Stable isotope composition (δ13C and δ15N) of larval krill, Euphausia superba, and two of its potential food sources in winter

We assessed the biomass and stable-isotope composition (δ13C and δ15N) of consumers (aquatic insects and fish (Cottus gobio)) and potential food sources (detritus, biofilm, seston, algae, and mosses) in channelized and restored streams in Sweden, assessing the hypotheses that restoration enhances detritus storage and detritus-based secondary production. Restored sites stored more detritus than channelized sites, with differences (+5.4% on average) prominent in margins, i.e., the channel area within 1.4 m from the banks. The biomass of other resources was similar between restored and channelized sites. Most common aquatic insects, including several putative detritivores, showed δ13C values indicating reliance on aquatic (probably algal) carbon sources. The insectivorous fish Cottus gobio, on the contrary, appeared to be more dependent on terrestrial (detrital) carbon sources. The biomass and mean δ13C values of the consumers were similar between restored and channelized sites, suggesting that restoration did not increase net secondary production or the fraction of secondary production based on detritus. We concluded that the increase in detritus storage at restored sites was either insufficient to enhance detritus-based production or the consumers were not limited by the availability of detritus.

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Spatio–temporal variation in stable isotope signatures (δ13C and δ15N) of sponges on the Saba Bank

PeerJ ◽

10.7717/peerj.5460 ◽

2018 ◽

Vol 6 ◽

pp. e5460 ◽

Cited By ~ 3

Author(s):

Fleur C. Van Duyl ◽

Benjamin Mueller ◽

Erik H. Meesters

Keyword(s):

Organic Matter ◽

Stable Isotope ◽

Environmental Changes ◽

Food Sources ◽

Sponge Species ◽

Isotopic Niche ◽

Δ13c And Δ15n ◽

Spatio Temporal ◽

Species Specific ◽

Potential Food

Sponges are ubiquitous on coral reefs, mostly long lived and therefore adaptive to changing environmental conditions. They feed on organic matter withdrawn from the passing water and they may harbor microorganisms (endosymbionts), which contribute to their nutrition. Their diets and stable isotope (SI) fractionation determine the SI signature of the sponge holobiont. Little is known of spatio–temporal variations in SI signatures of δ13C and δ15N in tropical sponges and whether they reflect variations in the environment. We investigated the SI signatures of seven common sponge species with different functional traits and their potential food sources between 15 and 32 m depth along the S-SE and E-NE side of the Saba Bank, Eastern Caribbean, in October 2011 and October 2013. SI signatures differed significantly between most sponge species, both in mean values and in variation, indicating different food preferences and/or fractionation, inferring sponge species-specific isotopic niche spaces. In 2011, all sponge species at the S-SE side were enriched in d13C compared to the E-NE side. In 2013, SI signatures of sponges did not differ between the two sides and were overall lighter in δ13C and δ15N than in 2011. Observed spatio–temporal changes in SI in sponges could not be attributed to changes in the SI signatures of their potential food sources, which remained stable with different SI signatures of pelagic (particulate organic matter (POM): δ13C −24.9‰, δ15N +4.3‰) and benthic-derived food (macroalgae: δ13C −15.4‰, δ15N +0.8‰). Enriched δ13C signatures in sponges at the S-SE side in 2011 are proposed to be attributed to predominantly feeding on benthic-derived C. This interpretation was supported by significant differences in water mass constituents between sides in October 2011. Elevated NO3 and dissolved organic matter concentrations point toward a stronger reef signal in reef overlying water at the S-SE than N-NE side of the Bank in 2011. The depletions of δ13C and δ15N in sponges in October 2013 compared to October 2011 concurred with significantly elevated POM concentrations. The contemporaneous decrease in δ15N suggests that sponges obtain their N mostly from benthic-derived food with a lower δ15N than pelagic food. Average proportional feeding on available sources varied between sponge species and ranged from 20% to 50% for benthic and 50% to 80% for pelagic-derived food, assuming trophic enrichment factors of 0.5‰ ± sd 0.5 for δ13C and 3‰ ± sd 0.5 for δ15N for sponges. We suggest that observed variation of SI in sponges between sides and years were the result of shifts in the proportion of ingested benthic- and pelagic-derived organic matter driven by environmental changes. We show that sponge SI signatures reflect environmental variability in space and time on the Saba Bank and that SI of sponges irrespective of their species-specific traits move in a similar direction in response to these environmental changes.

