Trophic Position of Consumers and Size Structure of Food Webs across Aquatic and Terrestrial Ecosystems

2019 ◽  
Vol 194 (6) ◽  
pp. 823-839 ◽  
Author(s):  
Anton M. Potapov ◽  
Ulrich Brose ◽  
Stefan Scheu ◽  
Alexei V. Tiunov
Keyword(s):  
Food Webs ◽  
Size Structure ◽  
Trophic Position ◽  
Terrestrial Ecosystems

scholarly journals On the Use of Stable Hydrogen Isotope Measurements (δ2H) to Discern Trophic Level in Avian Terrestrial Food Webs

Diversity ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 202
Author(s):  
Rien E. van Wijk ◽  
Yahkat Barshep ◽  
Keith A. Hobson
Keyword(s):  
Food Webs ◽  
Hydrogen Isotope ◽  
Trophic Position ◽  
Terrestrial Ecosystems ◽  
Forest Site ◽  
Trophic Enrichment ◽  
Terrestrial Environments ◽  
Closed Canopy ◽  
Stable Hydrogen Isotope ◽  
Δ15n And Δ13c

The measurement of stable hydrogen isotope ratios (δ2H) in animal tissues is a popular means of inferring spatial origins and migratory connections. However, the use of this isotope to infer diet and potentially trophic position remains poorly understood, especially in non-aquatic terrestrial ecosystems. In many animal communities, tissue δ15N values are strongly associated with trophic position. Correlations between tissue δ2H and δ15N are expected, then, if δ2H is affected by trophic enrichment of 2H. In addition, within sites, we would expect higher tissue δ2H values in insectivorous species compared to granivores or nectarivores. We tested these hypotheses for two resident avian communities in Nigeria consisting of 30 species representing a range of dietary guilds (granivores, frugivores, nectarivores, omnivores, insectivores) by comparing feather δ2H, δ15N and δ13C values. We found considerable isotopic overlap among all guilds except granivores, with no clear pattern of enrichment in 2H with trophic position. However, at one of our sites (open scrubland), feather δ2H was positively correlated with feather δ15N (R2 = 0.30) compared to a closed canopy forest site (R2 = 0.09). Our results indicate weak evidence for predictable trophic enrichment in 2H in terrestrial environments and indicate that controlled studies are now required to definitively elucidate the behavior of H isotopes in terrestrial food webs.

scholarly journals Trophic roles determine coral reef fish community size structure

2016 ◽  
Vol 73 (4) ◽  
pp. 496-505 ◽  
Author(s):  
James P.W. Robinson ◽  
Julia K. Baum
Keyword(s):  
Body Size ◽  
Coral Reef ◽  
Food Webs ◽  
Reef Fish ◽  
Coral Reef Fish ◽  
Census Data ◽  
Size Structure ◽  
Trophic Position ◽  
Great Promise ◽  
Metabolic Scaling

Relationships between abundance – body size and trophic position – body size can reveal size structuring in food webs and test ecological theory. Although there is considerable evidence of size structuring in temperate aquatic food webs, little is known about the structure of tropical coral reef food webs. Here, we use underwater visual-census data and nitrogen stable isotope analysis to test if coral reef fish communities (i) are size structured and (ii) follow metabolic scaling rules. After examining individuals from over 160 species spanning four orders of magnitude in body size, we show that abundance scaled negatively with body size and, as predicted, individuals sharing energy through predation (carnivorous fishes) scaled more steeply than those individuals sharing a common energy source (herbivorous fishes). Estimated size spectra were, however, shallower than predicted by metabolic theory. Trophic position scaled positively with body size across species and across individuals, providing novel evidence of size structuring in a diverse tropical food web. Size-based approaches hold great promise for integrating the complexities of food webs into simple quantitative measures, thus providing new insights into the structure and function of aquatic ecosystems.

scholarly journals Eutrophication induces shifts in the trophic position of invertebrates in aquatic food webs

