Micrograzer Impact and Substrate Limitation of Bacterioplankton in Lake Michigan

1990 ◽  
Vol 47 (9) ◽  
pp. 1836-1841 ◽  
Author(s):  
Gwenyth Laird Pernie ◽  
Donald Scavia ◽  
Michael L. Pace ◽  
Hunter J. Carrick
Keyword(s):  
Bacterial Growth ◽  
Growth Rates ◽  
Lake Michigan ◽  
Heterotrophic Bacteria ◽  
Organic Substrate ◽  
Trophic Levels ◽  
Heterotrophic Flagellates ◽  
Bacterial Cells ◽  
Substrate Limitation ◽  
Loss Rates

We estimated Lake Michigan epilimnetic heterotrophic bacterial loss rates, predator size, and substrate limitation in 1986 and 1987. The bacterial growth rates were always enhanced by organic substrate additions indicating that bacterial growth is limited, to some degree, by substrate availablility. In this study we obtained loss rates and intrinsic growth rates each between 0.32 and 1.45 d−1. The grazers were predominantly picoplankton-size organisms, presumably heterotrophic flagellates. Using radiolabeled bacteria, only a small percentage (2–3%) of bacterial cells were incorporated into larger size fractions after 24 h. These results indicate that during our experiments heterotrophic bacteria were not a direct, significant, carbon source for the upper trophic levels.

Using Stable Isotope Probing and Raman Microspectroscopy to measure growth rates of heterotrophic bacteria

2021 ◽  
Author(s):  
Felix Weber ◽  
Tatiana Zaliznyak ◽  
Virginia P. Edgcomb ◽  
Gordon T. Taylor
Keyword(s):  
Stable Isotope ◽  
Single Cell ◽  
Bacterial Growth ◽  
Growth Rates ◽  
Heterotrophic Bacteria ◽  
Raman Microspectroscopy ◽  
Stable Isotope Probing ◽  
Single Cell Level ◽  
Cell Level ◽  
E Coli

The suitability of stable isotope probing (SIP) and Raman microspectroscopy to measure growth rates of heterotrophic bacteria at the single-cell level was evaluated. Label assimilation into E. coli biomass during growth on a complex 13 C-labeled carbon source was monitored in time course experiments. 13 C-incorporation into various biomolecules was measured by spectral “red shifts” of Raman-scattered emissions. The 13 C- and 12 C-isotopologues of the amino acid phenylalanine (Phe) proved to be a quantitatively accurate reporter molecules of cellular isotopic fractional abundances ( f cell ). Values of f cell determined by Raman microspectroscopy and independently by isotope-ratio mass spectrometry (IRMS) over a range of isotopic enrichments were statistically indistinguishable. Progressive labeling of Phe in E. coli cells among a range of 13 C/ 12 C organic substrate admixtures occurred predictably through time. Relative isotopologue abundances of Phe determined by Raman spectral analysis enabled accurate calculation of bacterial growth rates as confirmed independently by optical density (OD) measurements. Results demonstrate that combining stable isotope probing (SIP) and Raman microspectroscopy can be a powerful tool for studying bacterial growth at the single-cell level when grown on defined or complex organic 13 C-carbon sources even in mixed microbial assemblages. Importance: Population growth dynamics and individual cell growth rates are the ultimate expressions of a microorganism’s fitness to its environmental conditions, whether natural or engineered. Natural habitats and many industrial settings harbor complex microbial assemblages. Their heterogeneity in growth responses to existing and changing conditions is often difficult to grasp by standard methodologies. In this proof of concept study, we tested whether Raman microspectroscopy can reliably quantify assimilation of isotopically-labeled nutrients into E. coli cells and enable determination of individual growth rates among heterotrophic bacteria. Raman-derived growth rate estimates were statistically indistinguishable from those derived by standard optical density measurements of the same cultures. Raman microspectroscopy also can be combined with methods for phylogenetic identification. We report development of Raman-based techniques that enable researchers to directly link genetic identity to functional traits and rate measurements of single cells within mixed microbial assemblages, currently a major technical challenge in microbiological research.

