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Full-Text Articles in Animal Sciences
Obligatory Urea Production And The Cost Of Living In The Magadi Tilapia Revealed By Acclimation To Reduced Salinity And Alkalinity, C. M. Wood, P. Wilson, Harold Bergman, A. N. Bergman
Obligatory Urea Production And The Cost Of Living In The Magadi Tilapia Revealed By Acclimation To Reduced Salinity And Alkalinity, C. M. Wood, P. Wilson, Harold Bergman, A. N. Bergman
Harold Bergman
Alcolapia grahami is a unique ureotelic tilapia that lives in the highly alkaline, saline Lake Magadi, Kenya (pH, similar to 10.0; alkalinity, similar to380 mmol L-1; Na+, similar to350 mmol L-1; Cl-, similar to110 mmol L-1; osmolality, similar to580 mosm kg(-1)). The fish survived well upon gradual exposure to dilute lake water (down to 1%, essentially freshwater). Urea excretion continued, and there was no ammonia excretion despite favorable conditions, indicating that ureotelism is obligatory. Levels of most ornithine-urea cycle enzymes in the liver were unchanged relative to controls kept for the same period in 100% lake water. The fish exhibited …
Respiratory Physiology Of The Lake Magadi Tilapia (Oreochromis Alcalicus Grahami), A Fish Adapted To A Hot, Alkaline, And Frequently Hypoxic Environment, A. Narahara, Harold Bergman, P. Laurent, J. N. Maina, P. J. Walsh, C. M. Wood
Respiratory Physiology Of The Lake Magadi Tilapia (Oreochromis Alcalicus Grahami), A Fish Adapted To A Hot, Alkaline, And Frequently Hypoxic Environment, A. Narahara, Harold Bergman, P. Laurent, J. N. Maina, P. J. Walsh, C. M. Wood
Harold Bergman
The tilapia Oreochromis alcalicus grahami is a unique ureotelic teleost, that only fish that lives in the alkaline hotsprings of Lake Magadi, Kenya. Physical conditions and fish behavior were monitored in the Fish Springs Lagoon area, a site where the tilapia were particularly abundant. Water Po-2 and temperature fluctuated more or less in parallel in a diurnal cycle from less than 20 Torr and less than 25 degrees C at night to greater than 400 Torr and 38 degrees C during the day, whereas pH remained constant at approximately 9.8. Field laboratory tests demonstrated that routine Mo-2 (under normoxia) increased …
Responses Of An Amazonian Teleost, The Tambaqui (Colossoma Macropomum), To Low Ph In Extremely Soft Water, C. M. Wood, R. W. Wilson, R. J. Gonzalez, M. L. Patrick, Harold Bergman, A. Narahara, A. L. Val
Responses Of An Amazonian Teleost, The Tambaqui (Colossoma Macropomum), To Low Ph In Extremely Soft Water, C. M. Wood, R. W. Wilson, R. J. Gonzalez, M. L. Patrick, Harold Bergman, A. Narahara, A. L. Val
Harold Bergman
Our goal was to compare the internal physiological responses to acid challenge in an acidophilic tropical teleost endemic to dilute low-pH waters with those in nonacidophilic temperate species such as salmonids, which have been the subject of most previous investigations The Amazonian tambaqui (Colossoma macropomum), which migrates between circumneutral water and dilute acidic "blackwater" of the Rio Negro, was exposed to a graded low-pH and recovery regime in representative soft water (Na+ = 15, Cl- = 16, Ca2+ = 20 mu mol L-1). Fish were fitted with arterial catheters for repetitive blood sampling. Water PH was altered from 6.5 (control) …
Effects Of Water Ph And Calcium Concentration On Ion Balance In Fish Of The Rio Negro, Amazon, R. J. Gonzalez, C. M. Wood, R. W. Wilson, M. L. Patrick, Harold Bergman, A. Narahara, A. L. Val
Effects Of Water Ph And Calcium Concentration On Ion Balance In Fish Of The Rio Negro, Amazon, R. J. Gonzalez, C. M. Wood, R. W. Wilson, M. L. Patrick, Harold Bergman, A. Narahara, A. L. Val
Harold Bergman
We examined the effects of acute low-pH exposure on ion balance (Na+, Cl-, K+) in several species of fish captured from the Rio Negro, a dilute, acidic tributary of the Amazon. At pH 5.5 (untreated Rio Negro water), the four Rio Negro species tested (piranha preta, Serrasalmus rhombeus; piranha branca, Serrasalmus cf. holandi; aracu, Leporinus fasciatus; and pacu, Myleus sp.) were at or near ion balance; upon exposure to pH 3.5, while Na+ and Cl- loss rates became significant, they were relatively mild. In comparison, tambaqui (Colossoma macropomum), which were obtained from aquaculture and held and tested under the same …
Ion And Acid-Base Balance In Three Species Of Amazonian Fish During Gradual Acidification Of Extremely Soft Water, R. W. Wilson, C. M. Wood, R. J. Gonzalez, M. L. Patrick, Harold Bergman, A. Narahara, A. L. Val
Ion And Acid-Base Balance In Three Species Of Amazonian Fish During Gradual Acidification Of Extremely Soft Water, R. W. Wilson, C. M. Wood, R. J. Gonzalez, M. L. Patrick, Harold Bergman, A. Narahara, A. L. Val
Harold Bergman
Sensitivity to acid water was assessed in three species of Amazonian fish that encounter naturally acidic blackwaters to differing degrees in the wild: tambaqui (Colossoma macropomum), matrincha (Brycon erythropterum), and tamoata (Hoplosternum littorale), in decreasing order of occurrence in blackwater. Fish were exposed to a graded reduction in water pH, from pH 6 to 5 to 4 to 3.5, followed by return to pH 6. Fish were exposed to each new pH for 24 h. During these exposures, net transfers of ions (Na+, K+, Cl-, and Ca2+) and acid-base equivalents to and from the external water were used as physiological …
Discordance Between Genetic Structure And Morphological, Ecological, And Physiological Adaptation In Lake Magadi Tilapia, P. J. Wilson, C. M. Wood, P. J. Walsh, A. N. Bergman, Harold Bergman, P. Laurent, B. N. White
Discordance Between Genetic Structure And Morphological, Ecological, And Physiological Adaptation In Lake Magadi Tilapia, P. J. Wilson, C. M. Wood, P. J. Walsh, A. N. Bergman, Harold Bergman, P. Laurent, B. N. White
Harold Bergman
The Magadi tilapia (Alcolapia grahami, formerly Oreochromis alcalicus grahami) is a remarkable example of teleost life in an extreme environment. Typical conditions include water, pH=10, titration alkalinity >300 mM, osmolality=525 mOsm, temperatures ranging from 23degrees to 42degreesC, and O-2 levels fluctuating diurnally between extreme hyperoxia and anoxia. A number of relatively small tilapia populations are present in various thermal spring lagoons around the margin of the lake separated by kilometers of solid trona crust (floating Na2CO3) underlain by anoxic water. Despite the apparent isolation of different populations, annual floods may provide opportunities for exchange of fish across the surface of …