scholarly journals First study of food webs in a large glacial river: the trophic role of invasive trout

2020 ◽  
Vol 18 (3) ◽  
Author(s):  
Marina Tagliaferro ◽  
Sean P. Kelly ◽  
Miguel Pascual
Keyword(s):  
Rainbow Trout ◽  
Food Webs ◽  
Fish Species ◽  
Lake Trout ◽  
Trophic Position ◽  
Life Stage ◽  
Trophic Levels ◽  
Basal Resources ◽  
Ecological Importance ◽  
Δ15n And Δ13c

Abstract The aim of this study was to determine the food webs structure of a large Patagonian river in two river sections (Upstream and Midstream) and to evaluate isotopic overlap between native and introduced species. We used stable isotope analyses of δ15N and δ13C and stomach content. The Upstream section had a more complex food webs structure with a greater richness of macroinvertebrates and fish species than Midstream. Upstream basal resources were dominated by filamentous algae. Lake Trout were found to have a higher trophic position than all other fish species in that area although, the most abundant fish species, were Rainbow Trout. Depending on the life stage, Rainbow Trout shifted from prey to competitor/predator. In the Midstream section, the base of the food webs was dominated by coarse particulate organic matter, and adult Rainbow Trout had the highest trophic level. Isotopic values changed among macroinvertebrates and fish for both areas. The two most abundant native and invasive species — Puyen and Rainbow Trout — showed an isotopic separation in Midstream but did not in Upstream areas. The presence of invasive fish that occupy top trophic levels can have a significant impact on native fish populations that have great ecological importance in the region.

scholarly journals ‘Taking Fishers’ Knowledge to the Lab’: An Interdisciplinary Approach to Understand Fish Trophic Relationships in the Brazilian Amazon

2021 ◽  
Vol 9 ◽  
Author(s):  
Paula Evelyn Rubira Pereyra ◽  
Gustavo Hallwass ◽  
Mark Poesch ◽  
Renato Azevedo Matias Silvano
Keyword(s):  
Stable Isotopes ◽  
Food Webs ◽  
Fish Species ◽  
Trophic Interactions ◽  
Brazilian Amazon ◽  
Trophic Levels ◽  
Trophic Relationships ◽  
Ecological Knowledge ◽  
Data Limitations ◽  
Combining Data

Trophic levels can be applied to describe the ecological role of organisms in food webs and assess changes in ecosystems. Stable isotopes analysis can assist in the understanding of trophic interactions and use of food resources by aquatic organisms. The local ecological knowledge (LEK) of fishers can be an alternative to advance understanding about fish trophic interactions and to construct aquatic food webs, especially in regions lacking research capacity. The objectives of this study are: to calculate the trophic levels of six fish species important to fishing by combining data from stable isotopes analysis and fishers’ LEK in two clear water rivers (Tapajós and Tocantins) in the Brazilian Amazon; to compare the trophic levels of these fish between the two methods (stable isotopes analysis and LEK) and the two rivers; and to develop diagrams representing the trophic webs of the main fish prey and predators based on fisher’s LEK. The fish species studied were Pescada (Plagioscion squamosissimus), Tucunaré (Cichla pinima), Piranha (Serrasalmus rhombeus), Aracu (Leporinus fasciatus), Charuto (Hemiodus unimaculatus), and Jaraqui (Semaprochilodus spp.). A total of 98 interviews and 63 samples for stable isotopes analysis were carried out in both rivers. The average fish trophic levels did not differ between the stable isotopes analysis and the LEK in the Tapajós, nor in the Tocantins Rivers. The overall trophic level of the studied fish species obtained through the LEK did not differ from data obtained through the stable isotopes analysis in both rivers, except for the Aracu in the Tapajós River. The main food items consumed by the fish according to fishers’ LEK did agree with fish diets as described in the biological literature. Fishers provided useful information on fish predators and feeding habits of endangered species, such as river dolphin and river otter. Collaboration with fishers through LEK studies can be a viable approach to produce reliable data on fish trophic ecology to improve fisheries management and species conservation in tropical freshwater environments and other regions with data limitations.

A Trophic Position Model of Pelagic Food Webs: Impact on Contaminant Bioaccumulation in Lake Trout

1996 ◽  
Vol 66 (4) ◽  
pp. 451-477 ◽  
Author(s):  
M. Jake Vander Zanden ◽  
Joseph B. Rasmussen
Keyword(s):  
Food Webs ◽  
Lake Trout ◽  
Trophic Position ◽  
Pelagic Food Webs

scholarly journals On the Use of Stable Hydrogen Isotope Measurements (δ2H) to Discern Trophic Level in Avian Terrestrial Food Webs

Diversity ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 202
Author(s):  
Rien E. van Wijk ◽  
Yahkat Barshep ◽  
Keith A. Hobson
Keyword(s):  
Food Webs ◽  
Hydrogen Isotope ◽  
Trophic Position ◽  
Terrestrial Ecosystems ◽  
Forest Site ◽  
Trophic Enrichment ◽  
Terrestrial Environments ◽  
Closed Canopy ◽  
Stable Hydrogen Isotope ◽  
Δ15n And Δ13c

