scholarly journals Trophic Patterns of Bighead Carp and Silver Carp Follow the Seasonality of Resource Availability

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1429
Author(s):  
Jia Yu ◽  
Jun Chen ◽  
Xuwei Deng ◽  
Zhixu Wu ◽  
Zuoming Yu ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Food Web ◽  
Trophic Level ◽  
Seasonal Variations ◽  
Silver Carp ◽  
Food Resources ◽  
Freshwater Ecosystems ◽  
Trophic Levels ◽  
Bighead Carp ◽  
Filter Feeding

The influence of seasonality of the aquatic environment on food web has been notoriously understudied in empirical ecology. In this study, we focus on seasonal changes in one key attribute of a food web, the trophic level. We determine whether seasonal variations of fish trophic levels could be indicated by the change in food resources. Silver carp (Hypophthalmichthys molitrix) and bighead carp (H. nobilis) were used to explore the responses of trophic levels of the filter-feeding fish to seasonal variations of food resources. Combined stable isotopic analysis and dietary analysis revealed that filter-feeding fish tended to have a higher trophic level in spring (May) and autumn (September and October). This may result from the abundant density of food resources (zooplankton and phytoplankton) and fish flexible foraging strategy, as we predicted that the trophic level follows the seasonality of food availability. Pearson’ correlation analysis and a structural equation model showed that seasonal variation of total phosphorus and water temperature could indirectly affect trophic levels of silver carp and bighead carp by mediating the abundance of phytoplankton and zooplankton directly and indirectly along the food chain. According to these findings, the seasonal variation of food resources could be an important indicator of the temporal dynamics of the food web trophic pattern in freshwater ecosystems.

scholarly journals Drivers of trophic amplification of ocean productivity trends in a changing climate

2014 ◽  
Vol 11 (24) ◽  
pp. 7125-7135 ◽  
Author(s):  
C. A. Stock ◽  
J. P. Dunne ◽  
J. G. John
Keyword(s):  
Food Web ◽  
21St Century ◽  
Trophic Level ◽  
Net Primary Production ◽  
Trophic Levels ◽  
The Arctic ◽  
Phytoplankton Production ◽  
Planktonic Food ◽  
Projected Changes ◽  
Zooplankton Growth

Abstract. Pronounced projected 21st century trends in regional oceanic net primary production (NPP) raise the prospect of significant redistributions of marine resources. Recent results further suggest that NPP changes may be amplified at higher trophic levels. Here, we elucidate the role of planktonic food web dynamics in driving projected changes in mesozooplankton production (MESOZP) found to be, on average, twice as large as projected changes in NPP by the latter half of the 21st century under a high emissions scenario in the Geophysical Fluid Dynamics Laboratory's ESM2M–COBALT (Carbon, Ocean Biogeochemistry and Lower Trophics) earth system model. Globally, MESOZP was projected to decline by 7.9% but regional MESOZP changes sometimes exceeded 50%. Changes in three planktonic food web properties – zooplankton growth efficiency (ZGE), the trophic level of mesozooplankton (MESOTL), and the fraction of NPP consumed by zooplankton (zooplankton–phytoplankton coupling, ZPC), explain the projected amplification. Zooplankton growth efficiencies (ZGE) changed with NPP, amplifying both NPP increases and decreases. Negative amplification (i.e., exacerbation) of projected subtropical NPP declines via this mechanism was particularly strong since consumers in the subtropics have limited surplus energy above basal metabolic costs. Increased mesozooplankton trophic level (MESOTL) resulted from projected declines in large phytoplankton production. This further amplified negative subtropical NPP declines but was secondary to ZGE and, at higher latitudes, was often offset by increased ZPC. Marked ZPC increases were projected for high-latitude regions experiencing shoaling of deep winter mixing or decreased winter sea ice – both tending to increase winter zooplankton biomass and enhance grazer control of spring blooms. Increased ZPC amplified projected NPP increases in the Arctic and damped projected NPP declines in the northwestern Atlantic and Southern Ocean. Improved understanding of the physical and biological interactions governing ZGE, MESOTL and ZPC is needed to further refine estimates of climate-driven productivity changes across trophic levels.

