Can fairy shrimps (Crustacea: Anostraca) structure zooplankton communities in temporary ponds?

2007 ◽  
Vol 58 (9) ◽  
pp. 827 ◽  
Author(s):  
Beatriz Sánchez ◽  
David G. Angeler
Keyword(s):  
Community Dynamics ◽  
Environmental Variability ◽  
Keystone Species ◽  
Zooplankton Community ◽  
Temporary Ponds ◽  
Temporary Wetland ◽  
Fairy Shrimps ◽  
Zooplankton Communities ◽  
High Degree

Predation and competition are recognised as strong community structuring forces, and these processes are often mediated by keystone species. However, the role of keystone species in the plankton of temporary wetlands has hardly been evaluated. In the present study, the potential structuring role of fairy shrimps (Anostraca, Branchiopoda) on temporary wetland zooplankton communities was assessed. Dry sediments were collected from randomly chosen temporary ponds in the Campo de Calatrava area (Central Spain), and these were rewetted in outdoor microcosms. Zooplankton community dynamics of three wetlands that lacked fairy shrimps (controls) were contrasted with three wetlands that contained Branchinecta orientalis (G. O. Sars) (treatment). ANOVA analyses showed no significant differences in zooplankton community metrics and in taxonomic groups between the controls and treatments. Analyses of similarity (ANOSIM) and similarity percentages (SIMPER) revealed significant differences and a high degree of community dissimilarity within and between treatment levels. The high degree of environmental variability between wetlands compromised the detection of the structuring role of fairy shrimps on zooplankton in the present study. Studies based on manipulative designs could be more appropriate to test for the keystone role of fairy shrimps in temporary wetland food webs. Replicated before-after control-impact (BACI) designs could be especially useful for understanding basic ecological processes and this knowledge could then be used for the development of sound management strategies of ecologically poorly understood temporary ponds.

Hyperbenthic and pelagic predators regulate alternate key planktonic copepods in shallow temperate estuaries

2014 ◽  
Vol 65 (9) ◽  
pp. 791 ◽  
Author(s):  
R. J. Wasserman ◽  
T. J. F. Vink ◽  
R. Kramer ◽  
P. W. Froneman
Keyword(s):  
Population Regulation ◽  
Zooplankton Community ◽  
Copepod Species ◽  
Benthic Fish ◽  
Predator Diversity ◽  
Predatory Impact ◽  
Experimental Treatments ◽  
Zooplankton Communities ◽  
Predatory Pressure

Although predation has been identified as an important community driver, the role of predator diversity in structuring estuarine zooplankton has not been assessed. As such, we investigated the effects of two different zooplanktivorous fish species on the estuarine zooplankton community during a 12-day mesocosm study. Three experimental treatments were established, whereby natural zooplankton communities were subject to either (1) no predatory pressure, (2) predation by a pelagic predator (Monodactylus falciformis) or (3) predation by a hyper-benthic predator (Glossogobius callidus). The pelagic feeding M. falciformis fed largely on the numerically dominant mid-water copepod species, Paracartia longipatella. In contrast, the hyper-benthic fish had a greater predatory impact on the less numerically dominant copepod, Pseudodiaptomus hessei, which demonstrates strong diel vertical migration. Variations in prey-population regulation are ascribed to the distinct behavioural differences of the predators, and mediated by the differences in behaviour of the copepod species.

scholarly journals The role of food availability and phytoplankton community dynamics in the seasonal succession of zooplankton community in a subtropical reservoir

Limnologica ◽  
2014 ◽  
Vol 46 ◽  
pp. 131-138 ◽  
Author(s):  
Chun-Wei Chang ◽  
Fuh-Kwo Shiah ◽  
Jiunn-Tzong Wu ◽  
Takeshi Miki ◽  
Chih-hao Hsieh
Keyword(s):  
Food Availability ◽  
Community Dynamics ◽  
Phytoplankton Community ◽  
Seasonal Succession ◽  
Zooplankton Community

scholarly journals Zooplankton Community Responses to Oxygen Stress

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 706 ◽  
Author(s):  
Maciej Karpowicz ◽  
Jolanta Ejsmont-Karabin ◽  
Joanna Kozłowska ◽  
Irina Feniova ◽  
Andrew R. Dzialowski
Keyword(s):  
Zooplankton Community ◽  
Oxygen Depletion ◽  
Zooplankton Biomass ◽  
Oxygen Stress ◽  
Carbon Transfer ◽  
Oxygen Conditions ◽  
Anoxic Layer ◽  
Zooplankton Communities ◽  
The Impact