The importance of microzooplankton versus phytoplankton to copepod populations during late winter and early spring in Lake Michigan

2005 ◽  
Vol 62 (10) ◽  
pp. 2371-2385 ◽  
Author(s):  
Marie H Bundy ◽  
Henry A Vanderploeg ◽  
Peter J Lavrentyev ◽  
Paul A Kovalcik
Keyword(s):  
Chlorophyll A ◽  
Lake Michigan ◽  
Calanoid Copepod ◽  
Early Spring ◽  
Trophic Levels ◽  
Total Carbon ◽  
Late Winter ◽  
Heterotrophic Flagellates ◽  
Ingestion Rates ◽  
Size Fractions

Feeding rates of the calanoid copepod Leptodiaptomus sicilis on natural assemblages of phytoplankton and microzooplankton were evaluated during late winter and early spring in Lake Michigan. Microzooplankton were the preferred food source for this copepod, and larger size fractions of phytoplankton were preferred to smaller size fractions. Ingestion rates of total chlorophyll a ranged from 2 to 14 ng·copepod–1·day–1, while ingestion rates of micro zoo plank ton biomass ranged from 0.04 to 0.15 µg C·copepod–1·day–1. In these experiments, microzooplankton carbon accounted for 22%–74% of the total carbon ingested. Clearance rates of microzooplankton carbon were positively related to the larger size fractions of chlorophyll a and to total suspended solids. Measured ingestion rates of microzooplankton and phyto plankton carbon suggest that calanoid copepod populations have the potential to control microzooplankton production in late winter and early spring, and even with an abundance of phytoplankton carbon, food availability may limit the reproduction of L. sicilis. Because microzooplankton contribute significantly to the diet of these copepods, stimulation of the microbial food web by terrigenous inputs of nutrients and carbon may be transmitted to higher trophic levels (i.e., mesozooplankton and their predators) through heterotrophic flagellates and protozoans.

Bacterial presence in polar regions associated with environment modification by chemical compounds including contaminants

2017 ◽  
Vol 25 (4) ◽  
pp. 481-491 ◽  
Author(s):  
Klaudia Kosek ◽  
Katarzyna Jankowska ◽  
Żaneta Polkowska
Keyword(s):  
Bacterial Communities ◽  
Chemical Compounds ◽  
Freshwater Ecosystems ◽  
Trophic Levels ◽  
Polar Regions ◽  
Bacterial Cells ◽  
Chemical Contamination ◽  
Climate Conditions ◽  
Biological Communities ◽  
Long Time

Microbes are omnipresent and diverse members of all biological communities. In marine and freshwater ecosystems, microorganisms form the base of the food chain supporting higher trophic levels. Even though microbes are generally thought to live in warm regions of Earth, many of them develop in cold climates. Polar regions remain relatively protected from widespread anthropogenic disturbances, which is a consequence of thier remoteness and extreme climate conditions. For a long time these regions were considered to be free from chemical contamination until scientists discovered a presence of pollutants there. Chemical contamination may induce serious disorders in the integrity of polar ecosystems influencing the growth of bacterial communities. Xenobiotics including persistent organic pollutants are transported thousands of kilometers by the air and ocean currents, and they are deposed in high-latitude regions and accumulate in all elements of the environment including bacterial communities. It is important to determine their concentration levels in bacterial cells to assess the possibility of contaminants becoming transferred to higher trophic levels; however, some species of bacteria are capable of metabolizing xenobiotics, which makes them less toxic or even removes them from the environment.

Density, growth, and change in density of coho salmon and rainbow trout in three Lake Michigan tributaries

1983 ◽  
Vol 61 (5) ◽  
pp. 1120-1127 ◽  
Author(s):  
L. M. Carl
Keyword(s):  
Rainbow Trout ◽  
Growth Rates ◽  
Lake Michigan ◽  
Coho Salmon ◽  
Daily Growth ◽  
Salmon Fry ◽  
Daily Change ◽  
Early Fall ◽  
Growth And Change ◽  
Downstream Movement

Coho salmon spawning peaked in the late fall. Spawning densities ranged from fewer than 5 coho salmon per hectare up to 90 fish per hectare. Subyearling coho salmon densities ranged from 10 to 60 fish per 100 m2 in June and dropped to 5–20 fish by early fall. Coho salmon fry increased in length from 40 mm in early May, to over 120 mm by smolt out-migration in the following April. Coho salmon instantaneous daily change in density coefficients ranged from 0.004 to 0.019 and were dependent on initial coho density. Daily coho salmon growth rates ranged from 0.38 to 0.60 mm per day and were not dependent on initial coho salmon density. Downstream movement of rainbow trout fry began in May, and continued into July. In the spring 10–20 yearlings and one to five 2-year-olds per 100 m2 were present. Most fry emerged in June at a size of 25 mm and grew to 85 mm by fall. Daily growth rates varied from 0.23 to 0.45 mm per day for yearling rainbow trout and were not correlated with rainbow trout density.

