Food Web Structure Research Articles

Comparing food web structure and trophic diversity between natural and artificial habitats: a case study in the Bohai Sea, China

Comparing food web structure and trophic diversity between natural and artificial habitats: a case study in the Bohai Sea, China

Ten years (2013-2023) of fish assemblage data collected seasonally with diver surveys on artificial and natural reefs.

The study of assembly patterns and dynamics of organisms has long remained a foundational theme in ecology. Further, the relationship between assemblages and different habitats can provide important insight into ecological processes and guide management and conservation efforts (e.g., restoration, protected areas). We conducted underwater visual surveys of reef-fish assemblages at 14 sites in the eastern Gulf of Mexico, including 8 that were paired artificial and natural reefs. By using a paired design, we controlled biotic (e.g., larval supply), abiotic (e.g., depth), and socio variables (e.g., fishing access) to isolate the effect(s) of reef type. Trained scientific SCUBA divers with extensive experience with reef fishes from the broader tropical western Atlantic region conducted 10-min stationary surveys on the paired reefs each season (i.e., calendar quarters) for 10 years from spring 2013 to spring 2023. We also surveyed six additional artificial reefs from winter 2020 to spring 2023 that lacked natural reef pairs. During each survey, the divers identified and estimated the total lengths of all taxa observed within an imaginary cylinder around them. The imaginary cylinders had a radius of up to 7.5 m (depending on horizontal visibility) and extended from the seafloor to the highest visible water above the diver. During the study period, we conducted a total of 1349 surveys and counted 544,736 fish that represented 171 taxa (most at the species level). Analyses of these data have revealed habitat-specific heterogeneity of the fish assemblages at both taxonomic and functional trait levels, the importance of herbivory in structuring the benthos, and socio-ecological interactions in the system, among other findings. These data may be useful for other researchers interested in patterns and dynamics of populations and communities, functional traits, food web structure, and taxa-habitat relationships and for parameterizing statistical, joint distribution, metacommunity, and ecosystem models. In addition, because many of the observed taxa are of management concern, they may be useful for researchers interested in fisheries science. The data are free to use and are not copyright restricted. We ask users to cite this data paper.

Marine food web trophic interaction of trace elements and stable isotopes of carbon and nitrogen in Rabigh lagoon, Red Sea, Saudi Arabia.

Marine food web trophic interaction of trace elements and stable isotopes of carbon and nitrogen in Rabigh lagoon, Red Sea, Saudi Arabia.

Emergence of food webs with a multi-trophic hierarchical structure driven by nonlinear trait-matching.

Emergence of food webs with a multi-trophic hierarchical structure driven by nonlinear trait-matching.

Trophic dynamics and ecosystem health of a young tropical reservoir in Northeast India.

Small reservoirs are recognised as the most productive man-made ecosystem inhabiting diverse flora and fauna, having a scope for small-scale fisheries to support food security, livelihood, and many other ecological services. This study aimed to determine the trophic structure and ecosystem functioning of the Maphou Reservoir, located in the Northeastern Hill region,India, using the Ecopath mass-balance modelling approach, to figure out the strategic scientific ecosystem-based fisheries management. Ten functional groups were identified, most of which were confined in trophic level II (low order primary consumer). Exotic fish was the most utilized group based on ecotrophic efficiency (EE = 0.782), followed by herbivorous fish (EE = 0.623), and carnivorous fish group arefound to be the keystone species. Based on the mixed trophic index (MTI), lowertrophic level functional groups(detritus and phytoplankton) had a positive impact on the higher trophic levels, manifesting a 'bottom-up control' ecosystem. The reservoir is a primary producer-driven ecosystem (transfer efficiency from primary producer, PP = 4.864%), and mean transfer efficiency is low (4.732%), indicating scope for enhancing the fish stock sizes. The total primary producer/total respiration (TPP/TR) (3.629) and total primary producer/total biomass (TPP/TB) (70.70) suggested that the reservoir is in immature and developing ecosystem with high resilience against external perturbations (Overhead = 63.25%). The reservoir shows a moderately complex food web structure (connectance index = 0.457). The study recommended management measures for stocking enhancement of detritivores (Cirrhinus mrigala, Cyprinus carpio) and phyto-planktivorous fishes (Hypophthalmichthys molitrix, H. nobilis) to improve ecosystem efficiency; both groups have fairly low EE (detritus EE = 0.105 and phytoplankton EE = 0.379). These findings will be an essential input for policy formulation and scientific management of the small reservoir ecosystems in the tropics.

