What are trace elements?
Trace elements are mineral substances that are present in nature, and that, unlike macro elements, are eaten by organisms, because of their important metabolic vital functions. For a substance to be considered a trace element, the needed daily dose should be up to 50 mg per kilogram of body weight: if the needed dose of a substance is below this limit, it is considered a trace element.
The essential trace elements, whose functions are usually known, are: arsenic, chromium, iron, fluorine, iodine, cobalt, copper, manganese, molybdenum, selenium, vanadium, zinc and tin. They are important components of hormones, enzymes or vitamins, or they have a catalysing coenzymatic effect on certain metabolic functions. If they are missing, there will be a malfunction of the metabolic processes or other functions.
Some of the non-essential trace elements are aluminium, barium, bismuth, boron, bromine, germanium, lithium, nickel, mercury, rubidium, silicon, strontium, tellurium, titanium and tungsten. Science is still debating what their function is, but that does not mean that they are not important for the metabolism of living organisms. Often it is just the chance of recognizing or testing their function that is missing. Strontium is a good example in relation to corals.
The elements that are necessary in higher quantities are sodium, magnesium, barium, calcium, phosphorus, sulphur and chlorine. They are important for several specific functions, such as the content of water or the acid-basic balance of an organism (sodium, chlorine).
Manganese and iron, for example, play a role in the action of a specific enzyme that helps corals to limit excess oxygen and the effects related to it. This is necessary for detoxing from harmful oxygen radicals. If manganese and iron were missing, problems caused by the excessive oxygen saturation in the tissues might appear in corals, quickly turning them white (Expulsion of the symbiotic algae) even in normal temperature and lighting.