scholarly journals Role of infochemical mediated zooplankton grazing in a phytoplankton competition model

2013 ◽  
Vol 16 ◽  
pp. 41-50 ◽  
Author(s):  
Nicola D. Lewis ◽  
Mark N. Breckels ◽  
Michael Steinke ◽  
Edward A. Codling
Keyword(s):  
Competition Model ◽  
Zooplankton Grazing

Psychobiological Responses to Competition in Women

2016 ◽  
Author(s):  
Raquel Costa ◽  
Miguel A. Serrano ◽  
Alicia Salvador
Keyword(s):  
Coping Strategies ◽  
Agonistic Behavior ◽  
Functional Role ◽  
Response Pattern ◽  
Competition Model ◽  
Stress Model ◽  
Evolutionary Perspective ◽  
Coping Response ◽  
Challenge Hypothesis

From an evolutionary perspective, questions have been raised about whether women have a psychobiological pattern similar to that of men. In humans, hormonal effects of competition and its outcome have been investigated under the biosocial status hypothesis, which proposes that, after a competition, winners would show increases in testosterone whereas losers would show reductions, and the challenge hypothesis, which emphasizes the functional role of testosterone increases in the spring to promote agonistic behavior related to territoriality and access to females. Subsequently, the coping competition model has defended the study of competition within a more general stress model, considering the psychobiological responses as part of the coping response. This chapter shows that women investigations are increasing in number in recent years and that, in competitive situations, they present coping strategies with a psychobiological response pattern that can be enlightened by the coping competition model.

Possible impacts of zooplankton grazing on dimethylsulfide production in the Antarctic Ocean

2004 ◽  
Vol 61 (5) ◽  
pp. 736-743 ◽  
Author(s):  
Nobue Kasamatsu ◽  
So Kawaguchi ◽  
Shuichi Watanabe ◽  
Tsuneo Odate ◽  
Mitsuo Fukuchi
Keyword(s):  
Production Rate ◽  
Antarctic Krill ◽  
Ingestion Rate ◽  
Euphausia Superba ◽  
Zooplankton Grazing ◽  
Antarctic Ocean ◽  
Incubation Experiments ◽  
The Antarctic ◽  
Phytoplankton Cells

The role of zooplankton grazing on dimethylsulfide (DMS) and dissolved dimethylsulfoniopropionate (DMSPd) production was investigated in the Antarctic Ocean in January and February 2002. Dominant herbivorous macrozooplankton of this region, the Antarctic krill Euphausia superba and the tunicate Salpa thompsoni, were used in shipboard incubation experiments. The concentration of DMSPd + DMS increased in the water during incubation with krill. The production rate was 2.96 ± 2.78 nmol DMSPd + DMS·krill–1·h–1 (mean ± SD). In addition, the DMSPd + DMS production rate was linearly related to the ingestion rate of krill (r2 = 0.664, p ≤ 0.01). Addition of salps to natural surface water, however, did not change the DMSPd + DMS concentrations. During the experiments, both animals fed on phytoplankton cells. The fecal pellets of krill contained broken phytoplankton cells, whereas those of salps contained unbroken cells. These results suggest that sloppy feeding by krill is a more likely mechanism for producing DMS and DMSPd than the direct ingestion of phytoplankton cells by salps. The decrease of DMS concentrations in the upper 200 m of the water column from January to February may be explained, in part, by changes in the composition of the macrozooplankton community.

Carbon intake by zooplankton. Importance and role of zooplankton grazing in the Indian sector of the Southern Ocean

2002 ◽  
Vol 49 (16) ◽  
pp. 3169-3187 ◽  
Author(s):  
P. Mayzaud ◽  
V. Tirelli ◽  
A. Errhif ◽  
J.P. Labat ◽  
S. Razouls ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Zooplankton Grazing ◽  
Carbon Intake ◽  
Indian Sector

Role of nutrients and zooplankton grazing on phytoplankton growth in a temperate reservoir in New South Wales, Australia

2003 ◽  
Vol 54 (5) ◽  
pp. 609 ◽  
Author(s):  
Tsuyoshi Kobayashi ◽  
Anthony G. Church
Keyword(s):  
Nutrient Enrichment ◽  
Phytoplankton Community ◽  
New South ◽  
Phytoplankton Growth ◽  
Zooplankton Grazing ◽  
P Limitation ◽  
South Wales ◽  
Qualitative Effect

