1
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Wolny JL, Whereat EB, Egerton TA, Gibala-Smith LA, McKay JR, O'Neil JM, Wazniak CE, Mulholland MR. The Occurrence of Karenia species in mid-Atlantic coastal waters: Data from the Delmarva Peninsula, USA. Harmful Algae 2024; 132:102579. [PMID: 38331544 DOI: 10.1016/j.hal.2024.102579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 11/22/2023] [Accepted: 01/09/2024] [Indexed: 02/10/2024]
Abstract
A bloom of Karenia papilionacea that occurred along the Delaware coast in late summer of 2007 was the first Karenia bloom reported on the Delmarva Peninsula (Delaware, Maryland, and Virginia, USA). Limited spatial and temporal monitoring conducted by state agencies and citizen science groups since 2007 have documented that several Karenia species are an annual component of the coastal phytoplankton community along the Delmarva Peninsula, often present at background to low concentrations (100 to 10,000 cells L-1). Blooms of Karenia (> 105 cells L-1) occurred in 2010, 2016, 2018, and 2019 in different areas along the Delmarva Peninsula coast. In late summer and early autumn of 2017, the lower Chesapeake Bay experienced a K. papilionacea bloom, the first recorded in Bay waters. Blooms typically occurred summer into autumn but were not monospecific; rather, they were dominated by either K. mikimotoi or K. papilionacea, with K. selliformis, K. brevis-like cells, and an undescribed Karenia species also present. Cell concentrations during these mid-Atlantic Karenia spp. blooms equalled concentrations reported for other Karenia blooms. However, the negative impacts to environmental and human health often associated with Karenia red tides were not observed. The data compiled here report on the presence of multiple Karenia species in coastal waters of the Delmarva Peninsula detected through routine monitoring and opportunistic sampling conducted between 2007 and 2022, as well as findings from research cruises undertaken in 2018 and 2019. These data should be used as a baseline for future phytoplankton community analyses supporting coastal HAB monitoring programs.
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Affiliation(s)
- Jennifer L Wolny
- Maryland Department of Natural Resources, Resource Assessment Service, 580 Taylor Avenue, Annapolis MD 21401 USA.
| | - Edward B Whereat
- University of Delaware, Delaware Sea Grant, 700 Pilottown Road, Lewes DE 19958 USA
| | - Todd A Egerton
- Virginia Department of Health, Division of Shellfish Safety and Waterborne Hazards, 830 Southampton Avenue, Suite 200, Norfolk VA 23510 USA
| | - Leah A Gibala-Smith
- Old Dominion University, Department of Ocean and Earth Sciences, 4402 Elkhorn Avenue, Norfolk VA 23508 USA
| | - John R McKay
- Maryland Department of Environment, Water and Science Administration, 416 Chinquapin Round Road, Annapolis MD 21401 USA
| | - Judith M O'Neil
- University of Maryland Center for Environmental Science, Horn Point Laboratory, 2020 Horns Point Road, Cambridge MD 21613 USA
| | - Catherine E Wazniak
- Maryland Department of Natural Resources, Resource Assessment Service, 580 Taylor Avenue, Annapolis MD 21401 USA
| | - Margaret R Mulholland
- Old Dominion University, Department of Ocean and Earth Sciences, 4402 Elkhorn Avenue, Norfolk VA 23508 USA
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2
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Clayton S, Gibala-Smith L, Mogatas K, Flores-Vargas C, Marciniak K, Wigginton M, Mulholland MR. Imaging Technologies Build Capacity and Accessibility in Phytoplankton Species Identification Expertise for Research and Monitoring: Lessons Learned During the COVID-19 Pandemic. Front Microbiol 2022; 13:823109. [PMID: 35495707 PMCID: PMC9048821 DOI: 10.3389/fmicb.2022.823109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 03/07/2022] [Indexed: 11/21/2022] Open
Abstract
As primary producers, phytoplankton play an integral role in global biogeochemical cycles through their production of oxygen and fixation of carbon. They also provide significant ecosystem services, by supporting secondary production and fisheries. Phytoplankton biomass and diversity have been identified by the Global Ocean Observing System (GOOS) as Essential Ocean Variables (EOVs), properties that need to be monitored to better understand and predict the ocean system. Phytoplankton identification and enumeration relies on the skills and expertise of highly trained taxonomic analysts. The training of new taxonomic analysts is intensive and requires months to years of supervised training before an analyst is able to independently and consistently apply identification skills to a sample. During the COVID-19 pandemic, access to laboratories was greatly restricted and social distancing requirements prevented supervised training. However, access to phytoplankton imaging technologies such as the Imaging FlowCytobot (IFCB), FlowCam, and PlanktoScope, combined with open online taxonomic identification platforms such as EcoTaxa, provided a means to continue monitoring, research, and training activities remotely when in-person activities were restricted. Although such technologies can not entirely replace microscopy, they have a great potential for supporting an expansion in taxonomic training, monitoring, surveillance, and research capacity. In this paper we highlight a set of imaging and collaboration tools and describe how they were leveraged during laboratory lockdowns to advance research and monitoring goals. Anecdotally, we found that the use of imaging tools accelerated the training of new taxonomic analysts in our phytoplankton analysis laboratory. Based on these experiences, we outline how these technologies can be used to increase capacity in taxonomic training and expertise, as well as how they can be used more broadly to expand research opportunities and capacity.