Ecology ◽  
2020 ◽  
Author(s):  
Gea H. Lee ◽  
J. Arie Vonk ◽  
Ralf C.M. Verdonschot ◽  
Michiel H.S. Kraak ◽  
Piet F.M. Verdonschot ◽  
...  
Keyword(s):  
Food Webs ◽  
Trophic Position ◽  
Aquatic Food Webs ◽  
Aquatic Food

scholarly journals On the biogeography of salt limitation: A study of ant communities

2008 ◽  
Vol 105 (46) ◽  
pp. 17848-17851 ◽  
Author(s):  
Michael Kaspari ◽  
Stephen P. Yanoviak ◽  
Robert Dudley
Keyword(s):  
Global Change ◽  
Food Webs ◽  
New World ◽  
Terrestrial Ecosystems ◽  
Forest Litter ◽  
Sodium Concentration ◽  
Ant Communities ◽  
Sodium Toxicity ◽  
Changing Patterns ◽  
Essential Nutrient

Sodium is an essential nutrient whose deposition in rainfall decreases with distance inland. The herbivores and microbial decomposers that feed on sodium-poor vegetation should be particularly constrained along gradients of decreasing sodium. We studied the use of sucrose and NaCl baits in 17 New World ant communities located 4–2757 km inland. Sodium use was higher in genera and subfamilies characterized as omnivores/herbivores compared with those classified as carnivores and was lower in communities embedded in forest litter than in those embedded in abundant vegetation. Sodium use was increased in ant communities further inland, as was preference for the baits with the highest sodium concentration. Sucrose use, a measure of ant activity, peaked in communities 10–100 km inland. We suggest that the geography of ant activity is shaped by sodium toxicity near the shore and by sodium deficit farther inland. Given the importance of ants in terrestrial ecosystems, changing patterns of rainfall with global change may ramify through inland food webs.

scholarly journals Preliminary Estimations of Insect Mediated Transfers of Mercury and Physiologically Important Fatty Acids from Water to Land

Biomolecules ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 129 ◽  
Author(s):  
Sydney Moyo
Keyword(s):  
Fatty Acids ◽  
Food Webs ◽  
Organic Contaminants ◽  
Aquatic Insects ◽  
Total Mercury ◽  
Empirical Studies ◽  
Aquatic Insect ◽  
Terrestrial Ecosystems ◽  
Energy Subsidy

Aquatic insects provide an energy subsidy to riparian food webs. However, most empirical studies have considered the role of subsidies only in terms of magnitude (using biomass measurements) and quality (using physiologically important fatty acids), negating an aspect of subsidies that may affect their impact on recipient food webs: the potential of insects to transport contaminants (e.g., mercury) to terrestrial ecosystems. To this end, I used empirical data to estimate the magnitude of nutrients (using physiologically important fatty acids as a proxy) and contaminants (total mercury (Hg) and methylmercury (MeHg)) exported by insects from rivers and lacustrine systems in each continent. The results reveal that North American rivers may export more physiologically important fatty acids per unit area (93.0 ± 32.6 Kg Km−2 year−1) than other continents. Owing to the amount of variation in Hg and MeHg, there were no significant differences in MeHg and Hg among continents in lakes (Hg: 1.5 × 10−4 to 1.0 × 10−3 Kg Km−2 year−1; MeHg: 7.7 × 10−5 to 1.0 × 10−4 Kg Km−2 year−1) and rivers (Hg: 3.2 × 10−4 to 1.1 × 10−3 Kg Km−2 year−1; MeHg: 3.3 × 10−4 to 8.9 × 10−4 Kg Km−2 year−1), with rivers exporting significantly larger quantities of mercury across all continents than lakes. Globally, insect export of physiologically important fatty acids by insect was estimated to be ~43.9 × 106 Kg year−1 while MeHg was ~649.6 Kg year−1. The calculated estimates add to the growing body of literature, which suggests that emerging aquatic insects are important in supplying essential nutrients to terrestrial consumers; however, with the increase of pollutants in freshwater systems, emergent aquatic insect may also be sentinels of organic contaminants to terrestrial consumers.