The role of nitrogen (N) and phosphorus (P) and zooplankton grazing on the growth of a phytoplankton community was investigated at different times in the Ben Chifley reservoir. In situ nutrient enrichment bioassays (n�= 12) indicated that phytoplankton growth was limited by P in 33% of experiments, by both N and P in 25% of experiments and no limitation was found in 42%. The hypothesis that N or P limitation occurred when ambient N : P ratios were different from the Redfield ratio was supported in 33% of bioassay experiments, suggesting that ambient N : P ratios do not always correctly indicate if N or P is limiting. Grazing rates of the reservoir zooplankton (>150�μm in size) ranged from 0.023–0.199 day–1 (mean: 0.078 day–1, n = 8). The grazing efficiency, as measured by a weight-specific clearance rate, ranged from 0.049–0.743 mL μg dry wt–1 day–1, and was positively correlated with the relative biomass of Daphnia in the community. The nutrient-stimulated growth of phytoplankton ranged from 0.085–1.031 day–1 (mean: 0.461 day–1, n = 10). The effect of nutrient enrichment exceeded that of zooplankton grazing in 62% of experiments. Further study is necessary to understand a qualitative effect of nutrients and zooplankton grazing on the phytoplankton community structure in the Ben Chifley reservoir.

scholarly journals Assessing the role of bacterial plasmid replication in a competition model of sensitive and resistant bacteria to antibiotics

2021 ◽  
Vol 6 (9) ◽  
pp. 9446-9467
Author(s):  
Eduardo Ibargüen-Mondragón ◽  
◽  
Miller Cerón Gómez ◽  
Edith M. Burbano-Rosero ◽  
Keyword(s):  
Competition Model ◽  
Resistant Bacteria ◽  
Plasmid Replication ◽  
Bacterial Plasmid

The Role of Zooplankton Grazing and Nutrient Loading in the Occurrence of Harmful Cyanobacterial Blooms in Florida Bay, USA

2010 ◽  
Vol 33 (5) ◽  
pp. 1202-1215 ◽  
Author(s):  
Jennifer A. Goleski ◽  
Florian Koch ◽  
Maria A. Marcoval ◽  
Charles C. Wall ◽  
Frank J. Jochem ◽  
...  
Keyword(s):  
Nutrient Loading ◽  
Florida Bay ◽  
Cyanobacterial Blooms ◽  
Zooplankton Grazing ◽  
Harmful Cyanobacterial Blooms

scholarly journals Morpho-Functional Traits Reveal Differences in Size Fractionated Phytoplankton Communities but Do Not Significantly Affect Zooplankton Grazing

2022 ◽  
Vol 10 (1) ◽  
pp. 182
Author(s):  
Jessica Titocci ◽  
Melanie Bon ◽  
Patrick Fink
Keyword(s):  
Functional Traits ◽  
Comprehensive Evaluation ◽  
Functional Trait ◽  
Zooplankton Grazing ◽  
Filter Feeder ◽  
Freshwater Phytoplankton ◽  
Composition And Structure ◽  
Phytoplankton Communities ◽  
Recent Emergence

The recent emergence of approaches based on functional traits allows a more comprehensive evaluation of the role of functions and interactions within communities. As phytoplankton size and shape are the major determinants of its edibility to herbivores, alteration or loss of some morpho-functional phytoplankton traits should affect zooplankton grazing, fitness and population dynamics. Here, we investigated the response of altered phytoplankton morpho-functional trait distribution to grazing by zooplankton with contrasting food size preferences and feeding behaviors. To test this, we performed feeding trials in laboratory microcosms with size-fractionated freshwater phytoplankton (3 size classes, >30 µm; 5–30 µm and <5 µm) and two different consumer types: the cladoceran Daphnia longispina, (generalist unselective filter feeder) and the calanoid copepod Eudiaptomus sp. (selective feeder). We observed no significant changes in traits and composition between the controls and grazed phytoplankton communities. However, community composition and structure varied widely between the small and large size fractions, demonstrating the key role of size in structuring natural phytoplankton communities. Our findings also highlight the necessity to combine taxonomy and trait-based morpho-functional approaches when studying ecological dynamics in phytoplankton-zooplankton interactions.

