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

2014 ◽  
Vol 11 (8) ◽  
pp. 2357-2371 ◽  
Author(s):  
J. J. Middelburg
Keyword(s):  
Stable Isotopes ◽  
Food Web ◽  
Food Webs ◽  
Web Studies ◽  
Challenges And Opportunities ◽  
Recent Developments ◽  
End To End ◽  
Aquatic Food ◽  
Small Producers ◽  
Web Reconstruction

Abstract. Stable isotopes have been used extensively to study food-web functioning, that is, the flow of energy and matter among organisms. Traditional food-web studies are based on the natural variability of 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 the measurement of entire food webs, in other words, 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 isotopes 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 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.

Carbon sources for aquatic food webs of riverine and lacustrine tropical waterholes with variable groundwater influence

2017 ◽  
Vol 68 (3) ◽  
pp. 442 ◽  
Author(s):  
N. E. Pettit ◽  
D. M. Warfe ◽  
P. G. Close ◽  
B. J. Pusey ◽  
R. Dobbs ◽  
...  
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Isotope Analysis ◽  
Carbon Sources ◽  
Freshwater Wetlands ◽  
Food Sources ◽  
Web Studies ◽  
Aquatic Food Webs ◽  
Aquatic Food ◽  
Groundwater Reserves

Food web studies integrate ecological information and provide understanding of ecosystem function. Aquatic ecosystems of the Kimberley region (north-western Australia) have high conservation significance as hotspots for maintaining local and regional biodiversity. This study investigated the influence of waterhole type and persistence on the strength of consumer reliance on local energy resources for aquatic food webs. Changes in water isotopic composition indicated groundwater inputs were enough to overcome evaporative losses in some waterholes. Other waterholes had varying levels of isotope enrichment suggesting insufficient groundwater input to ‘compensate’ for evaporative loss. C and N isotope analysis indicated considerable overlap among energy sources in waterholes between macrophytes and periphyton but gradient analysis indicated that periphyton is a major carbon source for aquatic consumers. Groundwater-fed waterholes appeared to have higher quality food sources (indicated by lower C:N ratios), but there was minimal evidence that direct groundwater contributions were related to food web processes. Nonetheless, in a region where groundwater is influential in maintaining aquatic habitats, future development of groundwater reserves will likely affect the ecological and cultural value of freshwater wetlands by either reducing their permanence or size or indirectly through possible alteration to the role of periphyton in supporting the food web.

scholarly journals The use of DNA barcodes in food web construction—terrestrial and aquatic ecologists unite!

Genome ◽  
2016 ◽  
Vol 59 (9) ◽  
pp. 603-628 ◽  
Author(s):  
Tomas Roslin ◽  
Sanna Majaneva
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Taxonomic Resolution ◽  
Dna Barcodes ◽  
Food Web Structure ◽  
Web Studies ◽  
Web Structure ◽  
Asking Questions ◽  
Web Construction ◽  
Interaction Webs

By depicting who eats whom, food webs offer descriptions of how groupings in nature (typically species or populations) are linked to each other. For asking questions on how food webs are built and work, we need descriptions of food webs at different levels of resolution. DNA techniques provide opportunities for highly resolved webs. In this paper, we offer an exposé of how DNA-based techniques, and DNA barcodes in particular, have recently been used to construct food web structure in both terrestrial and aquatic systems. We highlight how such techniques can be applied to simultaneously improve the taxonomic resolution of the nodes of the web (i.e., the species), and the links between them (i.e., who eats whom). We end by proposing how DNA barcodes and DNA information may allow new approaches to the construction of larger interaction webs, and overcome some hurdles to achieving adequate sample size. Most importantly, we propose that the joint adoption and development of these techniques may serve to unite approaches to food web studies in aquatic and terrestrial systems—revealing the extent to which food webs in these environments are structured similarly to or differently from each other, and how they are linked by dispersal.

scholarly journals Effects of experimental warming, litter species, and presence of macroinvertebrates on litter decomposition and associated decomposers in a temperate mountain stream

2015 ◽  
Vol 72 (2) ◽  
pp. 206-216 ◽  
Author(s):  
Verónica Ferreira ◽  
Eric Chauvet ◽  
Cristina Canhoto
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Litter Decomposition ◽  
Castanea Sativa ◽  
Mountain Stream ◽  
Ambient Temperatures ◽  
C Cycle ◽  
Detrital Food Web ◽  
Water Courses ◽  
Aquatic Food

