scholarly journals Trophic structure of an African savanna river and organic matter inputs by large terrestrial herbivores: A stable isotope approach

2018 ◽  
Vol 63 (11) ◽  
pp. 1365-1380 ◽  
Author(s):  
Frank O. Masese ◽  
Kátya G. Abrantes ◽  
Gretchen M. Gettel ◽  
Kenneth Irvine ◽  
Steven Bouillon ◽  
...  
Keyword(s):  
Organic Matter ◽  
Stable Isotope ◽  
Trophic Structure ◽  
African Savanna

Trophic structure of stream macroinvertebrate communities revealed by stable isotope analysis

2008 ◽  
Vol 58 (3) ◽  
pp. 503-512 ◽  
Author(s):  
Kozo Watanabe ◽  
Tatsuo Omura
Keyword(s):  
Organic Matter ◽  
Stable Isotope ◽  
Particulate Organic Matter ◽  
Stable Isotope Analysis ◽  
Trophic Structure ◽  
Isotope Analysis ◽  
Main Channel ◽  
Macroinvertebrate Community ◽  
Δ13c And Δ15n ◽  
Stream Macroinvertebrate

The trophic structure of a macroinvertebrate community was investigated using carbon and nitrogen stable isotopes analysis (δ13C and δ15N) at three longitudinal sites along the main channel of the Hirose River, Japan, and at an outlet site of the tributary reservoir. Along the main channel, primal food supply gradually changed from allochthonous to autochthonous source. The percentage of autochthonous origin of the macroinvertebrate community calculated by a carbon-mixing model (=38–83%) increased with that of suspended fine particulate organic matter (FPOM = 21–67%), a main resource for filtering-collectors that dominated the communities. The lowest percentage of autochthonous in the lake outlet community (=21%) was a result of the notably low percentage autochthonous of FPOM due to the decomposition of allochthonous coarse particulate organic matter (e.g., leaf) strained in the reservoir. Predators had higher mean δ15N than non-predators in three sites. The average enrichments of δ15N signature per trophic level for all sites were 3.82‰ from producers to first consumers and 1.24‰ from first to second consumers. Our data suggest the strong potential for stable isotope analysis to enhance our understanding of the trophic structure of stream macroinvertebrate community.

scholarly journals Trophic structure and energy flow in a shallow-water hydrothermal vent: Insights from a stable isotope approach

PLoS ONE ◽  
2018 ◽  
Vol 13 (10) ◽  
pp. e0204753 ◽  
Author(s):  
Ni-Na Chang ◽  
Li-Hung Lin ◽  
Tzu-Hsuan Tu ◽  
Ming-Shiou Jeng ◽  
Yoshito Chikaraishi ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Shallow Water ◽  
Hydrothermal Vent ◽  
Energy Flow ◽  
Trophic Structure

Stable-isotope Raman microspectroscopy for the analysis of soil organic matter

2017 ◽  
Vol 410 (3) ◽  
pp. 923-931 ◽  
Author(s):  
Alexandra C. Wiesheu ◽  
Ramona Brejcha ◽  
Carsten W. Mueller ◽  
Ingrid Kögel-Knabner ◽  
Martin Elsner ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Stable Isotope ◽  
Raman Microspectroscopy

scholarly journals Barium stable isotopes as a fingerprint of biological cycling in the Amazon River basin

2020 ◽  
Vol 17 (23) ◽  
pp. 5989-6015
Author(s):  
Quentin Charbonnier ◽  
Julien Bouchez ◽  
Jérôme Gaillardet ◽  
Éric Gayer
Keyword(s):  
Organic Matter ◽  
Stable Isotope ◽  
Trace Element ◽  
Isotope Composition ◽  
Silicate Weathering ◽  
Biological Cycling ◽  
Biological Uptake ◽  
Dissolved Load ◽  
Silicate Rocks

