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Coleman, David C., and E. R. Ingham. "Terrestrial nutrient cycles." Biogeochemistry 5, no. 1 (February 1988): 3–5. http://dx.doi.org/10.1007/bf02180315.
Natural forests may be viewed as containing nested nutrient cycles: an "external" cycle mediated by atmospheric processes, a "soil" cycle of litter production and decay, and one or more "plant" cycles involving retranslocation and internal storage pools. The goal of plantation forest management should be to enhance all of these cycles. Stimulating the "external" cycle by adding fertilizer nutrients is likely to increase "soil" and "plant" cycling rates as well. A basic understanding of how these nested cycles are linked can improve the management of nutrients in forest plantations.
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COMERFORD, N. "Forest Soils and Nutrient Cycles." Soil Science 146, no. 6 (December 1988): 467. http://dx.doi.org/10.1097/00010694-198812000-00009.
In an oligotrophic bay, Mitsu Bay, Japan, artificial timber reefs (ATRs) are deployed to increase fish production. In such man-made ecosystems, the biological activities of other organisms as well as the physical structures of ATRs could influence nutrient cycling. A pelagic–benthic coupling model expressing both phosphorus and nitrogen cycling was developed to investigate seasonal variation in the associated nutrients and their annual budget in the ATR areas and the entire bay system. The model consists of equations representing all the relevant physical and biological processes. The model reproduced the observed seasonal variations in dissolved inorganic P, ammonium, and nitrate concentrations that were low in spring and summer and high in autumn and winter. The internal regeneration rates of the nutrients were two times higher in the ATRs than in the bay area, so that fish production was predicted to be higher in the ATRs than in the bay area. Considering the inflows from the land and precipitation are quite low, nutrient regeneration is an important source of nutrients for the water in Mitsu Bay. ATR deployment could be an important local nutrient source in an oligotrophic bay, and could increase fish production.
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Moore, C. M. "Microbial proteins and oceanic nutrient cycles." Science 345, no. 6201 (September 4, 2014): 1120–21. http://dx.doi.org/10.1126/science.1258133.
Arrigo, Kevin R. "Marine microorganisms and global nutrient cycles." Nature 437, no. 7057 (September 14, 2004): 349–55. http://dx.doi.org/10.1038/nature04159.
Fasham, M. J. R. "Antarctic nutrient cycles and food webs." Estuarine, Coastal and Shelf Science 25, no. 4 (October 1987): 483. http://dx.doi.org/10.1016/0272-7714(87)90041-2.
Pascual, Mercedes, and Hal Caswell. "From the Cell Cycle to Population Cycles in Phytoplankton-Nutrient Interactions." Ecology 78, no. 3 (April 1997): 897. http://dx.doi.org/10.2307/2266068.
Pascual, Mercedes, and Hal Caswell. "FROM THE CELL CYCLE TO POPULATION CYCLES IN PHYTOPLANKTON–NUTRIENT INTERACTIONS." Ecology 78, no. 3 (April 1997): 897–912. http://dx.doi.org/10.1890/0012-9658(1997)078[0897:ftcctp]2.0.co;2.
Abell, Jeffrey Thomas. "Giving a damn about DOM in the subtropical North Pacific : quantifying the role of dissolved organic matter in the cycling of carbon, oxygen and nutrients in the upper ocean /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/11060.
Anderson, Laurence Anthony. "The determination of Redfield ratios for use in global oceanic nutrient cycle models." [Princeton, N.J.] : Princeton University, Dept. of Geological and Geophysical Sciences, Program in Atmospheric and Oceanic Sciences, 1993. http://catalog.hathitrust.org/api/volumes/oclc/75401374.html.
Crump, Byron C. "Bacterial activity and community structure in the Columbia River estuarine turbidity maxima /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/10989.
Mielke, Nora. "The role of nitrogen and phosphorus in carbon and nutrient cycling of bryophyte-dominated exosystems." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=231758.