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Affiliation(s)
- Sophie Clayton
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, United States
- *Correspondence: Sophie Clayton,
| | - Leah Gibala-Smith
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, United States
- New Jersey Department of Environmental Protection, Trenton, NJ, United States
| | - Kathryn Mogatas
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, United States
| | - Chanel Flores-Vargas
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, United States
| | - Kayla Marciniak
- Department of Biology, Old Dominion University, Norfolk, VA, United States
| | - Maci Wigginton
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, United States
| | - Margaret R. Mulholland
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, United States
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3
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Macías-Tapia A, Mulholland MR, Selden CR, Loftis JD, Bernhardt PW. Effects of tidal flooding on estuarine biogeochemistry: Quantifying flood-driven nitrogen inputs in an urban, lower Chesapeake Bay sub-tributary. Water Res 2021; 201:117329. [PMID: 34161874 DOI: 10.1016/j.watres.2021.117329] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 05/29/2021] [Accepted: 06/01/2021] [Indexed: 06/13/2023]
Abstract
Sea level rise has increased the frequency of tidal flooding even without accompanying precipitation in many coastal areas worldwide. As the tide rises, inundates the landscape, and then recedes, it can transport organic and inorganic matter between terrestrial systems and adjacent aquatic environments. However, the chemical and biological effects of tidal flooding on urban estuarine systems remain poorly constrained. Here, we provide the first extensive quantification of floodwater nutrient concentrations during a tidal flooding event and estimate the nitrogen (N) loading to the Lafayette River, an urban tidal sub-tributary of the lower Chesapeake Bay (USA). To enable the scale of synoptic sampling necessary to accomplish this, we trained citizen-scientist volunteers to collect 190 flood water samples during a perigean spring tide to measure total dissolved N (TDN), dissolved inorganic N (DIN) and phosphate concentrations, and Enterococcus abundance from the retreating ebb tide while using a phone application to measure the extent of tidal inundation. Almost 95% of Enterococcus results had concentrations that exceeded the standard established for recreational waters (104 MPN 100 mL-1). Floodwater dissolved nutrient concentrations were higher than concentrations measured in natural estuarine waters, suggesting floodwater as a source of dissolved nutrients to the estuary. However, only DIN concentrations were statistically higher in floodwater samples than in the estuary. Using a hydrodynamic model to calculate the volume of water inundating the landscape, and the differences between the median DIN concentrations in floodwaters and the estuary, we estimate that 1,145 kg of DIN entered the Lafayette River during this single, blue sky, tidal flooding event. This amount exceeds the annual N load allocation for overland flow established by federal regulations for this segment of the Chesapeake Bay by 30%. Because tidal flooding is projected to increase in the future as sea levels continue to rise, it is crucial we quantify nutrient loading from tidal flooding in order to set realistic water quality restoration targets for tidally influenced water bodies.
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Affiliation(s)
- Alfonso Macías-Tapia
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, USA.
| | | | - Corday R Selden
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, USA
| | - J Derek Loftis
- Center for Coastal Resources Management, Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA, USA
| | - Peter W Bernhardt
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, USA
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4
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Hofmann EE, Klinck JM, Filippino KC, Egerton T, Davis LB, Echevarría M, Pérez-Vega E, Mulholland MR. Understanding controls on Margalefidinium polykrikoides blooms in the lower Chesapeake Bay. Harmful Algae 2021; 107:102064. [PMID: 34456021 DOI: 10.1016/j.hal.2021.102064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 05/31/2021] [Accepted: 06/01/2021] [Indexed: 06/13/2023]
Abstract
A time-dependent model of Margalefidinium polykrikoides, a mixotrophic dinoflagellate, cell growth was implemented to assess controls on blooms in the Lafayette River, a shallow, tidal sub-tributary of the lower Chesapeake Bay. Simulated cell growth included autotrophic and heterotrophic contributions. Autotrophic cell growth with no nutrient limitation resulted in a bloom but produced chlorophyll concentrations that were 45% less than observed bloom concentrations (~80 mg Chl m-3 vs. 145 mg Chl m-3) and a bloom progression that did not match observations. Excystment (cyst germination) was important for bloom initiation, but did not influence the development of algal biomass or bloom duration. Encystment (cyst formation) resulted in small losses of biomass throughout the bloom but similarly, did not influence M. polykrikoides cell density or the duration of blooms. In contrast, the degree of heterotrophy significantly impacted cell densities achieved and bloom duration. When heterotrophy contributed a constant 30% to cell growth, and dissolved inorganic nitrogen was not limiting, simulated chlorophyll concentrations were within those observed during blooms (maximum ~140 mg Chl m-3). However, nitrogen limitation quenched the maximum chlorophyll concentration by a factor of three. Specifying heterotrophy as an increasing function of nutrient limitation, allowing it to contribute up to 50% and 70% of total growth, resulted in simulated maximum chlorophyll concentrations of 90 mg Chl m-3 and 180 mg Chl m-3, respectively. This suggested that blooms of M. polykrikoides in the Lafayette River are fortified and maintained by substantial heterotrophic nutritional inputs. The timing and progression of the simulated bloom was controlled by the temperature range, 23 °C to 28 °C, that supports M. polykrikoides growth. Temperature increases of 0.5 °C and 1.0 °C, consistent with current warming trends in the lower Chesapeake Bay due to climate change, shifted the timing of bloom initiation to be earlier and extended the duration of blooms; maximum bloom magnitude was reduced by 50% and 65%, respectively. Warming by 5 °C suppressed the summer bloom. The simulations suggested that the timing of M. polykrikoides blooms in the Lafayette River is controlled by temperature and the bloom magnitude is determined by trade-offs between the severity of nutrient limitation and the relative contribution of mixotrophy to cell growth.