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BASIN TCP STABLE ISOTOPE COMPOSITION OF CO2 IN TERRESTRIAL ECOSYSTEMS

ORNL Distributed Active Archive Center Datasets ◽

10.3334/ornldaac/963 ◽

2010 ◽

Author(s):

C.T. LAI, ◽

J.R. EHLERINGER,

Keyword(s):

Stable Isotope ◽

Isotope Composition ◽

Terrestrial Ecosystems ◽

Stable Isotope Composition

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Ontogenetic trends in resource partitioning and trophic geography of sympatric skates (Rajidae) inferred from stable isotope composition across eye lenses

Marine Ecology Progress Series ◽

10.3354/meps13030 ◽

2019 ◽

Vol 624 ◽

pp. 103-116 ◽

Cited By ~ 5

Author(s):

SJ Simpson ◽

DW Sims ◽

CN Trueman

Keyword(s):

Stable Isotope ◽

Resource Partitioning ◽

Isotope Composition ◽

Stable Isotope Composition

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Determining the stable isotope composition of porewater using low temperature multi-step extraction for low water content soils

Journal of Hydrology ◽

10.1016/j.jhydrol.2021.126079 ◽

2021 ◽

Vol 596 ◽

pp. 126079

Author(s):

Sanyuan Jiang ◽

Wenbo Rao ◽

Liangfeng Han

Keyword(s):

Stable Isotope ◽

Low Temperature ◽

Water Content ◽

Isotope Composition ◽

Stable Isotope Composition

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Multi-regression analysis between stable isotope composition and hydrochemical parameters in karst springs to provide insights into groundwater origin and subsurface processes: regional application to Lebanon

Environmental Earth Sciences ◽

10.1007/s12665-021-09519-4 ◽

2021 ◽

Vol 80 (6) ◽

Author(s):

Reda ElGhawi ◽

Karlo Pekhazis ◽

Joanna Doummar

Keyword(s):

Regression Analysis ◽

Stable Isotope ◽

Isotope Composition ◽

Stable Isotope Composition ◽

Hydrochemical Parameters ◽

Karst Springs ◽

Groundwater Origin

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Chemical and stable isotope composition of surface and groundwater in the surroundings of the Los Humeros Caldera, Puebla, Mexico

E3S Web of Conferences ◽

10.1051/e3sconf/20199807013 ◽

2019 ◽

Vol 98 ◽

pp. 07013

Author(s):

Thomas Kretzschmar ◽

Matteo Lelli ◽

Ruth Alfaro ◽

Juan Ignacio Sanchez ◽

Yann Rene Ramos

Keyword(s):

Stable Isotope ◽

Isotope Composition ◽

Regression Line ◽

Sustainable Use ◽

Geothermal Reservoir ◽

Maximum Temperature ◽

Stable Isotope Composition ◽

Local Fracture ◽

Hydrogeological Model ◽

Fracture Systems

It is important to develop a regional hydrogeological model to identify possible recharge and discharge areas for a sustainable use of a geothermal reservoir. The Los Humeros geothermal area is situated within five surficial watersheds and coveres an area of more than 15.000 km2. A total of 208 well and spring samples were collected between June 2017 and November 2018. The stable isotope data for this region define a regression line of δDH2O = 8.032·δ18O + 12 and indicate that groundwater is recharged by regional precipitation. At least 39 groundwater wells, with a maximum temperature of 35 °C, show temperatures above the reported mean average surface temperature of 15 °C. Characteristic elements for geothermal reservoir fluids (B, Li, As) are also present in these groundwaters, indicating a possible connection between the reservoir fluid and the local groundwater through local fracture systems. Concentration of B in these hot wells is between 150 and 35000 ppb.

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