Bryophytes form an important component of northern vegetation communities. Mosses efficiently capture aerially deposited nutrients, restricting nutrient availability to the soil. Given that key ecosystem processes of northern ecosystems are nutrient-limited, understanding nutrient cycling of the moss layer is key to understanding ecosystem nutrient and C cycling in these systems. However, the role of the moss layer in regulating ecosystem-scale nutrient and C cycling, while potentially significant, is largely unknown. The aim of this thesis is to investigate the effect of the relative availability of N and P on aspects of bryophyte nutrient uptake, retention and C acquisition. The hypothesis investigated is that the availability of one nutrient will influence the demand for the other and thereby moss nutrient acquisition and retention mechanisms. To test this hypothesis, various aspects of moss nutrient cycling in response to the relative availability of N and P were investigated. As the C cycle is tightly linked to the N and P cycles, the hypothesis extended to include bryophyte C assimilation and decomposition processes of an arctic tundra. Bryophyte nutrient demand was chiefly governed by the tissue N:P ratio. Consequently, nutrient uptake, both from aerially deposited nutrients and through moss-cyanobacteria N2 fixation, and nutrient losses after a simulated rainfall event were mostly in response to the relative availability of N and P rather than the availability of one nutrient alone. This thesis provides novel evidence that ectohydric mosses have the ability to internally translocate nutrients. In conjunction with efficient nutrient capture, this trait makes mosses strong nutrient sinks which are likely to exert considerable control over ecosystem nutrient cycling. The relative availability of N and P played a role in C uptake of mosses. Through the production of recalcitrant litter and their insulating effect on soil microclimate mosses exerted an influence over ecosystem C cycling.
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Neu, Silke, Jörg Schaller, and E. Gert Dudel. "Silicon availability modifies nutrient use efficiency and content, C:N:P stoichiometry, and productivity of winter wheat (Triticum aestivum L.)." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-221008.
Silicon (Si) is known as beneficial element for graminaceous plants. The importance of Si for plant functioning of cereals was recently emphasized. However, about the effect of Si availability on biomass production, grain yield, nutrient status and nutrient use efficiency for wheat (Triticum aestivum L.), as one of the most important crop plants worldwide, less is known so far. Consequently, we assessed the effect of a broad range of supply levels of amorphous SiO2 on wheat plant performance. Our results revealed that Si is readily taken up and accumulated basically in aboveground vegetative organs. Carbon (C) and phosphorus (P) status of plants were altered in response to varying Si supply. In bulk straw biomass C concentration decreased with increasing Si supply, while P concentration increased from slight limitation towards optimal nutrition. Thereby, aboveground biomass production increased at low to medium supply levels of silica whereas grain yield increased at medium supply level only. Nutrient use efficiency was improved by Si insofar that biomass production was enhanced at constant nitrogen (N) status of substrate and plants. Consequently, our findings imply fundamental influences of Si on C turnover, P availability and nitrogen use efficiency for wheat as a major staple crop.
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Auguères, Anne-Sophie. "Régulation biotique des cycles biogéochimiques globaux : une approche théorique." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30290/document.
Les activités anthropiques affectent les cycles biogéochimiques globaux, principalement par l'ajout de nutriments dans les écosystèmes. Il est donc crucial de déterminer dans quelle mesure les cycles biogéochimiques globaux peuvent être régulés. Les autotrophes peuvent réguler les réservoirs de nutriments par la consommation des ressources, mais la majorité des ressources leur sont inaccessibles à l'échelle globale. Par des modèles théoriques, nous avons cherché à évaluer la manière dont les autotrophes répondent à la fertilisation à l'échelle globale et leur capacité à réguler les concentrations des nutriments quand leur accessibilité est limitée. Nous avons également étudié les mécanismes qui déterminent la régulation des rapports de Redfield dans l'océan, ainsi que les effets de l'ajout de nutriments sur la production primaire océanique totale. Nous avons montré que les organismes ne régulent pas efficacement les réservoirs de nutriments. Le couplage des cycles biogéochimiques et la compétition entre groupes fonctionnels peuvent altérer, négativement ou positivement, la régulation des cycles biogéochimiques globaux par les organismes. Une régulation inefficace des concentrations de nutriments n'exclut par contre pas une forte régulation des rapports entre ces nutriments, comme dans le cas des rapports de Redfield. La fertilisation des écosystèmes terrestres et océaniques risque donc de fortement impacter la production primaire et les cycles biogéochimiques globaux, à de courtes comme à de grandes échelles de temps Anthropogenic activities heavily impact global biogeochemical cycles, mainly through nutrient fertilisation of ecosystems; thus it is crucial to assess the extent to which global biogeochemical cycles are regulated. Autotrophs can regulate nutrient pools locally through resource consumption, but most resources are inaccessible to them at global scales. We used theoretical models to assess how organisms respond nutrient fertilisation at global scales and how they can regulate the concentration of these nutrients when their accessibility of is limited. We further investigated the mechanisms driving the regulation of Redfield ratios in oceans, and the effects of nutrient fertilisation on total oceanic primary production. We showed that organisms cannot efficiently regulate nutrient pools. Mechanisms such as coupling of nutrient cycles and competition between functional groups can alter the strength of biotic regulation of global biogeochemical cycles, either positively or negatively. An inefficient regulation of inaccessible nutrient concentration, however, does not exclude a strong biotic regulation of nutrient ratios, as is the case with Redfield ratios in oceans. Nutrient fertilization of oceanic and terrestrial ecosystems is thus likely to have a strong impact on primary production and global nutrient cycles at both small and long timescales
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Oates, Richard Hunter. "Phosphate-mineral interactions and potential consequences for nutrient cycling." Thesis, Online version of original thesis, 2008. http://hdl.handle.net/1912/2395.