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Affiliation(s)
- Eileen E Hofmann
- Center for Coastal Physical Oceanography, Old Dominion University, Norfolk 23508, VA, USA.
| | - John M Klinck
- Center for Coastal Physical Oceanography, Old Dominion University, Norfolk 23508, VA, USA
| | - Katherine C Filippino
- Department of Ocean & Earth Sciences, Old Dominion University, Norfolk 23508, VA, USA; Current Affiliation: Hampton Roads Planning District Commission, 723 Woodlake Drive, Chesapeake 23320, VA, USA
| | - Todd Egerton
- Division of Shellfish Safety and Waterborne Hazards, Virginia Department of Health, 830 Southampton Avenue, Norfolk 23510, VA, USA
| | - L Brynn Davis
- Center for Coastal Physical Oceanography, Old Dominion University, Norfolk 23508, VA, USA
| | - Michael Echevarría
- Department of Ocean & Earth Sciences, Old Dominion University, Norfolk 23508, VA, USA
| | - Eduardo Pérez-Vega
- Department of Ocean & Earth Sciences, Old Dominion University, Norfolk 23508, VA, USA
| | - Margaret R Mulholland
- Department of Ocean & Earth Sciences, Old Dominion University, Norfolk 23508, VA, USA
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5
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Qin Q, Shen J, Reece KS, Mulholland MR. Developing a 3D mechanistic model for examining factors contributing to harmful blooms of Margalefidinium polykrikoides in a temperate estuary. Harmful Algae 2021; 105:102055. [PMID: 34303516 DOI: 10.1016/j.hal.2021.102055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 05/12/2021] [Accepted: 05/17/2021] [Indexed: 06/13/2023]
Abstract
Blooms of Margalefidinium (previously Cochlodinium) polykrikoides occur almost annually in summer in the lower Chesapeake Bay and its tributaries (e.g., the James and York Rivers). The Lafayette River, a sub-tributary of the lower James River, has been recognized as an initiation location for blooms in this region. The timing of bloom initiation varies interannually, ranging from late June to early August. To fully understand critical environmental factors controlling bloom initiation and interactions between physical and biological processes, a numerical module simulating M. polykrikoides blooms was developed with a focus on the bloom initiation. The module also includes life cycle and behavioral strategies such as mixotrophy, vertical migration, cyst dynamics and grazing suppression. Parameterizations for these behaviors were assigned based on published laboratory culture experiments. The module was coupled with a 3D physical-biogeochemical model for the James River that examined the contribution of each environmental factor and behavioral strategy to bloom initiation and development. Model simulation results highlight the importance of mixotrophy in maintaining high growth rates for M. polykrikoides in this region. Model results suggest that while many factors contribute to the initiation process, temperature, physical transport processes, and cyst germination are the three dominant factors controlling the interannual variability in the timing of bloom initiation.
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Affiliation(s)
- Qubin Qin
- Virginia Institute of Marine Science, William & Mary, Gloucester Point, VA 23062, USA.
| | - Jian Shen
- Virginia Institute of Marine Science, William & Mary, Gloucester Point, VA 23062, USA
| | - Kimberly S Reece
- Virginia Institute of Marine Science, William & Mary, Gloucester Point, VA 23062, USA
| | - Margaret R Mulholland
- Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, 4600 Elkhorn Avenue, Norfolk, VA 23529-0276, USA
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6
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Gazitúa MC, Vik DR, Roux S, Gregory AC, Bolduc B, Widner B, Mulholland MR, Hallam SJ, Ulloa O, Sullivan MB. Potential virus-mediated nitrogen cycling in oxygen-depleted oceanic waters. ISME J 2021; 15:981-998. [PMID: 33199808 PMCID: PMC8115048 DOI: 10.1038/s41396-020-00825-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 09/30/2020] [Accepted: 10/27/2020] [Indexed: 01/29/2023]
Abstract
Viruses play an important role in the ecology and biogeochemistry of marine ecosystems. Beyond mortality and gene transfer, viruses can reprogram microbial metabolism during infection by expressing auxiliary metabolic genes (AMGs) involved in photosynthesis, central carbon metabolism, and nutrient cycling. While previous studies have focused on AMG diversity in the sunlit and dark ocean, less is known about the role of viruses in shaping metabolic networks along redox gradients associated with marine oxygen minimum zones (OMZs). Here, we analyzed relatively quantitative viral metagenomic datasets that profiled the oxygen gradient across Eastern Tropical South Pacific (ETSP) OMZ waters, assessing whether OMZ viruses might impact nitrogen (N) cycling via AMGs. Identified viral genomes encoded six N-cycle AMGs associated with denitrification, nitrification, assimilatory nitrate reduction, and nitrite transport. The majority of these AMGs (80%) were identified in T4-like Myoviridae phages, predicted to infect Cyanobacteria and Proteobacteria, or in unclassified archaeal viruses predicted to infect Thaumarchaeota. Four AMGs were exclusive to anoxic waters and had distributions that paralleled homologous microbial genes. Together, these findings suggest viruses modulate N-cycling processes within the ETSP OMZ and may contribute to nitrogen loss throughout the global oceans thus providing a baseline for their inclusion in the ecosystem and geochemical models.
