Evidence of circadian rhythm, oxygen regulation capacity, metabolic repeatability and positive correlations between forced and spontaneous maximal metabolic rates in Lake Sturgeon Acipenser fulvescens

Jon Christian Svendsen, Janet Genz, W. Gary Anderson, Jennifer A. Stol, Douglas A. Watkinson, Eva C. Enders, Erik V. Thuesen (Editor)

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Abstract

Animal metabolic rate is variable and may be affected by endogenous and exogenous factors, but such relationships remain poorly understood in many primitive fishes, including members of the family Acipenseridae (sturgeons). Using juvenile lake sturgeon (Acipenser fulvescens), the objective of this study was to test four hypotheses: 1) A. fulvescens exhibits a circadian rhythm influencing metabolic rate and behaviour; 2) A. fulvescens has the capacity to regulate metabolic rate when exposed to environmental hypoxia; 3) measurements of forced maximum metabolic rate (MMRF) are repeatable in individual fish; and 4) MMRF correlates positively with spontaneous maximum metabolic rate (MMRS). Metabolic rates were measured using intermittent flow respirometry, and a standard chase protocol was employed to elicit MMRF. Trials lasting 24 h were used to measure standard metabolic rate (SMR) and MMRS. Repeatability and correlations between MMRF and MMRS were analyzed using residual body mass corrected values. Results revealed that A. fulvescens exhibit a circadian rhythm in metabolic rate, with metabolism peaking at dawn. SMR was unaffected by hypoxia (30% air saturation (O-2sat)), demonstrating oxygen regulation. In contrast, MMRF was affected by hypoxia and decreased across the range from 100% O-2sat to 70% O-2sat. MMRF was repeatable in individual fish, and MMRF correlated positively with MMRS, but the relationships between MMRF and MMRS were only revealed in fish exposed to hypoxia or 24 h constant light (i.e. environmental stressor). Our study provides evidence that the physiology of A. fulvescens is influenced by a circadian rhythm and suggests that A. fulvescens is an oxygen regulator, like most teleost fish. Finally, metabolic repeatability and positive correlations between MMRF and MMRS support the conjecture that MMRF represents a measure of organism performance that could be a target of natural selection.
Original languageEnglish
Article numbere94693
JournalP L o S One
Volume9
Issue number4
ISSN1932-6203
DOIs
Publication statusPublished - 2014
Externally publishedYes

Keywords

  • Animals
  • Basal Metabolism
  • Behavior, Animal
  • Body Weight
  • Circadian Rhythm
  • Fishes
  • Lakes
  • Oxygen
  • Photoperiod
  • Reproducibility of Results
  • Time Factors
  • circadian rhythm
  • maximum metabolic rate
  • Pisces Vertebrata Chordata Animalia (Animals, Chordates, Fish, Nonhuman Vertebrates, Vertebrates) - Osteichthyes [85206] Oreochromis niloticus species teleost fish common Acipenser fulvescens species lake sturgeon common Takifugu obscurus species
  • 07002, Behavioral biology - General and comparative behavior
  • 07003, Behavioral biology - Animal behavior
  • 07508, Ecology: environmental biology - Animal
  • 07514, Ecology: environmental biology - Limnology
  • 13002, Metabolism - General metabolism and metabolic pathways
  • Ecology, Environmental Sciences
  • correlation analysis mathematical and computer techniques
  • flow respirometry mathematical and computer techniques
  • Behavior
  • Freshwater Ecology
  • Metabolism

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