Neu, Silke, Jörg Schaller, and E. Gert Dudel. "Silicon availability modifies nutrient use efficiency and content, C:N:P stoichiometry, and productivity of winter wheat (Triticum aestivum L.)." Nature Publishing Group, 2016. https://tud.qucosa.de/id/qucosa%3A30213.
Silicon (Si) is known as beneficial element for graminaceous plants. The importance of Si for plant functioning of cereals was recently emphasized. However, about the effect of Si availability on biomass production, grain yield, nutrient status and nutrient use efficiency for wheat (Triticum aestivum L.), as one of the most important crop plants worldwide, less is known so far. Consequently, we assessed the effect of a broad range of supply levels of amorphous SiO2 on wheat plant performance. Our results revealed that Si is readily taken up and accumulated basically in aboveground vegetative organs. Carbon (C) and phosphorus (P) status of plants were altered in response to varying Si supply. In bulk straw biomass C concentration decreased with increasing Si supply, while P concentration increased from slight limitation towards optimal nutrition. Thereby, aboveground biomass production increased at low to medium supply levels of silica whereas grain yield increased at medium supply level only. Nutrient use efficiency was improved by Si insofar that biomass production was enhanced at constant nitrogen (N) status of substrate and plants. Consequently, our findings imply fundamental influences of Si on C turnover, P availability and nitrogen use efficiency for wheat as a major staple crop.
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Klein, Lawrence S. "An Ecosystem Dynamics Model of Monterey Bay, California." Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/KleinLS2002.pdf.
Murphy, Conor. "Investigation of rhizosphere priming effects for N mineralisation in contrasting soils." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=228575.
In the context of nutrient cycling in soil, plant-mediated mineralisation of carbon (C) and nitrogen (N) is poorly understood. The broad focus of this thesis was to investigate the potential importance of plant-mediated mineralisation (i.e.priming) on C and N mineralisation in soils with contrasting crop productivities. The studies focus on two soils, which had similar chemical and physical properties but contrasting plant productivities relating to their N supply capacity. These soils were used to investigate the potential importance of priming processes in contributing to the contrasting capacities of these soils to supply N for plant growth. 13C and 15N stable isotopes were used to measure specific gross C and N fluxes. Sole C or N and combined C with N treatments were established to disentangle the effect of carbon and nitrogen availability on plant-mediated mineralisation. The addition of labile C increased gross carbon and nitrogen fluxes from native soil organic matter (SOM) but the effect was soil specific. The addition of nitrogen did not affect SOM mineralisation in either soil. The much lower C-to-N ratio of the 'primed' flux compared to the 'basal' flux indicated that the primed flux utilises different OM pools highlighting that primed and basal mineralisation may be distinct processes. The priming response (i.e. positive or negative and associated mechanisms) was different depending on carbon and nitrogen supply to the microbial community. Overall, the studies in this thesis places the microbial community as the focal point of soil N supply. This data strongly supports the concept that the release of labile carbon from plant roots functions as a nutrient acquisition response, increasing mineralisation of SOM. From the data a conceptual model of priming mechanisms, based on nutrient availability to the microbial community, was established. This could be used as the foundation to develop key concepts for sustainable agricultural practice.
Siegfried, Walter R., Pat R. Condy, and Richard M. Laws, eds. Antarctic Nutrient Cycles and Food Webs. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82275-9.
Collinson, A. S. "Nutrients and nutrient cycles." In Introduction to World Vegetation, 84–110. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-015-3935-7_4.
Likens, Gene E., and F. Herbert Bormann. "Nutrient Cycles." In Biogeochemistry of a Forested Ecosystem, 103–11. New York, NY: Springer New York, 1995. http://dx.doi.org/10.1007/978-1-4612-4232-1_6.
Valiela, Ivan. "Nutrient Cycles in Ecosystems." In Marine Ecological Processes, 529–76. New York, NY: Springer New York, 2015. http://dx.doi.org/10.1007/978-0-387-79070-1_17.
