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Relationship between the age of freshwater pearl mussel and the number of increments in shell section
TOMAN, Jan
The aim of this thesis was to determine the relationship between the age of dead individuals of the freshwater pearl mussel (Margaritifera margaritifera) and the number of incremental lines on the shell section. A total of 124 pearl mussel shells of known age were collected from several Czech, German and Finnish localities. There was a statistically significant difference between the actual age and the age according to the number of incremental lines on shell section. On average, the age determined by increment lines was higher than the actual age by 2.6 years, which is 42 ? 25% (? S.D.). Thus, the increment lines on the section of the pearl mussel shell do not correspond to the annual increments. It was confirmed that increment lines count on the shell surface or estimating age from shell size are less reliable approaches to determine the true age of individuals.
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Calcium volume and ratio effect in food of freshwater pearl mussel (Margaritifera margaritifera) on its survival and growth rate
Macháček, Vojtěch ; Horáčková, Jitka (advisor) ; Tichá, Kamila (referee)
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...
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Limit factors for survival of Unionoidea in the freshwater hyporeal with a focus on Margaritifera margaritifera
Macháček, Vojtěch ; Horáčková, Jitka (advisor) ; Barák, Vojtěch (referee)
This bachelor thesis deals with physical, mechanical, chemical and biological factors that limit the occurrence, survival and reproduction of large bivalve molluscs of the Unionoidea superfamily. Accent is placed on freshwater pearl mussel (Margaritifera margaritifera) for which a rescue action plan is being implemented in the Czech Republic, as it is one of the most endangered bivalve mollusc in our country and in Europe. In addition to the already thoroughly explored factors as - water temperature, conductivity, river dynamics, river bed structure, pH, concentration of various forms of nitrogen, phosphorus and oxygen, and the interaction of large bivalve molluscs with other animals, I deal with relatively new issues of pesticides and pharmaceuticals. These are appearing in the streams due to human (in)activity, and we know almost nothing about their impact on large freshwater bivalve molluscs. I also deal in more detail with the issue of calcium, which is essential for bivalve molluscs, because they make their shells out of it, although it is not yet clear which form they accept.
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Limit factors for survival of Unionoidea in the freshwater hyporeal with a focus on Margaritifera margaritifera
Macháček, Vojtěch ; Horáčková, Jitka (advisor) ; Barák, Vojtěch (referee)
This bachelor thesis deals with physical, mechanical, chemical and biological factors that limit the occurrence, survival and reproduction of large bivalve molluscs of the Unionoidea superfamily. Accent is placed on freshwater pearl mussel (Margaritifera margaritifera) for which a rescue action plan is being implemented in the Czech Republic, as it is one of the most endangered bivalve mollusc in our country and in Europe. In addition to the already thoroughly explored factors as - water temperature, conductivity, river dynamics, river bed structure, pH, concentration of various forms of nitrogen, phosphorus and oxygen, and the interaction of large bivalve molluscs with other animals, I deal with relatively new issues of pesticides and pharmaceuticals. These are appearing in the streams due to human (in)activity, and we know almost nothing about their impact on large freshwater bivalve molluscs. I also deal in more detail with the issue of calcium, which is essential for bivalve molluscs, because they make their shells out of it, although it is not yet clear which form they accept.
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Freshwater mussels breeding methods for the purpose of conservation programs
Plechingerová, Věra ; Douda, Karel (advisor) ; Matasová, Klára (referee)
Bachelor thesis is written in an overview form of problems breeding freshwater molluscs. At the beginning of the thesis I first evaluate the overall status of the populations in the Czech Republic and then in the world. Next I describe the anatomy and biology of molluscs, especially their reproduction, which is crucial for rearing juveniles in the laboratory or seminatural environment. The return of molluscs populations into the waters ecosystems is problematic in terms of ongoing changes in the biotope, particularly because of the anthropogenic influences and too few suitable host fish, without which it can not complete its glochidia development. To prevent the complete extinction of some species, there have been researched different methods of rearing, which help recover viable populations in the natural water environment. Methods of rearing are also described in this thesis. In the experimental part of the thesis I evaluate types of detritus that have different effects in length gain of mussels. For the experiment was selected freshwater pearl mussel (Margaritifera margaritifera), whose population is highly endangered. Freshwater mussels are an important bio-indicator of waters ecosystems, where they have an irreplaceable function, so it is important to regenerate their populations and the overall condition of the biotopes.
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Growth and survival of pearl mussel (Margaritifera margaritifera) for bioindication
NIEDLOVÁ, Eva
Growth and survival of juvenile pearl mussels (Margaritifera margaritifera Linnaeus, 1758) "in-situ" indicates suitable habitats for their rearing and subsequent reintroduction. Six streams in Aš region (Rokytnice, Lužní potok, Pekelský potok, Újezdský potok, Perlový potok, Bockbach) including 15 profiles were evaluated throughout the season (1. 6. 31. 8. 2015). One year old pearl mussels (n = 580) sized from 700 1400 ?m. Mean survival of pearl mussels was 63 % in all streams. Mean absolute growth increment attained 755 ?m throughout the season. Growth of pearl mussels (1+) was positively correlated with the water temperature (R2 = 0,1084). Both the highest survival (70 %) and the highest absolute growth (1027 ?m and 997 ?m) of pearl mussels was determined on localities in Bockbach (Bockbach 11 and 1). In contrast to Bockbach 11 and 1 mean survival (28%) and absolute growth (304 ?m) was the lowest in Lužní potok 2. Survival rate of two years old pearl mussels was higher than that of one year old pearl mussels. Both of these age categories grew similarly.
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The ecology of freshwater pearl mussel (Margaritifera margaritifera L.) and evaluation of its mortality on locations in the Czech Republic.
MÁSÍLKO, Jan
The aim of this thesis was to monitor mortality or more precisely population changes of freshwater pearl mussel (Margaritifera margaritifera L.), which settle in oligothropic stream. Brown trout (Salmo trutta morpha fario L.) is the only one fish host of larval stage of freshwater pearl mussel. The counting of the population was pursued at 2 localities: on the Blanice river and on the stream of Lužní potok in the Czech Republic. For general counting of population a net instrument and an optical instrument were used, that enabling to see them. Population of freshwater pear mussel is in decline in all Europe due to many factors like eutrophication, water pollution, etc. Results of work indicated a decline in population of freshwater pearl mussel at the first area about 15,38 % and at the second area about 15,22 % of the stream Lužní potok. There was not recorded a decline on the Blanice river, on the contrary, the number of population was higher. Among others, the habitation of juveniles was recorded at the first area.
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