Sources of Organic Carbon in the Food Webs of Two Florida Lakes Indicated by Stable Isotopes

Introduction to the Principles of δ18O, δ13C, and 87Sr/86Sr in the Palaeosciences.

10.31233/osf.io/kn7cw ◽

2021 ◽

Author(s):

Jack Wilkin

Keyword(s):

Stable Isotopes ◽

Organic Carbon ◽

Food Webs ◽

Quantitative Data ◽

Ecological Change ◽

Metabolic Rates ◽

Research Institutions ◽

Glacial Ice ◽

Weathering Rates ◽

The World

The stable isotopes of oxygen (O), carbon (C), strontium (Sr), hydrogen (H), and nitrogen (N) have all been utilised for great effect in palaeoclimate, palaeoecological and palaeobiological studies. Of these, O and C have been by far the most important and, in many types of study, their use has become routine in universities and research institutions around the world. Stable isotopes provide quantitative data about palaeotemperatures, metabolic rates, food webs, palaeosalinity, palaeoprecipitation and evaporation rates as well as glacial ice volumes, production and burial of organic carbon, and other processes related to palaeoclimatic/biological/ecological change. Except for Sr, all the previously mentioned isotopes (O, C, H, and N) directly record paleoclimatic, biological and palaeoecological processes. Conversely, Sr reflects the composition of rocks at the Earth's surface, and its values reflect on the climate indirectly as it is a proxy for global weathering rates and seafloor spreading. This review will only be focusing on three isotopes commonly deployed by palaeo-researchers: carbon, oxygen, and strontium.

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Stable isotopes of a terrestrial amphibian illustrate fertilizer-related nitrogen enrichment of food webs in agricultural habitats

Agriculture Ecosystems & Environment ◽

10.1016/j.agee.2021.107553 ◽

2021 ◽

Vol 319 ◽

pp. 107553

Author(s):

Matthias Renoirt ◽

Frédéric Angelier ◽

Marion Cheron ◽

Paco Bustamante ◽

Yves Cherel ◽

...

Keyword(s):

Stable Isotopes ◽

Food Webs ◽

Nitrogen Enrichment

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Boomerang ecosystem fluxes: organic carbon inputs from land to lakes are returned to terrestrial food webs via aquatic insects

Oikos ◽

10.1111/oik.01524 ◽

2014 ◽

Vol 123 (12) ◽

pp. 1439-1448 ◽

Cited By ~ 26

Author(s):

K. Scharnweber ◽

M. J. Vanni ◽

S. Hilt ◽

J. Syväranta ◽

T. Mehner

Keyword(s):

Organic Carbon ◽

Food Webs ◽

Aquatic Insects

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δ¹³C evidence of the origins and fates of organic carbon in estuarine and near-shore food webs

Marine Ecology Progress Series ◽

10.3354/meps022141 ◽

1985 ◽

Vol 22 ◽

pp. 141-152 ◽

Cited By ~ 93

Author(s):

CA Simenstad ◽

RC Wissmar

Keyword(s):

Organic Carbon ◽

Food Webs ◽

Near Shore

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‘Taking Fishers’ Knowledge to the Lab’: An Interdisciplinary Approach to Understand Fish Trophic Relationships in the Brazilian Amazon

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2021.723026 ◽

2021 ◽

Vol 9 ◽

Author(s):

Paula Evelyn Rubira Pereyra ◽

Gustavo Hallwass ◽

Mark Poesch ◽

Renato Azevedo Matias Silvano

Keyword(s):