Paddlefish Management, Propagation, and Conservation in the 21st Century

2009 ◽  
Keyword(s):  
Invasive Species ◽  
Native Species ◽  
Silver Carp ◽  
Negative Influence ◽  
Trophic Levels ◽  
Bighead Carp ◽  
Native Fish ◽  
Central United States ◽  
Restrict Movement ◽  
Negative Interactions

<em>Abstract</em>.—Invasive species are one of the dominant problems fisheries managers face when dealing with management, conservation, or preservation of native fishes. The primary concern is the potential for negative interactions between invasive and native species where the outcome is reduced abundance, fitness, growth, or extirpated native fish species. These negative interactions can come from direct competition for resources, vectors for the spread of disease or parasites, and subtle effects such as altering the flow of energy within and among other trophic levels. Paddlefish <em>Polyodon spathula </em>are not exempt from these threats and may even be at a higher risk because they are endemic to historically lotic systems in the central United States where many invasive species are now becoming established. The most prominent invasive threat to paddlefish may be from fellow filter-feeders bighead carp <em>Hypophthalmichthys nobilis </em>and silver carp <em>H. molitrix </em>because they consume similar food resources, possibly displace other pelagic species, and can also change the plankton community to one that cannot be as efficiently used by paddlefish. These two carp species have had a negative influence on native fish communities in other parts of the world, and have been shown to negatively interact with juvenile paddlefish in North America. Response plans that implement a movement barrier or removal of invasive species may also have ramifications for paddlefish in that they restrict movement patterns or reduce abundances as bycatch through harvest schemes. Gaining insights into potential invasive species threats to paddlefish is critical so that informed decisions can be made to prevent ecological damage from the invasive species while optimizing sustainability of native species.

scholarly journals Spatial variation in the stable isotopes of 13C and 15N and trophic position of Leporinus friderici (Characiformes, Anostomidae) in Corumbá Reservoir, Brazil

2007 ◽  
Vol 79 (1) ◽  
pp. 41-49 ◽  
Author(s):  
Alexandre L. Pereira ◽  
Evanilde Benedito ◽  
Cássia M. Sakuragui
Keyword(s):  
Stable Isotopes ◽  
Carbon Source ◽  
Isotopic Composition ◽  
Spatial Variation ◽  
Food Web ◽  
Trophic Level ◽  
Trophic Position ◽  
Trophic Levels ◽  
C3 Plants ◽  
The One

Stable isotopes of carbon (delta13C) and nitrogen (delta15N) were used to describe sources of energy and trophic position for adult Leporinus friderici in the area of the Corumbá Reservoir, Brazil. Samples were collected from April 1999 to March 2000. Spatial variations were not identified in the isotopic composition. The maximum and minimum contribution of C4 plants calculated integrating the variation of plants and fish were 47.7% and 2.4%, respectively. Among C3 plants, periphyton presented closer isotopic values to those observed for fishes, corresponding to an important carbon source. The proportion of ingested plant item is larger in rivers upstream from the reservoir (42.7%), which justifies the smaller trophic level among there. However, in the reservoir, the ingestion of fish was 81.4%, while ingested plants contributed with 18.6%. Downstream from the dam, participation of plant item was even smaller (14.4%). Although the trophic position calculated with diet data was proportional to the one calculated with delta15N values, the former elevated the trophic level of L. friderici in the food web, because estimated trophic positions were based on fish items belonging to the 2nd (a) and to the 3rd (b) trophic levels.

Dominant aquatic species and their hydrological niches in freshwater ecosystems in a developing city

2019 ◽  
Vol 70 (5) ◽  
pp. 615
Author(s):  
S. Yang ◽  
T. Pan ◽  
X. Wang ◽  
Y. Sun ◽  
Y. Zhang ◽  
...  
Keyword(s):  
Food Web ◽  
Water Resource Management ◽  
Keystone Species ◽  
Aquatic Organisms ◽  
Freshwater Ecosystems ◽  
Trophic Levels ◽  
Food Web Structure ◽  
Spatial And Temporal Scales ◽  
Web Structure ◽  
Jinan City

Maintenance of appropriate hydrological niches is crucial to aquatic organisms. This study identified keystone species using the Ecopath with Ecosim food web model for hydrological niche analysis in Jinan City, the first pilot city of the Water Ecological Civilisation Project in China. The niche breadth of keystone species was analysed using Levins’ breadth model. Results revealed 35 keystone species in the aquatic ecosystems of Jinan City, including 5 phytoplankton, 7 zooplankton, 9 zoobenthos and 14 fish species. Streamflow was the most important hydrological factor affecting the phytoplankton, zooplankton, zoobenthos and fish communities in the study area, and excess variation in streamflow had an adverse effect on the normal evolution of the four biotic communities. We found that: (1) higher trophic levels in the food web contained more keystone species in the corresponding community; (2) carbon is an important element constraining the food web structure, and the magnitude of its effect on energy flow determines the degree of importance of the keystone species in the food web; and (3) changes to the survey season and at the spatiotemporal scale will have strong effects on the results of hydrological niche analysis and, to reduce these effects, it will be important to lengthen the spatial and temporal scales to cover both dry and flood seasons in the future. These results may provide an important basis for decision making regarding ecological scheduling and remediation of rivers in the study area, and potentially regions worldwide, thus facilitating aquatic ecological remediation and sustainable water resource management.