Recent changes in climate and eutrophication have caused increases in oxygen depletion in both freshwater and marine ecosystems. However, the impact of oxygen stress on zooplankton, which is the major trophic link between primary producers and fish, remains largely unknown in lakes. Therefore, we studied 41 lakes with different trophic and oxygen conditions to assess the role of oxygen stress on zooplankton communities and carbon transfer between phytoplankton and zooplankton. Samples were collected from each lake at the peak of summer stratification from three depth layers (the epilimnion, metalimnion, and hypolimnion). Our results revealed that freshwater zooplankton were relatively tolerant to anoxic conditions and the greatest changes in community structure were found in lakes with the highest oxygen deficits. This caused a switch in dominance from large to small species and reduced the zooplankton biomass in lower, anoxic layers of water, but not in the upper layers of water where the oxygen deficits began. This upper anoxic layer could thus be a very important refuge for zooplankton to avoid predation during the day. However, the reduction of zooplankton in the lower water layers was the main factor that reduced the effectiveness of carbon transfer between the phytoplankton and zooplankton.

Testing ecological release as a compensating mechanism for mass mortality in a keystone predator

2020 ◽  
Vol 637 ◽  
pp. 59-69 ◽  
Author(s):  
J Sullivan-Stack ◽  
BA Menge
Keyword(s):  
Community Dynamics ◽  
Limiting Factor ◽  
Sea Star ◽  
Top Predator ◽  
Oregon Coast ◽  
Ecological Release ◽  
Keystone Predator ◽  
Pisaster Ochraceus ◽  
Wasting Syndrome

Top predator decline has been ubiquitous across systems over the past decades and centuries, and predicting changes in resultant community dynamics is a major challenge for ecologists and managers. Ecological release predicts that loss of a limiting factor, such as a dominant competitor or predator, can release a species from control, thus allowing increases in its size, density, and/or distribution. The 2014 sea star wasting syndrome (SSWS) outbreak decimated populations of the keystone predator Pisaster ochraceus along the Oregon coast, USA. This event provided an opportunity to test the predictions of ecological release across a broad spatial scale and determine the role of competitive dynamics in top predator recovery. We hypothesized that after P. ochraceus loss, populations of the subordinate sea star Leptasterias sp. would grow larger, more abundant, and move downshore. We based these predictions on prior research in Washington State showing that Leptasterias sp. competed with P. ochraceus for food. Further, we predicted that ecological release of Leptasterias sp. could provide a bottleneck to P. ochraceus recovery. Using field surveys, we found no clear change in density or distribution in Leptasterias sp. populations post-SSWS, and decreases in body size. In a field experiment, we found no evidence of competition between similar-sized Leptasterias sp. and P. ochraceus. Thus, the mechanisms underlying our predictions were not in effect along the Oregon coast, which we attribute to differences in habitat overlap and food availability between the 2 regions. Our results suggest that response to the loss of a dominant competitor can be unpredictable even when based in theory and previous research.

scholarly journals Roles of ncRNAs as ceRNAs in Gastric Cancer

Genes ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 1036
Author(s):  
Junhong Ye ◽  
Jifu Li ◽  
Ping Zhao
Keyword(s):  
Gastric Cancer ◽  
Research Strategy ◽  
Circular Rnas ◽  
Messenger Rnas ◽  
Cerna Network ◽  
Degree Of Malignancy ◽  
High Degree ◽  
Competitive Endogenous Rna ◽  
Made In

Although ignored in the past, with the recent deepening of research, significant progress has been made in the field of non-coding RNAs (ncRNAs). Accumulating evidence has revealed that microRNA (miRNA) response elements regulate RNA. Long ncRNAs, circular RNAs, pseudogenes, miRNAs, and messenger RNAs (mRNAs) form a competitive endogenous RNA (ceRNA) network that plays an essential role in cancer and cardiovascular, neurodegenerative, and autoimmune diseases. Gastric cancer (GC) is one of the most common cancers, with a high degree of malignancy. Considerable progress has been made in understanding the molecular mechanism and treatment of GC, but GC’s mortality rate is still high. Studies have shown a complex ceRNA crosstalk mechanism in GC. lncRNAs, circRNAs, and pseudogenes can interact with miRNAs to affect mRNA transcription. The study of the involvement of ceRNA in GC could improve our understanding of GC and lead to the identification of potential effective therapeutic targets. The research strategy for ceRNA is mainly to screen the different miRNAs, lncRNAs, circRNAs, pseudogenes, and mRNAs in each sample through microarray or sequencing technology, predict the ceRNA regulatory network, and, finally, conduct functional research on ceRNA. In this review, we briefly discuss the proposal and development of the ceRNA hypothesis and the biological function and principle of ceRNAs in GC, and briefly introduce the role of ncRNAs in the GC’s ceRNA network.