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Affiliation(s)
- M. Consuelo Gazitúa
- grid.261331.40000 0001 2285 7943Department of Microbiology, The Ohio State University, Columbus, OH 43210 USA ,Viromica Consulting, Santiago, Chile
| | - Dean R. Vik
- grid.261331.40000 0001 2285 7943Department of Microbiology, The Ohio State University, Columbus, OH 43210 USA
| | - Simon Roux
- grid.451309.a0000 0004 0449 479XDOE Joint Genome Institute, Berkeley, CA USA
| | - Ann C. Gregory
- grid.261331.40000 0001 2285 7943Department of Microbiology, The Ohio State University, Columbus, OH 43210 USA
| | - Benjamin Bolduc
- grid.261331.40000 0001 2285 7943Department of Microbiology, The Ohio State University, Columbus, OH 43210 USA
| | - Brittany Widner
- grid.261368.80000 0001 2164 3177Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, VA USA ,grid.56466.370000 0004 0504 7510Woods Hole Oceanographic Institution, Woods Hole, MA USA
| | - Margaret R. Mulholland
- grid.261368.80000 0001 2164 3177Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, VA USA
| | - Steven J. Hallam
- grid.17091.3e0000 0001 2288 9830Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC Canada
| | - Osvaldo Ulloa
- grid.5380.e0000 0001 2298 9663Departamento de Oceanografía & Instituto Milenio de Oceanografía, Universidad de Concepción, Concepción, Chile
| | - Matthew B. Sullivan
- grid.261331.40000 0001 2285 7943Department of Microbiology, The Ohio State University, Columbus, OH 43210 USA ,grid.261331.40000 0001 2285 7943Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, Columbus, OH USA
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7
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Vik D, Gazitúa MC, Sun CL, Zayed AA, Aldunate M, Mulholland MR, Ulloa O, Sullivan MB. Genome-resolved viral ecology in a marine oxygen minimum zone. Environ Microbiol 2020; 23:2858-2874. [PMID: 33185964 DOI: 10.1111/1462-2920.15313] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 11/09/2020] [Indexed: 11/28/2022]
Abstract
Oxygen minimum zones (OMZs) are critical to marine nitrogen cycling and global climate change. While OMZ microbial communities are relatively well-studied, little is known about their viruses. Here, we assess the viral community ecology of 22 deeply sequenced viral metagenomes along a gradient of oxygenated to anoxic waters (<0.02 μmol/l O2 ) in the Eastern Tropical South Pacific (ETSP) OMZ. We identified 46 127 viral populations (≥5 kb), which augments the known viruses from ETSP by 10-fold. Viral communities clustered into six groups that correspond to oceanographic features. Oxygen concentration was the predominant environmental feature driving viral community structure. Alpha and beta diversity of viral communities in the anoxic zone were lower than in surface waters, which parallels the low microbial diversity seen in other studies. ETSP viruses were largely endemic, with the majority of shared viruses (87%) also present in other OMZ samples. We detected 543 putative viral-encoded auxiliary metabolic genes (AMGs), of which some have a distribution that reflects physico-chemical characteristics across depth. Together these findings provide an ecological baseline for viral community structure, drivers and population variability in OMZs that will help future studies assess the role of viruses in these climate-critical environments.
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Affiliation(s)
- Dean Vik
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
| | - Maria Consuelo Gazitúa
- Department of Microbiology, The Ohio State University, Columbus, OH, USA.,Viromica Consulting, Santiago, Chile
| | - Christine L Sun
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
| | - Ahmed A Zayed
- Department of Microbiology, The Ohio State University, Columbus, OH, USA.,Center of Microbiome Science, The Ohio State University, Columbus, OH, USA
| | - Montserrat Aldunate
- Department of Oceanography, Universidad de Concepción, Concepción, Chile.,Millennium Institute of Oceanography, Universidad de Concepción, Concepción, Chile
| | - Margaret R Mulholland
- Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, VA, USA
| | - Osvaldo Ulloa
- Center of Microbiome Science, The Ohio State University, Columbus, OH, USA.,Millennium Institute of Oceanography, Universidad de Concepción, Concepción, Chile
| | - Matthew B Sullivan
- Department of Microbiology, The Ohio State University, Columbus, OH, USA.,Center of Microbiome Science, The Ohio State University, Columbus, OH, USA.,Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, Columbus, OH, USA
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8
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Widner B, Fuchsman CA, Chang BX, Rocap G, Mulholland MR. Utilization of urea and cyanate in waters overlying and within the eastern tropical north Pacific oxygen deficient zone. FEMS Microbiol Ecol 2019; 94:5055141. [PMID: 30016420 DOI: 10.1093/femsec/fiy138] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 07/16/2018] [Indexed: 11/15/2022] Open
Abstract
In marine oxygen deficient zones (ODZs), which contribute up to half of marine N loss, microbes use nitrogen (N) for assimilatory and dissimilatory processes. Here, we examine N utilization above and within the ODZ of the Eastern Tropical North Pacific Ocean, focusing on distribution, uptake and genes for the utilization of two simple organic N compounds, urea and cyanate. Ammonium, urea and cyanate concentrations generally peaked in the oxycline while uptake rates were highest in the surface. Within the ODZ, concentrations were lower, but urea N and C and cyanate C were taken up. All identified autotrophs had an N assimilation pathway that did not require external ammonium: ODZ Prochlorococcus possessed genes to assimilate nitrate, nitrite and urea; nitrite oxidizers (Nitrospina) possessed genes to assimilate nitrite, urea and cyanate; anammox bacteria (Scalindua) possessed genes to utilize cyanate; and ammonia-oxidizing Thaumarchaeota possessed genes to utilize urea. Urease genes were present in 20% of microbes, including SAR11, suggesting the urea utilization capacity was widespread. In the ODZ core, cyanate genes were largely (∼95%) associated with Scalindua, suggesting that, within this ODZ, cyanate N is primarily used for N loss via anammox (cyanammox), and that anammox does not require ammonium for N loss.
