Fish status and water quality
Fish status is correlated to a set of water quality parameters, such as pH, dissolved inorganic aluminium and also calcium. Toxic aluminium dissolves in acidified terrestrial systems and may be detrimental to both fish and other aquatic organisms. Calcium may ameliorate the toxic effects of aluminium in acidic water and dissolved organic matter forms complexes with aluminium and thereby reduces the toxic, inorganic aluminium.
Acidic water affects aquatic organisms at different pH/aluminium levels. Differences have been found between fish species, fish strains, invertebrate species and zooplankton/phytoplankton species. The critical chemical value of pH or a combination of pH, Al or other components may therefore vary from species to species. Also, regional differenes in pH/Al-tolerance may be found due to large variations in the natural water quality and climate.

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