Aquatic food webs in restored marshes: a stable‐isotope approach in the Gironde estuary (SW France)

Intertidal marshes are important habitats for nekton. However, historical draining and dyking hampered European coastal wetlands. Marsh restoration is therefore critical not only to improve their capacity to protect coastal lines but also to rehabilitate their ecological functionalities. The benefits of intertidal marsh restoration for nekton community composition and feeding ecology are examined in a case study within the largest macrotidal estuary in Western Europe (Gironde). The structure and functioning of nekton food webs are addressed using stable isotopes of carbon (δ13C) and nitrogen (δ15N). δ13C values of suspended particulate matter illustrated the influence of the tidal connectivity with the adjacent estuary in restored habitats. δ15N values of nekton and its resources evidenced little difference in food‐web complexity, but spatial or seasonal variations for some resources and consumers, related to a combination of temporal and tidal effects. The European eel (Anguilla anguilla) and the introduced freshwater topmouth gudgeon (Pseudorasbora parva) dominated food webs in the fully and partially connected marsh habitats, respectively. The isotopic niche and diet composition of A. anguilla also varied between habitats, as did the diet of other nekton species (Chelon ramada and Palaemon longirostris). This study informs the rehabilitation process of important functionalities of restored aquatic habitats for nekton.

The role of land use in terrestrial support of boreal lake food webs

There is growing awareness of the importance of cross-boundary energy and nutrient transfers between adjacent ecosystems. Lake ecosystems receive inputs of terrestrial organic matter that microbes can make available to higher level consumers. However, how environmental drivers influence this terrestrial support of benthic and pelagic consumers at multiple trophic levels remains underexplored. Using hydrogen stable isotopes as a tracer of terrestrial organic matter, we find large variation in terrestrial support of aquatic consumers (i.e., consumer allochthony) among 35 boreal lakes. Of 19 different aquatic organisms, benthic consumers show the highest allochthony. Consumer allochthony decreases along an environmental gradient from forested to agricultural catchments, likely due to shifts in the origin and nature of lake organic matter. Our results demonstrate how cross-ecosystem transfer of organic matter can influence community dynamics in recipient ecosystems, with anthropogenic management of donor terrestrial ecosystems affecting the structure and function of food webs in recipient aquatic ecosystems.

Comparing Ecosystem Structure and Function of the Geheyan Reservoir Based on the Ecopath Model After a Fishing Ban

The Geheyan Reservoir, located on the Qingjiang River, a tributary of the Yangtze River, is important for regional water supplies and ecological conservation. Understanding changes in ecosystem structure and function has become critical for assessing efficacy after the implementation of a fishing ban. This study employs the Ecopath model to examine the ecosystem characteristics of the Geheyan Reservoir before (2017) and after (2022) the fishing ban. The results show significant differences in trophic levels, energy transfer efficiency, and ecosystem maturity between the two periods. The trophic levels increased from 3.36 pre-fishing ban to 3.89 post-ban, indicating an enhanced complexity in the food web structure. The highest eco-trophic efficiency for major commercial fish species increased after the ban, indicating improved energy utilization efficiency. However, energy transfer bottlenecks were still observed between trophic levels II and IV, suggesting ongoing challenges in nutrient cycling. The total primary production-to-total respiration ratio (6.93) and the connectivity index (0.25) indicate that the ecosystem’s maturity and stability have improved after the fishing ban. These findings underscore the ban’s effectiveness and provide a scientific foundation for sustainable management of Geheyan Reservoir and similar ecosystems in the Yangtze River Basin.

