Event Abstract

Hierarchy formation and hormonal profiles in Australoherus facetus, an invasive freshwater fish in Portugal.

  • 1 University of Algarve, Centre of Marine Sciences, Portugal
  • 2 Centre of Marine Sciences, Portugal
  • 3 University of Algarve, Portugal

Australoheros facetus is a highly social neotropical cichlid that is invasive in the Guadiana and Odelouca basins (Southern Portugal). Phenotypic plasticity is believed to be a key component for invasive success. However, its biology remains largely unknown. In this research we aimed to characterize the behaviour and hormone profiles (Testosterone (T), Estradiol (E), 11-keto-testosterone (11KT) and Cortisol) throughout the formation of stable social groups, a crucial step in the life-history of A. facetus. Fifteen social groups (n=4-6 size matched individuals per group) were observed and filmed until stable hierarchies were formed (7 days) at different periods of the year. An ethogram was established and a dominance index (DI=wins/ total interactions) was used to quantify social dominance. Blood samples were taken from all fish at the beginning and end of the experiment. After the trial period, the animals were sacrificed and the gonads inspected for sex determination. A pair breeding strategy with territorial behaviour was found, and territorial status was attributed to fish that formed a breeding couple and defended an arena. A positive correlation was found between dominance and size for both sexes (length: females R=0.63, males R=0.74; Weight: females R=0.79; males R=0.69; p<0.05). There were no differences between individuals in the initial levels of all hormones, but while T and E showed no evident pattern, final 11KT was higher in territorial males (territorial=2.30ng/mL, non-territorial=1.11ng/mL, p<0.05). Final cortisol were higher in non-territorial males (territorial=96.91ng/mL, non-territorial=163.3ng/mL, p<0.05) and negatively correlated with dominance (R=-0.47, p<0.05). These results suggest that size is the main driver for social dominance and that high social status lowers stress in all fish and increases 11KT secretion in males. Further analysis are in progress to understand the complex reproductive processes and the interspecific interactions that lead to a high recruitment success in this species, and may provide tools to control its propagation.


FB is receipient of a doctoral fellowship from the Brazilian CNPq Program Science without Borders (245971/2012-2); JLS is recipient of an FCT grant SFRH/BPD/67008/2009. This study is partially funded by FCT grant CCMAR/Multi/04326/2013

Keywords: invasive species, Hormonal profile, hierarchy formation, phenotipic plasticity, Cichlid

Conference: XV European Congress of Ichthyology, Porto, Portugal, 7 Sep - 11 Sep, 2015.

Presentation Type: Poster Presentation

Topic: Physiology, Behavior and Toxicology

Citation: Baduy F, Guerreiro PM, Vargas M, Canario AV and Saraiva JL (2015). Hierarchy formation and hormonal profiles in Australoherus facetus, an invasive freshwater fish in Portugal.. Front. Mar. Sci. Conference Abstract: XV European Congress of Ichthyology. doi: 10.3389/conf.fmars.2015.03.00064

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Received: 09 Nov 2015; Published Online: 11 Nov 2015.

* Correspondence: Miss. Flávia Baduy, University of Algarve, Centre of Marine Sciences, Faro, 8005-139, Portugal, flabaduy@gmail.com