Rees, Paul A. "Nutrient and material cycles." In Key questions in ecology: a study and revision guide, 65–81. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247572.0065.
Conley, Daniel J. "Biogeochemical nutrient cycles and nutrient management strategies." In Man and River Systems, 87–96. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-017-2163-9_10.
Eck, Mathilde, Oliver Körner, and M. Haïssam Jijakli. "Nutrient Cycling in Aquaponics Systems." In Aquaponics Food Production Systems, 231–46. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-15943-6_9.
AbstractIn aquaponics, nutrients originate mainly from the fish feed and water inputs in the system. A substantial part of the feed is ingested by the fish and either used for growth and metabolism or excreted as soluble and solid faeces, while the rest of any uneaten feed decays in the tanks. While the soluble excretions are readily available for the plants, the solid faeces need to be mineralised by microorganisms in order for its nutrient content to be available for plant uptake. It is thus more challenging to control the available nutrient concentrations in aquaponics than in hydroponics. Furthermore, many factors, amongst others pH, temperature and light intensity, influence the nutrient availability and plant uptake. Until today, most studies have focused on the nitrogen and phosphorus cycles. However, to ensure good crop yields, it is necessary to provide the plants with sufficient levels of all key nutrients. It is therefore essential to better understand and control nutrient cycles in aquaponics.
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Binkley, Dan, Charles T. Driscoll, H. Lee Allen, Philip Schoeneberger, and Drew McAvoy. "Nutrient Cycles and Nutrient Limitations in the South." In Ecological Studies, 86–109. New York, NY: Springer New York, 1989. http://dx.doi.org/10.1007/978-1-4612-3586-6_6.
Likens, Gene E. "Nutrient Cycles and Mass Balances." In Biogeochemistry of a Forested Ecosystem, 139–61. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-7810-2_6.
Valiela, Ivan. "Nutrient Cycles and Ecosystem Stoichiometry." In Marine Ecological Processes, 425–66. New York, NY: Springer New York, 1995. http://dx.doi.org/10.1007/978-1-4757-4125-4_14.
Тези доповідей конференцій з теми "Nutrient cycles":
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Uhlig, David, and Friedhelm von Blanckenburg. "The interaction of organic and geogenic nutrient cycles." In Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.7080.
Jau, Yi-Ren, and Shu-Hsing Chen. "The Concept of Energy Flow and Nutrient Cycles in Managing Biocalcification." In The 4th Virtual International Conference on Advanced Research in Scientific Areas. Publishing Society, 2015. http://dx.doi.org/10.18638/arsa.2015.4.1.794.
Curtin, Tara M., and Keri Geiser. "CULTURAL EUTROPHICATION CAUSES MODIFICATION OF NUTRIENT CYCLES IN THE NEW YORK FINGER LAKES." In GSA Annual Meeting in Indianapolis, Indiana, USA - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018am-322839.
James, Jason, and Rob Harrison. "INTERACTION BETWEEN CARBON AND NUTRIENT CYCLES IN DEEP SOILS OF THE PACIFIC NORTHWEST." In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-303364.
Wang, Xinqiang, Zhipeng Wang, Xiaoying Shi, Dongjie Tang, Eva Stüeken, Huyue Song, and Yongbo Peng. "Feedbacks between Multiple Nutrient Cycles Facilitated the Expansion of Eukaryotic Life at ca. 1.56 Ga." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.2783.
Chang, Ni-Bin, and Zhemin Xuan. "Exploring the nutrient inputs and cycles in Tampa Bay and coastal watersheds using MODIS images and data mining." In SPIE Optical Engineering + Applications, edited by Wei Gao, Thomas J. Jackson, Jinnian Wang, and Ni-Bin Chang. SPIE, 2011. http://dx.doi.org/10.1117/12.891871.
Orekhova, Natalia, Natalia Orekhova, Eugene Medvedev, Eugene Medvedev, Sergey Konovalov, and Sergey Konovalov. "CARBONATE SYSTEM TRANSFORMATION IN THE SEVASTOPOL BAY (THE BLACK SEA)." In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.31519/conferencearticle_5b1b93867499f8.32847275.