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Affiliation(s)
- Brittany Widner
- Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, USA
| | - Clara A Fuchsman
- University of Washington, School of Oceanography, Seattle, USA.,Horn Point Laboratory, University of Maryland Center for Environmental Science, Cambridge, USA
| | - Bonnie X Chang
- Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle, USA.,Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, USA
| | - Gabrielle Rocap
- University of Washington, School of Oceanography, Seattle, USA
| | - Margaret R Mulholland
- Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, USA
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9
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Fuchsman CA, Palevsky HI, Widner B, Duffy M, Carlson MCG, Neibauer JA, Mulholland MR, Keil RG, Devol AH, Rocap G. Cyanobacteria and cyanophage contributions to carbon and nitrogen cycling in an oligotrophic oxygen-deficient zone. ISME J 2019; 13:2714-2726. [PMID: 31249393 PMCID: PMC6794308 DOI: 10.1038/s41396-019-0452-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 04/20/2019] [Accepted: 05/26/2019] [Indexed: 12/03/2022]
Abstract
Up to half of marine N losses occur in oxygen-deficient zones (ODZs). Organic matter flux from productive surface waters is considered a primary control on N2 production. Here we investigate the offshore Eastern Tropical North Pacific (ETNP) where a secondary chlorophyll a maximum resides within the ODZ. Rates of primary production and carbon export from the mixed layer and productivity in the primary chlorophyll a maximum were consistent with oligotrophic waters. However, sediment trap carbon and nitrogen fluxes increased between 105 and 150 m, indicating organic matter production within the ODZ. Metagenomic and metaproteomic characterization indicated that the secondary chlorophyll a maximum was attributable to the cyanobacterium Prochlorococcus, and numerous photosynthesis and carbon fixation proteins were detected. The presence of chemoautotrophic ammonia-oxidizing archaea and the nitrite oxidizer Nitrospina and detection of nitrate oxidoreductase was consistent with cyanobacterial oxygen production within the ODZ. Cyanobacteria and cyanophage were also present on large (>30 μm) particles and in sediment trap material. Particle cyanophage-to-host ratio exceeded 50, suggesting that viruses help convert cyanobacteria into sinking organic matter. Nitrate reduction and anammox proteins were detected, congruent with previously reported N2 production. We suggest that autochthonous organic matter production within the ODZ contributes to N2 production in the offshore ETNP.
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Affiliation(s)
- Clara A Fuchsman
- School of Oceanography, University of Washington, Seattle, WA, USA. .,Horn Point Laboratory, University of Maryland, Cambridge, MD, USA.
| | - Hilary I Palevsky
- School of Oceanography, University of Washington, Seattle, WA, USA.,Geosciences Department, Wellesley College, Wellesley, MA, USA
| | - Brittany Widner
- Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.,Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, VA, USA
| | - Megan Duffy
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Michael C G Carlson
- School of Oceanography, University of Washington, Seattle, WA, USA.,Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | | | - Margaret R Mulholland
- Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Richard G Keil
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Allan H Devol
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Gabrielle Rocap
- School of Oceanography, University of Washington, Seattle, WA, USA.
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10
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Cao X, Mulholland MR, Helms JR, Bernhardt PW, Duan P, Mao J, Schmidt-Rohr K. A Major Step in Opening the Black Box of High-Molecular-Weight Dissolved Organic Nitrogen by Isotopic Labeling of Synechococcus and Multibond Two-Dimensional NMR. Anal Chem 2017; 89:11990-11998. [DOI: 10.1021/acs.analchem.7b02335] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiaoyan Cao
- Department
of Chemistry, Brandeis University, 415 South Street, Waltham, Massachusetts 02453, United States
| | - Margaret R. Mulholland
- Department
of Ocean, Earth and Atmospheric Sciences, Old Dominion University, 4600 Elkhorn Avenue, Norfolk, Virginia 23529, United States
| | - John R. Helms
- Department
of Chemistry and Biochemistry, Old Dominion University, 4541 Hampton
Boulevard, Norfolk, Virginia 23529, United States
- Biology
and Chemistry Department, Morningside College, 1501 Morningside Avenue, Sioux City, Iowa 51106, United States
| | - Peter W. Bernhardt
- Department
of Ocean, Earth and Atmospheric Sciences, Old Dominion University, 4600 Elkhorn Avenue, Norfolk, Virginia 23529, United States
| | - Pu Duan
- Department
of Chemistry, Brandeis University, 415 South Street, Waltham, Massachusetts 02453, United States
| | - Jingdong Mao
- Department
of Chemistry and Biochemistry, Old Dominion University, 4541 Hampton
Boulevard, Norfolk, Virginia 23529, United States
| | - Klaus Schmidt-Rohr
- Department
of Chemistry, Brandeis University, 415 South Street, Waltham, Massachusetts 02453, United States
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Abstract
We compared growth kinetics of Prorocentrum donghaiense cultures on different nitrogen (N) compounds including nitrate (NO3-), ammonium (NH4+), urea, glutamic acid (glu), dialanine (diala) and cyanate. P. donghaiense exhibited standard Monod-type growth kinetics over a range of N concentraions (0.5-500 μmol N L-1 for NO3- and NH4+, 0.5-50 μmol N L-1 for urea, 0.5-100 μmol N L-1 for glu and cyanate, and 0.5-200 μmol N L-1 for diala) for all of the N compounds tested. Cultures grown on glu and urea had the highest maximum growth rates (μm, 1.51±0.06 d-1 and 1.50±0.05 d-1, respectively). However, cultures grown on cyanate, NO3-, and NH4+ had lower half saturation constants (Kμ, 0.28-0.51 μmol N L-1). N uptake kinetics were measured in NO3--deplete and -replete batch cultures of P. donghaiense. In NO3--deplete batch cultures, P. donghaiense exhibited Michaelis-Menten type uptake kinetics for NO3-, NH4+, urea and algal amino acids; uptake was saturated at or below 50 μmol N L-1. In NO3--replete batch cultures, NH4+, urea, and algal amino acid uptake kinetics were similar to those measured in NO3--deplete batch cultures. Together, our results demonstrate that P. donghaiense can grow well on a variety of N sources, and exhibits similar uptake kinetics under both nutrient replete and deplete conditions. This may be an important factor facilitating their growth during bloom initiation and development in N-enriched estuaries where many algae compete for bioavailable N and the nutrient environment changes as a result of algal growth.
