The impact of nonlinear functional responses on the long-term evolution of food web structure

AbstractIn big lakes with strong anthropogenic pressure, it is usually difficult to disentangle the impacts of climate variability from those driven by eutrophication. The present work aimed at the reconstruction of change in the species distribution and density of subfossil Cladocera in Lake Iseo (Italy) in relation to climate and anthropogenic pressure. We related subfossil Cladocera species composition and density in an 80-cm sediment core collected in the pelagic zone of Lake Iseo to long-term temperature trends and phosphorus concentration inferred by diatoms frustules. The Cladocera remains detected in Lake Iseo sediment reflected the species composition and density of modern pelagic Cladocera assemblages. Cladocera rapidly respond to environmental change, and that climate change combined with eutrophication can induce changes in community composition and species density. At the beginning of twentieth century, when global warming was not yet so accentuated, the nutrient increase in water resulted as the principal driver in determining the long-term development of plankton communities and pelagic food web structure. Moreover, catchment-related processes may decisively affect both species composition and density of the lake planktonic communities due to the decrease of lake water transparency induced by input of inorganic material from the catchment area to the lake. The paleolimnological investigation, through the combined study of biotic and abiotic factor, allowed clarifying the synergic effects of the most important drivers of change in lake ecosystems, suggesting that climatic factors should be considered with nutrient availability as determinant element in controlling the temporal development of plankton communities and pelagic food web structure.

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Impact of fertilization and stocking on trophic interactions and growth of juvenile sockeye salmon (Oncorhynchus nerka)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f02-111 ◽

2002 ◽

Vol 59 (8) ◽

pp. 1361-1373 ◽

Cited By ~ 21

Author(s):

Asit Mazumder ◽

Jim A Edmundson

Keyword(s):

Food Web ◽

Sockeye Salmon ◽

Oncorhynchus Nerka ◽

Trophic Levels ◽

Food Web Structure ◽

Web Structure ◽

Mean Size ◽

Average Size ◽

The Impact

Using 16 years of data on nutrients, plankton, and sockeye fry and smolts from Packers Lake, Alaska, we test the impact of nutrients and fry stocking on the growth and productivity of juvenile sockeye salmon (Oncorhynchus nerka). To enhance sockeye production, this lake was fertilized (19831996) and stocked annually (19871996) with sockeye fry. Before fertilization, the density of sockeye fry was low (<0.20 fry·m2), the size and biomass of Daphnia were low, and sockeye smolts were relatively small. Before stocking, all trophic levels responded positively to fertilization. The biomass and mean size of Daphnia increased significantly. The average size of age-1 and age-2 smolts increased three- to four-fold. Fry stocking produced dramatic declines in both biomass and mean length of Daphnia and in size of smolts. When large-sized (>1 mm) Daphnia were significantly reduced in density under heavy predation by sockeye fry, the growth of juvenile sockeye declined, even under continued fertilization. We show that fry density and associated food web structure are major determinants of juvenile sockeye responses to fertilization and stocking. This study probably provides the first long-term experimental results linking limnological and nutrient food web concepts to trophodynamics and productivity of juvenile sockeye salmon.

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The impact of intraspecific variation on food web structure

Ecology ◽

10.1002/ecy.2523 ◽

2018 ◽

Vol 99 (12) ◽

pp. 2712-2720 ◽

Cited By ~ 9

Author(s):

Tom Clegg ◽

Mohammad Ali ◽

Andrew P. Beckerman

Keyword(s):

Food Web ◽

Intraspecific Variation ◽

Food Web Structure ◽

Web Structure ◽

The Impact

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Untangling the roles of parasites in food webs with generative network models

10.1101/019497 ◽

2015 ◽

Cited By ~ 1

Author(s):

Abigail Z. Jacobs ◽

Jennifer A. Dunne ◽

Cristopher Moore ◽

Aaron Clauset

Keyword(s):

Food Web ◽

Food Webs ◽

Statistical Physics ◽

Network Models ◽

Food Web Structure ◽

Free Living ◽

Web Structure ◽

Living Species ◽

Parasitic Interactions ◽

The Impact

Food webs represent the set of consumer-resource interactions among a set of species that co-occur in a habitat, but most food web studies have omitted parasites and their interactions. Recent studies have provided conflicting evidence on whether including parasites changes food web structure, with some suggesting that parasitic interactions are structurally distinct from those among free-living species while others claim the opposite. Here, we describe a principled method for understanding food web structure that combines an efficient optimization algorithm from statistical physics called parallel tempering with a probabilistic generalization of the empirically well-supported food web niche model. This generative model approach allows us to rigorously estimate the degree to which interactions that involve parasites are statistically distinguishable from interactions among free-living species, whether parasite niches behave similarly to free-living niches, and the degree to which existing hypotheses about food web structure are naturally recovered. We apply this method to the well-studied Flensburg Fjord food web and show that while predation on parasites, concomitant predation of parasites, and parasitic intraguild trophic interactions are largely indistinguishable from free-living predation interactions, parasite-host interactions are different. These results provide a powerful new tool for evaluating the impact of classes of species and interactions on food web structure to shed new light on the roles of parasites in food webs.

