In oceanic biogeochemistry, the f-ratio is the fraction of total primary production fuelled by nitrate (as opposed to that fuelled by other nitrogen compounds such as ammonium). This fraction is significant because it is assumed to be directly related to the sinking (export) flux of organic marine snow from the surface ocean by the biological pump. The ratio was originally defined by Richard Eppley and Bruce Peterson in one of the first papers estimating global oceanic production.^[1]

Overview[link]

Gravitational sinking of organisms (or the remains of organisms) transfers carbon from the surface waters of the ocean to its deep interior. This process is known as the biological pump, and quantifying it is of interest to scientists because it is an important aspect of the Earth's carbon cycle. Essentially, this is because carbon transported to the deep ocean is isolated from the atmosphere, allowing the ocean to act as a reservoir of carbon. This biological mechanism is accompanied by a physico-chemical mechanism known as the solubility pump which also acts to transfer carbon to the ocean's deep interior.

Measuring the flux of sinking material (so-called marine snow) is usually done by deploying sediment traps which intercept and store material as it sinks down the water column. However, this is a relatively difficult process, since traps can be awkward to deploy or recover, and they must be left in situ over a long period to integrate the sinking flux. Furthermore, they are known to experience biases and to integrate horizontal as well as vertical fluxes because of water currents.^[2][3] For this reason, scientists are interested in ocean properties that can be more easily measured, and that act as a proxy for the sinking flux. The f-ratio is one such proxy.

"New" and "regenerated" production[link]

Bio-available nitrogen occurs in the ocean in several forms, including simple ionic forms such as nitrate (NO₃⁻), nitrite (NO₂⁻) and ammonium (NH₄⁺), and more complex organic forms such as urea ((NH₂)₂CO). These forms are utilised by autotrophic phytoplankton to synthesise organic molecules such as amino acids (the building blocks of proteins). Grazing of phytoplankton by zooplankton and larger organisms transfers this organic nitrogen up the food chain and throughout the marine food-web.

When nitrogenous organic molecules are ultimately metabolised by organisms, they are returned to the water column as ammonium (or more complex molecules that are then metabolised to ammonium). This is known as regeneration, since the ammonium can be used by phytoplankton, and again enter the food-web. Primary production fuelled by ammonium in this way is thus referred to as regenerated production.^[4]

However, ammonium can also be oxidised to nitrate (via nitrite), by the process of nitrification. This is performed by different bacteria in two stages :

NH₃ + O₂ → NO₂⁻ + 3H⁺ + 2e⁻

NO₂⁻ + H₂O → NO₃⁻ + 2H⁺ + 2e⁻

Crucially, this process is believed to only occur in the absence of light (or as some other function of depth). In the ocean, this leads to a vertical separation of nitrification from primary production, and confines it to the aphotic zone. This leads to the situation whereby any nitrate in the water column must be from the aphotic zone, and must have originated from organic material transported there by sinking. Primary production fuelled by nitrate is, therefore, making use of a "fresh" nutrient source rather than a regenerated one. Production by nitrate is thus referred to as new production.^[4]

The figure at the head of this section illustrates this. Nitrate and ammonium are taken up by primary producers, processed through the food-web, and then regenerated as ammonium. Some of this return flux is released into the surface ocean (where it is available again for uptake), while some is returned at depth. The ammonium returned at depth is nitrified to nitrate, and ultimately mixed or upwelled into the surface ocean to repeat the cycle.

Consequently, the significance of new production lies in its connection to sinking material. At equilibrium, the export flux of organic material sinking into the aphotic zone is balanced by the upward flux of nitrate. By measuring how much nitrate is consumed by primary production, relative to that of regenerated ammonium, one should be able to estimate the export flux indirectly.

As an aside, the f-ratio can also reveal important aspects of local ecosystem function.^[5] High f-ratio values are typically associated with productive ecosystems dominated by large, eukaryotic phytoplankton (such as diatoms) that are grazed by large zooplankton (and, in turn, by larger organisms such as fish). By contrast, low f-ratio values are generally associated with low biomass, oligotrophic food webs consisting of small, prokaryotic phytoplankton (such as Prochlorococcus) which are kept in check by microzooplankton.^[6][7]

Assumptions[link]

A fundamental assumption in this interpretation of the f-ratio is the spatial separation of primary production and nitrification. Indeed, in their original paper, Eppley & Peterson noted that: "To relate new production to export requires that nitrification in the euphotic zone be negligible".^[1] However, subsequent observational work on the distribution of nitrification has found that nitrification can occur at shallower depths, and even within the photic zone.^[8][9][10]

As the diagram to the right shows, if ammonium is indeed nitrified to nitrate in the ocean's surface waters it essentially "short circuits" the deep pathway of nitrate. In practice, this would lead to an overestimation of new production and a higher f-ratio, since some of the ostensibly new production would actually be fuelled by recently nitrified nitrate that had never left the surface ocean. After including nitrification measurements in its parameterisation, an ecosystem model of the oligotrophic subtropical gyre region (specifically the BATS site) found that, on an annual basis, around 40% of surface nitrate was recently nitrified (rising to almost 90% during summer).^[11] A further study synthesising geographically diverse nitrification measurements found high variability but no relationship with depth, and applied this in a global-scale model to estimate that up to a half of surface nitrate is supplied by surface nitrification rather than upwelling.^[12]

