scholarly journals Assessing the utility of sulfur isotope values for understanding mercury concentrations in water and biota from high Arctic lakes

2019 ◽  
Vol 5 (2) ◽  
pp. 90-106 ◽  
Author(s):  
Gretchen L. Lescord ◽  
Meredith G. Clayden ◽  
Karen A. Kidd ◽  
Jane L. Kirk ◽  
Xiaowa Wang ◽  
...  
Keyword(s):  
Food Webs ◽  
Total Mercury ◽  
Nitrogen Isotopes ◽  
Sulfur Isotopes ◽  
High Arctic ◽  
Arctic Lakes ◽  
Carbon And Nitrogen ◽  
Resolute Bay ◽  
Aquatic Food ◽  
Globally Stable

Methylmercury (MeHg) biomagnifies through aquatic food webs resulting in elevated concentrations in fish globally. Stable carbon and nitrogen isotopes are frequently used to determine dietary sources of MeHg and to model its biomagnification. However, given the strong links between MeHg and sulfur cycling, we investigated whether sulfur isotopes (δ34S) would improve our understanding of MeHg concentrations ([MeHg]) in Arctic lacustrine food webs. Delta34S values and total mercury (THg) or MeHg were measured in water, sediments, and biota from six lakes near Resolute Bay, NU, Canada. In two lakes impacted by historical eutrophication, aqueous sulfate δ34S was ∼8‰ more positive than sedimentary δ34S, suggestive of bacterial sulfate reduction in the sediment. In addition, aqueous δ34S showed a significant positive relationship with aqueous [MeHg] across lakes. Within taxa across lakes, [THg] in Arctic char muscle and [MeHg] in their main prey, chironomids, were positively related to their δ34S values across lakes, but inconsistent relationships were found across entire food webs among lakes. Across lakes, nitrogen isotopes were better predictors of biotic [THg] and [MeHg] than δ34S within this dataset. Our results suggest some linkages between Hg and S biogeochemistry in high Arctic lakes, which is an important consideration given anticipated climate-mediated changes in nutrient cycling.

scholarly journals Aquatic food webs in mangrove and seagrass habitats of Centla Wetland, a Biosphere Reserve in Southeastern Mexico

2010 ◽  
Vol 8 (1) ◽  
pp. 171-178 ◽  
Author(s):  
Manuel Mendoza-Carranza ◽  
David J Hoeinghaus ◽  
Alexandre M Garcia ◽  
Ángel Romero-Rodriguez
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Native Species ◽  
Human Impacts ◽  
Biosphere Reserve ◽  
Isotope Ratios ◽  
Future Research ◽  
Carbon And Nitrogen ◽  
Aquatic Food Webs ◽  
Aquatic Food

Mangrove and seagrass habitats are important components of tropical coastal zones worldwide, and are conspicuous habitats of Centla Wetland Biosphere Reserve (CWBR) in Tabasco, Mexico. In this study, we examine food webs in mangrove- and seagrass-dominated habitats of CWBR using stable isotope ratios of carbon and nitrogen. Our objective was to identify the importance of carbon derived from mangroves and seagrasses to secondary production of aquatic consumers in this poorly studied conservation area. Carbon and nitrogen isotope ratios of basal sources and aquatic consumers indicated that the species-rich food webs of both habitats are dependent on riparian production sources. The abundant Red mangrove Rhizophora mangle appears to be a primary source of carbon for the mangrove creek food web. Even though dense seagrass beds were ubiquitous, most consumers in the lagoon food web appeared to rely on carbon derived from riparian vegetation (e.g. Phragmites australis). The introduced Amazon sailfin catfish Pterygoplichthys pardalis had isotope signatures overlapping with native species (including high-value fisheries species), suggesting potential competition for resources. Future research should examine the role played by terrestrial insects in linking riparian and aquatic food webs, and impacts of the expanding P. pardalis population on ecosystem function and fisheries in CWBR. Our findings can be used as a baseline to reinforce the conservation and management of this important reserve in the face of diverse external and internal human impacts.

scholarly journals Stable isotopes dissect food webs from top to the bottom

2013 ◽  
Vol 10 (9) ◽  
pp. 14923-14952 ◽  
Author(s):  
J. J. Middelburg
Keyword(s):  
Stable Isotopes ◽  
Food Web ◽  
Food Webs ◽  
Nitrogen Isotopes ◽  
Web Studies ◽  
Carbon And Nitrogen ◽  
Challenges And Opportunities ◽  
Recent Developments ◽  
End To End ◽  
Small Producers

Abstract. Stable isotopes have been used extensively to study food web functioning, i.e. the flow of energy and matter among organisms. Traditional food-web studies are based on the natural variability of carbon and nitrogen isotopes and are limited to larger organisms that can be physically separated from their environment. Recent developments allow isotope ratio measurements of microbes and this in turn allows then measurement of entire food webs, i.e. from small producers at the bottom to large consumers at the top. Here, I provide a concise review on the use and potential of stable isotope to reconstruct end-to-end food webs. I will first discuss food web reconstruction based on natural abundances isotope data and will then show that the use of stable isotopes as deliberately added tracers provides complementary information. Finally, challenges and opportunities for end-to-end food web reconstructions in a changing world are discussed.