A 20% increase of the carbon dioxide concentration in the atmosphere during the last century and a dramatic increase in nutrient load to marine systems due to human activity have resulted in pronounced carbon cycle transformation in coastal areas. Acidification and carbon dioxide increasing in the water column and appearance of oxygen minimum zones are reported for the worldwide coast. This makes ecological assessment of aquatic systems, including key cycles of elements, an important social and scientific task. In this study, we present information on the inorganic part of the carbon cycle and its transformation in the Sevastopol Bay (the Black Sea). This semi-enclosed coastal area has been under heavy anthropogenic pressure over the last century. Municipal and industrial sewage discharge, maritime activities, including excavation of bottom sediments, provide additional sources of nutrients and organic carbon. We present data on dynamics of the inorganic part of the carbon cycle from 1998 – 2015. Values of pH and total alkalinity were obtained analytically, whereas CO2, HCO3-, CO32- concentrations and pCO2 values were calculated. Dissolved inorganic carbon (DIC) and its partitioning into CO2, HCO3-, CO32- demonstrate the state of the carbon cycle and its evolution. Our observations reveal up to 2% increase of DIC from 1998 – 2015, but the value of pCO2 has increased by up to 20% in line with declining pH (acidification). Seasonal variations are far more pronounced and reveal extremes for areas of oxygen minimum zones. This results in negative consequences for the ecosystem, but these consequences for the Sevastopol Bay’s ecosystem remain reversible and the carbonate system can be restored to its natural state.
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Orekhova, Natalia, Natalia Orekhova, Eugene Medvedev, Eugene Medvedev, Sergey Konovalov, and Sergey Konovalov. "CARBONATE SYSTEM TRANSFORMATION IN THE SEVASTOPOL BAY (THE BLACK SEA)." In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.21610/conferencearticle_58b431683c672.
A 20% increase of the carbon dioxide concentration in the atmosphere during the last century and a dramatic increase in nutrient load to marine systems due to human activity have resulted in pronounced carbon cycle transformation in coastal areas. Acidification and carbon dioxide increasing in the water column and appearance of oxygen minimum zones are reported for the worldwide coast. This makes ecological assessment of aquatic systems, including key cycles of elements, an important social and scientific task. In this study, we present information on the inorganic part of the carbon cycle and its transformation in the Sevastopol Bay (the Black Sea). This semi-enclosed coastal area has been under heavy anthropogenic pressure over the last century. Municipal and industrial sewage discharge, maritime activities, including excavation of bottom sediments, provide additional sources of nutrients and organic carbon. We present data on dynamics of the inorganic part of the carbon cycle from 1998 – 2015. Values of pH and total alkalinity were obtained analytically, whereas CO2, HCO3-, CO32- concentrations and pCO2 values were calculated. Dissolved inorganic carbon (DIC) and its partitioning into CO2, HCO3-, CO32- demonstrate the state of the carbon cycle and its evolution. Our observations reveal up to 2% increase of DIC from 1998 – 2015, but the value of pCO2 has increased by up to 20% in line with declining pH (acidification). Seasonal variations are far more pronounced and reveal extremes for areas of oxygen minimum zones. This results in negative consequences for the ecosystem, but these consequences for the Sevastopol Bay’s ecosystem remain reversible and the carbonate system can be restored to its natural state.
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Mu, Di. "Notice of Retraction: A Model Study on the Nutrient Cycles and Plankton Dynamics in the Red Tide Monitoring Area of Bohai Bay." In 2011 5th International Conference on Bioinformatics and Biomedical Engineering. IEEE, 2011. http://dx.doi.org/10.1109/icbbe.2011.5780761.
Chu, Shaoping, and Scott Elliott. "Eddy resolving nutrient ecodynamics in the global Parallel Ocean Program and connections with trace gases in the sulfur, halogen, and NMHC cycles." In Europto Remote Sensing, edited by Charles R. Bostater, Jr. and Rosalia Santoleri. SPIE, 2000. http://dx.doi.org/10.1117/12.411691.
Cai, Yingqi. SnRK1-ZmRFWD3-Opaque2: A Nexus of Seed Nutrient Accumulation and Diurnal Cycles. Office of Scientific and Technical Information (OSTI), September 2020. http://dx.doi.org/10.2172/1716748.
Shpigel, Muki, Allen Place, William Koven, Oded (Odi) Zmora, Sheenan Harpaz, and Mordechai Harel. Development of Sodium Alginate Encapsulation of Diatom Concentrates as a Nutrient Delivery System to Enhance Growth and Survival of Post-Larvae Abalone. United States Department of Agriculture, September 2001. http://dx.doi.org/10.32747/2001.7586480.bard.
