Responses of juvenile rainbow trout, under food limitation, to chronic low pH and elevated summer temperatures, alone and in combination

J. J. Dockray, I. J. Morgan, S. D. Reid, C. M. Wood

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Rainbow trout were exposed (90 days) in synthetic soft water to sublethal low pH (5.2) and a simulated climate warming scenario (+2°C above the control summer temperature range of 16.5-21°C), alone and in combination, under conditions of limited food (~4% dry body weight day-1). Weight specific oxygen consumption rates (M(O2)) were ~55% of M(O2(max)), in contrast to ~75% of M(O2(max)) found in trout fed an unlimited ration. This is likely due to a reduction in food quantity and thus feeding activity. However, the trout exposed to low pH at control temperatures exhibited higher conversion efficiencies and increased growth. in contrast, trout exposed to +2°C had reduced growth rates. No ionoregulatory disturbance occurred in any treatment, suggesting that this ration was sufficient to provide a replacement salt load in the diet. Energy budgets indicated that the limited ration resulted in a lowered optimum temperature for growth, with a greater proportion of the energy intake dissipated for metabolic expenditure, resulting in reduced conversion efficiencies. A fourfold reduction in faecal and unaccounted energy losses indicated higher absorption efficiencies than in satiation-fed trout.

Original languageEnglish (US)
Pages (from-to)62-82
Number of pages21
JournalJournal of Fish Biology
Volume52
Issue number1
DOIs
StatePublished - Jan 1 1998

Keywords

  • Acidification
  • Energy budget
  • Food limitation
  • Rainbow trout
  • Temperature

ASJC Scopus subject areas

  • Aquatic Science

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