Frontiers in Marine Science (Dec 2015)
Provenancing fish in freshwaters of the Alpine Foreland using Sr/Ca and 87Sr/86Sr ratios in otoliths and otolith shape parameters
Abstract
Analysis of elemental and isotopic compositions and of the shape of fish otoliths has become an important tool in fish ecology. Highly relevant questions like origin and migration of fish over their life time cannot be answered easily with other methods. However, before otolith chemistry and shape can be applied for such kind of studies, the relation between the specific environmental conditions and both, the chemistry and shape of otoliths, needs to be understood. Therefore in this study, a reference database of otolith chemistry and shape, as a basis for further ecological and migration studies, was established. Otoliths of different fish species from lake Chiemsee (Bavaria, Germany) and its surrounding waterbodies were analysed for (1) their Sr/Ca and 87Sr/86Sr ratios and (2) for potential differences in otolith shape within the same species. The Alpine foreland was chosen because it is characterized by a wide range of waterbodies of different structure, temperature and nutrient conditions hosting a diverse spectrum of fish species. Microchemical analysis of water samples was accomplished by inductively coupled plasma-mass spectrometry (ICP-MS) and otoliths were examined by laser ablation ICP-MS. Different otolith shape parameters were determined via analysing general form parameters and elliptical Fourier descriptors using the software Image-Pro Plus 7.0 and SHAPE 1.3, respectively. Although the studied freshwaters were located only in a 50 km range around lake Chiemsee on a similar geological background, differences in water chemistry, fish otolith chemistry and shape were identified. Species specific differences in reflection of the Sr/Ca ratio of a specific water body were detected. Microchemical and morphological otoliths analyses complemented each other and allowed assigning fish to specific groups of waters of origin. This information provides an important basis for the further application of otolith chemistry and shape analysis in the Alpine foreland for a diverse range of ecological questions.
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