The major bottlenecks in rearing the highly priced gastropod abalone (Haliotis spp.) are the slow growth rate and the high mortality during the first 8 to 12 weeks following metamorphosis and settling. The most likely reason flor these problems is related to nutritional deficiencies in the diatom diet on which the post larvae (PL) feed almost exclusively in captivity. Higher survival and improved growth rate will reduce the considerable expense of hatchery-nursery resisdence time and thereflore the production costs. BARD supported our research for one year only and the support was given to us in order to prove that "(1) Abalone PL feed on encapsulated diatoms, and (2) heterotrophic diatoms can be mass produced." In the course of this year we have developed a novel nutrient delivery system specifically designed to enhance growth and survival of post-larval abalone. This approach is based on the sodium-alginate encapsulation of heterotrophically grown diatoms or diatom extracts, including appetite-stimulating factors. Diatom species that attract the PL and promote the highest growth and survival have been identified. These were also tested by incorporating them (either intact cells or as cell extracts) into a sodium-alginate matrix while comparing the growth to that achieved when using diatoms (singel sp. or as a mixture). A number of potential chemoattractants to act as appetite-stimulating factors for abalone PL have been tested. Preliminary results show that the incorporation of the amino acid methionine at a level of 10-3M to the sodim alginate matrix leads to a marked enhancement of growth. The results ol these studies provided basic knowledge on the growth of abalone and showed that it is possible to obtain, on a regular basis, survival rates exceeding 10% for this stage. Prior to this study the survival rates ranged between 2-4%, less than half of the values achieved today. Several diatom species originated from the National Center for Mariculture (Nitzchia laevis, Navicula lenzi, Amphora T3, and Navicula tennerima) and Cylindrotheca fusiformis (2083, 2084, 2085, 2086 and 2087 UTEX strains, Austin TX) were tested for heterotrophic growth. Axenic colonies were initially obtained and following intensive selection cycles and mutagenesis treatments, Amphora T3, Navicula tennerima and Cylindrotheca fusiformis (2083 UTEX strain) were capable of growing under heterotrophic conditions and to sustain highly enriched mediums. A highly efficient selection procedure as well as cost effective matrix of media components were developed and optimized. Glucose was identified as the best carbon source for all diatom strains. Doubling times ranging from 20-40 h were observed, and stable heterotroph cultures at a densities range of 103-104 were achieved. Although current growth rates are not yet sufficient for full economical fermentation, we estimate that further selections and mutagenesis treatments cycles should result in much faster growing colonies suitable for a fermentor scale-up. As rightfully pointed out by one of the reviewers, "There would be no point in assessing the optimum levels of dietary inclusions into micro-capsules, if the post-larvae cannot be induced to consume those capsules in the first place." We believe that the results of the first year of research provide a foundationfor the continuation of this research following the objectives put forth in the original proposal. Future work should concentrate on the optimization of incorporation of intact cells and cell extracts of the developed heterotrophic strains in the alginate matrix, as well as improving this delivery system by including liposomes and chemoattractants to ensure food consumption and enhanced growth.
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Sengupta, Sukalyan, Beni Lew, and Lee Blaney. Closing the nutrient cycle through sustainable agricultural waste management. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7600040.bard.
Twining, Benjamin S., Mak A. Saito, Alyson E. Santoro, Adrian Marchetti, and Naomi M. Levine. US National BioGeoSCAPES Workshop Report. Woods Hole Oceangraphic Institution, January 2023. http://dx.doi.org/10.1575/1912/29604.
BioGeoSCAPES (BGS) is an international program being developed to understand controls on ocean productivity and metabolism by integrating systems biology (‘omics) and biogeochemistry (Figure 1). To ensure global input into the design of the BGS Program, countries interested in participating were tasked with holding an organizing meeting to discuss the country-specific research priorities. A United States BGS planning meeting, sponsored by the Ocean Carbon & Biogeochemistry (OCB) Project Office, was convened virtually November 10-12, 2021. The objectives of the meeting were to communicate the planning underway by international partners, engage the US community to explore possible national contributions to such a program, and build understanding, support, and momentum for US efforts towards BGS. The meeting was well-attended, with 154 participants and many fruitful discussions that are summarized in this document. Key outcomes from the meeting were the identification of additional programs and partners for BGS, a prioritization of measurements requiring intercalibration, and the development of a consensus around key considerations to be addressed in a science plan. Looking forward, the hope is that this workshop will serve as the foundation for future US and international discussions and planning for a BGS program, enabled by NSF funding for an AccelNet project (AccelNet - Implementation: Development of an International Network for the Study of Ocean Metabolism and Nutrient Cycles on a Changing Planet (BioGeoSCAPES)), beginning in 2022.