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The long-term changes in food web structure and ecosystem functioning of a shallow lake: Implications for the lake management

Journal of Environmental Management ◽

10.1016/j.jenvman.2021.113804 ◽

2022 ◽

Vol 301 ◽

pp. 113804

Author(s):

Xiaoxin Zhang ◽

Yujun Yi ◽

Zhifeng Yang

Keyword(s):

Food Web ◽

Shallow Lake ◽

Ecosystem Functioning ◽

Lake Management ◽

Food Web Structure ◽

Web Structure ◽

Long Term Changes

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The long-term evolution of neutron star merger remnants - I. The impact of r-process nucleosynthesis

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stt2502 ◽

2014 ◽

Vol 439 (1) ◽

pp. 744-756 ◽

Cited By ~ 146

Author(s):

S. Rosswog ◽

O. Korobkin ◽

A. Arcones ◽

F.- K. Thielemann ◽

T. Piran

Keyword(s):

Neutron Star ◽

Long Term Evolution ◽

Term Evolution ◽

R Process ◽

The Impact

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A Microanalytical Simulation Model to Predict the Long-Term Evolution of Employment Biographies in Austria: The Demographics Module

Austrian Journal of Statistics ◽

10.17713/ajs.v38i4.277 ◽

2016 ◽

Vol 38 (4) ◽

Author(s):

Marcus Wurzer ◽

Reinhold Hatzinger

Keyword(s):

Pension System ◽

Age Groups ◽

Long Term Evolution ◽

Population Ageing ◽

Cross Sectional ◽

Longitudinal Outcomes ◽

Term Evolution ◽

Policy Measures ◽

The Impact

The well-known problems of decreasing birth rates and population ageing represent a major challenge for the Austrian pension system. It is expected that the group of pensioners will grow steadily in the future, while the proportion of people that support them – the taxpayers – will shrink. In this regard, microsimulation provides a valuable tool to identify the impact of various policy measures. With microsimulation, it is not only possibleto predict cross-sectional data (e.g., the distribution of age groups in 2050), but also to simulate lifecourses of people, providing longitudinal outcomes. The demographics module is the first in a series of modules that are part of a microsimulation prototype. This prototype is being developed in order to predict the long-term evolution of Employment Biographies in Austria.

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Hydrogeological simulation of sedimentary basin evolution during a glacial cycle

10.5194/egusphere-egu21-13299 ◽

2021 ◽

Author(s):

Christian Silbermann

Keyword(s):

Boundary Conditions ◽

Large Scale ◽

Sedimentary Basin ◽

Long Term Evolution ◽

Nuclear Waste Repository ◽

Glacial Cycle ◽

Thermal Problem ◽

Term Evolution ◽

The Impact

Co-authors: Francesco Parisio, Thomas NagelGlaciation cycles affect the long-term evolution of geosystems by crustal deformation, ground freezing and thawing, as well as large-scale hydrogeological changes. In order to properly understand the present and future conditions of potential nuclear waste repository sites, we need to simulate the past history.&#160; For this, a sedimentary basin is considered here as a large-scale hydrogeological benchmark study. The long-term evolution during one glacial cycle is simulated using the open-source multi-field finite element code OpenGeoSys. The impact of the glacial loading (weight and induced shear) is taken into account using appropriate time-dependent stress boundary conditions. As a preliminary study, the hydro-mechanically coupled problem and the thermal problem are considered separately. For comparison with a previously published study by Bense et al. (2008), the entire displacement field is prescribed and the groundwater evolution (hydraulic problem) is regarded. Then, the displacement is only prescribed by means of boundary conditions. The impact of different constitutive assumptions on the deformation and hydraulic behavior is analyzed. The thermal problem is used to simulate the evolution of frost bodies in the subsurface beneath and ahead of the glacier.V. F. Bense and M. A. Person. Transient hydrodynamics within intercratonic sedimentary basins during glacial cycles. Journal of Geophysical Research, 113(F4):F04005, 10 2008.

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