scholarly journals Contrasting Effects of Bioturbation Studied in Intact and Reconstructed Estuarine Sediments

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3125
Author(s):  
Marco Bartoli ◽  
Sara Benelli ◽  
Monia Magri ◽  
Cristina Ribaudo ◽  
Paula Carpintero Moraes ◽  
...  
Keyword(s):  
Deposit Feeder ◽  
Estuarine Sediments ◽  
Benthic Fluxes ◽  
Filter Feeder ◽  
Carbon And Nitrogen ◽  
Benthic Respiration ◽  
Deposit Feeders ◽  
Sediment Biogeochemistry ◽  
Long Time ◽  
Experimental Approaches

Macrofauna can produce contrasting biogeochemical effects in intact and reconstructed sediments. We measured benthic fluxes of oxygen, inorganic carbon, and nitrogen and denitrification rates in intact sediments dominated by a filter and a deposit feeder and in reconstructed sediments added with increasing densities of the same organisms. Measurements in reconstructed sediments were carried out 5 days after macrofauna addition. The degree of stimulation of the measured fluxes in the intact and reconstructed sediments was then compared. Results confirmed that high densities of bioturbating macrofauna produce profound effects on sediment biogeochemistry, enhancing benthic respiration and ammonium recycling by up to a factor of ~3 and ~9, respectively, as compared to control sediments. The deposit feeder also increased total denitrification by a factor of ~2, whereas the filter feeder activity did not stimulate nitrogen removal. Moreover, the effects of deposit feeders on benthic fluxes were significantly higher (e.g., on respiration and ammonium recycling) or different (e.g., on denitrification) when measured in intact and reconstructed sediments. In intact sediments, deposit feeders enhanced the denitrification coupled to nitrification and had no effects on the denitrification of water column nitrate, whereas in reconstructed sediments, the opposite was true. This may reflect active burrowing in reconstructed sediments and the long time needed for slow growing nitrifiers to develop within burrows. Results suggest that, in bioturbation studies, oversimplified experimental approaches and insufficient preincubation time might lead to wrong interpretation of the role of macrofauna in sediment biogeochemistry, far from that occurring in nature.

scholarly journals The Secret Lives of Fluorescent Membrane Probes as Revealed by Molecular Dynamics Simulations

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3424
Author(s):  
Hugo A. L. Filipe ◽  
Maria João Moreno ◽  
Luís M. S. Loura
Keyword(s):  
Molecular Dynamics ◽  
Membrane System ◽  
Md Simulations ◽  
Fluorescence Probes ◽  
Host Membrane ◽  
Tremendous Progress ◽  
Long Time ◽  
Experimental Approaches ◽  
Dynamics Simulations ◽  
Membrane Probes

Fluorescent probes have been employed for more than half a century to study the structure and dynamics of model and biological membranes, using spectroscopic and/or microscopic experimental approaches. While their utilization has led to tremendous progress in our knowledge of membrane biophysics and physiology, in some respects the behavior of bilayer-inserted membrane probes has long remained inscrutable. The location, orientation and interaction of fluorophores with lipid and/or water molecules are often not well known, and they are crucial for understanding what the probe is actually reporting. Moreover, because the probe is an extraneous inclusion, it may perturb the properties of the host membrane system, altering the very properties it is supposed to measure. For these reasons, the need for independent methodologies to assess the behavior of bilayer-inserted fluorescence probes has been recognized for a long time. Because of recent improvements in computational tools, molecular dynamics (MD) simulations have become a popular means of obtaining this important information. The present review addresses MD studies of all major classes of fluorescent membrane probes, focusing in the period between 2011 and 2020, during which such work has undergone a dramatic surge in both the number of studies and the variety of probes and properties accessed.