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Fisher, Joshua, Richard Phillips, and Tom Evans. Nutrient Cycle Impacts on Forest Ecosystem Carbon Cycling: Improved Prediction of Climate Feedbacks from Coupled C–Nutrient Dynamics from Ecosystem to Regional Scales. Office of Scientific and Technical Information (OSTI), August 2017. http://dx.doi.org/10.2172/1377633.
Or, Dani, Shmulik Friedman, and Jeanette Norton. Physical processes affecting microbial habitats and activity in unsaturated agricultural soils. United States Department of Agriculture, October 2002. http://dx.doi.org/10.32747/2002.7587239.bard.
experimental methods for quantifying effects of water content and other dynamic environmental factors on bacterial growth in partially-saturated soils. Towards this end we reviewed critically the relevant scientific literature and performed theoretical and experimental studies of bacterial growth and activity in modeled, idealized and real unsaturated soils. The natural wetting-drying cycles common to agricultural soils affect water content and liquid organization resulting in fragmentation of aquatic habitats and limit hydraulic connections. Consequently, substrate diffusion pathways to soil microbial communities become limiting and reduce nutrient fluxes, microbial growth, and mobility. Key elements that govern the extent and manifestation of such ubiquitous interactions include characteristics of diffusion pathways and pore space, the timing, duration, and extent of environmental perturbations, the nature of microbiological adjustments (short-term and longterm), and spatial distribution and properties of EPS clusters (microcolonies). Of these key elements we have chosen to focus on a manageable subset namely on modeling microbial growth and coexistence on simple rough surfaces, and experiments on bacterial growth in variably saturated sand samples and columns. Our extensive review paper providing a definitive “snap-shot” of present scientific understanding of microbial behavior in unsaturated soils revealed a lack of modeling tools that are essential for enhanced predictability of microbial processes in soils. We therefore embarked on two pronged approach of development of simple microbial growth models based on diffusion-reaction principles to incorporate key controls for microbial activity in soils such as diffusion coefficients and temporal variations in soil water content (and related substrate diffusion rates), and development of new methodologies in support of experiments on microbial growth in simple and observable porous media under controlled water status conditions. Experimental efforts led to a series of microbial growth experiments in granular media under variable saturation and ambient conditions, and introduction of atomic force microscopy (AFM) and confocal scanning laser microscopy (CSLM) to study cell size, morphology and multi-cell arrangement at a high resolution from growth experiments in various porous media. The modeling efforts elucidated important links between unsaturated conditions and microbial coexistence which is believed to support the unparallel diversity found in soils. We examined the role of spatial and temporal variation in hydration conditions (such as exist in agricultural soils) on local growth rates and on interactions between two competing microbial species. Interestingly, the complexity of soil spaces and aquatic niches are necessary for supporting a rich microbial diversity and the wide array of microbial functions in unsaturated soils. This project supported collaboration between soil physicists and soil microbiologist that is absolutely essential for making progress in both disciplines. It provided a few basic tools (models, parameterization) for guiding future experiments and for gathering key information necessary for prediction of biological processes in agricultural soils. The project sparked a series of ongoing studies (at DTU and EPFL and in the ARO) into effects of soil hydration dynamics on microbial survival strategy under short term and prolonged desiccation (important for general scientific and agricultural applications).
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Shtienberg, Dan, William Fry, Amos Dinoor, Thomas Zitter, and Uzi Kafkafi. Reduction in Pesticide Use in Plant Disease Control by Integration of Chemical and Non-Chemical Factors. United States Department of Agriculture, May 1995. http://dx.doi.org/10.32747/1995.7613027.bard.
