Behavioral adjustments of a pipefish to bacterial Vibrio challenge
Animals can profit from increasing temperatures by prolonged breeding seasons and faster growth rates. However, these fitness benefits are traded off against higher parasite load and increased virulence of temperature-sensitive pathogens. In thermally stratified habitats, behavioral plasticity can allow hosts to choose the optimal temperature to enhance individual fitness and to escape parasite pressure. To test this idea, we performed a temperature choice experiment with the host–parasite system of the sex-role reversed broad-nosed pipefish (Syngnathus typhle) and its bacterial pathogen Vibrio spp. In this species, pregnant males are expected to face a trade-off between shortening their brooding period in warm water and decreasing the effect of the infection in cold water. We found that exposure to Vibrio changed the temperature preference for both pregnant and nonpregnant males, as well as females compared to nonchallenged fish that tended to prefer warm water. This study shows that behavioral plasticity is one option for avoidance of higher bacterial prevalence, as expected due to rising ocean temperatures.
KeywordsBehavioral chills Global warming Temperature Host–parasite Syngnathus typhle Vibrio spp
Funding was provided by the Volkswagen Foundation and the future ocean excellence cluster (to SHL and OR), Zoologiska stiftelsen and Inez Johanssons stiftelse (JS), and the Norwegian Research Council (grant number 186163/V40) (GR). We thank R. Höglund, S. Birrer, J. Goldhammer, K. Lohbeck, and P. Schubert for the field assistance; A. Berglund for providing the field equipment; and Ar Research Station for the working facilities. We thank J. Frommen for the input during the review process of this manuscript and for the statistical advice.
Conflict of interest
The authors declare that they have no conflict of interest.
The experiment was performed according to current national legislation on Animal Welfare under licence Dnr S 155-09 from the Swedish Board of Agriculture and the Ministerium für Landwirtschaft, Umwelt und ländliche Räume des Landes Schleswig-Holstein (project: “Effects of global change on the immunological interaction of pipefish and their natural bacterial communities”).
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