Effect of vegetation loss on freshwater diversity

Bc. Anna Marie Poskočilová

Master's thesis

Abstract:

Agricultural intensification is the main cause of loss of aquatic invertebrate species in farm ponds. The vast majority of our ponds are used for fish breeding, predominantly carps, and are often overfished. Homogenous fish stock and minimal cover of littoral vegetation negatively affects the population of aquatic invertebrates. The literature review summarizes the issue of intensive agricultural management and its impact on aquatic invertebrates. Furthermore, it analyses the influence of aquatic vegetation on aquatic invertebrates and equally summarizes the defense antipredation mechanisms of aquatic invertebrates. The experiment took place at twelve ponds used for intensive fish farming in three regions of the Czech Republic. The aim was to create alternative fish-free zones within homogeneous ponds (using fences) and plant vegetation artificially in half of them. Sampling took place throughout the season of 2019 (April-October). The experiment has demonstrated that only several invertebrate groups proved more abundant in cages without fish (Gerridae, Notonectidae, Noteridae), and that aquatic Hemiptera were attracted to microhabitats with natural vegetation. Moreover, the experiment has shown that species composition did not differ significantly between the researched localities. All the groups captured during the field experiment were pioneer species, which tend to quickly colonize new environments, and they were not particularly selective in their habitat preferences.

Keywords

freshwater invertebrates, diversity loss, freshwater ponds, vegetation loss, fish predation, intensive management

Language used: English

Date on which the thesis was submitted / produced: 30. 6. 2020

Thesis defence

• Supervisor: Mgr. Filip Harabiš, Ph.D.

Czech University of Life Sciences Prague

Faculty of Environmental Sciences

Master programme / field:
Engineering Ecology / Nature Conservation