Przewalski's naked carp (Gymnocypris przewalskii): An endangered species taking a metabolic holiday in Lake Qinghai, China

Chris M. Wood, Jizeng Du, Joe Rogers, Colin J. Brauner, Jeffrey G. Richards, Jeffrey W. Semple, Brent W. Murray, X. Q. Chen, Yuxiang Wang

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

The naked carp is an endangered cyprinid that migrates annually between freshwater rivers, where it spawns, and Lake Qinghai, where it feeds and grows. Lake Qinghai is a high-altitude lake (3,200 m) in western China that currently exhibits the following composition (in mmol L-1: [Na+] 200, [Cl-] 173, [Mg2+] 36, [Ca2+] 0.23, [K +] 5.3, total CO2 21, titration alkalinity 29; osmolality 375 mOsm kg-1; pH 9.3), but concentrations are increasing because of water diversion and climate change. We studied the physiology of river water to lake water transfer. When river fish are transferred to lake water, there is a transitory metabolic acidosis followed by a slight respiratory alkalosis, and hemoconcentration occurs. All plasma electrolytes rise over the initial 48 h, and final levels in lake water-acclimated fish are very close to lake water concentrations for [Na+], [Cl-], [K+], and osmolality, whereas [Ca2+] continues to be regulated well above ambient levels. However, [Mg2+] rises to a much greater extent (fourfold in 48 h); final plasma levels in lake fish may reach 12 mmol L -1 but are still much lower than in lake water (36 mmol L -1). At the same time, urine flow rate decreases drastically to <5% of river water values; only the renal excretion of Mg2+ is maintained. Both gill and kidney Na+,K+-ATPase rapidly decline, with final levels in lake water fish only 30% and 70%, respectively, of those in river water fish. Metabolic rate also quickly decreases on exposure to lake water, with O2 consumption and ammonia-N excretion rates eventually falling to only 60% and 30%, respectively, of those in river fish, while plasma ammonia rises fivefold. The fish appear to be benefiting from a metabolic holiday at present because of decreases in iono- and osmoregulatory costs while in lake water; elevated plasma [Mg2+] and ammonia may be additional factors depressing metabolic rate. If the lake continues to dehydrate, these benefits may change to pathology.

Original languageEnglish (US)
Pages (from-to)59-77
Number of pages19
JournalPhysiological and Biochemical Zoology
Volume80
Issue number1
DOIs
StatePublished - Jan 1 2007

ASJC Scopus subject areas

  • Physiology
  • Biochemistry
  • Animal Science and Zoology

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    Wood, C. M., Du, J., Rogers, J., Brauner, C. J., Richards, J. G., Semple, J. W., Murray, B. W., Chen, X. Q., & Wang, Y. (2007). Przewalski's naked carp (Gymnocypris przewalskii): An endangered species taking a metabolic holiday in Lake Qinghai, China. Physiological and Biochemical Zoology, 80(1), 59-77. https://doi.org/10.1086/509212