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Affiliation(s)
- Zhangxi Hu
- Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Research Center of Hydrobiology, Jinan University, Guangzhou, Guangdong, China
| | - Shunshan Duan
- Research Center of Hydrobiology, Jinan University, Guangzhou, Guangdong, China
| | - Ning Xu
- Research Center of Hydrobiology, Jinan University, Guangzhou, Guangdong, China
- * E-mail: (NX); (MRM)
| | - Margaret R. Mulholland
- Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, Virginia, United States of America
- * E-mail: (NX); (MRM)
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Rahav E, Bar-Zeev E, Ohayon S, Elifantz H, Belkin N, Herut B, Mulholland MR, Berman-Frank I. Dinitrogen fixation in aphotic oxygenated marine environments. Front Microbiol 2013; 4:227. [PMID: 23986748 PMCID: PMC3753716 DOI: 10.3389/fmicb.2013.00227] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Accepted: 07/26/2013] [Indexed: 11/13/2022] Open
Abstract
We measured N2 fixation rates from oceanic zones that have traditionally been ignored as sources of biological N2 fixation; the aphotic, fully oxygenated, nitrate (NO−3)-rich, waters of the oligotrophic Levantine Basin (LB) and the Gulf of Aqaba (GA). N2 fixation rates measured from pelagic aphotic waters to depths up to 720 m, during the mixed and stratified periods, ranged from 0.01 nmol N L−1 d−1 to 0.38 nmol N L−1 d−1. N2 fixation rates correlated significantly with bacterial productivity and heterotrophic diazotrophs were identified from aphotic as well as photic depths. Dissolved free amino acid amendments to whole water from the GA enhanced bacterial productivity by 2–3.5 fold and N2 fixation rates by ~2-fold in samples collected from aphotic depths while in amendments to water from photic depths bacterial productivity increased 2–6 fold while N2 fixation rates increased by a factor of 2 to 4 illustrating that both BP and heterotrophic N2 fixation were carbon limited. Experimental manipulations of aphotic waters from the LB demonstrated a significant positive correlation between transparent exopolymeric particle (TEP) concentrations and N2 fixation rates. This suggests that sinking organic material and high carbon (C): nitrogen (N) micro-environments (such as TEP-based aggregates or marine snow) could support high heterotrophic N2 fixation rates in oxygenated surface waters and in the aphotic zones. Indeed, our calculations show that aphotic N2 fixation accounted for 37 to 75% of the total daily integrated N2 fixation rates at both locations in the Mediterranean and Red Seas with rates equal or greater to those measured from the photic layers. Moreover, our results indicate that that while N2 fixation may be limited in the surface waters, aphotic, pelagic N2 fixation may contribute significantly to new N inputs in other oligotrophic basins, yet it is currently not included in regional or global N budgets.
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Affiliation(s)
- Eyal Rahav
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University Ramat Gan, Israel ; Israel Oceanographic and Limnological Research, National Institute of Oceanography Haifa, Israel
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Widner B, Mulholland MR, Mopper K. Chromatographic Determination of Nanomolar Cyanate Concentrations in Estuarine and Sea Waters by Precolumn Fluorescence Derivatization. Anal Chem 2013; 85:6661-6. [DOI: 10.1021/ac400351c] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Brittany Widner
- Department of Ocean,
Earth and Atmospheric Sciences, Old Dominion University, 4600 Elkhorn
Ave. Norfolk, Virginia 23529, United States
| | - Margaret R. Mulholland
- Department of Ocean,
Earth and Atmospheric Sciences, Old Dominion University, 4600 Elkhorn
Ave. Norfolk, Virginia 23529, United States
| | - Kenneth Mopper
- Department of Ocean,
Earth and Atmospheric Sciences, Old Dominion University, 4600 Elkhorn
Ave. Norfolk, Virginia 23529, United States
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Boyd PW, Rynearson TA, Armstrong EA, Fu F, Hayashi K, Hu Z, Hutchins DA, Kudela RM, Litchman E, Mulholland MR, Passow U, Strzepek RF, Whittaker KA, Yu E, Thomas MK. Marine phytoplankton temperature versus growth responses from polar to tropical waters--outcome of a scientific community-wide study. PLoS One 2013. [PMID: 23704890 DOI: 10.1371/journal.-pone.0063091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023] Open
Abstract
"It takes a village to finish (marine) science these days" Paraphrased from Curtis Huttenhower (the Human Microbiome project) The rapidity and complexity of climate change and its potential effects on ocean biota are challenging how ocean scientists conduct research. One way in which we can begin to better tackle these challenges is to conduct community-wide scientific studies. This study provides physiological datasets fundamental to understanding functional responses of phytoplankton growth rates to temperature. While physiological experiments are not new, our experiments were conducted in many laboratories using agreed upon protocols and 25 strains of eukaryotic and prokaryotic phytoplankton isolated across a wide range of marine environments from polar to tropical, and from nearshore waters to the open ocean. This community-wide approach provides both comprehensive and internally consistent datasets produced over considerably shorter time scales than conventional individual and often uncoordinated lab efforts. Such datasets can be used to parameterise global ocean model projections of environmental change and to provide initial insights into the magnitude of regional biogeographic change in ocean biota in the coming decades. Here, we compare our datasets with a compilation of literature data on phytoplankton growth responses to temperature. A comparison with prior published data suggests that the optimal temperatures of individual species and, to a lesser degree, thermal niches were similar across studies. However, a comparison of the maximum growth rate across studies revealed significant departures between this and previously collected datasets, which may be due to differences in the cultured isolates, temporal changes in the clonal isolates in cultures, and/or differences in culture conditions. Such methodological differences mean that using particular trait measurements from the prior literature might introduce unknown errors and bias into modelling projections. Using our community-wide approach we can reduce such protocol-driven variability in culture studies, and can begin to address more complex issues such as the effect of multiple environmental drivers on ocean biota.
