ph. D. Biological Oceanography, University of Washington, 1990

Publications

2000-present and while at APL-UW

High temporal variability of total organic carbon in the deep Northeastern Pacific

Lopez, C.N., M. Robert, M. Galbraith, S.K. Bercovici, M.V. Orellana, and D.A. Hansell, "High temporal variability of total organic carbon in the deep Northeastern Pacific," Front. Earth Sci., 8, doi:10.3389/feart.2020.00080, 2020.

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27 Mar 2020

The interseasonal and interannual variability of total organic carbon (TOC) was assessed in the deep northeastern Pacific Ocean, an area characterized by high primary production and organic matter export. Samples were collected from throughout the deeper water column (>250 m) seasonally in 2017 and 2018 along the Line P transect, as well as one distribution of dissolved organic carbon (DOC) in spring 2018. High heterogeneity was observed in TOC concentrations at depths greater than 1,000 m, both within seasons (concentration differences of ~2–6 μmol kg-1) and across seasons (~2–12 μmol kg-1), coinciding with changes in fluorescence in the overlying waters. Such observations suggest that biogenic particles sinking from the upper ocean are seasonally delivering observable TOC to depth. The presence of these particles also appeared to contribute to the DOC pool, as suggested by differences in the TOC and DOC distributions in spring 2018. Seasonal TOC net accumulation and removal rates differed between the years: 0.5 and 2.1 μmol kg-1 day-1 (accumulation) and 0.6 and 2.1 μmol kg-1 day-1 (removal) for 2017 and 2018, respectively. The rate estimates indicated that introduction of organic carbon to the bathypelagic occurred at approximately the same rate as removal post-bloom, demonstrating the efficient removal of seasonally produced organic carbon. High abundances of gelatinous zooplankton in spring 2018, supported by higher abundances of phytoplankton, enhanced the export of organic carbon to the bathypelagic zone during the seasonal bloom, resulting in localized TOC concentrations up to 148 μmol kg-1 in the bathypelagic. These results indicate high variability in bathypelagic TOC concentrations at high latitude, unlike oligotrophic systems.

Temporal and metabolic overlap between lipid accumulation and programmed cell death due to nitrogen starvation in the unicellular chlorophyte Chlamydomonas reinhardtii

Sathe, S., M.V. Orellana, N.S. Baliga, and P.M. Durand, "Temporal and metabolic overlap between lipid accumulation and programmed cell death due to nitrogen starvation in the unicellular chlorophyte Chlamydomonas reinhardtii," Phycol. Res., 67, 173-183, doi:10.1111/pre.12368, 2019.

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1 Jul 2019

Lipid accumulation due to nitrogen depletion has been studied extensively in Chlamydomonas reinhardtii and the metabolic changes that lead to triacylglycerol biosynthesis have been of particular interest to researchers in the biodiesel industry. The induction of programmed cell death (PCD) in response to nitrogen starvation has also been documented in related chlorophytes. Here, we examined the temporal and metabolic overlap of lipid accumulation and PCD in response to nitrogen starvation in the important model organism C. reinhardtii. Nitrogen starvation induced physiological stress, measured by the progressive decline in chlorophyll a fluorescence, reduced photosynthetic efficiency and decreased growth. In keeping with previous reports, cells accumulated lipids reaching a peak after 2–3 days. At the same time, DNA nicking and caspase‐like protease activity was observed in a proportion of cells, and ultrastructural observations confirmed that death was via PCD. Our results demonstrate that DNA nicking and caspase‐like activity are observed during PCD in C. reinhardtii in response to nitrogen starvation, and that death occurs at the same time as lipid biosynthesis. Microalgal lipid production due to nitrogen depletion in C. reinhardtii is limited by the decrease in culture growth and knowing that the loss of culture density is, at least in part, due to PCD is important for the biotechnology industry.

Physical and optical characteristics of heavily melted 'rotten' Arctic sea ice

Frantz, C.M., B. Light, S.M. Farley, S. Carpenter, R. Lieblappen, Z. Courville, M.V. Orellana, and K. Junge, "Physical and optical characteristics of heavily melted 'rotten' Arctic sea ice," Cryosphere, 13, 775-793, doi:10.5194/tc-13-775-2019, 2019.

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5 Mar 2019

Field investigations of the properties of heavily melted "rotten" Arctic sea ice were carried out on shorefast and drifting ice off the coast of Utqiagvik (formerly Barrow), Alaska, during the melt season. While no formal criteria exist to qualify when ice becomes rotten, the objective of this study was to sample melting ice at the point at which its structural and optical properties are sufficiently advanced beyond the peak of the summer season. Baseline data on the physical (temperature, salinity, density, microstructure) and optical (light scattering) properties of shorefast ice were recorded in May and June 2015. In July of both 2015 and 2017, small boats were used to access drifting rotten ice within ~32 km of Utqiagvik. Measurements showed that pore space increased as ice temperature increased (–8 to 0°C), ice salinity decreased (10 to 0 ppt), and bulk density decreased (0.9 to 0.6 g cm-3). Changes in pore space were characterized with thin-section microphotography and X-ray micro-computed tomography in the laboratory. These analyses yielded changes in average brine inclusion number density (which decreased from 32 to 0.01 mm-3), mean pore size (which increased from 80 μm to 3 mm), and total porosity (increased from 0% to > 45%) and structural anisotropy (variable, with values of generally less than 0.7). Additionally, light-scattering coefficients of the ice increased from approximately 0.06 to > 0.35 cm-1 as the ice melt progressed. Together, these findings indicate that the properties of Arctic sea ice at the end of melt season are significantly distinct from those of often-studied summertime ice. If such rotten ice were to become more prevalent in a warmer Arctic with longer melt seasons, this could have implications for the exchange of fluid and heat at the ocean surface.

More Publications

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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