New home, new life: The effect of shifts in the habitat choice of salamander larvae on population performance and their effect on pond invertebrate communities

• Main Author: Reinhardt, Timm
• Other Authors: Technische Universität Dresden, Fakultät Umweltwissenschaften
• Format: Doctoral Thesis
• Language: English
• Published: Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden 2017
• Subjects: Ökologie; Nahrungsnetze; Habitatwechsel; Anpassung; Ecology; Amphibians; Food webs; Habitat change; adaptation; ddc:597; rvk:WI 4700; rvk:WH 9430
• Online Access: http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-157607; http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-157607; http://www.qucosa.de/fileadmin/data/qucosa/documents/15760/DissertationREINHARDT2014_PDFA.pdf

Changes of habitats are amongst the main drivers of evolutionary processes. Corresponding shifts in the behaviour and life history traits of species might in turn also alter ecosystem attributes. The reproduction of Western European fire salamanders (Salamandra salamandra), in small pond habitats instead of first order streams, is one example of a recent local adaptation. Since fire salamander larvae are important top-predators in these fish free habitats, their presence likely changes various aspects of ecosystem functioning. Here, it was analysed how the ecological performance of salamander larvae in ponds in the Kottenforst in Western Germany changed in comparison to sympatric stream populations. Further, it was analysed how their presence in ponds influenced key ecosystem attributes such as prey density and diversity and aquatic-terrestrial linkage. To assess the impact of the life cycle shifts in salamanders on the pond functioning, detailed investigations of salamander larvae population dynamics, phenology, and macroinvertebrate community development in ponds were combined with experimental manipulations of the salamander presence. In the first part of this study, the impact of pond presence of fire salamanders in terms of ecosystem functioning focussing on aquatic terrestrial subsidy transfer was calculated. The study could show, that the adaptation of fire salamanders to breed in pools led to strong increases of animal-mediated import of terrestrial matter into the aquatic habitats. The hypothesis about the impact on macroinvertebrate communities derived from these calculations was then tested experimentally. It was shown, that presence of salamander larvae could influence some taxa of macroinvertebrates but they had only limited effects on the food web structure in their aquatic habitats. Yet, a high relevance of the subsidy exchange from aquatic to terrestrial and its high relevance for the predator persistence in the system could again be confirmed. Moreover, it was demonstrated, that the larval behaviour and performance could have a high inter-annual variability as a reaction to contrasting ecosystem constraints in comparison to the stream habitats. A fact that integrally separates the pond ecotype from stream ecotype conspecifics.