Marine Biology

, 163:187 | Cite as

Effects of short-term exposure to ectoparasites on fish cortisol and hematocrit levels

  • Zegni TrikiEmail author
  • Alexandra S. Grutter
  • Redouan Bshary
  • Albert F. H. Ros
Original paper


On coral reef systems, ‘client’ fishes combat relentless ectoparasitic infections by engaging in frequent mutualistic interactions with various ‘cleaner’ organisms. Clients are known to adjust their visits to cleaners according to their ectoparasite load. Whether physiological changes due to the ectoparasitic infection, prior to engaging in cleaning interactions, might inform clients of their current need to visit cleaners remains unclear. Here, we tested whether fish blood parameters vary with ectoparasitic infection: we exposed clients (Scolopsis bilineatus) to hematophagous ectoparasite gnathiid isopods (Gnathia aureamaculosa) or a control situation for 30 min, then collected fish blood and counted gnathiids attached to fish. We found that gnathiid-exposed fish had higher blood cortisol hormone levels compared with controls. This suggests gnathiid presence in the experimental situation results in an acute stress hormone response in a fish. In contrast, while hematocrit level, a correlate of blood loss, did not significantly differ between treatments, within gnathiid-exposed fish hematocrit was negatively related to attached gnathiid number. This suggests hematocrit could provide information to a fish about gnathiid load. Thus, short-term exposure to an ectoparasite translates into possible proximate physiological mechanisms underlying client’s decisions involving interactions with cleaners.


Cortisol Cortisol Level Parasite Load Hematocrit Level Fish Blood 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



We thank the LIRS directors and staff for their support and friendship. We also thank D. Nusbaumer, S. Gingins, and D. Sun for their assistance, and G. Glauser and A. Vallat from the Chemical Analytical Service of the University of Neuchâtel for their assistance with MS-HPLC analysis.


This study was funded by the Australian Research Council (ASG and RB), the Swiss Science Foundation (RB), and the Swiss Scholarships for foreign students (ZT).

Compliance with ethical standards

Conflict of interest

All authors declare that they have no conflict of interest.

Ethical standards

The University of Queensland Animal Ethics Committee approved the project.

Supplementary material

227_2016_2959_MOESM1_ESM.pdf (77 kb)
Supplementary material 1 (PDF 79 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Zegni Triki
    • 1
    Email author
  • Alexandra S. Grutter
    • 2
  • Redouan Bshary
    • 1
  • Albert F. H. Ros
    • 1
  1. 1.Behavioral Ecology Laboratory, Faculty of ScienceUniversity of NeuchâtelNeuchâtelSwitzerland
  2. 2.School of Biological SciencesThe University of QueenslandBrisbaneAustralia

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