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Selected aspects of biology of the invasive species \kur{Pectinatella magnifica}
JEŽKOVÁ, Eva
Pectinatella magnifica, invazní organismus, statoblast, rozmnožování, laboratorní kultivace SUMMARY Pectinatella magnifica is an invasive organism transfered to Czech republic from the USA with the international boat transport. Here it poses a lot of potencial threats toour native species, as well as to submerged technical constructions. It is a species of freshwater Bryozoan that is able to create colonies of considerable sizes. On the surface of a gelatinuous matrix there are small living indiviuals called the zooids. These can reproduce both sexually and asexually, which gives them a huge competitive potential. The dormant asexual spores, e.g. statoblasts, are extremely resistant towards various natural conditions and have characteristics enabling them to spread to substantial distances. This thesis aimed to identify and describe several life aspects of Pectinatella magnifica, especially reproduction and spreading strategy. I monitored the organism in the nature, as well as in a number of laboratory experiments. I was able to succesfully transfer the colonies of Pectinatella from the ponds into a special aquarium system. Under the laboratory conditions, 80 % of statoblasts germinated within five to eight days, depending on the water temperature. Then the zooids emerged and survived for around eight weeks, enabling me to observe different development and behaviour. Obtained photo and viceodocumentation shows details of a sexual reproduction of zooids, proving that it occurs even in our environment. The most prefered natural conditions seem to be the flooded mezotrophic sand quarries and protected and recreational ponds with a low fishing stock (without a massive algeae presence, fluctuating oxygen levels, etc.) The results do not suggest that Pectinatella magnifica is currently a significant competitor to our native Bryozoan species.
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Biology and ecology of invasive species bryozoan Pectinatella magnifica
SKUHROVEC, Tomáš
Biology and ecology of invasive species bryozoan Pectinatella magnifica The aim of this bachelor theses is to create a literary overview containing available information about biology and ecology of the species Pectinatella magnifica. This invasive bryozoan originates from North America. Its occurrence in the Czech Republic was first recorded in the 30s of the twentieth century around the rivers Labe and Vltava. However its first massive presence was reported in the year 2003 in the sand pit Cep in the national protected landscape area Třeboňsko. From the reservoir Cep, it spread into other locations (sand pits Cep I, Vlkov, Veselí, Veselí I., Horusice and into ponds Hejtman, Nový Kanclíř, Staňkovský and Podřezaný, where it found suitable conditions for its life. It can be found in other locations in the Czech Republic as well, but its occurrence does not reach such big amounts. Outside our country it can be found in other European states and in some Asian countries. Pectinatella magnifica is a colonial fresh water animal preferring asexual reproduction. The colonies have yellow and brown colour, a structure of a hard gelatine and a spherical or oblong shape. Pectinatella magnifica is an effective filter feeding invertebrate, its diet consists of phytoplankton, especially diatoms. The most significant ecological factor effecting its seasonal dynamics is the temperature, as it is a thermophilic species preferring the optimal temperature of 20°C. If the temperature sinks bellow 20°C, the colonies start to decline and the hibernating units, called statoblasts, are released. Pectinatella magnifica tends to occur in slightly alkaline fresh water with a lower conductivity (bellow 200 S.cm-1). Regarding the trophy, water, qualified from oligotrophic to mesotrophic, is suitable for Pectinatella magnifica. It is found especially on submerged branches and on driftwood in the areas of river banks. Within this species, the association with other water animals has been proved, for example with small crustaceans and snails. In the cavity of coelom, the sexual evolution of parasitic species Trichonosema and Tetracapsula has been proved, these species represent a group of significant parasites of salmonids. To be able to estimate and describe the influence of this species, recently spreading in biotopes, which it inhabits, it is necessary to get acquainted with its biology.
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