Animal abundance and food availability in coastal lagoons and intertidal marine sediments

2000 ◽  
Vol 80 (2) ◽  
pp. 193-202 ◽  
Author(s):  
R.S.K. Barnes ◽  
C.J. de Villiers
Keyword(s):  
Coastal Lagoons ◽  
Deposit Feeder ◽  
Seasonal Abundance ◽  
Animal Abundance ◽  
Abundance Patterns ◽  
Deposit Feeders ◽  
High Level ◽  
Deposit Feeding ◽  
Potential Food ◽  
Potential Maximum

The relationships between the standing stocks of deposit-feeding benthic invertebrates and benthic chlorophyll-a, phaeopigment and total combustible organic matter were investigated at a series of coastal lagoons and in the type of intertidal soft-sediment sites from which the lagoons originated. Across all the sites, in Norfolk, UK, an inverse relationship occurred between (a) the amounts of chlorophyll-a and of other potential food materials and (b) the degree of coverage by water. The biomass of consumers also decreased with increased water coverage, so that the lagoons supported less biomass than the adjacent high-level intertidal sites. Further, the deposit-feeder biomass supported by unit food decreased with extent of water coverage.There was no evidence of any relationship between deposit-feeder and food biomass within any single site, in spite of the study period being selected to be that in which there was maximum likelihood of competition for microphytobenthic food. Whilst chlorophyll concentrations may set the maximum achievable level of consumer biomass at these sites, including in the deeper lagoons setting very low potential maximum population densities, the seasonal abundance patterns of the deposit feeders appear to be determined by other factor(s).

scholarly journals Determination of the Effects of Copper (Cu) and Lead (Pb) Heavy Metals on Soil Carbon and Nitrogen Mineralization

2021 ◽  
Vol 50 (10) ◽  
pp. 2957-2964
Author(s):  
Nacide Kizildağ
Keyword(s):  
Soil Carbon ◽  
Nitrogen Mineralization ◽  
Carbon Mineralization ◽  
Field Capacity ◽  
Carbon And Nitrogen ◽  
Soil Carbon And Nitrogen ◽  
Soil Ecosystems ◽  
Significant Difference ◽  
Long Time ◽  
Negative Effect

Heavy metal (HM) pollution has become one of the most important environmental problems of the present day, as a result of the developing industrial activities. Accordingly, it is important to understand microorganism activities in soil ecosystems that have been exposed to HMs for a long time. The aim of this study was to show the potential effects of ores on soil carbon and nitrogen mineralizations which were taken from copper (Cu) and lead (Pb) mines in Balıkesir-Balya and Kastamonu-Küre districts in Turkey. The carbon (C) and nitrogen (N) mineralizations were determined by using the CO2 respiration method (30 days) and the Parnas Wagner method (42 days) under the controlled laboratory conditions (28 °C, 80% of field capacity), respectively. It was observed that carbon mineralization decreased depending on the dose increase. 250 mg kg-1 treatment with Pb was lower than the control and there was a significant difference between them (P < 0.001). In terms of nitrogen mineralization rate (%), there was no significant difference among all treatments. According to the results, Pb affected microorganisms more negatively; however, the presence of Cu slightly decreased its negative effect. It is possible to conclude that carbon mineralization can be indicator for HM pollution in the soil. However, nitrogen mineralization was not a determining factor at HM pollution in this study.

scholarly journals Filter Feeding and Carbon and Nitrogen Assimilation of a Freshwater Bivalve (Unio douglasiae) on a Toxic Cyanobacterium (Microcystis aeruginosa)

2021 ◽  
Vol 11 (19) ◽  
pp. 9294
Author(s):  
Soon-Jin Hwang ◽  
Yun-Ju Lee ◽  
Min-Seob Kim ◽  
Baik-Ho Kim
Keyword(s):  
Microcystis Aeruginosa ◽  
Nitrogen Assimilation ◽  
Clearance Rates ◽  
Freshwater Bivalve ◽  
Filter Feeder ◽  
Dual Isotope ◽  
Carbon And Nitrogen ◽  
Isotope Tracers ◽  
Toxic Cyanobacteria ◽  
Flowing System

We investigated the possible intake of toxic cyanobacteria (Microcystis aeruginosa) as a nutrient resource for a filter-feeder bivalve (Unio douglasiae) based on the measurement of feeding and assimilation rates of carbon and nitrogen in a limited space with no current for 72 h using 13C and 15N dual isotope tracers. With high clearance rates, the unionid rapidly removed Microcystis cells within 24 h, but only a small amount of carbon and nitrogen were incorporated into the tissues. Even with the low assimilation rates, the mussels showed more favorable uptake of carbon than of nitrogen from toxic Microcystis water, and of tissues, the gills and gut accumulated more carbon and nitrogen than the muscle and mantle. Collectively, our findings indicate that although Unio douglasiae effectively uptake toxic Microcystis cells, they can assimilate only low amounts of nutrients into tissues within three days, despite a non-flowing system.

