0000000000276897
AUTHOR
Martin W. Hahn
Methane-oxidizing and photoautotrophic bacteria are major producers in a humic lake with large anoxic hypolimnion
Heterotrophic processes are considered to prevail in lakes with high terrestrial loading and a high content of dissolved organic carbon. However, previous studies have shown abundant methanotrophic bacteria (MOB) and photoautotrophic green sulphur bacteria (GSB) in some boreal lakes. We used genetic and lipid biomarkers to follow the seasonal succession of the abundance and carbon biomass of the major bacterial groups in Lake Mekkojarvi, a small Finnish polyhumic lake with a large anoxic hypolimnion. Biomarkers were based on length heterogeneity analysis of 16S rRNA gene amplification by polymerase chain reaction (PCR) (LH-PCR) and on phospholipid fatty acid (PLFA) analysis. Representative …
Inferring Phytoplankton, Terrestrial Plant and Bacteria Bulk δ¹³C Values from Compound Specific Analyses of Lipids and Fatty Acids.
Stable isotope mixing models in aquatic ecology require δ13C values for food web end members such as phytoplankton and bacteria, however it is rarely possible to measure these directly. Hence there is a critical need for improved methods for estimating the δ13C ratios of phytoplankton, bacteria and terrestrial detritus from within mixed seston. We determined the δ13C values of lipids, phospholipids and biomarker fatty acids and used these to calculate isotopic differences compared to the whole-cell δ13C values for eight phytoplankton classes, five bacterial taxa, and three types of terrestrial organic matter (two trees and one grass). The lipid content was higher amongst the phytoplankton (…
DifferingDaphnia magnaassimilation efficiencies for terrestrial, bacterial, and algal carbon and fatty acids
There is considerable interest in the pathways by which carbon and growth-limiting elemental and biochemical nutrients are supplied to upper trophic levels. Fatty acids and sterols are among the most important molecules transferred across the plant-animal interface of food webs. In lake ecosystems, in addition to phytoplankton, bacteria and terrestrial organic matter are potential trophic resources for zooplankton, especially in those receiving high terrestrial organic matter inputs. We therefore tested carbon, nitrogen, and fatty acid assimilation by the crustacean Daphnia magna when consuming these resources. We fed Daphnia with monospecific diets of high-quality (Cryptomonas marssonii) a…
Rhodoluna lacicola gen. nov., sp. nov., a planktonic freshwater bacterium with stream-lined genome
A pure culture of an actinobacterium previously described as 'Candidatus Rhodoluna lacicola' strain MWH-Ta8 was established and deposited in two public culture collections. Strain MWH-Ta8(T) represents a free-living planktonic freshwater bacterium obtained from hypertrophic Meiliang Bay, Lake Taihu, PR China. The strain was characterized by phylogenetic and taxonomic investigations, as well as by determination of its complete genome sequence. Strain MWH-Ta8(T) is noticeable due to its unusually low values of cell size (0.05 µm(3)), genome size (1.43 Mbp), and DNA G+C content (51.5 mol%). Phylogenetic analyses based on 16S rRNA gene and RpoB sequences suggested that strain MWH-Ta8(T) is affi…
Differing Daphnia magna assimilation efficiencies for terrestrial, bacterial, and algal carbon and fatty acids
There is considerable interest in the pathways by which carbon and growthlimiting elemental and biochemical nutrients are supplied to upper trophic levels. Fatty acids and sterols are among the most important molecules transferred across the plant–animal interface of food webs. In lake ecosystems, in addition to phytoplankton, bacteria and terrestrial organic matter are potential trophic resources for zooplankton, especially in those receiving high terrestrial organic matter inputs. We therefore tested carbon, nitrogen, and fatty acid assimilation by the crustacean Daphnia magna when consuming these resources. We fed Daphnia with monospecific diets of high-quality (Cryptomonas marssonii) an…
Appendix C. Results of Cox regression survival analysis of experiments.
Results of Cox regression survival analysis of experiments.
Appendix E. Principal component analysis of diets and Daphnia.
Principal component analysis of diets and Daphnia.
Appendix A. Detailed concentration information of added nutrients in batch and life table experiments.
Detailed concentration information of added nutrients in batch and life table experiments.
Appendix B. Fatty acid and sterol profiles of terrestrial particulate organic carbon (t-POC), bacteria, and phytoplankton diets.
Fatty acid and sterol profiles of terrestrial particulate organic carbon (t-POC), bacteria, and phytoplankton diets.
Appendix D. Correlations between different nutrients of diets and offspring and body size of Daphnia.
Correlations between different nutrients of diets and offspring and body size of Daphnia.
Appendix F. The parameter estimates of t-POC diets for power functions.
The parameter estimates of t-POC diets for power functions.