A greater consumption of pharmaceutical drugs entails an increased concentration of active benzodiazepines in aquatic ecosystems. Consequently, aquatic organisms are experiencing altered behavior that may affect dominance hierarchies since social status (among other variables) is associated with behavioral traits. The aim of this study was to determine whether dominance hierarchies of brown trout (Salmo trutta) were affected by exposure to a benzodiazepine (oxazepam). Hypothetically, aggression (in dominants) and anxiety (in subordinates) will reduce following exposure. The fish should consequently display a significant disparity between treatment groups regarding the frequency of dominance change (i.e., who is dominant versus subordinate). This research included behavioral coding of 150 juvenile brown trout (Salmo trutta) divided into 50 size-matched social groups of 3 individuals. Each group was exposed to one of three oxazepam concentrations (30 µg/L, 1.5 µg/L and 0 µg/L). The results indicate no relationship between an altered aggression and oxazepam exposure. In addition, the level of aggression reduced over time (regardless of social status and concentration) and the initial subordinates remained significantly less aggressive than the initial dominants. The frequency of dominance change did not differ significantly between different treatment groups. Body size did not affect social status. The results in low treatment groups may be due to a low bioconcentration since previous research exhibited similar results. However, the lack of results in high treatment groups could be due to something else. In conclusion, the dominance hierarchy was not disrupted by oxazepam exposure because aggression was unaffected.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:umu-195932 |
| Date | January 2022 |
| Creators | Jirlén, Olivia |
| Publisher | Umeå universitet, Institutionen för ekologi, miljö och geovetenskap |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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