Improvement of in-vitro culture techniques for unionid bivalves

Bc. Juan Felipe Escobar Calderón

Master's thesis

Abstract:

The freshwater mussels are one of the most endangered groups of animals in the world in part due to their complicated life cycle which includes a parasitic stage in a host fish. Because of this, the disappearing of host fishes in many rivers can greatly affect mussel populations. The alternative of in vitro culture can be extremely helpful for the conservation of species in which there is no sufficient knowledge about the host species or for places where the host fish has disappeared. However, in vitro culture poses a series of methodological challenges. Currently, the calculation of metamorphosis rate is largely based on juvenile activity. Factors like time and dilution of medium can affect the observed activity of the juveniles and it is not known if this can have an effect on the observed metamorphosis rate. Additionally the medium composition needs to be enhanced for some species where in vitro culture has not been successful. This contribution presents the results from our experiments carried out with the glochidia of Anodonta anatina and Margaritifera margaritifera. For A. anatina we studied the effects of different count times and dilutions on the perceived metamorphosis rate of larvae subjected to different medium types and antibiotic concentrations. While the M. margaritifera experiment aimed to test the effects of taurine addition, serum type (horse or newborn calf) and source of lipids (cod liver or emulsified lipid mixture) on the early development of larvae. Our conclusions point out that the measure of metamorphosis success in in vitro experiments can be affected by both dilution and time of counting and shows the importance of considering additional methods for assessing in vitro metamorphosis success. Alternatively we found that early reaction of larvae from M. margaritifera is not enhanced by the addition of taurine, but we observe a consistent positive influence of the emulsified lipid mixture. There was strong variation of the performance of the serums used in the test. Further studies should include the addition of host or non-host fish plasma. Finally, none of the factors tested had any significant effect on the final length of the larvae from M. margaritifera. This results can help to develop better protocols for the comparison of in vitro culture techniques for unionid bivalves.

Keywords

freshwater mussels, conservation, metamorphosis success, in vitro, Margaritifera margaritifera, Anodonta anatina

Language used: English

Date on which the thesis was submitted / produced: 12. 4. 2019

Thesis defence

• Supervisor: Ing. Karel Douda, Ph.D.

Czech University of Life Sciences Prague

Faculty of Agrobiology, Food and Natural Resources

Master programme / field:
Natural Resources and Environment / Natural Resources and Environment