Evaluation of genomic sequence-based growth rate methods for synchronized Synechococcus cultures

2021 ◽  
Author(s):  
Julia Carroll ◽  
Nicolas Van Oostende ◽  
Bess B. Ward
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Dna Replication ◽  
Growth Rates ◽  
Genomic Sequence ◽  
Niche Differentiation ◽  
Trophic Levels ◽  
Individual Species ◽  
Cell Counts

Standard methods for calculating microbial growth rates (μ) through the use of proxies, such as in situ fluorescence, cell cycle, or cell counts, are critical for determining the magnitude of the role bacteria play in marine carbon (C) and nitrogen (N) cycles. Taxon-specific growth rates in mixed assemblages would be useful for attributing biogeochemical processes to individual species and understanding niche differentiation among related clades, such as found in Synechococcus and Prochlorococcus . We tested three novel DNA sequencing-based methods (iRep, bPTR, and GRiD) for evaluating growth of light synchronized Synechococcus cultures under different light intensities and temperatures. In vivo fluorescence and cell cycle analysis were used to obtain standard estimates of growth rate for comparison with the sequence-based methods (SBM). None of the SBM values were correlated with growth rates calculated by standard techniques despite the fact that all three SBM were correlated with percentage of cells in S phase (DNA replication) over the diel cycle. Inaccuracy in determining the time of maximum DNA replication is unlikely to account entirely for the absence of relationship between SBM and growth rate, but the fact that most microbes in the surface ocean exhibit some degree of diel cyclicity is a caution for application of these methods. SBM correlate with DNA replication but cannot be interpreted quantitatively in terms of growth rate. Importance Small but abundant, cyanobacterial strains such as the photosynthetic Synechococcus spp. are essential because they contribute significantly to primary productivity in the ocean. These bacteria generate oxygen and provide biologically-available carbon, which is essential for organisms at higher trophic levels. The small size and diversity of natural microbial assemblages means that taxon-specific activities (e.g., growth rate) are difficult to obtain in the field. It has been suggested that sequence-based methods (SBM) may be able to solve this problem. We find, however, that SBM can detect DNA replication and are correlated with phases of the cell cycle but cannot be interpreted in terms of absolute growth rate for Synechococcus cultures growing under a day-night cycle, like that experienced in the ocean.

scholarly journals Response of heterotrophic and autotrophic microbial plankton to inorganic and organic inputs along a latitudinal transect in the Atlantic Ocean

2010 ◽  
Vol 7 (5) ◽  
pp. 1701-1713 ◽  
Author(s):  
S. Martínez-García ◽  
E. Fernández ◽  
A. Calvo-Díaz ◽  
E. Marañón ◽  
X. A. G. Morán ◽  
...  
Keyword(s):  
Organic Matter ◽  
Atlantic Ocean ◽  
Bacterial Growth ◽  
Heterotrophic Bacteria ◽  
Growth Efficiency ◽  
Bacterial Growth Efficiency ◽  
Organic Nutrient ◽  
Plankton Biomass ◽  
Latitudinal Transect ◽  
Microbial Plankton

Abstract. The effects of inorganic and/or organic nutrient inputs on phytoplankton and heterotrophic bacteria have never been concurrently assessed in open ocean oligotrophic communities over a wide spatial gradient. We studied the effects of potentially limiting inorganic (nitrate, ammonium, phosphate, silica) and organic nutrient (glucose, aminoacids) inputs added separately as well as jointly, on microbial plankton biomass, community structure and metabolism in five microcosm experiments conducted along a latitudinal transect in the Atlantic Ocean (from 26° N to 29° S). Primary production rates increased up to 1.8-fold. Bacterial respiration and microbial community respiration increased up to 14.3 and 12.7-fold respectively. Bacterial production and bacterial growth efficiency increased up to 58.8-fold and 2.5-fold respectively. The largest increases were measured after mixed inorganic-organic nutrients additions. Changes in microbial plankton biomass were small as compared with those in metabolic rates. A north to south increase in the response of heterotrophic bacteria was observed, which could be related to a latitudinal gradient in phosphorus availability. Our results suggest that organic matter inputs will result in a predominantly heterotrophic versus autotrophic response and in increases in bacterial growth efficiency, particularly in the southern hemisphere. Subtle differences in the initial environmental and biological conditions are likely to result in differential microbial responses to inorganic and organic matter inputs.

scholarly journals Evolutionary diversification of tiny ocean predators

2020 ◽  
Author(s):  
Francisco Latorre ◽  
Ina M. Deutschmann ◽  
Aurelie Labarre ◽  
Aleix Obiol ◽  
Anders Krabberød ◽  
...  
Keyword(s):  
Single Cells ◽  
Prey Type ◽  
Distribution Patterns ◽  
Trophic Levels ◽  
Glycoside Hydrolases ◽  
Global Ocean ◽  
Heterotrophic Flagellates ◽  
Evolutionary Diversification ◽  
Niche Adaptation ◽  
Different Temperatures

