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Positive Correlation Between Inhibition of Branchial and Renal Carbonic Anhydrase and Ammonia Produced by Cultured Silver Catfish Rhamdia quelen
Author(s) -
SouzaBastos Luciana R.,
Bastos Leonardo P.,
Freire Carolina A.
Publication year - 2015
Publication title -
north american journal of aquaculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 41
eISSN - 1548-8454
pISSN - 1522-2055
DOI - 10.1080/15222055.2014.960118
Subject(s) - catfish , carbonic anhydrase , gill , ammonia , biology , zoology , osmoregulation , endocrinology , medicine , biochemistry , fish <actinopterygii> , fishery , enzyme , ecology , salinity
Silver Catfish Rhamdia quelen , a native South American catfish relevant in intensive culture systems in Brazil, were exposed to three ammonia concentrations added to the water (0.5, 1.0, and 2.0 mg/L as ammonium chloride). After 5 and 24 h, measured water ammonia levels increased to maximum levels of 15.8–41.1 mg/L, reflecting the addition of ammonia excreted by the fish. Aquaria were aerated but kept closed, and pH and temperature were kept constant. Hematocrit, plasma ammonia, osmolality, Na + , Cl − , K + , glucose, and cortisol were assayed. Branchial and muscle hydration levels and branchial and renal specific activities of the carbonic anhydrase (CA) were determined. Silver Catfish did not show stress responses or signs of osmoregulatory disturbance upon the increased water ammonia levels. However, there was inhibition of the CA in gills and kidneys, especially after 24 h, in a dose‐dependent manner to the total ammonia accumulated in the water. Although Silver Catfish are tolerant of increase in ammonia, care should be taken to limit increases in ammonia levels and time of exposure because the severity of the deleterious effects will certainly increase. In addition, results have shown that the fish carbonic anhydrase (branchial and renal) is a sensitive biomarker of effect of ammonia.