Diurnal dynamics of the microbial loop in peatlands: structure, function and relationship to environmental parameters

Abstract

The interactions between bacteria and heterotrophic protists are essential for the ecosystem ecology of peatlands. We tested the hypothesis that fertility of a habitat may significantly influence the diurnal dynamics of the abundance of individual components of the microbial loop, as well as the number and intensity of correlations between bacteria and heterotrophic protists. Samples were taken in raised and carbonate peat bogs in three seasons, four times a day: at dawn, at noon, at dusk and at night. The results indicate that microbial community responses to physical and chemical parameters are complex but dependent on peatlands' type and variable among microbes. Concentrations of nutrients may significantly influence the diurnal dynamics of the microbial communities. The most significant correlations occurred in the afternoon. At that time, the number and biomass of metabolically active bacteria correlated to the highest degree with concentrations of dissolved organic carbon, while in the evening, a clearly positive correlation between the abundance of bacteria and protists was observed. In a carbonate fen, the correlations were significantly weaker. Such knowledge will provide a more comprehensive understanding of the implication of chemical disturbance on microbial functions in relation with nutrient and carbon dynamics.

The effect of epiphytic macroinvertebrates on microbial communities in different types of macrophyte-dominated shallow lakes

“…Temperature is another factor likely to substantially influence periphyton succession. According to Mieczan and Tarkowska-Kukuryk (2013), the growth and reproduction of freshwater microbial communities in the periphyton were strongly correlated with temperature. The temperature in the lakes studied had a significant influence on the number of algae and microorganisms.…”

“…Microbial communities are regulated both by top-predator grazing (top-down control) and nutrient resources (bottom-up control), and the strength of this control is dependent on trophic position and food web length (Pierce and Turner, 1992;Biyu, 2000;Xu et al, 2005). Metazoan grazing is an important process for the recycling of nutrients and the production of dissolved organic substrates for bacteria, it is also a controlling factor for heterotrophic protist community structure (Fermani et al, 2013;Mieczan and Tarkowska-Kukuryk, 2013). However, there have been very few studies on the influence of epiphytic fauna on microbial food webs in periphyton on different macrophyte species of shallow lakes.…”

Effect of water chemistry on zooplanktonic and microbial communities across freshwater ecotones in different macrophyte-dominated shallow lakes

“…Hillbricht-Ilkowska and Węgleńska, 2003;Segovia et al, 2015). While it is well established that metazoan grazing is an important process for the recycling of nutrients and the production of dissolved organic substrates for bacteria, it is also a controlling factor for heterotrophic protist community structure (Fermani et al, 2013;Mieczan and Tarkowska-Kukuryk, 2013). The microbial loop plays an important role in carbon flow and nutrient cycling through microbial components of aquatic communities.…”

Effects of rotifers, copepods and chironomid larvae on microbial communities in peatlands

“…Plant communities in Sphagnum-dominated peatlands are adequately documented (Bragazza et al 2006). Little is known about how short-term (days to months) variability of potential predators may influence microbial communities (Brown et al 2011;Mieczan and Tarkowska-Kukuryk 2013). 'Trophic cascade theory' describes direct and indirect impacts of predation on productivity, biomass and composition of lower trophic levels in freshwater ecosystems (Carpenter et al 1985;Shurin et al 2002;Miyashita and Niwa 2006).…”

“…Thus they seem to play a significant role in controlling the number of protozoa. However, our knowledge of the food web in peatlands remains fragmentary (Gilbert et al 1998;Mieczan and Tarkowska-Kukuryk 2013). There is still no well-recognized effect of macroinvertebrates on the structure of lower trophic levels in peatland ecosystems.…”