Nagissa Mahmoudi

Nagissa Mahmoudi
Harvard University | Harvard · Department of Earth and Planetary Sciences

PhD

About

27
Publications
6,320
Reads
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616
Citations
Citations since 2017
10 Research Items
500 Citations
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2017201820192020202120222023020406080
2017201820192020202120222023020406080
2017201820192020202120222023020406080
Education
September 2008 - June 2013
McMaster University
Field of study
September 2003 - December 2007
University of Toronto
Field of study
  • Biology

Publications

Publications (27)
Article
Full-text available
Marine microbial communities are a vital component of global carbon cycling, and numerous studies have shown that populations of petroleum-degrading bacteria are ubiquitous in the oceans. Few studies have attempted to distinguish all of the taxa that might contribute to petroleum biodegradation (including, e.g., heterotrophic and nondesignated micr...
Article
Full-text available
The environmental surveys following the 2010 Deepwater Horizon (DWH) spill identified a variety of hydrocarbon-degrading microorganisms, and laboratory studies with field-collected water samples then demonstrated faster-than-expected hydrocarbon biodegradation rates at 5°C. Knowledge about microbial community composition, diversity, and functional...
Article
Full-text available
Interest in extracting mineral resources from the seafloor through deep‐sea mining has accelerated in the past decade, driven by consumer demand for various metals like zinc, cobalt, and rare earth elements. While there are ongoing studies evaluating potential environmental impacts of deep‐sea mining activities, these focus primarily on impacts to...
Article
Marine microorganisms play a fundamental role in the global carbon cycle by mediating the sequestration of organic matter in ocean waters and sediments. A better understanding of how biological factors, such as microbial community composition, influence the lability and fate of organic matter is needed. Here, we explored the extent to which organic...
Preprint
Full-text available
Marine microorganisms play a fundamental role in the global carbon cycle by mediating the sequestration of organic matter in ocean waters and sediments. A better understanding of how biological factors, such as microbial community composition, influence the lability and fate of organic matter is needed. Here, we explored the extent to which organic...
Article
Full-text available
The Caspian Sea, which is the largest landlocked body of water on the planet, receives substantial annual hydrocarbon input from anthropogenic sources (e.g., industry, agriculture, oil exploration, and extraction) and natural sources (e.g., mud volcanoes and oil seeps). The Caspian Sea also receives substantial amounts of runoff from agricultural a...
Article
Full-text available
The Caspian Sea, which is the largest landlocked body of water on the planet, receives substantial annual hydrocarbon input from anthropogenic sources (e.g., industry, agriculture, oil exploration, and extraction) and natural sources (e.g., mud volcanoes and oil seeps). The Caspian Sea also receives substantial amounts of runoff from agricultural a...
Article
Full-text available
The nitrogen cycle in the marine environment is strongly affected by ammonia oxidizing Thaumarchaeota. In some marine settings Thaumarchaeotes can comprise a large % of the prokaryotic population. To better understand the biogeographic patterns of Thaumarchaeotes, we sought to investigate differences in their abundance and phylogenetic diversity be...
Article
Aquatic sediments harbor diverse microbial communities that mediate organic matter degradation and influence biogeochemical cycles. The pool of bioavailable carbon continuously changes as a result of abiotic processes and microbial activity. It remains unclear how microbial communities respond to heterogeneous organic matrices and how this ultimate...
Conference Paper
Mean annual precipitation and consecutive dry day lengths are projected to increase in the Southeastern United States and cause dramatic changes to the natural soil moisture regimes of non-irrigated land. Changes to moisture content can strongly affect the production of soil-respired carbon dioxide (CO2) and the structure of soil microbial communit...
Article
Crude oil has been part of the marine environment for millions of years, and microbes that use its rich source of energy and carbon are found in seawater, sediments and shorelines from the tropics to the polar regions. Catastrophic oil spills stimulate these organisms to 'bloom' in a reproducible fashion, and although oil does not provide bioavaila...
Article
Full-text available
Lipid/DNA co-extraction from one sample is attractive in limiting biases associated with microbial community analysis from separate extractions. We sought to enhance established co-extraction methods and use high-throughput 16S rRNA sequencing to identify preferentially extracted taxa from co-extracted DNA. Co-extraction results in low DNA yields a...
Article
Full-text available
The Caspian Sea is heavily polluted due to industrial and agricultural effluents as well as extraction of oil and gas reserves. Microbial communities can influence the fate of contaminants and nutrients. However, insight into the microbial ecology of the Caspian Sea significantly lags behind other marine systems. Here we describe microbial biomass,...
Conference Paper
The Mediterranean Sea is home to a diverse community of heterotrophic microbes responsible for cycling much of the organic carbon that enters its waters. The subset of those organisms that utilize macromolecules produce extracellular enzymes as a means of carbon degradation. However, this hydrolytic community is poorly characterized at water column...
Conference Paper
There is strong evidence of an increasing trend of severe drought and precipitation events in the Unites States (US) due to greenhouse gas emissions. However, there is a considerable knowledge gap between these severe weather events and soil microbial respiration. The objective of this study was to quantify soil microbial respiration and assess mic...
Conference Paper
The Caspian Sea is the world’s largest enclosed body of water and accounts for 40% of the total lacustrine waters of the world. Approximately 130 rivers drain into the Caspian Sea making riverine inputs the primary source of water and nutrients into this system. As a result, the salinity of the Caspian Sea differs significantly from other bodies of...
Article
The Deepwater Horizon oil spill led to the severe contamination of coastal environments in the Gulf of Mexico. A previous study detailed coastal salt-marsh erosion and recovery in a number of oil-impacted and non-impacted reference sites in Barataria Bay, Louisiana over the first 18 months after the spill. Concentrations of alkanes and polyaromatic...
Article
Polycyclic aromatic hydrocarbons (PAHs) are generated by a range of industrial processes in-cluding petroleum and gas production and are often found in high concentrations at industrial sites. Once PAHs enter the environment, the predominant mecha-nisms for removal are biological via microbial activity. However, PAHs have the potential to partition...
Article
Organic matter in soils is composed of diverse materials in various stages of decomposition. Soil organic matter is not in a single pool but rather in multiple carbon pools with different intrinsic turnover times that can be on annual to decadal and even millennial timescales. Microorganisms can influence the total amount of carbon stored in soils...
Article
Molecular characterization of the microbial populations of soils and sediments contaminated with polycyclic aromatic hydrocarbons (PAHs) is often a first step in assessing intrinsic biodegradation potential. However, soils are problematic for molecular analysis owing to the presence of organic matter, such as humic acids. Furthermore, the presence...
Article
Quantifying primary sex ratios is necessary for studies in a wide range of areas including adaptive sex ratio modification, population demography, and sex-biased developmental mortality. Adult and penultimate male spiders are easy to sex, due to the great thickening of the male pedipalps, which are used for delivering sperm to the female reproducti...

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