Intraseasonal influences on the ecology of testate amoebae and δ18O signal from an ombrotrophic peatland in southern Québec, Canada
Intraseasonal influences on the ecology of testate amoebae and δ18O signal from an ombrotrophic peatland in southern Québec, Canada
Abstract ID#: 36240
English Abstract:
Ombrotrophic peatlands (bogs) are Sphagnum-dominated ecosystems where accumulation of organic matter exceeds decomposition. Atmospheric precipitations primarily feed these ecosystems.
The isotopic signature of oxygen-18 (δ18O) and testate amoebae assemblages (Protozoa: Rhizopoda) are often used as indicators of palaeohydrological and paleoecological changes in peat sediments (e.g. Booth & al., 2010; Daley & al., 2010). Testate amoebae are sensitive to environmental changes (moisture, pH, water table level, chemicals) at the peatland surface (Mitchell, 2008). The δ18O signature in Sphagnum varies according to precipitation, evaporation, temperature and photosynthesis (Tillman & al., 2010). The modern seasonal variation of these indicators has not been the subject of many studies and could allow better interpretation of past changes. This study aims to assess whether meteorological (temperature, precipitation, evaporation, insolation, wind), hydrological (moisture, water table level) and physico-chemical (pH, conductivity) variables influence testate amoebae communities and δ18O signature in a peat bog during the growing season. Secondary objectives are to identify the water sources of capillary water through the Sphagnum cellulose using their δ18O signatures. This research is realized in an effort to assess the relationship between testate amoebae assemblages, isotopic signatures and growing season environmental variability over two years of monitoring (monthly from May to October 2014-15) Sphagnum moss samples are collected from the center of a raised bog in southern Québec, Canada. We hypothesize that hydroclimatic changes occurring during the growing season may cause a shift in the δ18O Sphagnum cellulose signature because the δ18O signal varies with temperature precipitation formations that constitute the source of water used by Sphagnum during the formation of the cellulose. We also hypothesize that hydrological and physico-chemical changes occurring during the growing season will cause variations in the testate amoebae assemblages, because these microorganisms are sensitive to changes in humidity and pH. Results will increase the precision of modern analogues transfer functions hence allowing a better interpretation of paleohydrological changes through time.
The isotopic signature of oxygen-18 (δ18O) and testate amoebae assemblages (Protozoa: Rhizopoda) are often used as indicators of palaeohydrological and paleoecological changes in peat sediments (e.g. Booth & al., 2010; Daley & al., 2010). Testate amoebae are sensitive to environmental changes (moisture, pH, water table level, chemicals) at the peatland surface (Mitchell, 2008). The δ18O signature in Sphagnum varies according to precipitation, evaporation, temperature and photosynthesis (Tillman & al., 2010). The modern seasonal variation of these indicators has not been the subject of many studies and could allow better interpretation of past changes. This study aims to assess whether meteorological (temperature, precipitation, evaporation, insolation, wind), hydrological (moisture, water table level) and physico-chemical (pH, conductivity) variables influence testate amoebae communities and δ18O signature in a peat bog during the growing season. Secondary objectives are to identify the water sources of capillary water through the Sphagnum cellulose using their δ18O signatures. This research is realized in an effort to assess the relationship between testate amoebae assemblages, isotopic signatures and growing season environmental variability over two years of monitoring (monthly from May to October 2014-15) Sphagnum moss samples are collected from the center of a raised bog in southern Québec, Canada. We hypothesize that hydroclimatic changes occurring during the growing season may cause a shift in the δ18O Sphagnum cellulose signature because the δ18O signal varies with temperature precipitation formations that constitute the source of water used by Sphagnum during the formation of the cellulose. We also hypothesize that hydrological and physico-chemical changes occurring during the growing season will cause variations in the testate amoebae assemblages, because these microorganisms are sensitive to changes in humidity and pH. Results will increase the precision of modern analogues transfer functions hence allowing a better interpretation of paleohydrological changes through time.