Although measurements of the rate of nitrification are still relatively rare, they do suggest that the f-ratio is not as straightforward a proxy for the biological pump as was once thought. For this reason, some workers have proposed distinguishing between the f-ratio and the ratio of particulate export to primary production, which they term the pe-ratio.^[7] While quantitatively different than the f-ratio, the pe-ratio shows similar qualitative variation between high productivity/high biomass/high export regimes and low productivity/low biomass/low export regimes.

See also[link]

• Biological pump
• Nitrification
• Primary production

References[link]

Aquatic ecosystems – general and freshwater components General Aquatic ecosystems Acoustic ecology Agent-based models Algal bloom Anoxic waters Aquatic adaptation Aquatic animals Aquatic biodiversity research Aquatic biomonitoring Aquatic insects Aquatic layers Aquatic mammals Aquatic plants Aquatic predation Aquatic respiration Aquatic science Aquatic toxicology Benthos Bioluminescence Biomass Cascade effect Colored dissolved organic matter Dead zone Ecohydrology Eutrophication Fisheries science Food chain Food web GIS and aquatic science Hydrobiology Hypoxia Isotope analysis Microbial ecology Microbial food web Microbial loop Nekton Neuston Particle Photic zone Phytoplankton Plankton Productivity Ramsar Convention Schooling Sediment trap Siltation Spawning Substrate Thermal pollution Trophic level Underwater camouflage and mimicry Water column Zooplankton More... Freshwater Freshwater ecosystems Brackish marsh Freshwater biology Freshwater biomes Freshwater fish Freshwater marsh Freshwater swamp forest Hyporheic zone Lake ecosystems Landscape limnology Limnology Lake stratification Macrophyte Pond Fish pond Rheotaxis River ecosystems Stream bed Stream pool Trophic state index Upland and lowland Water garden Wetland Environmental quality More... Ecoregions Freshwater ecoregions List of freshwater ecoregions Marine ecoregions List of marine ecoregions Ecology of the Everglades Ecology of the San Francisco Estuary Ecosystem of the North Pacific Subtropical Gyre Freshwater ecology of Maharashtra   Aquatic ecosystems – marine components Marine Marine ecosystem f-ratio Iron fertilization Iron Hypothesis Large marine ecosystem Marine biology Marine chemistry Marine snow Ocean nourishment Oceanic physical-biological process Ocean turbidity Photophore Thorson's rule Upwelling Whale fall More... Marine life forms Census of Marine Life Coastal fish Coral reef fish Deep sea communities Deep sea creature Deep sea fish Deep-water coral Demersal fish Marine bacteriophage Marine invertebrates Marine larval ecology Marine mammal Marine reptile Marine vertebrate Paradox of the plankton Pelagic fish Seabird Seashore wildlife Wild fisheries Marine habitats Bay mud Black smokers Coastal biogeomorphology Cold seeps Coral reefs Davidson Seamount Estuaries Intertidal ecology Intertidal wetlands Kelp forests Hydrothermal vents Lagoons Mangroves Marine biomes Marine habitats Mudflats Rocky shores Salt marshes Seagrass meadows Sponge reefs Tide pools Issues Ecological values of mangrove Fisheries and climate change HERMIONE Marine conservation Marine conservation activism Marine pollution Marine Protected Area

v t e Modelling ecosystems – trophic components General Abiotic component Abiotic stress Behaviour Biogeochemical cycle Biomass Biotic component Biotic stress Carrying capacity Competition Ecosystem Ecosystem ecology Ecosystem model Keystone species List of feeding behaviours Metabolic theory of ecology Productivity Producers Autotrophs Chemosynthesis Chemotrophs Foundation species Mixotrophs Myco-heterotrophy Mycotroph Organotrophs Photoheterotrophs Photosynthesis Photosynthetic efficiency Phototrophs Primary nutritional groups Primary production Consumers Apex predator Bacterivore Carnivores Chemoorganotroph Foraging Generalist and specialist species Intraguild predation Herbivores Heterotroph Heterotrophic nutrition Insectivore Mesopredator release hypothesis Omnivores Optimal foraging theory Predation Prey switching Decomposers Chemoorganoheterotrophy Decomposition Detritivores Detritus Microorganisms Archaea Bacteriophage Environmental microbiology Lithoautotroph Lithotrophy Microbial cooperation Microbial ecology Microbial food web Microbial intelligence Microbial loop Microbial mat Microbial metabolism Phage ecology Food webs Biomagnification Ecological efficiency Ecological pyramid Energy flow Food chain Trophic level Example webs Cold seeps Hydrothermal vents Intertidal Kelp forests Lakes North Pacific Subtropical Gyre Rivers San Francisco Estuary Soil Tidal pool Processes Ascendency Bioaccumulation Cascade effect Climax community Competitive exclusion principle Consumer-resource systems Copiotrophs Dominance Ecological network Ecological succession Energy quality Energy Systems Language f-ratio Feed conversion ratio Feeding frenzy Mesotrophic soil Nutrient cycle Oligotroph Paradox of the plankton Trophic cascade Trophic mutualism Trophic state index Defense/counter Animal coloration Antipredator adaptations Camouflage Herbivore adaptations to plant defense Mimicry Plant defense against herbivory Predator avoidance in schooling fish

