scholarly journals Sedimentary Organic Matter, Prokaryotes, and Meiofauna across a River-Lagoon-Sea Gradient

Diversity ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 189
Author(s):  
Silvia Bianchelli ◽  
Daniele Nizzoli ◽  
Marco Bartoli ◽  
Pierluigi Viaroli ◽  
Eugenio Rastelli ◽  
...  
Keyword(s):  
Organic Matter ◽  
Nutritional Quality ◽  
Benthic Communities ◽  
Relative Effect ◽  
Taxonomic Composition ◽  
Trophic Levels ◽  
Operational Taxonomic Units ◽  
Freshwater Inputs ◽  
Benthic Ecosystems ◽  
Meiofaunal Abundance

In benthic ecosystems, organic matter (OM), prokaryotes, and meiofauna represent a functional bottleneck in the energy transfer towards higher trophic levels and all respond to a variety of natural and anthropogenic disturbances. The relationships between OM and the different components of benthic communities are influenced by multiple environmental variables, which can vary across different habitats. However, analyses of these relationships have mostly been conducted by considering the different habitats separately, even though freshwater, transitional, and marine ecosystems, physically linked to each other, are not worlds apart. Here, we investigated the quantity and nutritional quality of sedimentary OM, along with the prokaryotic and meiofauna abundance, biomass, and biodiversity, in two sampling periods, corresponding to high vs. low freshwater inputs to the sea, along a river-to-sea transect. The highest values of sedimentary organic loads and their nutritional quality, prokaryotic and meiofaunal abundance, and biomass were consistently observed in lagoon systems. Differences in the prokaryotic Operational Taxonomic Units (OTUs) and meiofaunal taxonomic composition, rather than changes in the richness of taxa, were observed among the three habitats and, in each habitat, between sampling periods. Such differences were driven by either physical or trophic variables, though with differences between seasons. Overall, our results indicate that the apparent positive relationship between sedimentary OM, prokaryote and meiofaunal abundance, and biomass across the river-lagoon-sea transect under scrutiny is more the result of a pattern of specifically adapted prokaryotic and meiofaunal communities to different habitats, rather than an actually positive ‘response’ to OM enrichment. We conclude that the synoptic analysis of prokaryotes and meiofauna can provide useful information on the relative effect of organic enrichment and environmental settings across gradients of environmental continuums, including rivers, lagoons, and marine coastal ecosystems.

scholarly journals Small-scale distribution of metazoan meiofauna and sedimentary organic matter in subtidal sandy sediments (Mediterranean Sea)

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Davide Moccia ◽  
Alessandro Cau ◽  
Maria Carmela Meloni ◽  
Antonio Pusceddu
Keyword(s):  
Organic Matter ◽  
Biochemical Composition ◽  
Nutritional Quality ◽  
Random Distribution ◽  
Sedimentary Organic Matter ◽  
Small Scale ◽  
Metazoan Meiofauna ◽  
Sandy Sediments ◽  
Meiofaunal Abundance

While variations in sedimentary organic matter (OM) quantity, biochemical composition and nutritional quality as well as in meiofaunal abundance and assemblage composition at the macro- and mesoscale are relatively well known, information about variations at the microscale is much scarcer. To shed some light on this issue, we tested the null hypothesis by which abundance and composition of the meiofaunal assemblages, and the quantity, biochemical composition and nutritional quality of sedimentary organic matter in coastal shallow environments do not vary within a frame of 1 m2. No significant variation within the frame emerged for OM quantity, nutritional quality, biochemical composition and the abundance of meiofaunal assemblages. On the other hand, the composition of meiofaunal assemblages varied significantly within the frame and exhibited a clear segregation of assemblages farther to the shore, as a likely result of local micro-hydrodynamic conditions. Spatial autocorrelation analysis revealed that lipid and protein sedimentary contents had a random distribution, whereas carbohydrate and biopolymeric C contents and meiofaunal total abundance were characterized by a patchy distribution, with discrete peaks within the sub-frame squares (ca. 0.1 m2). Phytopigments showed a spatial positive autocorrelation distribution, following the micro-hydrodynamic pattern, with patches larger than the sub-frame square, but smaller than the entire one (1 m2). Overall, our results suggest that, within 1 m2 of subtidal sandy sediments, three replicates could be sufficient to assess correctly OM attributes and the abundance of meiofauna, but could be possibly inadequate for assessing meiofaunal assemblages’ composition at a finer scale (<1 m2).