A Trophic Position Model of Pelagic Food Webs: Impact on Contaminant Bioaccumulation in Lake Trout

1996 ◽  
Vol 66 (4) ◽  
pp. 451-477 ◽  
Author(s):  
M. Jake Vander Zanden ◽  
Joseph B. Rasmussen
Keyword(s):  
Food Webs ◽  
Lake Trout ◽  
Trophic Position ◽  
Pelagic Food Webs

scholarly journals Integrated trophic position decreases in more diverse communities of stream food webs

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Naoto F. Ishikawa ◽  
Yoshito Chikaraishi ◽  
Naohiko Ohkouchi ◽  
Aya R. Murakami ◽  
Ichiro Tayasu ◽  
...  
Keyword(s):  
Food Webs ◽  
Trophic Position ◽  
Diverse Communities ◽  
Stream Food Webs

scholarly journals Trophic interactions are mediated by the availability of water in temperate grassland ecosystems

2016 ◽  
Author(s):  
William Harrower ◽  
Lauchlan H Fraser ◽  
Roy Turkington
Keyword(s):  
Plant Growth ◽  
Food Webs ◽  
Water Availability ◽  
Species Interactions ◽  
Community Dynamics ◽  
Trophic Position ◽  
Food Web Structure ◽  
Rainfall Gradient ◽  
South Central ◽  
Vertebrate Predators

The addition or removal of predators from food webs by humans can have profound effects on the interactions between species. However, predators and primary producers are inextricably linked by the flow of energy through ecosystems. In temperate grasslands energy flow through ecosystems is often limited by water availability to plants. So, if the number and strength of interactions between species in grasslands depends on the amount of water available to plants, and we remove predators along a gradient in water availability, then we should see change in species interactions with predator removals along the gradient. After estimating trophic position and diet breadth of key predators, we excluded birds and small mammal predators from grasslands along a rainfall gradient in south central British Columbia for four years, and measured the response of plants and arthropods. Water availability significantly altered food web structure, and consequently the role of predators in structuring these ecosystems. When water was scarce, vertebrate predators impeded plant growth by feeding on spiders that would normally eat herbivorous insects. When water was more abundant, vertebrate predators facilitated plant growth by feeding on a broad range of arthropod prey. As water availability to plants increased they grew more. Herbivores were not able to consume all the new growth and thus dead plant material accumulated. Increasing detritus helped establish new links between predators and plants. Phenomena such as climate change can determine the availability of water entering ecosystems, which then alters trophic structure. If water availability can alter food webs there are no simple generalizations for community dynamics that are independent of climate.

scholarly journals Evolution of prudent predation in complex food webs: mechanism and evidence

2021 ◽  
Author(s):  
Orestes U. Gutierrez Al-Khudhairy ◽  
Axel G. Rossberg
Keyword(s):  
Food Webs ◽  
Latitudinal Gradient ◽  
Invasive Alien Species ◽  
Explanatory Power ◽  
Terrestrial Ecosystems ◽  
Complex Model ◽  
Population Fluctuations ◽  
Evolution Theory ◽  
Predator Prey ◽  
Stock Recruitment

Prudent predators catch sufficient prey to sustain their populations but not as much as to undermine their populations’ survival. The idea that predators evolve to be prudent has been dismissed in the 1970s, but the blunt arguments invoked then are untenable in light of modern evolution theory. Evolution of prudent predation has repeatedly been demonstrated in two-species predator-prey metacommunity models. However, the vigorous population fluctuations that these models predict are not widely observed. Here we show that in complex model food-webs prudent predation evolves by a different mechanism. We make testable predictions for empirical signatures of this mechanism and its outcomes. Then we discuss how these predictions are borne out across freshwater, marine, and terrestrial ecosystems. Demonstrating explanatory power of evolved prudent predation well beyond the question of predator-prey coexistence, the predicted signatures explain unexpected declines of invasive alien species, the shape of stock-recruitment relations of fish, and the clearance rates of pelagic consumers across the latitudinal gradient and 15 orders of magnitude in body mass. Specific research to further test and mobilise the utility of this theory is proposed.

Trophic Structure, Effective Trophic Position, and Connectivity in Food Webs

1975 ◽  
Vol 109 (966) ◽  
pp. 191-206 ◽  
Author(s):  
J. R. Kercher ◽  
H. H. Shugart,
Keyword(s):  
Food Webs ◽  
Trophic Structure ◽  
Trophic Position
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