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Development of resistant life stages and mechanisms of passive dispersal of freshwater copepods
Šliková, Adéla ; Juračka, Petr Jan (advisor) ; Fott, Jan (referee)
Copepods are an important part of metacommunities in freshwater and marine ecosystems. Freshwater copepods occur at all continents and are found in almost every water habitat. These small invertebrates cannot actively disperse among habitats and therefore have to rely on vectors of passive dispersal. Copepods can produce diapause life forms and are therefore able to survive unfavorable conditions during the transport. Throughout the ontogenetic development from an egg to adult stage, they have to pass naupliar and copepodit life stages. Various evolutionary lineages of copepods developed diapause phase at different life stage. Hence it is possible to observe both diapausing eggs as well as diapausing adults. Discussed vectors of passive dispersal are wind, floods, animal fur, animal gut, but also human recreational and industrial activity. This work summarizes basic knowledge about the mechanisms of development of copepods diapausing life stages and about their passive dispersal. Key words: passive dispersal, freshwater copepods, diapause
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Zooplankton of Bohemian Forest lakes as indicator of recovery from acidity
Kohout, Leoš ; Fott, Jan (advisor) ; Macháček, Jiří (referee) ; Bitušík, Peter (referee)
CONCLUSIONS In my Ph.D. thesisthe ťollowingitems arediscussed It is hypothesisedthat Al govems the P availability in the acidified lakes, as well as shapesthe foodweb structure. Substantialportion of the plankton biomass in the Bohemian Forest lakes is createdby hetelotrophic fi|amentswhen filtering cladocerans aÍenot present (theyareextinctor occuÍseasonal1y). After ťrrstsigns in the nineties further evidence for the ongoing biological recovery was collected. Nevertheless, the lakes are still stongly or partially influenced by acidification and standardfood web relationshipshave not been restored. The significant hysteresisof biological recovery behind the reversal of lake chemistryin theBohemianForest and elsewherecould have severalreasons: - Isolationofremote headwaterlakes makestheprocessofzooplankton re- colonizationstochastic,theprobability being atleastfor somecnrstacean specieslow. The successdependson suitablevector ofpropagules and size of inoculum. - Strong invertebrate predation in some fishless lakes can cause abiological resistancepreventing from zooplankton recovery until fish retum. ln theBohemian Forest for instancethereaÍeknown populations of corixids in some lakes and numerousChaoborus larvae are observed from Laka Lake. - Currenthydrochemicalconditions are still hard for...
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Development of resistant life stages and mechanisms of passive dispersal of freshwater copepods
Šliková, Adéla ; Juračka, Petr Jan (advisor) ; Fott, Jan (referee)
Copepods are an important part of metacommunities in freshwater and marine ecosystems. Freshwater copepods occur at all continents and are found in almost every water habitat. These small invertebrates cannot actively disperse among habitats and therefore have to rely on vectors of passive dispersal. Copepods can produce diapause life forms and are therefore able to survive unfavorable conditions during the transport. Throughout the ontogenetic development from an egg to adult stage, they have to pass naupliar and copepodit life stages. Various evolutionary lineages of copepods developed diapause phase at different life stage. Hence it is possible to observe both diapausing eggs as well as diapausing adults. Discussed vectors of passive dispersal are wind, floods, animal fur, animal gut, but also human recreational and industrial activity. This work summarizes basic knowledge about the mechanisms of development of copepods diapausing life stages and about their passive dispersal. Key words: passive dispersal, freshwater copepods, diapause
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