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Affiliation(s)
- Philip W Boyd
- NIWA Centre for Chemical and Physical Oceanography, Department of Chemistry, University of Otago, Dunedin, New Zealand.
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Jayakumar A, Al-Rshaidat MM, Ward BB, Mulholland MR. Diversity, distribution, and expression of diazotrophnifHgenes in oxygen-deficient waters of the Arabian Sea. FEMS Microbiol Ecol 2012; 82:597-606. [DOI: 10.1111/j.1574-6941.2012.01430.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 05/29/2012] [Accepted: 06/07/2012] [Indexed: 11/28/2022] Open
Affiliation(s)
- Amal Jayakumar
- Department of Geosciences; Princeton University; Princeton; NJ; USA
| | - Mamoon M.D. Al-Rshaidat
- Department of Ocean, Earth & Atmospheric Sciences; Old Dominion University; Norfolk; VA; USA
| | - Bess B. Ward
- Department of Geosciences; Princeton University; Princeton; NJ; USA
| | - Margaret R. Mulholland
- Department of Ocean, Earth & Atmospheric Sciences; Old Dominion University; Norfolk; VA; USA
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Mesfioui R, Love NG, Bronk DA, Mulholland MR, Hatcher PG. Reactivity and chemical characterization of effluent organic nitrogen from wastewater treatment plants determined by Fourier transform ion cyclotron resonance mass spectrometry. Water Res 2012; 46:622-34. [PMID: 22172558 DOI: 10.1016/j.watres.2011.11.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 10/27/2011] [Accepted: 11/04/2011] [Indexed: 05/23/2023]
Abstract
In advanced wastewater treatment plants that achieve high levels of nitrogen (N) removal, up to one-third of the N in effluent is organic, herein referred to as effluent organic N (EON). While we know that inorganic N is highly labile, it is unclear what fraction of EON is bioavailable. In this study, we demonstrate the utility of a method that can be used to examine the reactivity of EON in natural receiving waters to better understand both the ecosystem response and the potential bioavailability of EON. The technique is suitable for analyzing polar organic matter in natural waters; electrospray ionization coupled with Fourier transform mass spectrometry. Bioassays were performed on samples collected at the end of the biological process from two wastewater treatment plants achieving advanced N removal. The samples were concentrated, and then added to natural water samples collected from the oligohaline James River, a major tributary of the Chesapeake Bay. Our results demonstrate that while the lignin-like fraction of the effluent dissolved organic matter (some of which contains N) was conserved, a large portion of aliphatic and aromatic compounds containing N was removed (79-100%) during incubations, while other compounds were produced. Furthermore, the two effluents exhibited differences in the degree of degradation and type of degradation, which can be related both to the various processes employed in the two WWTPs and the dramatic differences in the type of influent they received. These findings suggest that EON is highly reactive in the natural environment and that simple assays examining net consumption or production of bulk dissolved organic N pools are inadequate for assessing the bioavailability of EON.
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Affiliation(s)
- Rajaa Mesfioui
- Chemistry and Biochemistry, Old Dominion University-Physical Sciences Building, 4402 Elkhorn Ave., Norfolk, VA 23529, USA
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Garcia NS, Fu FX, Breene CL, Bernhardt PW, Mulholland MR, Sohm JA, Hutchins DA. INTERACTIVE EFFECTS OF IRRADIANCE AND CO2 ON CO2 FIXATION AND N2 FIXATION IN THE DIAZOTROPH TRICHODESMIUM ERYTHRAEUM (CYANOBACTERIA)(1). J Phycol 2011; 47:1292-1303. [PMID: 27020353 DOI: 10.1111/j.1529-8817.2011.01078.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The diazotrophic cyanobacteria Trichodesmium spp. contribute approximately half of the known marine dinitrogen (N2 ) fixation. Rapidly changing environmental factors such as the rising atmospheric partial pressure of carbon dioxide (pCO2 ) and shallower mixed layers (higher light intensities) are likely to affect N2 -fixation rates in the future ocean. Several studies have documented that N2 fixation in laboratory cultures of T. erythraeum increased when pCO2 was doubled from present-day atmospheric concentrations (∼380 ppm) to projected future levels (∼750 ppm). We examined the interactive effects of light and pCO2 on two strains of T. erythraeum Ehrenb. (GBRTRLI101 and IMS101) in laboratory semicontinuous cultures. Elevated pCO2 stimulated gross N2 -fixation rates in cultures growing at 38 μmol quanta · m(-2 ) · s(-1) (GBRTRLI101 and IMS101) and 100 μmol quanta · m(-2 ) · s(-1) (IMS101), but this effect was reduced in both strains growing at 220 μmol quanta · m(-2 ) · s(-1) . Conversely, CO2 -fixation rates increased significantly (P < 0.05) in response to high pCO2 under mid- and high irradiances only. These data imply that the stimulatory effect of elevated pCO2 on CO2 fixation and N2 fixation by T. erythraeum is correlated with light. The ratio of gross:net N2 fixation was also correlated with light and trichome length in IMS101. Our study suggests that elevated pCO2 may have a strong positive effect on Trichodesmium gross N2 fixation in intermediate and bottom layers of the euphotic zone, but perhaps not in light-saturated surface layers. Climate change models must consider the interactive effects of multiple environmental variables on phytoplankton and the biogeochemical cycles they mediate.
