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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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