The Ecologist and the New Ecology

2016 ◽  
Author(s):  
Oswald J. Schmitz
Keyword(s):  
Environmental Policy ◽  
Protected Areas ◽  
Human Nature ◽  
Ecosystem Functions ◽  
Global Trends ◽  
Sustainability Ethics ◽  
Long Time ◽  
Important Challenge ◽  
Experimental Approaches ◽  
Time Periods

This chapter examines the efforts of ecologists—with the help of the New Ecology—to better understand nature in ecosystems created and heavily populated by humans. Ecology has developed into a science in support of sustaining nature for people. This fresh scientific role is certainly helping to overcome the human–nature divide by promoting the view that biodiversity and ecosystem functions must be protected to provide the suite of environmental services, inside as well as outside of protected areas, in support of humanity. Ecologists are now realizing that understanding and predicting global trends in biodiversity has important implications for sustainability, ethics, and environmental policy in the interest of both humans and nature. An important challenge is to devise new experimental approaches that can speak to issues playing out at the large spatial extents and long time periods that are commensurate with the scales of human engagement with nature.

A Note on Feeding in Leptopentacta (=Cucumaria) Elongata

1984 ◽  
Vol 64 (3) ◽  
pp. 727-727 ◽  
Author(s):  
J. Douglas McKenzie ◽  
B. E. Picton
Keyword(s):  
Water Temperature ◽  
Deposit Feeder ◽  
Suspension Feeding ◽  
Suspended Material ◽  
Deposit Feeders ◽  
Deposit Feeding ◽  
Winter Hibernation

Conflicting opinions exist as to the method of feeding employed by Leptopentacta elongata (Dub. and Kor). Orton (1914) and Mortensen (1927) suggested that it may be a deposit feeder. Chia & Buchanan (1969) noted that post larval specimens up to 1 year old deposit fed. Fankboner (1981), in a short study, concluded that the adults were cryptic deposit feeders. Hunt (1925) and Fish (1967), however, observed what they concluded was suspension feeding. All the above observations were the result of aquarium studies. Fish (1967) also demonstrated that Leptopentacta hibernated between October and April or May both in the field and in aquarium. He also observed that hibernation could be induced in the summer months by reducing water temperature to 8°C but that winter hibernation could not be curtailed by raising the water temperature.Obsevations made by one of us (B.P.) while diving indicate that Leptopentacta suspension feeds. This behaviour has been observed on several occasions from several sites around the Irish coastline with specimens then being caught and their identity confirmed. While feeding the tentacles are held clear of the substrate to intercept suspended material.These observations clearly do not support the description of Leptopentacta solely as a cryptic deposit feeder, indeed the evidence for the adults deposit feeding at all is weak. Orton (1914) and Mortensen were only speculating on Leptopentacta being a deposit feeder based on the observation that specimens in aquaria spent much of their time completely buried. Hibernation, as shown by Fish (1967), is a possible explanation for this.

scholarly journals Population dynamics and secondary production of Euzonus furciferus Ehlers (Polychaeta, Opheliidae) in an exposed sandy beach of Southern Brazil

2007 ◽  
Vol 24 (4) ◽  
pp. 1139-1144 ◽  
Author(s):  
José R. B. de Souza ◽  
Carlos A. Borzone
Keyword(s):  
Population Dynamics ◽  
Secondary Production ◽  
Sandy Beach ◽  
Narrow Band ◽  
Deposit Feeder ◽  
Annual Production ◽  
Southern Brazil ◽  
Filter Feeder ◽  
Annual Biomass ◽  
Upper Intertidal

