Spatial and temporal variation in food web structure of an impounded river in Anatolia

2018 ◽  
Vol 69 (9) ◽  
pp. 1453 ◽  
Author(s):  
Nehir Kaymak ◽  
Kirk O. Winemiller ◽  
Senol Akin ◽  
Zekeriya Altuner ◽  
Fatih Polat ◽  
...  
Keyword(s):  
Food Web ◽  
Trophic Ecology ◽  
Fish Assemblages ◽  
Ecosystem Dynamics ◽  
Spatial And Temporal Variation ◽  
Fish Diversity ◽  
Isotopic Niche ◽  
Food Web Structure ◽  
Web Structure ◽  
Longitudinal Connectivity

Dams interrupt the longitudinal connectivity of rivers by impeding the movement of water, sediments and organisms, which, in turn, could affect aquatic biodiversity and food web ecology. Using stable isotope analysis, we examined spatiotemporal variation in food web structure at four sites in the upper Yeşilırmak River, Anatolia Peninsula, Turkey, in relation to environmental parameters and a dam. It was apparent that the dam created discontinuity in the longitudinal fluvial gradient of fish species richness, with more species observed at upstream sites. Fish assemblages from different sites and seasons occupied distinct areas of isotopic space. Isotopic niche space, trophic diversity, variation in δ13C of basal resources and assemblage redundancy were all higher for the fish assemblage at the site downstream from the dam compared with the site above the dam, a possible indication of greater interspecific dietary variation. Food chain length (the range in δ15N) was lower at the downstream site, possibly resulting from a greater tendency towards omnivory. The findings strongly suggest that the dam affects not only environmental conditions and fish diversity, but also trophic ecology. The results of the present study emphasise the need for research to assess potential effects of new dams in Anatolia on aquatic communities and ecosystem dynamics in rivers.

Changes in food web structure of fish assemblages along a river-to-ocean transect of a coastal subtropical system

2019 ◽  
Vol 70 (3) ◽  
pp. 402 ◽  
Author(s):  
Adna F. S. Garcia ◽  
Mauricio L. Santos ◽  
Alexandre M. Garcia ◽  
João P. Vieira
Keyword(s):  
Food Web ◽  
Fish Assemblages ◽  
Human Impacts ◽  
Environmental Gradients ◽  
Stomach Contents ◽  
Trophic Relationships ◽  
Food Sources ◽  
Bipartite Networks ◽  
Food Web Structure ◽  
Web Structure

There is an urgent need to understand how food web structure changes along environmental gradients. In this study we investigated changes in trophic organisation and the relative importance of autotrophic sources sustaining fish assemblages along a transect from river to ocean. In order to address these topics, we analysed fish stomach contents and isotopic composition of consumers and food sources. The findings revealed a greater number of autotrophic sources sustaining fish assemblages in the continental systems (especially in the river) than in the adjacent marine system. Bipartite networks depicting trophic relationships between fish and prey also changed along the transect, showing comparatively higher complexity in the estuary. These findings could be explained by the greater number of food web components (autotrophic sources, fish trophic guilds and prey) associated with pelagic and benthic food chains within the estuary compared with the adjacent systems studied. The findings of this study highlight the need to take into account river-to-ocean changes in food web structure of fish assemblages in management plans to mitigate human impacts in coastal systems.

scholarly journals Primary Sources and Food Web Structure of a Tropical Wetland with High Density of Mangrove Forest

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3105
Author(s):  
Victor M. Muro-Torres ◽  
Felipe Amezcua ◽  
Martin Soto-Jiménez ◽  
Eduardo F. Balart ◽  
Elisa Serviere-Zaragoza ◽  
...  
Keyword(s):  
Food Web ◽  
Gulf Of California ◽  
Trophic Ecology ◽  
Abundant Species ◽  
Trophic Levels ◽  
Isotopic Niche ◽  
Trophic Chain ◽  
Mangrove Forests ◽  
Food Web Structure ◽  
Wide Range