The Role of Advection in a Two-Species Competition Model: A Bifurcation Approach

2017 ◽  
Vol 245 (1161) ◽  
pp. 0-0 ◽  
Author(s):  
Isabel Averill ◽  
King-Yeung Lam ◽  
Yuan Lou
Keyword(s):  
Competition Model ◽  
Species Competition

scholarly journals Efflux Pumps in Chromobacterium Species Increase Antibiotic Resistance and Promote Survival in a Coculture Competition Model

2019 ◽  
Vol 85 (19) ◽  
Author(s):  
Saida Benomar ◽  
Kara C. Evans ◽  
Robert L. Unckless ◽  
Josephine R. Chandler
Keyword(s):  
Antibiotic Resistance ◽  
Efflux Pump ◽  
Gene Clusters ◽  
Efflux Pumps ◽  
Resistance Mechanisms ◽  
Competition Model ◽  
Content Type ◽  
Resistance Induction ◽  
Resistance Nodulation Division

ABSTRACT Members of the Chromobacterium genus include opportunistic but often-fatal pathogens and soil saprophytes with highly versatile metabolic capabilities. In previous studies of Chromobacterium subtsugae (formerly C. violaceum) strain CV017, we identified a resistance nodulation division (RND)-family efflux pump (CdeAB-OprM) that confers resistance to several antibiotics, including the bactobolin antibiotic produced by the soil saprophyte Burkholderia thailandensis. Here, we show the cdeAB-oprM genes increase C. subtsugae survival in a laboratory competition model with B. thailandensis. We also demonstrate that adding sublethal bactobolin concentrations to the coculture increases C. subtsugae survival, but this effect is not through CdeAB-OprM. Instead, the increased survival requires a second, previously unreported pump we call CseAB-OprN. We show that in cells exposed to sublethal bactobolin concentrations, the cseAB-oprN genes are transcriptionally induced, and this corresponds to an increase in bactobolin resistance. Induction of this pump is highly specific and sensitive to bactobolin, while CdeAB-OprM appears to have a broader range of antibiotic recognition. We examine the distribution of cseAB-oprN and cdeAB-oprM gene clusters in members of the Chromobacterium genus and find the cseAB-oprN genes are limited to the nonpathogenic C. subtsugae strains, whereas the cdeAB-oprM genes are more widely distributed among members of the Chromobacterium genus. Our results provide new information on the antibiotic resistance mechanisms of Chromobacterium species and highlight the importance of efflux pumps for saprophytic bacteria existing in multispecies communities. IMPORTANCE Antibiotic efflux pumps are best known for increasing antibiotic resistance of pathogens; however, the role of these pumps in saprophytes is much less well defined. This study describes two predicted efflux pump gene clusters in the Chromobacterium genus, which is comprised of both nonpathogenic saprophytes and species that cause highly fatal human infections. One of the predicted efflux pump clusters is present in every member of the Chromobacterium genus and increases resistance to a broad range of antibiotics. The other gene cluster has more narrow antibiotic specificity and is found only in Chromobacterium subtsugae, a subset of entirely nonpathogenic species. We demonstrate the role of both pumps in increasing antibiotic resistance and demonstrate the importance of efflux-dependent resistance induction for C. subtsugae survival in a dual-species competition model. These results have implications for managing antibiotic-resistant Chromobacterium infections and for understanding the evolution of efflux pumps outside the host.

scholarly journals The motivational role of affect in an ecological model

2021 ◽  
pp. 095935432199286
Author(s):  
Rami Gabriel
Keyword(s):  
Philosophy Of Mind ◽  
Ecological Model ◽  
Ecological Psychology ◽  
Action Selection ◽  
Competition Model ◽  
Empirical Literature ◽  
Affective Neuroscience ◽  
Perceptual Salience

Drawing from empirical literature on ecological psychology, affective neuroscience, and philosophy of mind, this article describes a model of affect-as-motivation in the intentional bond between organism and environment. An epistemological justification for the motivating role of emotions is provided through articulating the perceptual context of emotions as embodied, situated, and functional, and positing perceptual salience as a biasing signal in an affordance competition model. The motivational role of affect is pragmatically integrated into discussions of action selection in the neurosciences.

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