BONUS XWEBS policy brief No. 3.: Using trophic models to solve the food web indicator dilemma – How to match the legislative needs of food web assessments with the structure of food web constituents and associated key ecological processes

AbstractClimate change is altering naturally fluctuating environmental conditions in coastal and estuarine ecosystems across the globe. Departures from long-term averages and ranges of environmental variables are increasingly being observed as directional changes [e.g., rising sea levels, sea surface temperatures (SST)] and less predictable periodic cycles (e.g., Atlantic or Pacific decadal oscillations) and extremes (e.g., coastal flooding, marine heatwaves). Quantifying the short- and long-term impacts of climate change on tidal marsh seascape structure and function for nekton is a critical step toward fisheries conservation and management. The multiple stressor framework provides a promising approach for advancing integrative, cross-disciplinary research on tidal marshes and food web dynamics. It can be used to quantify climate change effects on and interactions between coastal oceans (e.g., SST, ocean currents, waves) and watersheds (e.g., precipitation, river flows), tidal marsh geomorphology (e.g., vegetation structure, elevation capital, sedimentation), and estuarine and coastal nekton (e.g., species distributions, life history adaptations, predator-prey dynamics). However, disentangling the cumulative impacts of multiple interacting stressors on tidal marshes, whether the effects are additive, synergistic, or antagonistic, and the time scales at which they occur, poses a significant research challenge. This perspective highlights the key physical and ecological processes affecting tidal marshes, with an emphasis on the trophic linkages between marsh production and estuarine and coastal nekton, recommended for consideration in future climate change studies. Such studies are urgently needed to understand climate change effects on tidal marshes now and into the future.

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Food web reconstruction through phylogenetic transfer of low-rank network representation

10.32942/osf.io/y7sdz ◽

2021 ◽

Author(s):

Tanya Strydom ◽

Salomé Bouskila ◽

Francis Banville ◽

Cerres Barros ◽

Dominique Caron ◽

...

Keyword(s):

Food Web ◽

Latent Variables ◽

Common Species ◽

Species Interaction ◽

Low Rank ◽

Ecological Interactions ◽

Ecological Processes ◽

Ecological Problems ◽

Previous Solution ◽

Web Reconstruction

Despite their importance in many ecological processes, collecting data and information on ecological interactions, and therefore species interaction networks, is an exceedingly challenging task. For this reason, large parts of the world have a deficit of data of which species interact, and what we can expect the network structure of these interactions to be. As data collection alone is unlikely to be sufficient at filling these global gaps, community ecologists must adopt predictive methods. In this contribution we develop such a method, relying on graph embedding (the extraction of explanatory latent variables from known graph structures) and transfer learning (the application of previous solution to novel problems with limited predictors overlap) in order to assemble a predicted list of trophic interactions between mammals of Canada. This interaction list is derived from extensive knowledge of the mammalian food web of Europe, despite the fact that there are fewer than 5% of common species between the two locations. We provide guidance on how this method can be adapted by substituting some approaches or predictors in order to make it more generally applicable to a broad family of ecological problems.

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Medium-sized exotic prey create novel food webs: the case of predators and scavengers consuming lagomorphs

PeerJ ◽

10.7717/peerj.2273 ◽

2016 ◽

Vol 4 ◽

pp. e2273 ◽

Cited By ~ 14

Author(s):

Facundo Barbar ◽

Fernando Hiraldo ◽

Sergio A. Lambertucci

Keyword(s):

Food Web ◽

Food Webs ◽

Apparent Competition ◽

Ecological Processes ◽

Novel Food ◽

Food Web Interactions ◽

Conservation Actions ◽

Upper Level ◽

Native Diversity ◽

Analytical Tools

Food web interactions are key to community structure. The introduction of species can be seen as an uncontrolled experiment of the addition of species. Introduced species lead to multiple changes, frequently threatening the native biodiversity. However, little is known about their direct effect on the upper level of the food web. In this study we review empirical data on the predator–prey relationship between the introduced lagomorphs and their consumers, and use meta-analytical tools to quantify the strength of their interactions. We expect that exotic lagomorphs will destabilize food webs, affect ecological processes and compromise the conservation of the invaded regions. We found 156 studies on the diet of 43 species of predators that consume lagomorphs as exotic preys in South America and Oceania. We found an average exotic lagomorphs-predator link of 20% which indicates a strong interaction, given that the average for the strongest links with native prey (when lagomorphs are not included in the predator diet) is about 24%. Additionally, this last link decreases to 17% when lagomorphs are present. When lagomorphs arrive in a new environment they may become the most important resource for predators, producing an unstable equilibrium in the novel food web. Any disruption of this interaction could have catastrophic consequences for the native diversity by directly impacting predators or indirectly impacting native preys by apparent competition. Eradication or any change in their abundances should be carefully considered in conservation actions since those will have great impacts on predator populations and ultimately in the whole communities.