The trophic ecology of wetlands with mangrove forests remains poorly understood. Through the use of stomach contents analysis, stable isotope signatures, and Bayesian mixing models, the food web of a tropical wetland in the gulf of California was investigated. Consumers had heterogeneous diets, omnivores were the most abundant species (47%), followed by planktivorous (21%), minor piscivores (10%), major piscivores (10%), macrobenthivores (9%), and herbivores (3%). The values of δ13C (from −12 to −29‰) and δ15N (from 4 to 24‰) showed a wide range of isotopic values of the consumers. Most of the species had a broad isotopic niche and there was a large diet overlap of species due to the exploitation of a common set of food resources. Five trophic levels were identified, with the weakfish (Cynoscion xanthulus) as the top predator of this system with detritus coming from the mangrove as the main source that supports the food chain. This highlights the importance of the mangrove forests to such ecosystems, because not only they are the most important primary food source, but also, they offer habitat to a large suite of fauna, which are important components of the trophic chain.

scholarly journals Characterization of Trophic Structure of Fish Assemblages in the East and South Seas of Korea Based on C and N Stable Isotope Ratios

Water ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 58
Author(s):  
Donghoon Shin ◽  
Tae Hee Park ◽  
Chung-Il Lee ◽  
Kangseok Hwang ◽  
Doo Nam Kim ◽  
...  
Keyword(s):  
Food Web ◽  
Fish Assemblages ◽  
East Sea ◽  
Trophic Relationships ◽  
Food Sources ◽  
Isotopic Niche ◽  
The South ◽  
Food Web Structure ◽  
Δ13c And Δ15n ◽  
South Sea

The aim of this study was to assess seasonal variation in the food-web structure of fish assemblages in the East (two sites) and the South (one site) Seas of Korea, and to compare the isotopic niche areas between the regions. To do this, we analyzed the community structures and the δ13C and δ15N values for fish assemblages, and their potential food sources collected during May and October 2020. There were spatial differences in the diversity and dominant species of fish assemblages between the two seas. The fish assemblages in the South Sea had relatively wide ranges of δ13C and δ15N (−22.4‰ to −15.3‰ and 7.4‰ to 13.8‰, respectively) compared to those (−22.1‰ to −18.0‰ and 9.8‰ to 13.6‰, respectively) in the East Sea. The δ13C and δ15N values of suspended particulate organic matter, zooplankton, and fish assemblages differed significantly among sites and between seasons (PERMANOVA, p < 0.05, in all cases). Moreover, isotopic niche indices were relatively higher in the South Sea compared to those in the East Sea. Such differences in food-web characteristics among sites are likely due to the specific environmental effects (especially, major currents) on the differences in the species compositions and, therefore, their trophic relationships. Overall, these results allow for a deeper understanding of the changing trophic diversity and community structure of fish assemblages resulting from climate variability.

scholarly journals Food web structure alters ecological communities top-heaviness with little effect on the biodiversity-functioning relationship

2020 ◽  
Author(s):  
Eva Delmas ◽  
Daniel B. Stouffer ◽  
Timothée Poisot
Keyword(s):  
Food Web ◽  
Food Chain ◽  
Ecosystem Functioning ◽  
Ecosystem Processes ◽  
Ecosystem Dynamics ◽  
Ecosystem Functions ◽  
Ecological Communities ◽  
Bioenergetic Model ◽  
Food Web Structure ◽  
Web Structure

In a rapidly changing world, the composition, diversity and structure of ecological communities face many threats. Biodiversity-Ecosystem Functioning (BEF) and community food-chain analyses have focused on investigating the consequences of these changes on ecosystem processes and the resulting functions. These different and diverging conceptual frameworks have each produced important results and identified a set of important mechanisms, that shape ecosystem functions. But the disconnection between these frameworks, and the various simplifications of the study systems are not representative of the complexity of real-world communities. Here we use food webs as a more realistic depiction of communities, and use a bioenergetic model to simulate their biomass dynamics and quantify the resulting flows and stocks of biomass. We use tools from food web analysis to investigate how the predictions from BEF and food-chain analyses fit together, how they correlate to food-web structure and how it might help us understand the interplay between various drivers of ecosystem functioning. We show that food web structure is correlated to the community’s efficiency in storing the captured biomass, which may explain the distribution of biomass (top heaviness) across the different trophic compartments (producers, primary and secondary consumers). While we know that ecological network structure is important in shaping ecosystem dynamics, identifying structural attributes important in shaping ecosystem processes and synthesizing how it affects various underpinning mechanisms may help prioritize key conservation targets to protect not only biodiversity but also its structure and the resulting services.