Stable Isotopes ◽

Food Webs ◽

Fish Species ◽

Trophic Interactions ◽

Brazilian Amazon ◽

Trophic Levels ◽

Trophic Relationships ◽

Ecological Knowledge ◽

Data Limitations ◽

Combining Data

Trophic levels can be applied to describe the ecological role of organisms in food webs and assess changes in ecosystems. Stable isotopes analysis can assist in the understanding of trophic interactions and use of food resources by aquatic organisms. The local ecological knowledge (LEK) of fishers can be an alternative to advance understanding about fish trophic interactions and to construct aquatic food webs, especially in regions lacking research capacity. The objectives of this study are: to calculate the trophic levels of six fish species important to fishing by combining data from stable isotopes analysis and fishers’ LEK in two clear water rivers (Tapajós and Tocantins) in the Brazilian Amazon; to compare the trophic levels of these fish between the two methods (stable isotopes analysis and LEK) and the two rivers; and to develop diagrams representing the trophic webs of the main fish prey and predators based on fisher’s LEK. The fish species studied were Pescada (Plagioscion squamosissimus), Tucunaré (Cichla pinima), Piranha (Serrasalmus rhombeus), Aracu (Leporinus fasciatus), Charuto (Hemiodus unimaculatus), and Jaraqui (Semaprochilodus spp.). A total of 98 interviews and 63 samples for stable isotopes analysis were carried out in both rivers. The average fish trophic levels did not differ between the stable isotopes analysis and the LEK in the Tapajós, nor in the Tocantins Rivers. The overall trophic level of the studied fish species obtained through the LEK did not differ from data obtained through the stable isotopes analysis in both rivers, except for the Aracu in the Tapajós River. The main food items consumed by the fish according to fishers’ LEK did agree with fish diets as described in the biological literature. Fishers provided useful information on fish predators and feeding habits of endangered species, such as river dolphin and river otter. Collaboration with fishers through LEK studies can be a viable approach to produce reliable data on fish trophic ecology to improve fisheries management and species conservation in tropical freshwater environments and other regions with data limitations.

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Substantial accumulation of mercury in the deepest parts of the ocean and implications for the environmental mercury cycle

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2102629118 ◽

2021 ◽

Vol 118 (51) ◽

pp. e2102629118

Author(s):

Maodian Liu ◽

Wenjie Xiao ◽

Qianru Zhang ◽

Shengliu Yuan ◽

Peter A. Raymond ◽

...

Keyword(s):

Organic Carbon ◽

Food Webs ◽

Deep Sea ◽

Anthropogenic Activities ◽

Sediment Cores ◽

Anthropogenic Sources ◽

Biogeochemical Cycle ◽

Vertical Profiles ◽

Surface Ocean ◽

Increasing Trends

Anthropogenic activities have led to widespread contamination with mercury (Hg), a potent neurotoxin that bioaccumulates through food webs. Recent models estimated that, presently, 200 to 600 t of Hg is sequestered annually in deep-sea sediments, approximately doubling since industrialization. However, most studies did not extend to the hadal zone (6,000- to 11,000-m depth), the deepest ocean realm. Here, we report on measurements of Hg and related parameters in sediment cores from four trench regions (1,560 to 10,840 m), showing that the world’s deepest ocean realm is accumulating Hg at remarkably high rates (depth-integrated minimum–maximum: 24 to 220 μg ⋅ m−2 ⋅ y−1) greater than the global deep-sea average by a factor of up to 400, with most Hg in these trenches being derived from the surface ocean. Furthermore, vertical profiles of Hg concentrations in trench cores show notable increasing trends from pre-1900 [average 51 ± 14 (1σ) ng ⋅ g−1] to post-1950 (81 ± 32 ng ⋅ g−1). This increase cannot be explained by changes in the delivery rate of organic carbon alone but also need increasing Hg delivery from anthropogenic sources. This evidence, along with recent findings on the high abundance of methylmercury in hadal biota [R. Sun et al., Nat. Commun. 11, 3389 (2020); J. D. Blum et al., Proc. Natl. Acad. Sci. U. S. A. 117, 29292–29298 (2020)], leads us to propose that hadal trenches are a large marine sink for Hg and may play an important role in the regulation of the global biogeochemical cycle of Hg.

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