Effect of body size on an age-structured food chainwith birth pulses in pests

An ecological challenge is to understand the effects of body size reduction in response to climate change, a phenomenon that could significantly disrupt agroecological systems. However, the effects of these changes in individual traits and trophic interactions on the structure of food webs in such systems have not yet been fully explored. In the Southern Hemisphere, the socioeconomic and cultural importance of agriculture justifies the need to investigate these systems. In this study, the selected host plant is watermelon (Citrullus lanatus), the pest corresponds to the cotton aphid (Aphis gossypii), and the potential biological control agent is the Chilean predatory mite (Eriopis chilensis). To theoretically understand the structure of this food chain, we developed a three-level model that includes biological control, two pests, and the host plant. The model combines a continuous dynamic system with discrete pulses representing births and the introduction of new individuals of the control agent. Holling’s type II functional responses, reproduction and mortality rates, and carrying capacity dependent on the body size of the species are integrated into the model. Additionally, a computational algorithm is presented, which enables the simulation of the behaviour of the agroecological system. This proposal offers a theoretical tool to improve the understanding of species interactions and to anticipate dynamics that could be useful in designing agroecological management and control strategies.

Parasite communities of the gafftopsail pompano Trachinotus rhodopus (Carangiformes: Carangidae): examining the parasite species richness and diversity over time.

In total 949 specimens of Trachinotus rhodopus (Gill) were collected over a 11-year period (from June 2013 to February 2024) from Acapulco Bay, Mexico. Parasite communities in T. rhodopus were quantified and analysed to explore two hypotheses related to their parasite species richness and diversity associated with the bentho-demersal and pelagic habits, and effects of the climatic fluctuations. Thirty-two metazoan parasite taxa/species were identified: three species of 'Monogenea', 14 Digenea, one Aspidogastrea, one Acanthocephala, two Cestoda, three Nematoda and eight Crustacea. The digeneans and copepods were the best represented groups. The component parasite communities were characterised by the numerical dominance of the acanthocephalan Rhadinorhynchus sp. Species richness (15-24 species) was similar to that reported for other species of carangid fish, but the richness of the digeneans was significantly higher. The parasite communities of T. rhodopus exhibited high variability in species composition, suggesting that each species of parasite may respond differently to environmental changes. However, the species richness and diversity were fairly stable over time. Climatic events of La Niña and El Niño probably generated notable changes in the structure of local food webs, thus indirectly influencing the transmission rates of several endoparasite species.

Baseline Assessment of Black Sea Food Web Integrity Using a Zooplankton-Based Approach Under the Marine Strategy Framework Directive

This study presents the first scientific evaluation of food web integrity in the Black Sea under the Marine Strategy Framework Directive (MSFD) Descriptor 4 (Food Webs), utilizing zooplankton indicators to assess the environmental status during the warm season (May to October) from 2018 to 2023. The research aims to analyze trophic interactions, biodiversity patterns, and ecological stability by examining three key indicators: the Shannon–Wiener diversity index, Copepoda biomass, and Mnemiopsis leidyi biomass. The findings reveal that the Shannon–Wiener diversity index failed to achieve Good Environmental Status (GES) in any of the four Marine Reporting Units (MRUs), suggesting insufficient community diversity and potential ecological imbalances. Copepoda biomass met GES criteria only in marine and offshore waters, indicating spatial variability in copepod population stability across the Black Sea. Meanwhile, M. leidyi biomass remained within GES thresholds in all MRUs, suggesting that its population levels do not currently threaten the food web, despite its known invasive impact. This study provides critical baseline data on food web structure and dynamics in the Black Sea, offering a scientifically grounded framework for future ecological monitoring and management strategies. The results emphasize the need for targeted conservation efforts and adaptive management approaches to enhance the ecological health of the Black Sea in alignment with MSFD objectives.

Hydrological variation drives changes in food web structure and ecosystem function with potential hysteresis in a large temperate shallow lake

Hydrological variation drives changes in food web structure and ecosystem function with potential hysteresis in a large temperate shallow lake

Food web structure, functions, drivers, and dynamics in the Barents Sea and adjacent seas

Food web structure, functions, drivers, and dynamics in the Barents Sea and adjacent seas

A Picky Predator and Its Prey: How Snow Conditions and Ptarmigan Abundance Impact Gyrfalcon Feeding Behaviour and Breeding Success.

