Effect of a temperature gradient on Sphagnum fallax and its associated living microbial communities: a study under controlled conditions

Abstract

Microbial communities living in Sphagnum are known to constitute early indicators of ecosystem disturbances, but little is known about their response (including their trophic relationships) to climate change. A microcosm experiment was designed to test the effects of a temperature gradient (15, 20, and 25°C) on microbial communities including different trophic groups (primary producers, decomposers, and unicellular predators) in Sphagnum segments (0-3 cm and 3-6 cm of the capitulum). Relationships between microbial communities and abiotic factors (pH, conductivity, temperature, and polyphenols) were also studied. The density and the biomass of testate amoebae in Sphagnum upper segments increased and their community structure changed in heated treatments. The biomass of testate amoebae was linked to the biomass of bacteria and to the total biomass of other groups added and, thus, suggests that indirect effects on the food web structure occurred. Redundancy analysis revealed that microbial assemblages differed strongly in Sphagnum upper segments along a temperature gradient in relation to abiotic factors. The sensitivity of these assemblages made them interesting indicators of climate change. Phenolic compounds represented an important explicative factor in microbial assemblages and outlined the potential direct and (or) indirect effects of phenolics on microbial communities.

Eight species in the Nebela collaris complex: Nebela gimlii (Arcellinida, Hyalospheniidae), a new species described from a Swiss raised bog

“…Indeed, we found it only in the forested part of the bog and the drained peatland margins where the water table was low, while it was apparently absent in the wetter parts. The presence of this small species in these comparatively dry habitats is consistent with the observation that smaller sized testate amoebae are favoured in drier environments (Jassey et al, 2011). However more work is clearly required to clarify the ecological optima of individual species within the N. collaris complex.…”

Sphagnum mosses harbour highly specific bacterial diversity during their whole lifecycle

“…This factor was often reported as the main driver, for example, in a global study of microbial communities in soil (Lauber et al, 2009). In microcosm experiments under controlled conditions, Jassey et al (2011) identified similar abiotic drivers of the S. fallax-associated microbial community, such as pH, conductivity and temperature. Especially, due to the latter, they suggest microbial communities living with Sphagnum as early indicators for ecosystem disturbance, especially climate change.…”

“…The bryophyte genus Sphagnum, consisting of approximately 300 different species, is distributed world wide and forms the dominant component of bog vegetation (Daniels and Eddy, 1985). Therefore, Sphagnum moss has been used globally as an indicator of climate change (Whinam and Copson, 2006;Granath et al, 2009), and microbial communities living in Sphagnum were shown early indicators of ecosystem disturbances in a microcosm experiment (Jassey et al, 2011). Hence, knowledge concerning microbial ecology is important to protect, maintain and manage Sphagnum bog ecosystems.…”

Estudos Da Biodiversidade De Amebas Testáceas Para Estratégias Voltadas À Preservação: Uma Revisão

“…Um recente estudo realizado por Mieczan et al (2015) mostrou que determinadas espécies de amebas testáceas apresentam um aumento na abundância de organismos em maiores concentrações de nutrientes, atuando como espécies indicadoras de ambientes produtivos. Ainda nesse contexto, as amebas testáceas são consideradas importantes bioindicadoras do gradiente de temperatura e das mudanças hidrológicas em ambientes de turfeiras ( JASSEY et al, 2011;SONG et al, 2014). Além disso, estudos indicam a importância ecológica desses organismos no ciclo biogeoquímico da sílica, e potencialmente, do nitrogênio (AOKI et al, 2007).…”

“…Dentre essas vantagens, destacam-se sua elevada tolerância a alterações das condições ambientais e seu ciclo de vida curto, que permitem investigações sobre processos demográficos tanto em escala espacial quanto temporal (PENNAK, 1953;HARDOIM, 1997;DABÉS;VELHO, 2001). Além disso, esses organismos são considerados como bioindicadores da qualidade da água ( JASSEY et al, 2011;SONG et al, 2014) e podem ser usados, também, em estudos de paleontologia devido à preservação de suas carapaças por um longo tempo nos ambientes (CHARMAN, 2001).…”