Bryozoan stable carbon and hydrogen isotopes: relationships between the isotopic composition of zooids, statoblasts and lake water
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We explored the extent to which δ13C and δD values of freshwater bryozoan statoblasts can provide information about the isotopic composition of zooids, bryozoan food and surrounding water. Bryozoan samples were collected from 23 sites and encompassed ranges of nearly 30‰ for δ13C and 100‰ for δD values. δ13C offsets between zooids and statoblasts generally ranged from −3 to +4.5‰, with larger offsets observed in four samples. However, a laboratory study with Plumatella emarginata and Lophopus crystallinus demonstrated that, in controlled settings, zooids had only 0–1.2‰ higher δ13C values than statoblasts, and 1.7‰ higher values than their food. At our field sites, we observed a strong positive correlation between median δ13C values of zooids and median δ13C values of corresponding statoblasts. We also observed a positive correlation between median δD values of zooids and statoblasts for Plumatella, and a positive correlation between median δD values of statoblasts and δD values of lake water for Plumatella and when all bryozoan taxa were examined together. Our results suggest that isotope measurements on statoblasts collected from flotsam or sediment samples can provide information on the feeding ecology of bryozoans and the H isotopic composition of lake water.
KeywordsFreshwater Bryozoa Stable isotopes Statoblasts Lakes Feeding ecology Palaeoecology
We thank Michiel van der Waaij for collecting samples in Dutch lakes and for useful information on the habitat and ecology of several freshwater bryozoan species (www.bryozoans.nl). Winfried Lampert, Peter Hammond, Alex Gruhl, and Elena Brand greatly helped during an exploratory field trip. Robert Dünner is kindly acknowledged for suggesting locations in a number of Swiss lakes. Peter Nyfeler’s work analysing the stable isotope data has been invaluable. We thank four anonymous reviewers for their comments on earlier versions of this manuscript. This study was funded by the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC Grant Agreement no. 239858 (RECONMET).
- Belle, S., C. Parent, V. Frossard, V. R. Verneaux, L. Millet, P.-M. Chronopoulou, P. Sabatier & M. Magny, 2014. Temporal changes in the contribution of methane-oxidizing bacteria to the biomass of chironomid larvae determined using stable carbon isotopes and ancient DNA. Journal of Paleolimnology 52: 215–228.CrossRefGoogle Scholar
- Bowen, G. J., 2014. The Online Isotopes in Precipitation Calculator, version 2.2. http://www.waterisotopes.org.
- Frey, D. G., 1964. Remains of animals in Quaternary lake and bog sediments and their interpretation. Archiv für Hydrobiologie Supplement 2: 1–114.Google Scholar
- Frossard, V., V. Verneaux, L. Millet, J.-P. Jenny, F. Arnaud, M. Magny & M.-E. Perga, 2014. Reconstructing long-term changes (150 years) in the carbon cycle of a clear-water lake based on the stable carbon isotope composition (δ13C) of chironomid and cladoceran subfossil remains. Freshwater Biology 59: 789–802.CrossRefGoogle Scholar
- Hammer, Ø., D. A. T. Harper, & P. D. Ryan, 2001. PAST: paleontological statistics software package for education and data analysis. Palaeontologia Electronica 4: 9 pp.Google Scholar
- Kaminski, M., 1984. Food composition of three bryozoan species (Bryozoa, Phylactolaemata) in a mesotrophic lake. Polish Archive of Hydrobiology 31: 45–53.Google Scholar
- Lacourt, A., 1968. A monograph of the freshwater Bryozoa-Phylactolaemata. Zoologische Verhandelungen 93: 1–155.Google Scholar
- R Core Team, 2013. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna.Google Scholar
- Van Hardenbroek, M., O. Heiri, F. J. W. Parmentier, D. Bastviken, B. P. Ilyashuk, J. A. Wiklund, R. I. Hall & A. F. Lotter, 2013a. Evidence for past variations in methane availability in a Siberian thermokarst lake based on δ13C of chitinous invertebrate remains. Quaternary Science Reviews 66: 74–84.CrossRefGoogle Scholar
- Van Riel, M. C., G. Velde, S. Rajagopal, S. Marguillier, F. Dehairs & A. B. Vaate, 2006. Trophic Relationships in the Rhine Food Web During Invasion and After Establishment of the Ponto-Caspian Invader Dikerogammarus Villosus. In Leuven, R. S. E. W., A. M. J. Ragas, A. J. M. Smits & G. Velde (eds), Living Rivers: Trends and Challenges in Science and Management, Developments in Hydrobiology. Springer, Dordrecht: 39–58.CrossRefGoogle Scholar
- Wood, T. S. & B. Okamura, 2005. A New Key to Freshwater Bryozoans of Britain, Ireland and Continental Europe, With Notes on Their Ecology. Freshwater Biological Association, London.Google Scholar
- Wooller, M., J. Pohlman, B. Gaglioti, P. Langdon, M. Jones, K. Walter Anthony, K. Becker, K.-U. Hinrichs & M. Elvert, 2012. Reconstruction of past methane availability in an Arctic Alaska wetland indicates climate influenced methane release during the past ~ 12,000 years. Journal of Paleolimnology 48: 27–42.CrossRefGoogle Scholar