dc.contributor.author | Naraharal, Annie | |
dc.contributor.author | Bergman, Harold L | |
dc.contributor.author | Laurent, Pierre | |
dc.contributor.author | Maina, JN | |
dc.contributor.author | Walsh, Patrick J | |
dc.contributor.author | Wood, Chris M | |
dc.date.accessioned | 2013-07-22T09:03:56Z | |
dc.date.available | 2013-07-22T09:03:56Z | |
dc.date.issued | 1996 | |
dc.identifier.citation | Physiological Zoology, Vol. 69, No. 5 (Sep. - Oct., 1996), pp. 1114-1136 | en |
dc.identifier.uri | http://www.jstor.org/stable/30164249 | |
dc.identifier.uri | http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/49584 | |
dc.description.abstract | The tilapia Oreochromis alcalicus grahami is a unique ureotelic teleost, the only
fish that lives in the alkaline hotsprings of Lake Magadi, Kenya. Physical condi-
tions and fish behavior were monitored in the Fish Springs Lagoon area, a site
where the tilapia were particularly abundant. Water Po2 and temperature fluc-
tuated more or less in parallel in a diurnal cycle from less than 20 Torr and less
than 25* C at night to greater than 400 Torr and 380 C during the day, whereas
pH remained constant at approximately 9.8. Field laboratory tests demonstrated
that routine Mo, (under normoxia) increased greatly from 270 C to 360 C (Qo
= 62) but then stabilized at a very high level (-~34.5 jgmol g-' h-1) up to the le-
thal temperature (- 42.5 " C), a pattern that was adaptive to the natural diurnal
regime. The Po2 threshold for survival during acute exposure (!; 1 h) was approx-
imately 16 Torr. Io, from water was well maintained down to a Po2 of 60 Torr,
below which it declined. Under such hypoxic conditions, the fish performed sup-
plementary surface breathing when allowed access to air. Both the better oxygen-
ated surface layer and air bubbles were inspired, resulting in significant uptake
of 02. The Po2 threshold for surface breathing was 1.8-fold higher at 3 7.50 C than at 310 C. Surface breathing and voluntary entry offish into air were observed in
the field. The blood O, dissociation curve at 300 -320 C was h3perbolic, with a
high afinity (P50o = 6 Torr), low cooperativity (Hill coeficient = 1. 18), and no
Bohr effect over the extracellularpH range 8.2-8.6. | en |
dc.language.iso | en | en |
dc.publisher | The University of Chicago Press | en |
dc.title | Respiratory Physiology of the Lake Magadi Tilapia (Oreochromis alcalicus grahami), a Fish Adapted to a Hot, Alkaline, and Frequently Hypoxic Environment | en |
dc.type | Article | en |
local.publisher | Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming 82071 | en |
local.publisher | Laboratoire de Morphologie Fonctionnelle et Ultrastructurale des Adaptations, Centre d'Ecologie et de Physiologie Energetique, CNRS, BP20CR, F-67037 Strasbourg cedex, France; | en |
local.publisher | Department of Veterinary Anatomy, University of Nairobi, Chiromo Campus | en |