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WATER BALANCE IN AQUATIC ENVIRONMENTS

WATER BALANCE IN AQUATIC ENVIRONMENTS. Fish remove nitrogenous waste as ammonia across gills. Kidney function is maintain water and mineral ion concentration. FRESHWATER. MARINE. Hi salts. Lo salts. Lo H 2 O. Hi H 2 O. Hi H 2 O. Lo H 2 O. Lo salts. Hi salts.

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WATER BALANCE IN AQUATIC ENVIRONMENTS

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  1. WATER BALANCE IN AQUATIC ENVIRONMENTS

  2. Fish remove nitrogenous waste as ammonia across gills Kidney function is maintain water and mineral ion concentration FRESHWATER MARINE Hi salts Lo salts Lo H2O Hi H2O Hi H2O Lo H2O Lo salts Hi salts Net movement of water out of fish Net movement of water into fish Net movement of salts into fish Net movement of salts out of fish Do not drink water Constantly drink water Produce almost no urine Produce large amount of very dilute urine Kidneys actively excrete salts Kidneys actively absorb salts Gills actively excrete salts Gills actively absorb ions Known as OSMOREGULATORS Other organism e.g. Sharks, rays and most aquatic plants are OSMOCONFORMERS

  3. ENANTIOSTASIS: • Maintaining metabolic function (not always optimum) by altering other physiological functions or allowing the internal environment to change as the external environment changes dramatically ESTUARIES Partially enclosed area where freshwater (river or stream) meets the sea. Salt and fresh water mix = brackish water Temperature, oxygen availability, and SALINITYvary greatly High tides = salt concentration increases (low tides= salt concentration decreases) Winter months = higher rainfall months = increase river flow = lower salt concentration (vice versa for summer months)

  4. Very few species of organisms can tolerate these changes in salinity. Osmoconformers, simply move with the tide, others show behaviourally adaptations e.g. Oysters close shells, crabs burrow into sand and mud, less salt variation here. Osmoregulators, such as salmon and eels, regulate their water loss, by drinking more water, excreting no urine and actively excreting salts on gills or skin

  5. MANGROVES - HALOPHYTES Plants that live in estuaries. Must survive changing water and oxygen availability and salinity PNEUMATOPHORES shoots that project up from the roots into the air to obtain oxygen They tolerate salt in their sap and have mechanisms to reduce the concentration of salt in their tissues: Exclusion: roots and lower stems have cells lining xylem that forms a barrier to salt Secretion: specialised glands in leaf concentrate and release salt onto leaf which is washed away in rain Accumulation: salt is accumulated in older tissue (leaves, branches) which dropped

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