scholarly journals Elevated temperature and browning increase dietary methylmercury, but decrease essential fatty acids at the base of lake food webs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pianpian Wu ◽  
Martin J. Kainz ◽  
Fernando Valdés ◽  
Siwen Zheng ◽  
Katharina Winter ◽  
...  
Keyword(s):  
Climate Change ◽  
Fatty Acids ◽  
Organic Matter ◽  
Food Webs ◽  
Essential Fatty Acids ◽  
Trophic Levels ◽  
Climate Change Scenarios ◽  
Essential Nutrients ◽  
Aquatic Food Webs ◽  
Aquatic Food

AbstractClimate change scenarios predict increases in temperature and organic matter supply from land to water, which affect trophic transfer of nutrients and contaminants in aquatic food webs. How essential nutrients, such as polyunsaturated fatty acids (PUFA), and potentially toxic contaminants, such as methylmercury (MeHg), at the base of aquatic food webs will be affected under climate change scenarios, remains unclear. The objective of this outdoor mesocosm study was to examine how increased water temperature and terrestrially-derived dissolved organic matter supply (tDOM; i.e., lake browning), and the interaction of both, will influence MeHg and PUFA in organisms at the base of food webs (i.e. seston; the most edible plankton size for zooplankton) in subalpine lake ecosystems. The interaction of higher temperature and tDOM increased the burden of MeHg in seston (< 40 μm) and larger sized plankton (microplankton; 40–200 μm), while the MeHg content per unit biomass remained stable. However, PUFA decreased in seston, but increased in microplankton, consisting mainly of filamentous algae, which are less readily bioavailable to zooplankton. We revealed elevated dietary exposure to MeHg, yet decreased supply of dietary PUFA to aquatic consumers with increasing temperature and tDOM supply. This experimental study provides evidence that the overall food quality at the base of aquatic food webs deteriorates during ongoing climate change scenarios by increasing the supply of toxic MeHg and lowering the dietary access to essential nutrients of consumers at higher trophic levels.

scholarly journals Glacial melt disturbance shifts community metabolism of an Antarctic seafloor ecosystem from net autotrophy to heterotrophy

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Ulrike Braeckman ◽  
Francesca Pasotti ◽  
Ralf Hoffmann ◽  
Susana Vázquez ◽  
Angela Wulff ◽  
...  
Keyword(s):  
Carbon Balance ◽  
Benthic Communities ◽  
Benthic Primary Production ◽  
Community Metabolism ◽  
West Antarctic ◽  
Run Off ◽  
Net Heterotrophy ◽  
Benthic Ecosystems ◽  
The Antarctic

AbstractClimate change-induced glacial melt affects benthic ecosystems along the West Antarctic Peninsula, but current understanding of the effects on benthic primary production and respiration is limited. Here we demonstrate with a series of in situ community metabolism measurements that climate-related glacial melt disturbance shifts benthic communities from net autotrophy to heterotrophy. With little glacial melt disturbance (during cold El Niño spring 2015), clear waters enabled high benthic microalgal production, resulting in net autotrophic benthic communities. In contrast, water column turbidity caused by increased glacial melt run-off (summer 2015 and warm La Niña spring 2016) limited benthic microalgal production and turned the benthic communities net heterotrophic. Ongoing accelerations in glacial melt and run-off may steer shallow Antarctic seafloor ecosystems towards net heterotrophy, altering the metabolic balance of benthic communities and potentially impacting the carbon balance and food webs at the Antarctic seafloor.

scholarly journals Sink or link? The bacterial role in benthic carbon cycling in the Arabian Sea's oxygen minimum zone

2013 ◽  
Vol 10 (11) ◽  
pp. 6879-6891 ◽  
Author(s):  
L. Pozzato ◽  
D. Van Oevelen ◽  
L. Moodley ◽  
K. Soetaert ◽  
J. J. Middelburg
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Particulate Organic Matter ◽  
Experimental Period ◽  
Oxygen Minimum Zone ◽  
Trophic Levels ◽  
Isotope Tracer ◽  
Oxygen Conditions ◽  
Minimum Zone ◽  
Oxygen Minimum