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Island Food Webs

Island Biogeography in the Sea of Cortés II ◽

10.1093/oso/9780195133462.003.0019 ◽

2002 ◽

Cited By ~ 1

Author(s):

Gary A. Palis ◽

Michael D. Rose

Keyword(s):

Food Web ◽

Food Webs ◽

Climatic Factors ◽

Spatial And Temporal Variability ◽

Ecological Processes ◽

Local Conditions ◽

Competitive Effects ◽

Structure And Dynamics ◽

Sea Of Cortes ◽

Secondary Productivity

Most of this book focuses on the biogeography and ecology of plants and various animal taxa on islands in the Sea of Cortés. These chapters highlight the historical and biogeographical factors that contributed to the patterns of species distribution and co-occurrence among islands. However, these patterns also reflect the action of ecological processes because the species present interact, directly or indirectly, within the food web that occurs on any given island. Island food webs may also be unique from other communities in the degree to which their structure and dynamics are also strongly influenced by the surrounding ocean. We believe that a deeper appreciation of the trophic connections between the sea and the land, and the resulting effects on the structure and dynamics of island food webs, is key to understanding the biogeography of species on islands. Many factors that operate through the food web can enhance or depress populations in a way that affects their local distribution and persistence, and, as a consequence, affects patterns of diversity on a biogeographical scale. Of these, we recognize three as being particularly important: the availability and quality of resources, competition, and consumption (i.e., by herbivores, predators, parasites). Bottom-up factors (nutrients, primary productivity, and food availability to consumers) set limits on island productivity and hence on the potential abundance of a particular group. Within a given community, secondary productivity and population density are subsequently constrained by top-down (i.e., consumption) and competitive effects. One of our goals in this chapter is to show how processes that influence productivity of gulf islands determine patterns of abundance of organisms on islands and affect interactions among species and trophic levels in these systems. Our second goal is to demonstrate the importance of spatial and temporal variability in productivity in determining the structure and dynamics of island food webs. Using our long-term studies of plants and consumers on islands in the northern gulf, we show that productivity varies greatly, both among years and islands, as a result of both local conditions and global climatic factors. Such variable productivity markedly affects food web dynamics and ultimately the abundance of species on the islands in the Sea of Cortés.

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Differential Responses of Food Web Properties to Opposite Assembly Rules and Species Richness

Water ◽

10.3390/w12102828 ◽

2020 ◽

Vol 12 (10) ◽

pp. 2828

Author(s):

Yulun Guo ◽

Tao Wang ◽

García Molinos Jorge ◽

Huan Zhang ◽

Peiyu Zhang ◽

...

Keyword(s):

Food Web ◽

Food Webs ◽

A Priori ◽

Limiting Similarity ◽

Assembly Rules ◽

Scale Invariant ◽

Ecological Processes ◽

Energetic Performance ◽

Food Web Theory ◽

Specific Food

Trophic niches condition the energetic performance of species within food webs providing a vital link between food web assembly, species diversity, and functioning of ecosystems. Our understanding of this important link is, however, limited by the lack of empirical tools that can be easily applied to compare entire food webs at regional scales. By comparison, with different a priori synthetic models defined according to specific assembly rules (i.e., purely random, limiting similarity, and niche filtering), we demonstrate that a set of food web properties (trophic richness, evenness, and divergence) are controlled by ecological processes. We further demonstrate that although both limiting similarity and niche filtering are statistically significant assembly processes shaping our studied lake food webs, their relative importance is richness-dependent, and contextual to the specific food web property under consideration. Our results have both important theoretical and practical implications. Theoretically, the observed richness-dependent variation on food web properties contradicts the common criticism on food web theory that food web properties are roughly scale-invariant. Practically, these properties can help avoiding spurious conclusions, while providing useful information for multiple food web niche spaces supporting the ecosystem functioning.

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Warming winters in lakes: Later ice onset promotes consumer overwintering and shapes springtime planktonic food webs

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2114840118 ◽

2021 ◽

Vol 118 (48) ◽

pp. e2114840118

Author(s):

Marie-Pier Hébert ◽

Beatrix E. Beisner ◽

Milla Rautio ◽

Gregor F. Fussmann

Keyword(s):

Food Web ◽

Global Climate ◽

Light Availability ◽

Open Water ◽

Early Winter ◽

Ecological Processes ◽

Cascading Effects ◽

Freshwater Ice ◽

Planktonic Food ◽

Sequence Of Events

Global climate warming is causing the loss of freshwater ice around the Northern Hemisphere. Although the timing and duration of ice covers are known to regulate ecological processes in seasonally ice-covered ecosystems, the consequences of shortening winters for freshwater biota are poorly understood owing to the scarcity of under-ice research. Here, we present one of the first in-lake experiments to postpone ice-cover onset (by ≤21 d), thereby extending light availability (by ≤40 d) in early winter, and explicitly demonstrate cascading effects on pelagic food web processes and phenologies. Delaying ice-on elicited a sequence of events from winter to spring: 1) relatively greater densities of algal resources and primary consumers in early winter; 2) an enhanced prevalence of winter-active (overwintering) consumers throughout the ice-covered period, associated with augmented storage of high-quality fats likely due to a longer access to algal resources in early winter; and 3) an altered trophic structure after ice-off, with greater initial springtime densities of overwintering consumers driving stronger, earlier top-down regulation, effectively reducing the spring algal bloom. Increasingly later ice onset may thus promote consumer overwintering, which can confer a competitive advantage on taxa capable of surviving winters upon ice-off; a process that may diminish spring food availability for other consumers, potentially disrupting trophic linkages and energy flow pathways over the subsequent open-water season. In considering a future with warmer winters, these results provide empirical evidence that may help anticipate phenological responses to freshwater ice loss and, more broadly, constitute a case of climate-induced cross-seasonal cascade on realized food web processes.

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