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Affiliation(s)
- Nathan S Garcia
- Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, USADepartment of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, Virginia 23529, USADepartment of Biological Sciences, University of Southern California, Los Angeles, California 90089, USA
| | - Fei-Xue Fu
- Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, USADepartment of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, Virginia 23529, USADepartment of Biological Sciences, University of Southern California, Los Angeles, California 90089, USA
| | - Cynthia L Breene
- Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, USADepartment of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, Virginia 23529, USADepartment of Biological Sciences, University of Southern California, Los Angeles, California 90089, USA
| | - Peter W Bernhardt
- Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, USADepartment of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, Virginia 23529, USADepartment of Biological Sciences, University of Southern California, Los Angeles, California 90089, USA
| | - Margaret R Mulholland
- Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, USADepartment of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, Virginia 23529, USADepartment of Biological Sciences, University of Southern California, Los Angeles, California 90089, USA
| | - Jill A Sohm
- Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, USADepartment of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, Virginia 23529, USADepartment of Biological Sciences, University of Southern California, Los Angeles, California 90089, USA
| | - David A Hutchins
- Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, USADepartment of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, Virginia 23529, USADepartment of Biological Sciences, University of Southern California, Los Angeles, California 90089, USA
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Yogev T, Rahav E, Bar-Zeev E, Man-Aharonovich D, Stambler N, Kress N, Béjà O, Mulholland MR, Herut B, Berman-Frank I. Is dinitrogen fixation significant in the Levantine Basin, East Mediterranean Sea? Environ Microbiol 2011; 13:854-71. [PMID: 21244595 DOI: 10.1111/j.1462-2920.2010.02402.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report N(2) fixation rates measured from two stations monitored monthly off the Mediterranean coast of Israel during 2006 and 2007, and along a transect from Israel to Crete in September 2008. Analyses of time-series data revealed expression of nifH genes from diazotrophs in nifH clusters I and II, including cyanobacterial bloom-formers Trichodesmium and diatom-Richelia intracellularis associations. However, nifH gene abundance and rates of N(2) fixation were very low in all size fractions measured (> 0.7 µm). Volumetric (15) N uptake ranged from below detection (∼ 36% of > 300 samples) to a high of 0.3 nmol N l(-1) d(-1) and did not vary distinctly with depth or season. Areal N(2) fixation averaged ∼ 1 to 4 µmol N m(-2) d(-1) and contributed only ∼ 1% and 2% of new production and ∼ 0.25% and 0.5% of primary production for the mixed (winter) and stratified (spring-fall) periods respectively. N(2) fixation rates along the 2008 east-west transect were also extremely low (0-0.04 nmol N l(-1) d(-1), integrated average 2.6 µmol N m(-2) d(-1) ) with 37% of samples below detection and no discernable difference between stations. We demonstrate that diazotrophy and N(2) fixation contribute only a minor amount of new N to the P impoverished eastern Mediterranean Sea.
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Affiliation(s)
- Tali Yogev
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
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Bronk DA, Roberts QN, Sanderson MP, Canuel EA, Hatcher PG, Mesfioui R, Filippino KC, Mulholland MR, Love NG. Effluent organic nitrogen (EON): bioavailability and photochemical and salinity-mediated release. Environ Sci Technol 2010; 44:5830-5835. [PMID: 20590151 DOI: 10.1021/es101115g] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The goal of this study was to investigate three potential ways that the soluble organic nitrogen (N) fraction of wastewater treatment plant (WWTP) effluents, termed effluent organic N (EON), could contribute to coastal eutrophication--direct biological removal, photochemical release of labile compounds, and salinity-mediated release of ammonium (NH4+). Effluents from two WWTPs were used in the experiments. For the bioassays, EON was added to water from four salinities (approximately 0 to 30) collected from the James River (VA) in August 2008, and then concentrations of N and phosphorus compounds were measured periodically over 48 h. Bioassay results, based on changes in DON concentrations, indicate that some fraction of the EON was removed and that the degree of EON removal varied between effluents and with salinity. Further, we caution that bioassay results should be interpreted within a broad context of detailed information on chemical characterization. EON from both WWTPs was also photoreactive, with labile NH4+ and dissolved primary amines released during exposure to sunlight. We also present the first data that demonstrate that when EON is exposed to higher salinities, increasing amounts of NH4+ are released, further facilitating EON use as effluent transits from freshwater through estuaries to the coast.
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Affiliation(s)
- Deborah A Bronk
- Virginia Institute of Marine Science, The College of William & Mary, Gloucester Point, Virginia 23062, Old Dominion University, Norfolk, Virginia 23529, USA.
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Mulholland MR, Capone DG. Dinitrogen fixation in the Indian Ocean. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2009gm000850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
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Simjouw JP, Mulholland MR, Minor EC. Changes in dissolved organic matter characteristics in Chincoteague Bay during a bloom of the pelagophyteAureococcus anophagefferens. ACTA ACUST UNITED AC 2004. [DOI: 10.1007/bf02803425] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
Trichodesmium spp. have proved to be enigmatic organisms, and their ecology and physiology are unusual among diazotrophs. Recent research shows that they can simultaneously fix N2 and take up combined nitrogen. The co-occurrence of these two processes is thought to be incompatible, but they could be obligatory in Trichodesmium spp. if only a small fraction of cells within a colony or along a filament are capable of N2 fixation. Combined nitrogen is released from cells during periods of active growth and N2 fixation, and concomitantly taken up by Trichodesmium spp. or cells living in association with colonies. Although the nitrogenase of Trichodesmium spp. is affected by high concentrations of combined nitrogen, it might be relatively less sensitive to low concentrations of combined nitrogen typical of the oligotrophic ocean and culture conditions. Nitrogenase activity and synthesis exhibits an endogenous rhythm in Trichodesmium spp. cultures, which is affected by the addition of nitrogen.
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Affiliation(s)
- M R Mulholland
- Marine Sciences Research Center, SUNY Stony Brook, NY 11794-5000, USA.
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Dupouy C, Neveux J, Subramaniam A, Mulholland MR, Montoya JP, Campbell L, Carpenter EJ, Capone DG. Satellite captures trichodesmium blooms in the southwestern tropical Pacific. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/00eo00008] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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