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  2. Aquatic respiration - Wikipedia

    en.wikipedia.org/wiki/Aquatic_respiration

    Countercurrent flow occurs when deoxygenated blood moves through the gill in one direction while oxygenated water moves through the gill in the opposite direction. This mechanism maintains the concentration gradient thus increasing the efficiency of the respiration process as well and prevents the oxygen levels from reaching an equilibrium ...

  3. Oxygen evolution - Wikipedia

    en.wikipedia.org/wiki/Oxygen_evolution

    Oxygen evolution is the chemical process of generating elemental diatomic oxygen (O 2) by a chemical reaction, usually from water, the most abundant oxide compound in the universe. Oxygen evolution on Earth is effected by biotic oxygenic photosynthesis, photodissociation, hydroelectrolysis, and thermal decomposition of various oxides and oxyacids.

  4. Oxygenation - Wikipedia

    en.wikipedia.org/wiki/Oxygenation

    Oxygen saturation (medicine), The percent of hemoglobin saturated by oxygen, usually in arterial blood. Water oxygenation, the process of increasing the oxygen saturation of the water; Dioxygen complex, the chemical details of how metals bind oxygen; Great Oxygenation Event, an ancient event that led to the rise of oxygen within our atmosphere

  5. Fish gill - Wikipedia

    en.wikipedia.org/wiki/Fish_gill

    The concentration of oxygen in water is lower than air and it diffuses more slowly. In a litre of freshwater the oxygen content is 8 cm 3 per litre compared to 210 in the same volume of air. [7] Water is 777 times more dense than air and is 100 times more viscous. [7] Oxygen has a diffusion rate in air 10,000 times greater than in water. [7]

  6. Fish physiology - Wikipedia

    en.wikipedia.org/wiki/Fish_physiology

    The fish draws oxygen-rich water in through the mouth (left). It then pumps it over gills so oxygen enters the bloodstream, and allows oxygen-depleted water to exit through the gill slits (right) In bony fish, the gills lie in a branchial chamber covered by a bony operculum. The great majority of bony fish species have five pairs of gills ...

  7. Oxygen cycle - Wikipedia

    en.wikipedia.org/wiki/Oxygen_cycle

    The oxygen cycle demonstrates how free oxygen is made available in each of these regions, as well as how it is used. The oxygen cycle is the biogeochemical cycle of oxygen atoms between different oxidation states in ions, oxides, and molecules through redox reactions within and between the spheres/reservoirs of the planet Earth. [1]

  8. Hypoxia in fish - Wikipedia

    en.wikipedia.org/wiki/Hypoxia_in_fish

    Oxygen diffuses into water from air and therefore the top layer of water in contact with air contains more oxygen. This is true only in stagnant water; in running water all layers are mixed together and oxygen levels are the same throughout the water column. One environment where ASR often takes place is tidepools, particularly at night. [34]

  9. Hypolimnetic aeration - Wikipedia

    en.wikipedia.org/wiki/Hypolimnetic_aeration

    Deep-water aeration, also known as hypolimnetic aeration, describes the provision of oxygen from the atmosphere to meet oxygen demand in deep water without disrupting the natural stratification of the water above. This process promotes the development of aerobic conditions in deep water, leading to a significant reduction in phosphate ...