Emil Fridolfsson

• PhD
• Researcher at Linnaeus University

Micronutrients such as vitamins are transferred from lower to higher trophic levels, but no general ecological concept describes the factors regulating this process. Here, we investigated thiamin (thiamine, vitamin B1), which is an example of a metabolically important water-soluble micronutrient. Thiamin is produced by organisms such as bacteria an...

Thiamin is an essential water‐soluble B vitamin known for its wide range of metabolic functions and antioxidant properties. Over the past decades, reproductive failures induced by thiamin deficiency have been observed in several salmonid species worldwide, but it is unclear why this micronutrient deficiency arises. Few studies have compared thiamin...

The planktonic realm from bacteria to zooplankton provides the baseline for pelagic aquatic food webs. However, multiple trophic levels are seldomly included in time series studies, hampering a holistic understanding of the influence of seasonal dynamics and species interactions on food web structure and biogeochemical cycles. Here, we investigated...

Vitamin B1 (thiamin) is primarily produced by bacteria, phytoplankton and fungi in aquatic food webs and transferred to higher trophic levels by ingestion. However, much remains unknown regarding the dynamics this water-soluble, essential micronutrient; e.g. how it relates to macronutrients (carbon, nitrogen and phosphorous). Nutrient limitation ha...

Although free-living (FL) and particle-attached (PA) bacteria are recognized as ecologically distinct compartments of marine microbial food-webs, few, if any, studies have determined their dynamics in abundance, function (production, respiration and substrate utilization) and taxonomy over a yearly cycle. In the Baltic Sea, abundance and production...

Havsmiljöinstitutets Rapport nr 2020:07

Thiamin (vitamin B 1) is primarily produced by bacteria and phytoplankton in aquatic food webs and transferred by ingestion to higher trophic levels. However, much remains unknown regarding production, content and transfer of this water-soluble, essential micronutrient. Hence, the thiamin content of six phytoplankton species from different taxa was...

Vitamin B1 (thiamin) deficiency is an issue periodically affecting a wide range of taxa worldwide. In aquatic pelagic systems, thiamin is mainly produced by bacteria and phytoplankton and is transferred to fish and birds via zooplankton, but there is no general consensus on when or why this transfer is disrupted. We focus on the occurrence in salmo...

Thiamin (vitamin B1) is required for several life-sustaining processes in most organisms and cells, e.g. in the conversion of food to energy. It also serves as an antioxidant and is important for proper nerve signaling. Thiamin is produced predominantly by bacteria and phytoplankton in the aquatic food web. Not all bacteria and phytoplankton, nor a...

Vitamin B1 is an essential exogenous micronutrient for animals. Mass death and reproductive failure in top aquatic consumers caused by vitamin B1 deficiency is an emerging conservation issue in Northern hemisphere aquatic ecosystems. We present for the first time a model that identifies conditions responsible for the constrained flow of vitamin B1...

Thiamin (vitamin B1) is mainly produced by bacteria and phytoplankton and then transferred to zooplankton and higher trophic levels but knowledge on the dynamics of these processes in aquatic ecosystems is lacking. Hence, the seasonal variation in thiamin content was assessed in field samples of copepods and in pico-, nano- and micro-plankton of tw...

Marine bacterioplankton are essential in global nutrient cycling and organic matter turnover. Time-series analyses, often at monthly sampling frequencies, have established the paramount role of abiotic and biotic variables in structuring bacterioplankton communities and productivities. However, fine-scale seasonal microbial activities, and underlyi...

Nutrient limitation assays during 2012–2014. Displayed are the bacterial heterotrophic production estimates (pmol Leu l-1 h-1) of single or combined nutrient addition assays after 24 h incubation (biological replicates 1 or 2, respectively): N treatments (ammonium), P treatments (phosphate), and C treatments (glucose). Error bars indicate standard...

Linegraph of (A) phosphate and (B) APase activity over time.

Graph of bacterial productivities and abundances plotted against phosphate concentrations during 2011–2014. (A) APase, (B) bacterial production, and (C) cell abundances. The color gradients denote temperatures at time of sampling.

Spearman’s rank correlation test results of abiotic and biotic variables against each other 2011–2014, excluding the variable DOC. Spearman’s rho is indicated as “Cor,” p-values are indicated as “p.” Colors denote significance thresholds: red p-values denote significant values after Bonferroni correction ∗p > 0.05, red Cor denote Spearman’s rho val...

Spearman’s rank correlation test results of abiotic and biotic variables against each other including DOC values but excluding 2011 data. Spearman’s rho is indicated as “Cor,” p-values are indicated as “p.” Colors denote significance thresholds: red p-values denote significant values after Bonferroni correction ∗p > 0.05, red Cor denote Spearman’s...

Subsampled data during 2011–2014. All data points that were sampled during the first week of the month (days 1–7) are labeled in red, underlying black points indicate all measured data for temperature (°C), bacterial heterotrophic production (μg C l-1 h-1), Chl a (μg l-1), and phytoplankton biomass (mgC m-3).

Chl a concentrations during summer time at LMO. Samples derive from 2m water depth and during the time between June and September.

Boxplots of enzyme activities and substrate uptake rate constants, grouped by season, year, or enzyme/substrate. Enzyme activities normalized to bacterial abundances (amol cell-1 h-1) grouped by (A) enzyme, (C) season, and (E) year. APase denotes alkaline phosphatase, BGase denotes β-glucosidase, and LApase denotes leucine aminopeptidase. Substrate...

Spearman’s rank correlation test results of substrate uptake rate constants and biologically relevant variables excluding DOC. Spearman’s rho is indicated as “Cor,” p-values are indicated as “p.” Colors denote significance thresholds: red p-values denote significant values after Bonferroni correction ∗p > 0.05, red Cor denote Spearman’s rho values...

Spearman’s rank correlation test results of substrate uptake rate constants and biologically relevant variables including DOC. Spearman’s rho is indicated as “Cor”, p-values are indicated as “p”. Colors denote significance thresholds: red p-values denote significant values after Bonferroni correction ∗p > 0.05, red Cor denote Spearman’s rho values...

Top predators in several aquatic food webs regularly display elevated reproductive failure, caused by thiamin (vitamin B1) deficiency. The reasons for these low‐thiamin levels are not understood and information about the transfer of thiamin from the producers (bacteria and phytoplankton) to higher trophic levels is limited. One main concern is whet...

The microbial part of the pelagic food web is seldom characterized in models despite its major contribution to biogeochemical cycles. In the Baltic Sea, spatial and temporal high frequency sampling over three years revealed changes in heterotrophic bacteria and phytoplankton coupling (biomass and production) related to hydrographic properties of th...