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.

scholarly journals The effect of parameter variability in the allometric projection of leaf growth rates for eelgrass (Zostera marina L.)

2014 ◽  
Vol 42 (5) ◽  
pp. 1099-1108 ◽  
Author(s):  
Elena Solana Arellano ◽  
Hector Echavarria Heras ◽  
Cecilia Leal Ramirez ◽  
Kun Seop Lee
Keyword(s):  
Growth Rates ◽  
Zostera Marina ◽  
Leaf Growth

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 Physiological and Transcriptional Responses of Different Industrial Microbes at Near-Zero Specific Growth Rates

2015 ◽  
Vol 81 (17) ◽  
pp. 5662-5670 ◽  
Author(s):  
Onur Ercan ◽  
Markus M. M. Bisschops ◽  
Wout Overkamp ◽  
Thomas R. Jørgensen ◽  
Arthur F. Ram ◽  
...  
Keyword(s):  
Gene Expression ◽  
Growth Rates ◽  
Microbial Growth ◽  
Current Knowledge ◽  
Product Formation ◽  
Natural Ecosystems ◽  
Transcriptional Responses ◽  
Content Type ◽  
Growth Physiology ◽  
Zero Growth

ABSTRACTThe current knowledge of the physiology and gene expression of industrially relevant microorganisms is largely based on laboratory studies under conditions of rapid growth and high metabolic activity. However, in natural ecosystems and industrial processes, microbes frequently encounter severe calorie restriction. As a consequence, microbial growth rates in such settings can be extremely slow and even approach zero. Furthermore, uncoupling microbial growth from product formation, while cellular integrity and activity are maintained, offers perspectives that are economically highly interesting. Retentostat cultures have been employed to investigate microbial physiology at (near-)zero growth rates. This minireview compares information from recent physiological and gene expression studies on retentostat cultures of the industrially relevant microorganismsLactobacillus plantarum,Lactococcus lactis,Bacillus subtilis,Saccharomyces cerevisiae, andAspergillus niger. Shared responses of these organisms to (near-)zero growth rates include increased stress tolerance and a downregulation of genes involved in protein synthesis. Other adaptations, such as changes in morphology and (secondary) metabolite production, were species specific. This comparison underlines the industrial and scientific significance of further research on microbial (near-)zero growth physiology.

Reproductive dynamics of a turtle (Pseudemys scripta) population in a reservoir receiving heated effluent from a nuclear reactor

1970 ◽  
Vol 48 (4) ◽  
pp. 881-885 ◽  
Author(s):  
J. Whitfield Gibbons
Keyword(s):  
South Carolina ◽  
Growth Rates ◽  
Nuclear Reactor ◽  
Large Body ◽  
Reproductive Rate ◽  
Hot Water ◽  
Trophic Levels ◽  
Body Sizes ◽  
Pseudemys Scripta ◽  
Growth Differences

Individual yellow-bellied turtles (Pseudemys scripta) in Par Pond, a thermally polluted reservoir on the Savannah River Plant, Aiken, South Carolina, U.S.A., reach exceedingly large body sizes and maintain extraordinary juvenile growth rates when compared with turtles of this species from other populations in the vicinity. Increased water temperatures are not directly responsible for the observed size and growth differences. Diet differences resulting from increased productivity at lower trophic levels as a result of the hot-water effluent may be the cause of the observed growth and size phenomena. The increased growth rates and larger body sizes in the Par Pond turtles result in changes in reproductive rate which may have interesting consequences on the demography of the population.

scholarly journals Barley Leaf Area and Leaf Growth Rates Are Maximized during the Pre-Anthesis Phase

Agronomy ◽  
2015 ◽  
Vol 5 (2) ◽  
pp. 107-129 ◽  
Author(s):  
Ahmad Alqudah ◽  
Thorsten Schnurbusch
Keyword(s):  
Leaf Area ◽  
Growth Rates ◽  
Leaf Growth ◽  
Barley Leaf

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.

scholarly journals Climate change effects on migration phenology may mismatch brood parasitic cuckoos and their hosts

2009 ◽  
Vol 5 (4) ◽  
pp. 539-541 ◽  
Author(s):  
Nicola Saino ◽  
Diego Rubolini ◽  
Esa Lehikoinen ◽  
Leonid V. Sokolov ◽  
Andrea Bonisoli-Alquati ◽  
...  
Keyword(s):  
Climate Change ◽  
Short Distance ◽  
Life Cycles ◽  
Trophic Levels ◽  
Negative Consequences ◽  
Long Distance ◽  
Climate Change Effects ◽  
Parasitism Rates ◽  
Migration Phenology ◽  
Spring Arrival

Phenological responses to climate change vary among taxa and across trophic levels. This can lead to a mismatch between the life cycles of ecologically interrelated populations (e.g. predators and prey), with negative consequences for population dynamics of some of the interacting species. Here we provide, to our knowledge, the first evidence that climate change might disrupt the association between the life cycles of the common cuckoo ( Cuculus canorus ), a migratory brood parasitic bird, and its hosts. We investigated changes in timing of spring arrival of the cuckoo and its hosts throughout Europe over six decades, and found that short-distance, but not long-distance, migratory hosts have advanced their arrival more than the cuckoo. Hence, cuckoos may keep track of phenological changes of long-distance, but not short-distance migrant hosts, with potential consequences for breeding of both cuckoo and hosts. The mismatch to some of the important hosts may contribute to the decline of cuckoo populations and explain some of the observed local changes in parasitism rates of migratory hosts.

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