scholarly journals Food webs of the Paraná River floodplain: Assessing basal sources using stable carbon and nitrogen isotopes

Limnologica ◽  
2014 ◽  
Vol 46 ◽  
pp. 22-30 ◽  
Author(s):  
Mercedes Rosa Marchese ◽  
Miguel Saigo ◽  
Florencia Lucila Zilli ◽  
Soledad Capello ◽  
Melina Devercelli ◽  
...  
Keyword(s):  
Food Webs ◽  
Nitrogen Isotopes ◽  
Paraná River ◽  
Stable Carbon ◽  
River Floodplain ◽  
Carbon And Nitrogen Isotopes ◽  
Carbon And Nitrogen ◽  
Parana River ◽  
Paraná River Floodplain

Eutrophication in the High Arctic — Meretta Lake, Cornwallis Island (75° N Lat.)

1974 ◽  
Vol 31 (5) ◽  
pp. 647-662 ◽  
Author(s):  
D. W. Schindler ◽  
J. Kalff ◽  
H. E. Welch ◽  
G. J. Brunskill ◽  
H. Kling ◽  
...  
Keyword(s):  
Algal Species ◽  
Oxygen Depletion ◽  
High Arctic ◽  
Arctic Lakes ◽  
Nutrient Inputs ◽  
Lake Surface ◽  
Annual Cycles ◽  
High Nutrient ◽  
Resolute Bay ◽  
Cornwallis Island

Sewage from the Department of Transport Airport Base at Resolute Bay has caused increases in phytoplankton standing crop, changes in algal species composition, oxygen depletion, and disappearance of Limnocalanus in Meretta Lake. The annual cycles of chemical and physical events associated with these changes are described. Minimum annual input of phosphorus to Meretta Lake was 0.24–0.29 g/m2 of lake surface per year in 1971, with 66–80% supplied by sewage. Nitrogen input was 0.55–0.78 g/m2 during the same year, with 41 to 58% from sewage. Results show that severe eutrophication problems may be expected to develop in response to high nutrient inputs, even at arctic latitudes. Arctic lakes, which are sealed under ice for several months of the year, appear to be particularly vulnerable to increased oxygen depletion which accompanies eutrophication.

scholarly journals Land use change in the Atlantic Forest affects carbon and nitrogen sources of streams as revealed by the isotopic composition of terrestrial invertebrates

2015 ◽  
Vol 15 (2) ◽  
Author(s):  
Fernanda Gaudio Augusto ◽  
Mauricio Tassoni Filho ◽  
Anderson Ferreira ◽  
Alexandre Leandro Pereira ◽  
Plínio Barbosa de Camargo ◽  
...  
Keyword(s):  
Land Cover ◽  
Food Webs ◽  
Atlantic Forest ◽  
Ecosystem Functioning ◽  
C4 Grasses ◽  
Terrestrial Invertebrates ◽  
Carbon And Nitrogen ◽  
Aquatic Food Webs ◽  
Forest Stream ◽  
Aquatic Food

Terrestrial invertebrates link terrestrial systems to aquatic ones, making vegetal material produced in the watershed available to aquatic food webs. In this study, using carbon and nitrogen stable isotopes, we evaluated the importance of introduced C4 grasses as a source of carbon in aquatic food webs of headwater streams of the coastal Atlantic Forest located on the north coast of the State of São Paulo, in the southeastern region of Brazil. Terrestrial invertebrates were collected in two streams: one where the main land cover was pristine montane Atlantic Forest (forest stream) and another where the main land cover was introduced C4 forage grasses for livestock (pasture stream). The average δ13C of terrestrial invertebrates collected in the forest stream (−26.3±2.1‰) was significantly (p<0.01) smaller than the average δ13C of terrestrial invertebrates collected in the pasture stream (−15.7±4.7‰), denoting a larger contribution of C4grasses to terrestrial invertebrates of the pasture stream. The average δ15N of terrestrial invertebrates of the forest stream (4.1±2.4‰) was significantly (p<0.01) lower than the average δ15N of terrestrial invertebrates of the pasture stream (9.5±2.7‰). The relative contribution of C3 and C4 plants to terrestrial invertebrates was estimated using SIAR. In the forest stream, the C3 contribution was on average 0.75 (0.72 minimum to 0.79 maximum), and the C4 contribution was on average 0.25 (0.21 minimum to 0.28 maximum). In the pasture stream, the C3contribution decreased to 0.20 (0.14 minimum to 0.26 maximum), and the C4 contribution increased to 0.80 (0.74 minimum to 0.86 maximum). These results have several implications for the ecosystem functioning as well as for recent changes in environmental policies of Brazil. The lower nutritional value of C4 grasses may not only decrease invertebrate performance, but also alter the stoichiometry of several components of the aquatic food webs with potential consequence for the whole ecosystem functioning. On the public policy side, recent changes in the Brazilian Forest Act, a series of laws that regulate land cover at the property level, reduced the width of the forested riparian area with potentially dangerous consequences for aquatic ecosystems.

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