Respiration rates in shallow lakes of different types: contribution of benthic microorganisms, macrophytes, plankton and macrozoobenthos

Abstract

The determination of the metabolic activity of organisms at various trophic levels is crucial for the proper assessment of the energy flow through the ecosystem, which is the basic process determining ecosystem functioning. We estimated the respiration rate in nine shallow, eutrophic lakes (macrophytedominated and phytoplankton-dominated) from northeastern Poland. Respiratory carbon loss (RCL) through bottom microbial communities, macrophytes, plankton and macrozoobenthos was estimated by measuring the Electron Transport System activity. The shares of the particular ecosystem components in respiration processes differed among the lake types and seasons. The bottom microbial communities contributed most to the RCL (from 50% in the macrophyte-dominated lakes to 90% in the shallower phytoplankton-dominated lakes) except in macrophytes-dominated lakes in summer, where the macrophyte contribution prevailed (80%). The contribution of plankton was considerable only in the deeper phytoplankton-dominated lakes (20%). Macrozoobenthos was important (20%) only in the macrophytedominated lakes in spring and autumn. The RCL through bottom microbial communities was substantially higher in the shallow lakes (especially phytoplankton-dominated) than in deep, stratified eutrophic lakes. Shallow eutrophic lakes can be highly productive due to intensive organic matter mineralization at the bottom and rapid flow and cycling of carbon and nutrients resulting from their polymictic character.

Macrophyte Controls on Urban Stream Microbial Metabolic Activity

“…There is evidence that microbial respiration in lake sediments near macrophytes is highly correlated with their biomass, independent of species type . Due to the duration of our experiments, we are unable to assess whether a longer-term change in microbial community in the sediment will affect the outcome of this experiment.…”

“…There is evidence that microbial respiration in lake sediments near macrophytes is highly correlated with their biomass, independent of species type. 56 Due to the duration of our experiments, we are unable to assess whether a longer-term change in microbial community in the sediment will affect the outcome of this experiment. In addition, in this study, we did not attempt to characterize the different microbial community structures and their specific responses, but the adopted tracer approach allowed us to quantify bulk microbial metabolic activity responses, notwithstanding on whether these were due to shifts between functional groups or increased or reduced activity of the same groups.…”

Submerged macrophytes affect the temporal variability of aquatic ecosystems

“…Dissolved organic carbon dynamics driven by competitive interactions between macrophytes and phytoplankton can also alter ecosystem metabolism (Findlay & Sinsabaugh, 2003; Kaenel et al, 2000; Mitchell, 1989; Reitsema et al., 2018). Growth and decay of macrophyte tissue can strongly affect metabolic rates of shallow lakes, depending on plant density, diversity, and lake depth (Żbikowski et al, 2019). In shallow lakes with a given nutrient load, ecosystem productivity is typically higher when macrophytes are dominant over phytoplankton (Brothers et al, 2013; Carpenter & Lodge, 1986; Wetzel, 1964).…”

Effects of Aquatic Plant Coverage on Diversity and Resource Use Efficiency of Phytoplankton in Urban Wetlands: A Case Study in Jinan, China

“…Emergent plants, such as Phragmites australis and Cyperus alternifolius, have an enhanced capacity to absorb water pollutants as they possess more supporting tissues to store nutrients over longer durations [10]. These plants are vital in controlling phytoplankton [11]. Aquatic plants affect phytoplankton dynamics by competing for nutrients and light [12,13].…”