Species interactions can be altered by climate change but can also mediate its effects. The gyrfalcon (Falco rusticolus) and the ptarmigan (Lagopus spp.) form a predator-prey couple that reflects the dynamics of boreal, tundra, and alpine ecosystems. To determine how climate change may impact the alpine food web, we investigated how ptarmigan abundance and local weather impact gyrfalcon diet and feeding behaviour, nest occupancy, and reproductive success. Using wildlife cameras, we monitored gyrfalcon nests throughout the nestling period to collect data on diet and feeding behaviour. We quantified the gyrfalcon's functional response by describing how ptarmigan kill rates relate to ptarmigan density. Additionally, we quantified the gyrfalcon's numerical demographic and aggregative response by describing how gyrfalcon reproductive success and nest occupancy, respectively, were related to ptarmigan density, using data from large-scale monitoring projects. Ptarmigan were the dominant prey species, representing 98% of the diet. The proportion of ptarmigan in the gyrfalcon diet and gyrfalcon breeding success increased in springs with more snow, but breeding success decreased with more snow during the nestling period. Gyrfalcon reproductive success was positively related to ptarmigan density, but gyrfalcon nest occupancy and the ptarmigan kill rate were not related to ptarmigan density. These results indicate that the effect of climate change is not straightforward, and investigating how (a)biotic factors impact both prey and predator is relevant in predicting how a predator will respond to climate change. Following current climate predictions, spring will occur earlier, which will change the food-web structure through prey availability and diversity and through interactions with other species. This requires adaptations from gyrfalcons and other predators. We emphasise that the impact of climate change on predators and other species can be more accurately evaluated on a multi-species level rather than individually.

Trout have weak effects on zooplankton diversity but strong effects on community biomass

AbstractThe introduction and extirpation of predators can have large impacts on food web structure and ecosystem function. The magnitude of these predator effects can be influenced by species diversity and turnover along environmental gradients in space or time, which have the potential to buffer or magnify the impact of trophic interactions on ecosystem functioning. In this study, we explored the individual species and community effects of fish predators on lake zooplankton in the Sierra Nevada, CA, USA. Local and beta diversity in zooplankton communities were resilient to fish, only marginally differing among fish and fishless sites, and were more structured along elevational gradients. Observed diversity changes were attributed to species turnover in zooplankton communities, which suggests elevational gradients and fish are acting as ecological filters excluding subsets of species rather than reducing species density. We found that fish significantly reduced densities of larger‐bodied zooplankton species. Further, as larger‐bodied species densities were lower in the presence of fish, we found that the community weighted mean of body mass decreased in the presence of fish in lakes. Although species turnover largely maintained diversity over elevational gradients and in the presence of fish, such changes in larger‐bodied taxa and community biomass may have important implications in the transfer of energy throughout the food web and to connected riparian and aquatic ecosystems that are dependent on the flow of biomass and nutrients.

Artificial wrecks: Unwanted consequences of the deliberate sinking of ships for recreational diving

Artificial reefs are submerged human-made objects. In particular, the artificial wrecks are intentionally submerged obsolete ships. Once deployed, these wrecks are rapidly colonized by diverse benthic communities. Currently, this effect is positively valued by the recreational diving industry, which uses this colonization effect as one of the main arguments to promote the deployment of artificial wrecks. However, there is increasing evidence that artificial wrecks are not a substitute for natural reefs and may alter complex ecological processes such as food web structure and increase the likelihood of invasive species establishment and spread. Here, we discuss our main concerns related to the unintended socioecological consequences of the creation of artificial wrecks, problematizing the paradigm that this practice favours marine conservation. Although we recognize that artificial wrecks have positive economic, social and even some environmental outcomes, we argue that the benefits are often usufructed by only a portion of society and that this practice requires a broader discussion. Finally, we also discuss the management implications of these concerns and propose alternatives to encourage recreational diving through the adoption of more environmentally sustainable and socially participative approaches. Hopefully, this will lead to better and more consensual practices for the management of coastal areas.

