Structuring factors for macroinvertebrate communities and the importance for ecosystem processing

Research output: ThesisDoctoral Thesis (compilation)

Abstract

Aquatic macroinvertebrates play important roles in our ecosystems and are essential for the ecosystem processing. An improved knowledge of structuring factors, such as competition and predation, and the way in which they operates in the macroinvertebrate community is crucial for our understanding of not only the macroinvertebrates but also the ecosystem in general. Furthermore, today our ecosystems are also faced with a new range of threats including brownification and invasive species. The objective of my thesis is therefore to enhance the knowledge of the structuring factors and how it affects the ecosystem processes. In this theses I have studied (both in field and in the laboratory), both the general and interactive effects of predation risk, competition, brownification and invasive species, on macroinvertebrate ( <I> Radix balthica, Cloeon dipterum, Gammarus pulex, Asellus aquaticus </I> and <I> Potamopyrgus antipodarum </I>) fitness factors (growth and mortality) as well as ecosystem processing (grazing and decomposition).
I found that indirect effects of predation affected ecosystem processing; decomposition increased whereas grazing decreased in treatments with predator cues. Furthermore, predator cues had a positive effect on R. balthica growth, most likely due to high quality leaf biofilm. Competition, both intraspecific and interspecific, had a negative effect on both ecosystem processing as well as fitness factors. However, I also found facilitation between species, cascading further to affect ecosystem processing. Furthermore, water colour had a significant effect on predation. In clear water fish predated selectively on <I>R. balthica</I> , whereas there was no difference in prey preference in brown water. An increase in water colour had a negative effect on both decomposition and grazing, most likely due to changes in species composition of periphyton and leaf biofilm. Increased water colour also had a negative effect on R. balthica growth. In contrast, the invasive species <I>P. antipodarum</I> was more tolerant, both to predation as well as the effect of water colour, explaining their success as an invasive species. P. antipodarum also had higher grazing rates than the native species, which may have implications for the invaded ecosystems. My results illustrate the importance of competition, indirect effects of predation, water colour as well as the introduction of invasive species, not only for the individual fitness of macroinvertebrates but also for ecosystem possessing. Furthermore, it also shows the complexity of macroinvertebrate population dynamics and how the outcome of interactions is greatly dependent on which species are involved and in what combinations.

Details

Authors
  • Pia Hertonsson
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Environmental Sciences
  • Ecology

Keywords

  • ephemeroptera, competition, Predation risk, brownification, invasive sp., decomposition, grazing, growth, gastropoda, mortality, amphipoda, isopoda
Original languageEnglish
QualificationDoctor
Awarding Institution
Supervisors/Assistant supervisor
Award date2010 Mar 19
Print ISBNs978-91-7105-307-7
Publication statusPublished - 2010
Publication categoryResearch

Bibliographic note

Defence details Date: 2010-03-19 Time: 09:30 Place: Blå hallen, Ekologihuset, Sölvegatan 37, Lund External reviewer(s) Name: Burks, Romi Title: Associate Professor Affiliation: Dept. of Biology, Southwestern University, Georgetown, USA --- The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Limnology (Closed 2011) (011007000)