[delta66]

Μηπως τα εχεις συνδεσει με αυτο που γραφει πιο πανω στο αρθρο για τους καρδιναλιους?

Ammonia and urea are the two main nitrogenous products excreted by teleosts, with ammonia usually representing 75-90% of the nitrogenous excretion (Handy & Poxton, 1993). Ammonia toxicity to fish depends on the concentration of unionized ammonia (NH3). Fish branchial membranes are relatively permeable to NH3, but not to NH4+, due to its molecular size. When dissolved in water, ionized and unionized forms of ammonia are in equilibrium, which is affected by water pH, temperature and salinity. Alterations in these parameters can result in the variation of the different forms of ammonia, whose concentrations can become toxic to fish (Arana, 1997). The exposure of freshwater or seawater fish to sublethal levels of ammonia can increase their subsequent resistance to lethal concentrations (EIFAC, 1973).

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