ABSTRACTUnicellular eukaryotic predators have a crucial role in the functioning of the ocean ecosystem by recycling nutrients and energy that are channeled to upper trophic levels. Traditionally, these evolutionary-diverse organisms have been combined into a single functional group (Heterotrophic flagellates), overlooking their organismal differences. Here we investigate four evolutionary related species belonging to one cosmopolitan family of uncultured marine picoeukaryotic predators: MAST-4 (species A, B, C, and E). Co-occurrence and distribution analyses in the global surface ocean indicated contrasting patterns in MAST-4A & C, suggesting adaptation to different temperatures. We then investigated whether these spatial distribution patterns were mirrored by MAST-4 genomic content using Single-Cell Genomics. Analyses of 69 single-cells recovered 66-83% of the MAST-4A/B/C/E genomes, which displayed substantial inter-species divergence. MAST-4 genomes were similar in terms of broad gene functional categories, but they differed in enzymes of ecological relevance, such as glycoside hydrolases (GHs), which are part of the food degradation machinery in MAST-4. Interestingly, MAST-4 species featuring a similar GH composition co-excluded each other (A & C) in the surface global ocean, while species with a different set of GHs appeared to be able to co-exist (species B & C) suggesting further niche diversification associated to prey digestion. We propose that differential niche adaptation to temperature and prey type has promoted adaptive evolutionary diversification in MAST-4. Altogether, we show that minute ocean predators from the same family may have different biogeography and genomic content, which need to be accounted to better comprehend marine food webs.

scholarly journals Seasonal Acclimation Modulates the Impacts of Simulated Warming and Light Reduction on Temperate Seagrass Productivity and Biochemical Composition

2021 ◽  
Vol 8 ◽  
Author(s):  
Pedro Beca-Carretero ◽  
Tomás Azcárate-García ◽  
Marc Julia-Miralles ◽  
Clara S. Stanschewski ◽  
Freddy Guihéneuf ◽  
...  
Keyword(s):  
Growth Rates ◽  
Zostera Marina ◽  
Leaf Growth ◽  
Seawater Temperature ◽  
Trophic Levels ◽  
Experimental Warming ◽  
Omega 3 ◽  
Growth Physiology ◽  
Light Reduction ◽  
Climate Change Effects

Increases in seawater temperature and reduction in light quality have emerged as some of the most important threats to marine coastal communities including seagrass ecosystems. Temperate seagrasses, including Zostera marina, typically have pronounced seasonal cycles which modulate seagrass growth, physiology and reproductive effort. These marked temporal patterns can affect experimental seagrass responses to climate change effects depending on the seasons of the year in which the experiments are conducted. This study aimed at evaluating how seasonal acclimatization modulates productivity and biochemical responses of Zostera marina to experimental warming and irradiance reduction. Seagrass shoots were exposed to different temperatures (6, 12, 16, 20, and 24°C), combined with high (180 μmol photons m–2 s–1) and low (60 μmol photons m–2 s–1) light conditions across four seasons (spring: April, summer: July, and autumn: November 2015, and winter: January 2016). Plants exhibited similar temperature growth rates between 16 and 20°C; at 24°C, a drastic reduction in growth was observed; this was more accentuated in colder months and under low irradiance conditions. Higher leaf growth rates occurred in winter while the largest rhizomes were reached in experiments conducted in spring and summer. Increases in temperature induced a significant reduction in polyunsaturated fatty acids (PUFA), particularly omega-3 (n-3 PUFA). Our results highlight that temperate seagrass populations currently living under temperature limitation will be favored by future increases in sea surface temperature in terms of leaf and rhizome productivity. Together with results from this study on Z. marina from a temperate region, a wider review of the reported impacts of experimental warming indicates the likely reduction in some compounds of nutritional importance for higher trophic levels in seagrass leaves. Our results further demonstrate that data derived from laboratory-based studies investigating environmental stress on seagrass growth and acclimation, and their subsequent interpretation, are strongly influenced by seasonality and in situ conditions that precede any experimental exposure.

Organic nitrogen mineralization and substrate limitation of bacteria in Lake Michigan

1989 ◽  
Vol 34 (2) ◽  
pp. 478-485 ◽  
Author(s):  
Wayne S. Gardner ◽  
Joann F. Chandler ◽  
Gwenyth A. Laird
Keyword(s):  
Nitrogen Mineralization ◽  
Organic Nitrogen ◽  
Lake Michigan ◽  
Substrate Limitation
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