Abstract. The biological cycle of rock-derived nutrients on the continents is a major component of element transfer between the Earth's surface compartments, but its magnitude currently remains elusive. The use of the stable isotope composition of rock-derived nutrients, which can be fractionated during biological uptake, provides a promising path forward with respect to quantifying biological cycling and its overall contribution to global element cycling. In this paper, we rely on the nutrient-like behaviour of the trace element barium (Ba) and use its elemental and stable isotope compositions in dissolved and sediment load river samples to investigate biological cycling in the Amazon Basin. From these measurements, we show that dissolved Ba mainly derives from silicate rocks, and a correlation between dissolved Ba and K abundances suggests that biological cycling plays a role in the Ba river budget. Furthermore, the isotope composition of Ba (δ138Ba) in the dissolved load was found to be significantly different from that of the parent silicate rocks, implying that dissolved Ba isotopic signatures are affected by (i) the precipitation of soil-forming secondary phases as well as (ii) biological uptake and release from dead organic matter. Results from an isotope mass balance method applied to the river dissolved load data indicate that, after its release to solution by rock weathering, Ba is partitioned between the river dissolved load, secondary weathering products (such as those found in soils and river sediments), and the biota. In most sub-catchments of the Amazon, river Ba abundances and isotope compositions are significantly affected by biological cycling. Relationships between estimates of Ba cycled through biota and independent metrics of ecosystem dynamics (such as gross primary production and terrestrial ecosystem respiration) allow us to discuss the role of environmental parameters such as climate or erosion rates on the biological cycling of Ba and, by extension, the role of major rock-derived nutrients. In addition, catchment-scale mass and isotope budgets of Ba show that the measured riverine export of Ba is lower than the estimated delivery of Ba to the Earth surface through rock alteration. This indicates the existence of a missing Ba component, which we attribute to the formation of Ba-bearing particulate organics (possibly accumulating as soil organic matter or currently growing biomass within the catchments) and to organic-bound Ba exported as “unsampled” river particulate organic matter. Given our findings on the trace element Ba, we explore whether the river fluxes of most major rock-derived nutrients (K, Mg, Ca) might also be significantly affected by biological uptake or release. A first-order correction of river-derived silicate weathering fluxes from biological cycling shows that the carbon dioxide (CO2) consumption by silicate weathering at the mouth of the Amazon could be several times higher than the previously reported value of 13 × 109 mol CO2 yr−1 (Gaillardet et al., 1997). Overall, our study clearly shows that the chemical and isotope compositions of rivers in the Amazon – and most likely in other large river basins – bear a biological imprint, thereby challenging common assumptions made in weathering studies.

scholarly journals Trophic structure of a nektobenthic community exploited by a multispecific bottom trawling fishery in Northeastern Brazil

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246491
Author(s):  
Alex Souza Lira ◽  
Flávia Lucena-Frédou ◽  
Frédéric Ménard ◽  
Thierry Frédou ◽  
Júlio Guazzelli Gonzalez ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Food Web ◽  
Benthic Invertebrates ◽  
Trophic Structure ◽  
Fish Fauna ◽  
Cumulative Effects ◽  
Northeastern Brazil ◽  
Population Parameters ◽  
Bottom Trawling ◽  
Trophic Pathways

We used complementary stable isotope (SIA) and stomach content (SCA) analyses to investigate feeding relationships among species of the nektobenthic communities and the potential ecological effects of the bottom trawling of a coastal ecosystem in northeastern Brazil. Carbon (δ13C) and nitrogen (δ15N) compositions were determined for five basal sources and 28 consumers, from zooplankton to shrimp and fish species. Fishes and basal sources showed a broad range of δ15N (fishes: 6.49–14.94‰; sources: 2.58–6.79‰) and δ13C values (fishes: -23.86 to -13.71‰; sources: -24.32 to -13.53‰), while shrimps and crabs exhibited similar nitrogen and carbon ratios. Six trophic consumer groups were determined among zooplankton, crustaceans and fishes by SIA, with trophic pathways associated mostly with benthic sources. SCA results indicated a preference for benthic invertebrates, mainly worms, crabs and shrimps, as prey for the fish fauna, highlighting their importance in the food web. In overall, differences between SCA and the SIA approaches were observed, except for groups composed mainly for shrimps and some species of high δ15N values, mostly piscivorous and zoobenthivores. Given the absence of regulation for bottom trawling activities in the area, the cumulative effects of trawling on population parameters, species composition, potentially decreasing the abundance of benthic preys (e.g., shrimps, worms and crabs) may lead to changes in the trophic structure potentially affect the food web and the sustainability of the fishery.

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