| Popis: |
The freshwater pearl mussel (Margaritifera margaritifera) is a protected critically endangered species in the Czech Republic, whose juvenile stages are currently unable to survive and grow on many streams, partly due to the absence of quality food with sufficient calcium supply. Pearl mussels only live in oligotrophic rivers and streams, which are generally poor in calcium. However, they need enough calcium in their food, as they use it, among other things, to build a hard shell. It is not yet clear in what form pearl mussels take calcium in their diet, but it is clear that some of its forms are a key factor for the growth and survival of juveniles. We therefore focused on the study of various forms of organic calcium in their diet (fine particulate organic matter, further shortened as "detritus") and further feeding experiments to evaluate their suitability. Within this work, detritus was collected in thirty-five localities in the upper Vltava and Blanice river basins in three seasons in two years. Samples originated both from main river channels, their tributaries and springs. Afterwards, two organic forms of calcium in the samples - citrate and oxalate - were quantified. Then, twenty localities with different contents of both forms of calcium were selected from the tested samples, from which... |