Bioaccumulation trends of arsenic and antimony in a freshwater ecosystem affected by mine drainage

2016 ◽  
Vol 13 (1) ◽  
pp. 149 ◽  
Author(s):  
Meghan A. Dovick ◽  
Thomas R. Kulp ◽  
Robert S. Arkle ◽  
David S. Pilliod
Keyword(s):  
Food Web ◽  
Trophic Level ◽  
Microbial Mats ◽  
Mine Drainage ◽  
Trophic Levels ◽  
Whole Body ◽  
Freshwater Ecosystem ◽  
High Tolerance ◽  
Mine Site ◽  
The Past

Environmental context The food web behaviours of As and Sb are poorly understood. We compare As and Sb bioaccumulation in a contaminated freshwater ecosystem. Metalloid accumulation decreased with increasing trophic level. Bioprecipitated minerals in microbial mats represent a direct route of uptake (by ingestion) of metalloids to tadpoles, which contained the highest concentrations ever reported. We demonstrate food web bioaccumulation, but not biomagification, of As and Sb. We also report an unexpectedly high tolerance of tadpoles to metalloid toxicity. Abstract We compared As and Sb bioaccumulation and biomagnification when these metalloids co-occurred at varying environmental concentrations in a stream and wetlands near a contaminated mine site in Idaho (USA). We measured As and Sb concentrations in water and substrate samples, and in tissues of organisms representing several trophic levels. Bioaccumulation of both As and Sb was observed in stream organisms with the following trend of bio-diminution with increasing trophic level: primary producers>tadpoles>macroinvertebrates>trout. We also note reductions in metalloid concentrations in one of two stream remediation reaches engineered within the past 17 years to ameliorate metalloid contamination in the stream. Several wetlands contained thick microbial mats and were highly populated with boreal toad tadpoles that fed on them. The mats were extremely contaminated (up to 76564mgkg–1 As and 675mgkg–1 Sb) with amorphous As- and Sb-bearing minerals that we interpret as biogenic precipitates from geomicrobiological As- and Sb-cycling. Ingested mat material provided a direct source of metalloids to tadpoles, and concentrations of 3867mgkg–1 (As) and 375mgkg–1 (Sb) reported here represent the highest whole body As and Sb levels ever reported in living tadpoles. The bulk of tadpole metalloid burden remained in the gut despite attempts to purge the tadpoles prior to analysis. This study adds to a number of recent investigations reporting bioaccumulation, but not biomagnification, of As and Sb in food webs. Moreover, our results suggest that tadpoles, in particular, may be more resistant to metalloid contamination than previously assumed.

scholarly journals Top predators govern multitrophic diversity effects in tritrophic food webs

2020 ◽  
Author(s):  
Ruben Ceulemans ◽  
Christian Guill ◽  
Ursula Gaedke
Keyword(s):  
Temporal Variation ◽  
Food Web ◽  
Food Webs ◽  
Functional Diversity ◽  
Trophic Level ◽  
Ecosystem Functioning ◽  
Initial Conditions ◽  
Trophic Levels ◽  
Natural Food ◽  
Model Parameters

AbstractIt is well known that functional diversity strongly affects ecosystem functioning. However, even in rather simple model communities consisting of only two or, at best, three trophic levels, the relationship between multitrophic functional diversity and ecosystem functioning appears difficult to generalize, due to its high contextuality. In this study, we considered several differently structured tritrophic food webs, in which the amount of functional diversity was varied independently on each trophic level. To achieve generalizable results, largely independent of parametrization, we examined the outcomes of 128, 000 parameter combinations sampled from ecologically plausible intervals, with each tested for 200 randomly sampled initial conditions. Analysis of our data was done by training a Random Forest model. This method enables the identification of complex patterns in the data through partial dependence graphs, and the comparison of the relative influence of model parameters, including the degree of diversity, on food web properties. We found that bottom-up and top-down effects cascade simultaneously throughout the food web, intimately linking the effects of functional diversity of any trophic level to the amount of diversity of other trophic levels, which may explain the difficulty in unifying results from previous studies. Strikingly, only with high diversity throughout the whole food web, different interactions synergize to ensure efficient exploitation of the available nutrients and efficient biomass transfer, ultimately leading to a high biomass and production on the top level. The temporal variation of biomass showed a more complex pattern with increasing multitrophic diversity: while the system initially became less variable, eventually the temporal variation rose again due to the increasingly complex dynamical patterns. Importantly, top predator diversity and food web parameters affecting the top trophic level were of highest importance to determine the biomass and temporal variability of any trophic level. Overall, our study reveals that the mechanisms by which diversity influences ecosystem functioning are affected by every part of the food web, hampering the extrapolation of insights from simple monotrophic or bitrophic systems to complex natural food webs.

