Standard metabolic rate and daily activity patterns of Australoheros facetus (Jenyns, 1842)

MOLINA J.M.; UBRIG R.; PONS J.; BLASINA G.E.

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Conferencia; The 3rd International Electronic Conference on Diversity; 2024

Multidisciplinary Digital Publishing Institute (MDPI) and Diversity (Journal)

We provide first-time estimates on standard metabolic rates (SMR) for Australoheros facetus, a freshwater cichlid fish that lives in streams and lakes of South America. Individuals of A. facetus were sourced from the Naposta Grande river, located in southern Buenos Aires province,Argentina, during spring (September-November in the southern hemisphere) of 2023. Theindividuals of A. facetus were captured using traps, baited and set close to submerged vegetationon the margins of the river at shallow depths. The traps were left undisturbed for up to 45 minutes.Traps were then pulled up by hand, and the individuals collected and transferred to aeratedtransportation tanks. The fish were allowed to recover in these acclimation tanks for 1 month fromthe stress originated from the capture and transport. Experiments were conducted following theguidelines established by the EU Directive 2010/63/EU and the Argentinean Law n° 14346 on “Theprotection of animals”, as well as recommendations of the Institutional committee for the use andcare of laboratory animals (CICUAL). We quantified SMR and aerobic scope and daily activitypatterns finding this fish to be active during the day and sluggish during the night. Its metabolicrate is within the ranges expected for cichlids (SMR: 104.48 mg O2 kg–1h–1), which increasesslightly during the daylight hours (126.25 mg O2 kg–1h–1). Having information on metabolic ratesand aerobic scope of this species provides another piece to the puzzle of the biology of A. facetus, complementing the research on oxidative stress and social behavior already published, andfuture research efforts to come. Furthermore, it constitutes progress towards the development ofpredictive models on the effects of increasing water temperature in a global warming scenario.