The long term goal of this research project was to improve control efficiency of Alternaria diseases while reducing fungicide use, by integration of chemical and non-chemical factors. Non-chemical factors were genotype resistance, age-related resistance and fertilizers. The Specific objectives were: 1) To quantify changes in resistance among genotypes and over time in terms of disease development and specific phases of the disease cycle; 2) To quantify the effects of fertilizers applied to the foliage alone, or in combination with a fungicide, on disease development; 3) To quantify the relative contribution of genotype resistance, age-related resistance and fungicide type to the reduction of disease development; 4) To develop a strategy for integration of chemical and non-chemical factors which will achieve optimal disease suppression. The influence of physiological age of cotton plants and of the individual leaves, on disease incidence and on the rate of lesion expansion of A. macrospora was examined on leaves sampled from the field. Both parameters increased with the physiological age of individual leaves but were not affected by the age of the whole plant. The hypothesis that enrichment of the foliage with nitrogen and potassium may enhance host resistance to Alternaria and thus reduce disease severity, was examined for potato and tomato (A. solani ) and for cotton (A. macrospora ). Under controlled environment conditions, application of urea or KNO3 resulted in some reduction in disease development; however, foliar application of both nutrients (8-10 sprays in total) did not affect Alternaria severity in the field. Systemic fungicides against Alternaria (e.g. , tebuconazole and difenoconazole) are more effective than the commonly used protectant fungicides (e.g. mancozeb and chlorothalonil). Concepts for the integration of genotype resistance, age-related resistances and fungicide for the suppression of Alternaria diseases were developed and evaluated. It was found that reduction in host resistance, with age and among genotypes, can be compensated for by adjusting the intensity of fungicide applications, i.e. by increasing the frequency of sprays and by spraying systemic fungicides towards the end of the season. In, moderately resistant cultivars protection can be achieved by spraying at longer intervals than susceptible cultivars. The concepts for integration were evaluated in field trials for cotton, potatoes and tomatoes. By following these concepts it was possible to save up to five sprays out of 8-10 in a growing season.
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Boisclair, Yves R., and Arieh Gertler. Development and Use of Leptin Receptor Antagonists to Increase Appetite and Adaptive Metabolism in Ruminants. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7697120.bard.
Objectives The original project had 2 major objectives: (1) To determine the effects of centrally administered leptin antagonist on appetite and adaptive metabolism in the sheep; (2) To develop and prepare second-generation leptin antagonists combining high binding affinity and prolonged in vivo half-life. Background Periods of suboptimal nutrition or exaggerated metabolic activity demands lead to a state of chronic energy insufficiency. Ruminants remain productive for a surprisingly long period of time under these circumstances by evoking adaptations sparing available energy and nutrients. The mechanism driving these adaptations in ruminant remains unknown, but could involve a reduction in plasma leptin, a hormone acting predominantly in the brain. In laboratory animals, reduced leptin signaling promotes survival during nutritional insufficiency by triggering energy sparing adaptations such as reduced thyroid hormone production and insulin resistance. Our overall hypothesis is that similar adaptations are triggered by reduced leptin signaling in the brain of ruminants. Testing of this hypothesis in ruminants has not been possible due to inability to block the actions of endogenous leptin and access to ruminant models where leptin antagonistic therapy is feasible and effective. Major achievements and conclusions The Israeli team had previously mutated 3 residues in ovine leptin, with no effect on receptor binding. This mutant was renamed ovine leptin antagonist (OLA) because it cannot activate signaling and therefore antagonizes the ability of wild type leptin to activate its receptor. To transform OLA into an effective in vivo antagonist, the Israeli made 2 important technical advances. First, it incorporated an additional mutation into OLA, increasing its binding affinity and thus transforming it into a super ovine leptin antagonist (SOLA). Second, the Israeli team developed a method whereby polyethylene glycol is covalently attached to SOLA (PEG-SOLA) with the goal of extending its half-life in vivo. The US team used OLA and PEG-SOLA in 2 separate animal models. First, OLA was chronically administered directly into the brain of mature sheep via a cannula implanted into the 3rdcerebroventricule. Unexpectedly, OLA had no effect of voluntary feed intake or various indicators of peripheral insulin action but reduced the plasma concentration of thyroid hormones. Second, the US team tested the effect of peripheral PEG-SOLA administration in an energy sensitive, rapidly growing lamb model. PEG-SOLA was administered for 14 consecutive days after birth or for 5 consecutive days before sacrifice on day 40 of life. Plasma PEG-SOLA had a half-life of over 16 h and circulated in 225- to 288-fold excess over endogenous leptin. PEG-SOLA administration reduced plasma thyroid hormones and resulted in a higher fat content in the carcass at slaughter, but had no effects on feed intake, body weight, plasma glucose or insulin. These results show that the team succeeded in developing a leptin antagonist with a long in vivo half-life. Moreover, in vivo results show that reduced leptin signaling promotes energy sparing in ruminants by repressing thyroid hormone production. Scientific and agricultural implications The physiological role of leptin in ruminants has been difficult to resolve because peripheral administration of wild type leptin causes little effects. Our work with leptin antagonists show for the first time in ruminants that reduced leptin signaling induces energy sparing mechanisms involving thyroid hormone production with little effect on peripheral insulin action. Additional work is needed to develop even more potent leptin antagonists, to establish optimal administration protocols and to narrow down phases of the ruminant life cycle when their use will improve productivity.