Trophic niche differences between coexisting omnivores silver carp and bighead carp in a pelagic food web

2016 ◽  
Vol 31 (6) ◽  
pp. 831-839 ◽  
Author(s):  
Xiaoyan Yao ◽  
Gentian Huang ◽  
Ping Xie ◽  
Jun Xu
Keyword(s):  
Food Web ◽  
Silver Carp ◽  
Trophic Niche ◽  
Bighead Carp ◽  
Pelagic Food Web ◽  
Niche Differences

scholarly journals Phenotypic variation explains food web structural patterns

2017 ◽  
Vol 114 (42) ◽  
pp. 11187-11192 ◽  
Author(s):  
Jean P. Gibert ◽  
John P. DeLong
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Trophic Level ◽  
Phenotypic Variation ◽  
Structural Features ◽  
Trophic Levels ◽  
Intake Rate ◽  
Food Web Structure ◽  
Total Food Intake ◽  
Variation Sets

Food webs (i.e., networks of species and their feeding interactions) share multiple structural features across ecosystems. The factors explaining such similarities are still debated, and the role played by most organismal traits and their intraspecific variation is unknown. Here, we assess how variation in traits controlling predator–prey interactions (e.g., body size) affects food web structure. We show that larger phenotypic variation increases connectivity among predators and their prey as well as total food intake rate. For predators able to eat only a few species (i.e., specialists), low phenotypic variation maximizes intake rates, while the opposite is true for consumers with broader diets (i.e., generalists). We also show that variation sets predator trophic level by determining interaction strengths with prey at different trophic levels. Merging these results, we make two general predictions about the structure of food webs: (i) trophic level should increase with predator connectivity, and (ii) interaction strengths should decrease with prey trophic level. We confirm these predictions empirically using a global dataset of well-resolved food webs. Our results provide understanding of the processes structuring food webs that include functional traits and their naturally occurring variation.

scholarly journals Drivers of trophic amplification of ocean productivity trends in a changing climate

2014 ◽  
Vol 11 (7) ◽  
pp. 11331-11359 ◽  
Author(s):  
C. A. Stock ◽  
J. P. Dunne ◽  
J. G. John
Keyword(s):  
Sea Ice ◽  
Food Web ◽  
21St Century ◽  
Trophic Level ◽  
Net Primary Production ◽  
Trophic Levels ◽  
Phytoplankton Production ◽  
Planktonic Food ◽  
Projected Changes ◽  
Zooplankton Growth

Abstract. Pronounced projected 21st century trends in regional oceanic net primary production (NPP) raise the prospect of significant redistributions of marine resources. Recent results further suggest that NPP changes may be amplified at higher trophic levels. Here, we elucidate the role of planktonic food web dynamics in driving projected changes in mesozooplankton production (MESOZP) found to be, on average, twice as large as projected changes in NPP by the latter half of the 21st century under a high emissions scenario. Globally, MESOZP was projected to decline by 7.9% but regional MESOZP changes sometimes exceeded 50%. Changes in three planktonic food web properties – zooplankton growth efficiency (ZGE), the trophic level of mesozooplankton (MESOTL), and the fraction of NPP consumed by zooplankton (zooplankton-phytoplankton coupling, ZPC), were demonstrated to be responsible for the projected amplification. Zooplankton growth efficiencies (ZGE) changed with NPP, amplifying both NPP increases and decreases. Negative amplification (i.e., exacerbation) of projected subtropical NPP declines via this mechanism was particularly strong since consumers in the subtropics already have limited surplus energy above basal metabolic costs. Increased mesozooplankton trophic level (MESOTL) resulted from projected declines in large phytoplankton production, the primary target of herbivorous mesozooplankton. This further amplified negative subtropical NPP declines but was secondary to ZGE and, at higher latitudes, was often offset by increased ZPC. Marked ZPC increases were projected for high latitude regions experiencing shoaling of deep winter mixing or decreased winter sea ice – both tending to increase winter zooplankton biomass and enhance grazer control of spring blooms. Increased ZPC amplified projected NPP increases associated with declining sea ice in the Artic and damped projected NPP declines associated with decreased mixing in the Northwest Atlantic and Southern Ocean. Improved understanding of the complex interactions governing these food web properties is essential to further refine estimates of climate-driven productivity changes across trophic levels.

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