Stress response of fire salamander larvae differs between habitat types

Laura Schulte; Pia Oswald; Max Mühlenhaupt; Edith Ossendorf; Sabine Kruse; Sylvia Kaiser; Barbara A Caspers

doi:10.1098/rsos.231304

Stress response of fire salamander larvae differs between habitat types

R Soc Open Sci. 2024 Apr 3;11(4):231304. doi: 10.1098/rsos.231304. eCollection 2024 Apr.

Authors

Laura Schulte¹, Pia Oswald¹, Max Mühlenhaupt¹, Edith Ossendorf², Sabine Kruse², Sylvia Kaiser^{2

3}, Barbara A Caspers^{1

3}

Affiliations

¹ Behavioural Ecology Department, Bielefeld University, Bielefeld 33615, Germany.
² Institute for Neuro- and Behavioural Biology, University of Münster, Münster 48149, Germany.
³ Joint Institute for Individualisation in a Changing Environment (JICE), University of Münster and Bielefeld University, Bielefeld, Germany.

Abstract

The larvae of the European fire salamander (Salamandra salamandra) can inhabit two different habitats: streams and ponds. Streams are characterized by lower predation risks and higher food availability. Thus, ponds are considered a less suitable habitat. To investigate the differential impacts of these two habitats on larval physiology, we measured the stress response of larvae. After successfully validating the measure of water-borne corticosterone release rates in fire salamander larvae, we measured the baseline and stress-induced corticosterone of 64 larvae from ponds and streams in the field. We found that larvae in ponds have a higher baseline and stress-induced corticosterone levels. Additionally, we performed a reciprocal transplant experiment (RTE) and tested whether larvae can adapt their stress responses to changing habitats. After two weeks, we did not find an increase in corticosterone levels when comparing stress-induced corticosterone values with baseline corticosterone values in larvae transferred into ponds, irrespective of their habitat of origin. However, larvae transferred into streams still exhibited an increase in the stress-induced corticosterone response in comparison with the baseline values. These results show that non-invasive hormone measurements can provide information on the habitat quality and potential adaptation and thus emphasize the potential for its use in conservation efforts.

Keywords: Salamandra salamandra; corticosterone phenotype; niche conformance; reciprocal transplant experiment; stress physiology; water-borne corticosterone release.