Small woodland streams make the majority of water courses in most watersheds. Litter decomposition is a key ecosystem process in these shaded streams, and its response to warming can have profound consequences for food webs and the carbon (C) cycle. However, these responses can be modulated by litter identity and the structure of the detrital food web. Here we report on a manipulative study aiming at evaluating the effects of warming (+2.8 °C), litter identity (chestnut (Castanea sativa) or oak (Quercus robur) litter), and the structure of the detrital food web (presence or absence of macroinvertebrates) on litter decomposition and decomposers in a small, temperate woodland stream. Warming significantly stimulated overall (microbial- + macroinvertebrate-driven) decomposition of oak and microbial-driven decomposition of chestnut. The similar shredder densities at elevated and ambient temperatures suggest that stimulated overall decomposition of oak resulted from increased activity of macroinvertebrate individuals. Stimulated microbial-driven decomposition of chestnut resulted from higher fungal activity with warming. Stimulation of litter decomposition by warming can lead to increases in the amount of C returned to the atmosphere and to a faster disappearance of litter from the benthos, with consequences to the C cycle and aquatic food webs.

scholarly journals Seasonal variability of the fatty acid composition in Aurelia aurita (Cnidaria: Scyphozoa): implications for gelativore food web studies

2020 ◽  
Vol 42 (4) ◽  
pp. 440-452
Author(s):  
Vanessa Stenvers ◽  
Xupeng Chi ◽  
Jamileh Javidpour
Keyword(s):  
Fatty Acid ◽  
Food Web ◽  
Seasonal Variability ◽  
Dry Weight ◽  
Aurelia Aurita ◽  
Web Studies ◽  
Dietary Requirements ◽  
Jellyfish Population ◽  
Aquatic Food ◽  
Insight Into

Abstract Jellyfish population play an important role in aquatic food chains, and many animals predate on this ‘mostly water containing’ organisms. However, what gelativores predators could gain from their prey is still poorly understood. This study provides insight into the nutritional value of the moon jelly (Aurelia aurita) by means of its fatty acid (FA) composition, while investigating seasonal variability and differences between its free-swimming life stages. A biweekly sampling was carried out in a temperate coastal ecosystem, the Kiel Fjord, Germany and during two consecutive years. FA profile of A. aurita showed significant seasonal variability, while mature medusae (due to reproductive tissues) possessed highest FA content. In addition, moon jelly contained several essential FAs (i.e. arachidonic acid, 20:4ω6; eicosapentaenoic acid, 20:5ω3; docosahexaenoic acid, 22:6ω3), which likely support predator’s vital physiological functions. Even though total FA contents proved to be low (7 × 10−3–34 × 10−3% per g dry weight), evidence supporting A. aurita’s capability to meet the dietary requirements of predators such as fish and crustaceans is provided. Finally, implications for gelativore and future food web configurations are discussed, while proposing that jellyfish are likely to be, and become, more than an opportunistic prey to many organisms.

Allocation of effort in stream food-web studies: the best compromise?

2001 ◽  
Vol 52 (3) ◽  
pp. 339 ◽  
Author(s):  
R. M. Thompson ◽  
E. D. Edwards ◽  
A. R. McIntosh ◽  
C. R. Townsend
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Dietary Analysis ◽  
Predator Species ◽  
Web Studies ◽  
Taxonomic Groups ◽  
Chain Lengths ◽  
Number Of Individuals ◽  
Animal Taxon ◽  
Stream Food Webs

The amount and allocation of effort needed to characterize stream food webs was investigated in five replicate streams. Two areas were considered:analysis of community composition (number of individuals sampled)and of diets (number of individuals gutted per animal taxon). Food webs were described by use of consistent methodology, then the effort was retrospectively reduced by considering half of the gut samples (halving dietary analysis effort)and by successively reducing the number of individuals included. Food webs with a reduced number of individuals overestimated connectance and prey:predator ratios, and underestimated species richness, links per species and mean chain lengths. These changes were due to loss of some invertebrate predator species when effort was reduced. In contrast, for dietary analysis the amount of effort expended on non-predatory invertebrates was more influential; halving effort in dietary analysis of non-predatory taxa reduced estimates of connectance and links per species. This study suggests that the effort needed to produce a reasonable estimate is highly dependent on the food-web attribute in question, and that aiming for equity of effort across taxonomic groups is as important as expending greater effort in general.

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