Surgeon-performed Ultrasound for Primary Hyperparathyroidism

2013 ◽  
Vol 79 (7) ◽  
pp. 681-685 ◽  
Author(s):  
Worthington G. Schenk ◽  
John B. Hanks ◽  
Philip W. Smith
Keyword(s):  
Primary Hyperparathyroidism ◽  
Class 1 ◽  
Additional Imaging ◽  
Surgical Cure ◽  
Operative Findings ◽  
Enhanced Computed Tomography ◽  
High Degree ◽  
Tomography Scan ◽  
Parathyroid Imaging

The role of preoperative parathyroid imaging continues to evolve. This study evaluated whether surgeon-performed ultrasound (U/S) obviates the need for other imaging studies and leads to a focused exploration with a high degree of surgical success. From July 2010 to February 2012, 200 patients presenting with nonfamilial primary hyperparathyroidism underwent neck U/S in the surgeon's office. The U/S interpretation was classified as Class 1 if an adenoma was identified with high confidence, Class 2 if a possible but not definite enlarged gland was imaged, and Class 0 (zero) if no adenoma was identified. The findings were correlated with subsequent intra-operative findings. There were 144 Class 1 U/Ss (72%); of 132 patients coming to surgery, 96.2 per cent had surgical findings concordant with preoperative U/S and all had apparent surgical cure. Twenty-nine patients (14.5%) had Class 2 U/S; the 31 per cent confirmed false-positives in this group were usually colloid nodules. Fourteen of 27 with Class 0 U/S underwent surgery after being offered dynamically enhanced computed tomography scan. All 200 patients were apparent surgical cures. Surgeon-performed U/S is expedient, convenient, inexpensive, and accurate. A clearly identified adenoma can safely lead to a focused limited exploration and avoid additional imaging 93 per cent of the time.

Changes in the crustacean communities of Lakes Michigan, Huron, and Erie following the invasion of the predatory cladoceran Bythotrephes longimanus

2004 ◽  
Vol 61 (11) ◽  
pp. 2111-2125 ◽  
Author(s):  
Richard P Barbiero ◽  
Marc L Tuchman
Keyword(s):  
Zooplankton Community ◽  
Crustacean Zooplankton ◽  
Bythotrephes Longimanus ◽  
Zooplankton Community Structure ◽  
Cladoceran Species ◽  
Invertebrate Predators ◽  
Predatory Cladoceran ◽  
Leptodora Kindti ◽  
Escape Responses ◽  
Zooplankton Communities

The crustacean zooplankton communities in Lakes Michigan and Huron and the central and eastern basins of Lake Erie have shown substantial, persistent changes since the invasion of the predatory cladoceran Bythotrephes in the mid-1980s. A number of cladoceran species have declined dramatically since the invasion, including Eubosmina coregoni, Holopedium gibberum, Daphnia retrocurva, Daphnia pulicaria, and Leptodora kindti, and overall species richness has decreased as a result. Copepods have been relatively unaffected, with the notable exception of Meso cyclops edax, which has virtually disappeared from the lakes. These species shifts have for the most part been consistent and equally pronounced across all three lakes. Responses of crustacean species to the Bythotrephes invasion do not appear to be solely a consequence of size, and it is likely that other factors, e.g., morphology, vertical distribution, or escape responses, are important determinants of vulnerability to predation. Our results indicate that invertebrate predators in general, and invasive ones in particular, can have pronounced, lasting effects on zooplankton community structure.