Unraveling food web structure in alpine lakes: insights from stable isotope analysis

ABSTRACT Understanding trophic relationships in alpine lakes is essential to explore ecosystem functioning in extreme habitats. This study analyzed aquatic food webs in three alpine lakes in the Sierra Nevada massif (southern Spain) using stable isotope analysis (δ13C and δ15N). Our main objectives were to examine the isotopic composition of food web components and trophic links between food sources and macroinvertebrates. Results showed niche overlap among macroinvertebrate species, leading to simple and short trophic relationships. Aguas Verdes lake showed a more complex food web and wider δ13C range due to its greater habitat diversity and primary source inputs, creating variability within the isotopic niche space. However, this complexity could increase vulnerability to environmental changes affecting community composition and primary production. Conversely, La Caldera lake had higher δ15N values, indicating more complex trophic structure. Its simpler food web was primarily based on particulate organic matter, with limited variability in consumer niches. Overlapping isotopic niches across lakes suggested shared resources, likely adaptations to oligotrophic conditions. High levels of intraguild predation and resource competition emphasize the stabilizing role of macroinvertebrates. Our findings advance understanding of alpine lake food web and support future ecological studies in these environments.

Multiple Stressors Simplify Freshwater Food Webs.

Globally, freshwater ecosystems are threatened by multiple stressors, yet our knowledge of how they interact to affect food web structure remains scant. To address this knowledge gap, we conducted a large-scale mesocosm experiment to quantify the single and combined effects of three common anthropogenic stressors: warming, increased nutrient loading, and insecticide pollution, on the network structure of shallow lake food webs. We identified both antagonistic and synergistic interactive effects depending on whether the stressors affected negative or positive feedback loops, respectively. Overall, multiple stressors simplified the food web, elongated energy transfer pathways, and shifted biomass distribution from benthic to more pelagic pathways. This increased the risk of a regime shift from a clear-water state dominated by submerged macrophytes to a turbid state dominated by phytoplankton. Our novel results highlight how multiple anthropogenic stressors can interactively disrupt food webs, with implications for understanding and managing aquatic ecosystems in a changing world.

Restored streams recover food web properties but with different scaling relationships when compared with natural streams.

Despite extensive studies revealing differences in the composition of aquatic assemblages between restored streams and natural or pre-restoration states, understanding the ecological consequences and trajectories of stream restoration remains challenging. Food webs are an important way of mapping biodiversity to ecosystem functioning by describing feeding linkages and energy transfer pathways. Describing food webs can provide ecological insights into stream restoration. This study analyzed an unprecedented large quantity of food web data (more than 1700 webs) based on long-term (2008-2018) biomonitoring data in South Korea using a feeding link extrapolation. By doing so, we aimed to describe general patterns for the reassembly of aquatic food webs in restored streams. Specifically, we analyzed 12 indices related to the food web structure and robustness of restored streams and compared them with those of natural streams. First, the species richness, link numbers, link density, and connectance of the restored streams were all lower than those of the natural streams, indicating smaller food webs with less complexity. Second, the scaling relationship analyses between the other food web indices and species richness and connectance showed different mechanisms for structuring food webs in restored streams compared with natural streams. In particular, greater generalist feeding by consumers was identified as a major mechanism that increased the connectance of restored streams, which may increase their robustness against external disturbances. The fractions of the top, intermediate, and basal nodes in the restored streams changed rapidly as species richness increased compared with those of natural streams. Food web connectance and robustness in the restored streams tended to increase over time, reaching a level similar to that of natural streams. This suggests that the long-term ecological recovery of the restored food webs is underway. Overall, our findings indicate that restored stream food webs have ecological features distinct from those of natural streams, suggesting high compositional flexibility, and that consumers with a broad diet are the major driving forces behind these differences. Our food web analyses provide a greater understanding of restored streams and help support sustainable stream management through restoration strategies. These results provide new insights into the ecological potential of stream restoration.

Targeted manipulation of food webs in the plant rhizosphere.

Targeted manipulation of food webs in the plant rhizosphere.