Abstract. The bacterial loop, the consumption of dissolved organic matter (DOM) by bacteria and subsequent transfer of bacterial carbon to higher trophic levels, plays a prominent role in pelagic food webs. However, its role in sedimentary ecosystems is not well documented. Here we present the results of isotope tracer experiments performed under in situ oxygen conditions in sediments from inside and outside the Arabian Sea's oxygen minimum zone (OMZ) to study the importance of the microbial loop in this setting. Particulate organic matter, added as phytodetritus, was processed by bacteria, protozoa and metazoans, while dissolved organic matter was processed only by bacteria and there was very little, if any, transfer to higher trophic levels within the 7 day experimental period. This lack of significant transfer of bacterial-derived carbon to metazoan consumers indicates that the bacterial loop is rather inefficient, in sediments both inside and outside the OMZ. Moreover, metazoans directly consumed labile particulate organic matter resources and thus competed with bacteria for phytodetritus.

scholarly journals Nutritional Quality and In Vitro Rumen Fermentation Characteristics of Silage Prepared with Lucerne, Sweet Maize Stalk, and Their Mixtures

Agriculture ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1205
Author(s):  
Musen Wang ◽  
Fujin Zhang ◽  
Xinxin Zhang ◽  
Ying Yun ◽  
Lei Wang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Nutritional Quality ◽  
Dry Matter ◽  
Rumen Fermentation ◽  
Gas Production ◽  
Neutral Detergent Fiber ◽  
Ruminal Fermentation ◽  
Fresh Matter ◽  
In Vitro Rumen Fermentation

The objective of this work was to evaluate the pH, chemical composition, minerals, vitamins, and in vitro rumen fermentation characteristics of silage prepared with lucerne, sweet maize stalk (MS), and their mixtures. Freshly chopped lucerne and MS were combined in ratios of 100:0 (M0, control), 80:20 (M20), 60:40 (M40), 40:60 (M60), 20:80 (M80), and 0:100 (M100) on a fresh matter basis. Each treatment was prepared in triplicate, and a total of eighteen silos were fermented for 65 days. After 65 days of fermentation, the pH values in M0, M20, M40, M60, M80, and M100 silages were 5.47, 4.84, 4.23, 4.13, 3.79, and 3.61, respectively. As the MS proportion in the mixtures increased, silage K, Ca, P, Na, Fe, and Cu concentrations linearly decreased (p < 0.001) and so did vitamins B5 and K1 and α-tocopherol. In vitro rumen dry matter and organic matter degradability, pH, ammonia, total volatile fatty acid, and gas production linearly decreased (p < 0.01), while neutral detergent fiber concentration linearly increased (p < 0.001), with increasing proportion of MS. The in vitro dry matter and organic matter degradability rapidly decreased when the MS percentage was ≥60%. In conclusion, the M40 silage is the most suitable for livestock utilization in local forage production considering the balance of silage pH, nutritional quality, and in vitro ruminal fermentation characteristics.

scholarly journals Type of organic fertilizer rather than organic amendment per se increases abundance of soil biota

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11204
Author(s):  
Maria Viketoft ◽  
Laura G.A. Riggi ◽  
Riccardo Bommarco ◽  
Sara Hallin ◽  
Astrid R. Taylor
Keyword(s):  
Organic Matter ◽  
Organic Amendments ◽  
Trophic Levels ◽  
Soil Biota ◽  
Organic Fertilizers ◽  
Nitrogen Fertilizers ◽  
Mineral Fertilizers ◽  
Soil Organisms ◽  
Wide Range