The academic profession in Russia’s two capitals: The impact of 20 years of transition

2017 ◽  
Vol 16 (5) ◽  
pp. 626-644 ◽  
Author(s):  
Elizaveta Sivak ◽  
Maria Yudkevich
Keyword(s):  
Large Scale ◽  
Academic Career ◽  
Academic Profession ◽  
University Faculty ◽  
Key Characteristics ◽  
Personal Strain ◽  
High Degree ◽  
The Impact ◽  
Russian Universities

This paper studies the dynamics of key characteristics of the academic profession in Russia based on the analysis of university faculty in the two largest cities in Russia – Moscow and St Petersburg. We use data on Russian university faculty from two large-scale comparative studies of the academic profession (‘The Carnegie Study’ carried out in 1992 in 14 countries, including Russia, and ‘The Changing Academic Profession Study’, 2007–2012, with 19 participating countries and which Russia joined in 2012) to look at how faculty’s characteristics and attitudes toward different aspects of their academic life changed over 20 years (1992–2011) such as faculty’s views on reasons to leave or to stay at a university, on university’s management and the role of faculty in decision making. Using the example of universities in the two largest Russian cities, we demonstrate that the high degree of overall centralization of governance in Russian universities barely changed in 20 years. Our paper provides comparisons of teaching/research preferences and views on statements concerning personal strain associated with work, academic career perspectives, etc., not only in Russian universities between the years 1992 and 2012, but also in Russia and other ‘Changing Academic Profession’ countries.

Myocardial CO2 buffering: role of transmembrane transport of H+ or HCO3-ions

1976 ◽  
Vol 230 (4) ◽  
pp. 1037-1041 ◽  
Author(s):  
DR Strome ◽  
RL Clancy ◽  
NC Gonzalez
Keyword(s):  
Small Volume ◽  
Coronary Circulation ◽  
Myocardial Cell ◽  
Ringer Solution ◽  
Red Cells ◽  
Transmembrane Transport ◽  
High Degree

Isolated rabbit hearts were perfused with rabbit red cells suspended in Ringer solution. A small volume of perfusate was recirculated for 10 min at Pco2 of 33.4 +/- 0.9 or 150.8 +/- 7.5 mmHg. Hypercapnia resulted in an increase in perfusate HCO3- concentration that was smaller than that observed when isolated perfusate was equilibrated in vitro with the same CO2 tensions (delta HCO-3e = 1.6 mM, P less than 0.01). This difference is consistent with a net movement of HCO3- into or H+ out of the mycardial cell, and cannot be accounted for by dilution of HCO3- in the myocardial interstitium. Recirculation of perfusate through the coronary circulation at normal Pco2 for two consecutive 10-min periods was not followed by changes in perfusate HCO3- concentration. A high degree of correlation (r = 0.81) was observed between intracellular HCO-3e concentration and the corresponding delta HCO-3e in individual experiments. The results suggest that transmembrane exchange of H+ or HCO3- is a buffer mechanism for CO2 in the myocardial cell.

INFLUENCE OF BACTRIO-CARRY IN THE FAMILY ON THE COURSE OF ATOPIC DERMATITIS IN A CHILD

2021 ◽  
pp. 114-119
Author(s):  
Vasileva E.A. ◽  
Kuyarov A.A. ◽  
Kuyarov A.V.
Keyword(s):  
Atopic Dermatitis ◽  
Secondary Infection ◽  
Family Members ◽  
Upper Respiratory Tract ◽  
Epidermal Barrier ◽  
The Family ◽  
Mucous Membranes ◽  
High Degree ◽  
Nose And Throat

The pathogenesis of atopic dermatitis (AD) is complex, and at present a unified concept of the development of the disease has not been formed. At the heart of pathogenesis, there is a complex interaction of numerous factors, such as genetic predisposition, dysfunction of the autonomic nervous system and the epidermal barrier. Previously, it has been proven that a high microbial contamination of the affected areas helps to maintain inflammation and aggravates skin dysfunction as a result of chronic inflammation, and favorable factors appear for the attachment of a secondary infection. However, little attention has been paid to dysfunctions of the epidermal barrier, the role of violations of the quantitative and qualitative composition of the microbiota in the development of AD, and this issue remains relevant at the present time. The aim of this study was to assess the effect of the carrier of bacteria on the mucous membranes of the upper respiratory tract in family members on the course of atopic dermatitis in a child. A bacteriological examination of the mucous membranes of the nose and throat was carried out in 34 children with AD and members of their families (74 people). When examining the mucous membranes of the nose and throat in family members of children with AD, it was found that the microflora isolated from family members in more than half of the cases has an increased potential for pathogenicity with a high degree of contamination (CFU lg 3), which forms an increased bacteriological load on the child. The tendency of bacterial carriage was revealed, contributing to the formation in the family of a permanent persistence of microflora with a high potential for pathogenicity. Asymptomatic carriage of bacteria forms an additional epidemiological load on the child, affects the severity of AD and is a risk factor in the development of secondary infection of the skin.

Sign in / Sign up

Export Citation Format

Share Document