v t e Modelling ecosystems – other components Population ecology Abundance Allee effect Depensation Ecological yield Effective population size Intraspecific competition Logistic function Malthusian growth model Maximum sustainable yield Overpopulation in wild animals Overexploitation Population cycle Population dynamics Population modeling Population size Predator–prey equations Recruitment Resilience Small population size Stability Species Biodiversity Density-dependent inhibition Ecological effects of biodiversity Ecological extinction Endemic species Flagship species Gradient analysis Indicator species Introduced species Invasive species Latitudinal gradients in species diversity Minimum viable population Neutral theory Occupancy-abundance relationship Population viability analysis Priority effect Rapoport's rule Relative abundance distribution Relative species abundance Species diversity Species homogeneity Species richness Species distribution Species-area curve Umbrella species Species interaction Antibiosis Biological interaction Commensalism Community ecology Ecological facilitation Interspecific competition Mutualism Storage effect Spatial ecology Biogeography Cross-boundary subsidy Ecocline Ecotone Ecotype Disturbance Edge effect Foster's rule Habitat fragmentation Ideal free distribution Intermediate Disturbance Hypothesis Island biogeography Landscape ecology Landscape epidemiology Landscape limnology Metapopulation Patch dynamics r/K selection theory Source–sink dynamics Niche Ecological niche Ecological trap Ecosystem engineer Environmental niche modelling Guild Habitat Limiting similarity Niche apportionment models Niche construction Niche differentiation Other networks Assembly rules Bateman's principle Bioluminescence Ecological collapse Ecological debt Ecological deficit Ecological energetics Ecological indicator Ecological threshold Ecosystem diversity Emergence Extinction debt Kleiber's law Liebig's law of the minimum Marginal value theorem Thorson's rule Xerosere Other Allometry Alternative stable state Balance of nature Biological data visualization Constructal theory Ecocline Ecological economics Ecological footprint Ecological forecasting Ecological humanities Ecological stoichiometry Ecopath Ecosystem based fisheries Endolith Evolutionary ecology Functional ecology Industrial ecology Macroecology Microecosystem Natural environment Systems ecology Theoretical ecology List of ecology topics

The Power Team is a group of Christian Evangelists, based in Dallas, Texas, who incorporate their preaching with displays of strength and martial arts skills. They were founded in the late 1970s by John Jacobs.^[1] Their performances, usually taped at large megachurches, were broadcast on TBN and other Christian television stations in the United States in the late 1980s.

History[link]

The Power Team often conducts performances in venues such as schools, to encourage audiences from outside church communities. As performances in public schools could not discuss religion, these performances instead promote social responsibility and abstention from drugs and alcohol.^[2] The group's promotional material indicated that it presented a "message that strengthens and restores the family."^[3]

Power Team leader John Jacobs divorced his wife, Ruthanne in May 2000, which was followed by numerous members leaving the Power Team to form a new ministry, Team Impact.^[3] In 2002 the Power Team filed for bankruptcy protection.^[4] Jacobs resigned from the Power Team organization on May 7, 2003.^[5] The Power Team's President since 2003 is Todd Keene, a long-time member of the ministry.^[6]

TV appearances[link]

In 1999, The Power Team portrayed themselves in "The Principal" episode of Walker, Texas Ranger to motivate a high school of wayward students.^[7][8]

The Power Team briefly appeared in a July 22, 2008 episode of America's Got Talent performing stunts including running through 2x4s bursting into flames and running head and shoulders first into an 8-foot wall of ice. Host Piers Morgan remarked, "You must be bonkers." The team was not selected to go on to the semi-finals.^{[citation needed]} Another appeared in June 2010 as a registered nurse, bending a frying pan as one of his stunts, which Piers thought he was able to unfold but could not. He advanced to Vegas but was not among the finals as of the second week in July, 2010.^{[citation needed]}

Media[link]

• John Jacobs & The Power Team - 1990 Frontline Records, 1 hour VHS video (V09085)
• John Jacobs & The Power Team - 1990 Frontline Records, CD (CD09085) & Cassette (C09085)

Further reading[link]

• Mazer, Sharon (Winter 1994). "The Power Team: Muscular Christianity and the Spectacle of Conversion". TDR (MIT Press) 38 (4): 162–188. DOI:10.2307/1146430. 
• Critical review by Phil Scovell of a Power Team performance
• Five Jefferson County (Wisconsin) public school districts cancel Power Team assemblies

References[link]

External links[link]

• Official website