Addition of organic amendments is a commonly used practice to offset potential loss of soil organic matter from agricultural soils. The aim of the present study was to examine how long-term addition of organic matter affects the abundance of different soil biota across trophic levels and the role that the quality of the organic amendments plays. Here we used a 17-year-old fertilization experiment to investigate soil biota responses to four different organic fertilizers, compared with two mineral nitrogen fertilizers and no fertilization, where the organic fertilizers had similar carbon content but varied in their carbon to nitrogen ratios. We collected soil samples and measured a wide range of organisms belonging to different functional groups and trophic levels of the soil food web. Long-term addition of organic and mineral fertilizers had beneficial effects on the abundances of most soil organisms compared with unfertilized soil, but the responses differed between soil biota. The organic fertilizers generally enhanced bacteria and earthworms. Fungi and nematodes responded positively to certain mineral and organic fertilizers, indicating that multiple factors influenced by the fertilization may affect these heterogeneous groups. Springtails and mites were less affected by fertilization than the other groups, as they were present at relatively high abundances even in the unfertilized treatment. However, soil pH had a great influence on springtail abundance. In summary, the specific fertilizer was more important in determining the numerical and compositional responses of soil biota than whether it was mineral or organic. Overall, biennial organic amendments emerge as insufficient, by themselves, to promote soil organisms in the long run, and would need to be added annually or combined with other practices affecting soil quality, such as no or reduced tillage and other crop rotations, to have a beneficial effect.

The impacts of deglaciation and human activity on the taxonomic structure of prokaryotic communities in Antarctic soils on King George Island

2018 ◽  
Vol 30 (5) ◽  
pp. 278-288 ◽  
Author(s):  
E.V. Pershina ◽  
E.A. Ivanova ◽  
E.V. Abakumov ◽  
E.E. Andronov
Keyword(s):  
Bacterial Species ◽  
Taxonomic Composition ◽  
South Shetland Islands ◽  
Soil Microbiome ◽  
Taxonomic Structure ◽  
Rrna Gene ◽  
King George Island ◽  
Antarctic Soils ◽  
Operational Taxonomic Units ◽  
Taxonomic Analysis

AbstractThe soil microbiome was investigated at environmentally distinct locations on King George Island in the South Shetland Islands (Antarctic Peninsula) using 16 S rRNA gene pyrosequencing. The taxonomic composition of the soil prokaryotes (bacteria and archaea) was evaluated at three sites representing human-disturbed soils (Bellingshausen Station) and soils undergoing different stages of deglaciation (fresh and old moraines located near Ecology Glacier). The taxonomic analysis revealed 20 bacterial and archaeal phyla, among which Proteobacteria (29.6%), Actinobacteria (25.3%), Bacteroidetes (15.8%), Cyanobacteria (11.2%), Acidobacteria (4.9%) and Verrucomicrobia (4.5%) comprised most of the microbiome. In a beta-diversity analysis, the samples formed separate clusters. The Bellingshausen Station samples were characterized by an increased amount ofNostocsp. andJanibactersp. Although the deglaciation history had less of an effect on the soil microbiome, the early stages of deglaciation (Sample 1) had a higher proportion of bacteria belonging to the families Xanthomonadaceae, Sphingomonadaceae and Nocardioidaceae, whereas the older moraines (Sample 2) were enriched with Chthoniobacteriacae and N1423WL. Solirubrobacteriales, Gaiellaceae and Chitinophagaceae bacteria were present in both stages of deglaciation, characterized by genus-level differences. Taxonomic analysis of the abundant operational taxonomic units (OTUs) revealed both endemic (Marisediminicola antarctica,Hymenobacter glaciei) and cosmopolitan bacterial species in the microbiomes.

The composition and functioning of benthic ecosystems in relation to the assessment of long-term effects of oil pollution

1982 ◽  
Vol 297 (1087) ◽  
pp. 257-267 ◽  
Keyword(s):  
Ecological Study ◽  
Sublethal Effects ◽  
Oil Pollution ◽  
Benthic Communities ◽  
Biological Interactions ◽  
Long Term Effects ◽  
Ecological Awareness ◽  
Different Types ◽  
Benthic Ecosystems

The assessment of long-term effects of oil pollution is ultimately a matter of field responses and ecological interpretation. Chronic conditions present much greater interpretative problems than the aftermath of a severe spill because the detection of subtle effects has to be made against the usually unknown scales of natural changes taking place. Examples from various coastal benthic communities illustrate types of biological interactions, different types and degrees of biological stability and the sometimes unpredictable timescales involved. Special attention is drawn to the significance of natural fluctuations in recruitment and to the geographical scales on which these may occur. Have such matters been taken into account in the past? For the future the extreme difficulty that may be involved in detecting subtle deterioration necessitates both a considerable increase in ecological awareness and the directing of work on sublethal effects to those species most am enable to ecological study.

Sign in / Sign up

Export Citation Format

Share Document