Seasonal Variability of Magnetotactic Bacteria in a Freshwater Pond

Abstract

Magnetotactic bacteria (MTB) synthesize ferrimagnetic crystals that contribute to the remanent magnetization in sediments, yet knowledge of how MTB populations vary in natural environments over time remains limited. We report abundances of three MTB morphotypes from nine sites collected and measured every month over a two‐year period from a natural pond near Munich, Germany. Morphotype populations underwent coherent temporal trends among the nine sites—especially at proximal sites with similar water depths. MTB populations varied independently of bottom water oxygen concentrations or temperature over the two‐year period, except for spirilla, which flourished during the summer at some sites. Magnetic properties of the sediments did not reflect living MTB abundances, but instead varied with water depth. Deeper sites, which were also lower in organic carbon, nitrogen, and oxygen concentrations than shallower sites, had higher saturation magnetizations and were richer in single‐domain particles.

Magnetofossil Abundance and Diversity as Paleoenvironmental Proxies: A Case Study From Southwest Iberian Margin Sediments

“…According to their results, M rs /M s also reflects the relative abundance of magnetofossils to some extent. Similarly, He et al (2018) found that the M rs /M s increased with water depth due to an increase in magnetofossil concentration.…”

Linking Uncultivated Microbial Populations and Benthic Carbon Turnover by Using Quantitative Stable Isotope Probing

“…Substrates were added immediately after sample collection. The sediments exhibited dynamic seasonal changes in total inorganic carbon (TOC) levels, with higher values in the summer (average, 10.09% ± 0.36%) than in the winter (average, 8.5% ± 0.22%) ( 47 ). The carbon-to-nitrogen ratio (C/N) is nearly constant in space and time (January 2015, 13.2% ± 0.8%; August 2016, 13.8% ± 1.3%; 1σ uncertainties) ( 47 ).…”

“…The sediments exhibited dynamic seasonal changes in total inorganic carbon (TOC) levels, with higher values in the summer (average, 10.09% ± 0.36%) than in the winter (average, 8.5% ± 0.22%) ( 47 ). The carbon-to-nitrogen ratio (C/N) is nearly constant in space and time (January 2015, 13.2% ± 0.8%; August 2016, 13.8% ± 1.3%; 1σ uncertainties) ( 47 ). The bottom water temperatures ranged from 13.6 to 18.5°C, 4.6 to 8.3°C, and 1.4 to 3.3°C in August, October, and December, respectively ( 47 ).…”

“…The carbon-to-nitrogen ratio (C/N) is nearly constant in space and time (January 2015, 13.2% ± 0.8%; August 2016, 13.8% ± 1.3%; 1σ uncertainties) ( 47 ). The bottom water temperatures ranged from 13.6 to 18.5°C, 4.6 to 8.3°C, and 1.4 to 3.3°C in August, October, and December, respectively ( 47 ).…”

A Multi‐Proxy Approach to Unravel Late Pleistocene Sediment Flux and Bottom Water Conditions in the Western South Atlantic Ocean

“…Their abundance has been linked to paleo‐environmental and sedimentary conditions (Hesse, 1994; Kopp & Kirschvink, 2008; Maher & Hounslow, 1999; Roberts, Florindo, et al., 2011). Although it has been demonstrated that the number of living MTB undergoes seasonal changes (Du et al., 2015; He et al., 2018) and that magnetofossil abundance in deep‐sea sediments can be modulated by organic carbon and dissolved iron availability (Roberts, Florindo, et al., 2011) or by primary productivity (Savian et al., 2014), our understanding of the conditions responsible for MTB magnetic mineral formation is still limited.…”