scholarly journals Climate change alters the structure of arctic marine food webs due to poleward shifts of boreal generalists

2015 ◽  
Vol 282 (1814) ◽  
pp. 20151546 ◽  
Author(s):  
Susanne Kortsch ◽  
Raul Primicerio ◽  
Maria Fossheim ◽  
Andrey V. Dolgov ◽  
Michaela Aschan
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Barents Sea ◽  
Ecosystem Dynamics ◽  
The Arctic ◽  
Food Web Structure ◽  
Marine Food Web ◽  
Web Structure ◽  
The Barents Sea ◽  
Marine Food

Climate-driven poleward shifts, leading to changes in species composition and relative abundances, have been recently documented in the Arctic. Among the fastest moving species are boreal generalist fish which are expected to affect arctic marine food web structure and ecosystem functioning substantially. Here, we address structural changes at the food web level induced by poleward shifts via topological network analysis of highly resolved boreal and arctic food webs of the Barents Sea. We detected considerable differences in structural properties and link configuration between the boreal and the arctic food webs, the latter being more modular and less connected. We found that a main characteristic of the boreal fish moving poleward into the arctic region of the Barents Sea is high generalism, a property that increases connectance and reduces modularity in the arctic marine food web. Our results reveal that habitats form natural boundaries for food web modules, and that generalists play an important functional role in coupling pelagic and benthic modules. We posit that these habitat couplers have the potential to promote the transfer of energy and matter between habitats, but also the spread of pertubations, thereby changing arctic marine food web structure considerably with implications for ecosystem dynamics and functioning.

scholarly journals Flooding affects food web structure and basal sources supporting fish guilds in a subtropical wetland and shallow lake

2021 ◽  
Author(s):  
Rodrigo Ferreira Bastos ◽  
Alexandre Miranda Garcia ◽  
Kirk O. Winemiller ◽  
Nelson Ferreira Fontoura
Keyword(s):  
Organic Matter ◽  
Food Web ◽  
Shallow Lake ◽  
Trophic Structure ◽  
Terrestrial Ecosystems ◽  
Spatial And Temporal Variation ◽  
Food Chains ◽  
Food Web Structure ◽  
Aquatic Animals ◽  
Web Structure

Abstract Aquatic ecosystems exchange nutrients and organic matter with surrounding terrestrial ecosystems, and floods import allochthonous material from riparian areas into fluvial systems. We surveyed food web components of a wetland and shallow lake in a subtropical coastal region of Brazil to examine how community trophic structure and the entrance of allochthonous material into the food web were affected by floods. Stable isotope analysis was performed for samples of terrestrial and aquatic basal production sources and aquatic animals to trace the origin of organic matter assimilated by aquatic animals and estimate vertical trophic positions and food chain length. Lake and wetland trophic structures were compared for cool/wet and warm/dry seasons. Food web structure was hypothesized to differ based on hydrology, with the more stable lake having greater food web complexity, and seasonal flooding resulting in greater allochthonous inputs to the aquatic food web. We compared spatial and temporal variation in assemblage trophic structure using an adapted isotopic ellipse approach that plots assemblage elements according to δ13C on the x-axis and estimated TP on the y-axis. Lake trophic structure was more complex with longer food chains compared to that of the wetland. A greater contribution from terrestrial resources to animal biomass was observed in the wetland during the cool/wet period, and food chains in both habitats tended to be longer during the cool/wet period. Findings supported the hypothesis of greater assimilation of allochthonous sources during floods and greater trophic complexity in the more hydrologically stable system.

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