The distribution, population dynamics and secondary production of the polychaete Euzonus furciferus was studied in Atami Beach (Southern Brazil), from February 1992 to March 1993. Euzonus furciferus Ehlers, 1897 is the only deposit feeder species of the upper intertidal region. The organisms were present in the sandy beach all over the year, concentrated in a narrow band, and reaching maximal densities of 3,029 individuals m-2. Peaks of abundance occurred in September 1992, with a mean of 681.8 individuals m-2. Recruitment occurred in winter, with a peak in July. Mean annual biomass was estimated in 0.218 gAFDW m-2, with a total annual production of 0.466 gAFDW m-2 y-1, giving a P/B ratio of 2.13 y-1. Similar values were found for a filter-feeder polychaete inhabiting the same beach, suggesting that general food disposability of each particular environment is more important for production than the trophic strategic employed by those organisms exploring this environment.

scholarly journals Peptide-Based Vaccinology: Experimental and Computational Approaches to Target Hypervariable Viruses through the Fine Characterization of Protective Epitopes Recognized by Monoclonal Antibodies and the Identification of T-Cell-Activating Peptides

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Matteo Castelli ◽  
Francesca Cappelletti ◽  
Roberta Antonia Diotti ◽  
Giuseppe Sautto ◽  
Elena Criscuolo ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
T Cell ◽  
Conserved Regions ◽  
Predictive Algorithms ◽  
Selective Targeting ◽  
Immunogen Design ◽  
Long Time ◽  
Human Therapy ◽  
Experimental Approaches

Defining immunogenic domains of viral proteins capable of eliciting a protective immune response is crucial in the development of novel epitope-based prophylactic strategies. This is particularly important for the selective targeting of conserved regions shared among hypervariable viruses. Studying postinfection and postimmunization sera, as well as cloning and characterization of monoclonal antibodies (mAbs), still represents the best approach to identify protective epitopes. In particular, a protective mAb directed against conserved regions can play a key role in immunogen design and in human therapy as well. Experimental approaches aiming to characterize protective mAb epitopes or to identify T-cell-activating peptides are often burdened by technical limitations and can require long time to be correctly addressed. Thus, in the last decade many epitope predictive algorithms have been developed. These algorithms are continually evolving, and their use to address the empirical research is widely increasing. Here, we review several strategies based on experimental techniques alone or addressed byin silicoanalysis that are frequently used to predict immunogens to be included in novel epitope-based vaccine approaches. We will list the main strategies aiming to design a new vaccine preparation conferring the protection of a neutralizing mAb combined with an effective cell-mediated response.

scholarly journals Drivers of sulfide intrusion in Zostera muelleri in a moderately affected estuary in south-eastern Australia

2017 ◽  
Vol 68 (11) ◽  
pp. 2134 ◽  
Author(s):  
Marianne Holmer ◽  
William W. Bennett ◽  
Angus J. P. Ferguson ◽  
Jaimie Potts ◽  
Harald Hasler-Sheetal ◽  
...  
Keyword(s):  
Organic Matter ◽  
Nutrient Content ◽  
Estuarine Sediments ◽  
Lower Estuary ◽  
High Productivity ◽  
Complex Interactions ◽  
Sediment Biogeochemistry ◽  
Eastern Australia ◽  
High Concentrations ◽  
Diffusive Gradients

The seagrass Zostera muelleri Irmisch ex Asch. is abundant in estuaries in Australia and is under pressure from coastal developments. We studied sulfide intrusion in Z. muelleri along a gradient of anthropogenic impact at five stations in the Wallis Lake estuary, Australia. Results showed differences in sediment biogeochemical conditions, seagrass metrics as well as nutrient content and sulfide intrusion along the gradient from the lower estuary (affected) to the lagoon (unaffected). Sulfide intrusion was driven by complex interactions and related to changes in seagrass morphology and sediment biogeochemistry and was modified by the exposure to wind and wave action. The sediments in the lower estuary had high contributions from phytoplanktonic detritus, whereas the organic pools in the lagoon were dominated by seagrass detritus. Despite high concentrations of organic matter, sulfide intrusion was lower at stations dominated by seagrass detritus, probably because of lower sulfide pressure from the less labile nature of organic matter. Porewater diffusive gradients in thin-film (DGT) sulfide samplers showed efficient sulfide reoxidation in the rhizosphere, with high sulfur incorporation in the plants from sedimentary sulfides being likely due to sulfate uptake from reoxidised sulfide. This is a unique adaptation of Z. muelleri, which allows high productivity in estuarine sediments.

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