The measurement of stable hydrogen isotope ratios (δ2H) in animal tissues is a popular means of inferring spatial origins and migratory connections. However, the use of this isotope to infer diet and potentially trophic position remains poorly understood, especially in non-aquatic terrestrial ecosystems. In many animal communities, tissue δ15N values are strongly associated with trophic position. Correlations between tissue δ2H and δ15N are expected, then, if δ2H is affected by trophic enrichment of 2H. In addition, within sites, we would expect higher tissue δ2H values in insectivorous species compared to granivores or nectarivores. We tested these hypotheses for two resident avian communities in Nigeria consisting of 30 species representing a range of dietary guilds (granivores, frugivores, nectarivores, omnivores, insectivores) by comparing feather δ2H, δ15N and δ13C values. We found considerable isotopic overlap among all guilds except granivores, with no clear pattern of enrichment in 2H with trophic position. However, at one of our sites (open scrubland), feather δ2H was positively correlated with feather δ15N (R2 = 0.30) compared to a closed canopy forest site (R2 = 0.09). Our results indicate weak evidence for predictable trophic enrichment in 2H in terrestrial environments and indicate that controlled studies are now required to definitively elucidate the behavior of H isotopes in terrestrial food webs.

Non-indigenous amphipods and mysids in coastal food webs of eastern Baltic Sea estuaries

2016 ◽  
Vol 97 (3) ◽  
pp. 581-590 ◽  
Author(s):  
Nadezhda A. Berezina ◽  
Arturas Razinkovas-Baziukas ◽  
Alexei V. Tiunov
Keyword(s):  
Baltic Sea ◽  
Food Webs ◽  
Trophic Position ◽  
Isotope Analysis ◽  
River Estuary ◽  
Trophic Levels ◽  
Gut Contents ◽  
Curonian Lagoon ◽  
Gammarus Tigrinus ◽  
Neva Estuary

The study analyses the role of non-indigenous invertebrates in the food webs of two eutrophic brackish estuarine ecosystems of the Baltic Sea: the Neva River estuary and the Curonian Lagoon, with the aim of clarifying several questions such as what trophic levels were occupied by newly established species (mainly amphipods and mysids) and whether they can affect the native benthic invertebrates as a result of their possible carnivorous nature. Stable isotope analysis (δ15N values) and gut contents analysis of field-collected specimens were used to estimate trophic level and trophic links of the newly established malacostracan crustaceans, while their consumption rates when feeding as carnivores were measured experimentally. The δ15N analysis allocated four trophic levels (TL) in the coastal food webs of both studied ecosystems with the lowest δ15N (2–4‰) for detritus and algae and the highest for fish (12–14‰). Through their high abundance, non-indigenous crustaceans (Pontogammarus robustoides, Gmelinoides fasciatus, Obessogammarus crassus, Gammarus tigrinus, Limnomysis benedeni and Paramysis lacustris) have become important members of food chains of the studied ecosystems. Their trophic position varied significantly within species during ontogenesis. This suggests that they turned from being typically detritivores/plantivorous (TL 2–2.4) at juvenile stages to omnivores (2.5–3) or to carnivores (>3) as adults. Assessment of the predation pressure by the adult amphipods on other coexisting invertebrates (in the example of the Neva Estuary) showed a low or medium impact, depending on species of predator and productivity of its potential prey organisms.

scholarly journals Persistent organic pollutants in river food webs: influence of trophic position and degree of heterotrophy

2005 ◽  
Vol 62 (9) ◽  
pp. 2021-2032 ◽  
Author(s):  
Olof Berglund ◽  
Per Nyström ◽  
Per Larsson
Keyword(s):  
Food Webs ◽  
Salmo Trutta ◽  
Trophic Position ◽  
Dry Weight ◽  
Grazing Pressure ◽  
Weight Basis ◽  
Trophic Levels ◽  
Brown Trout Salmo Trutta ◽  
Lipid Weight ◽  
The Mean

We investigated how the degree of autotrophy/heterotrophy and organism trophic position influenced the bioaccumulation of polychlorinated biphenyls (PCBs) in 10 benthic river food webs consisting of terrestrial detritus, periphyton, invertebrates, and age-0 brown trout (Salmo trutta) in southern Sweden. Concentrations of PCBs increased with trophic position, estimated from δ15N and δ13C, on a dry weight basis (ng·g–1 dry weight) but not on a lipid weight basis (ng·g–1 lipid). PCB biomagnification factors between the first and second trophic levels (invertebrates/ periphyton and invertebrates/detritus) ranged between 0.3 and 2.3 and between the second and third levels (trout/invertebrates) between 0.3 and 2.0 on a lipid weight basis. The mean proportion of carbon ultimately derived from terrestrial sources, α, was 0.82 ± 0.19 for invertebrates and 0.67 ± 0.28 for trout. Contrary to our hypothesis, PCB concentrations in trout were positively related to α (r2 = 0.58–0.77, p < 0.05). As α and the periphyton density (g C·m–2) in the rivers was positively related (r2 = 0.88, p < 0.01), we propose that this relationship was due to an increased retention and exposure of PCBs to trout in rivers with low grazing pressure and high periphyton density.

scholarly journals Food web persistence in fragmented landscapes

2017 ◽  
Vol 284 (1859) ◽  
pp. 20170350 ◽  
Author(s):  
Jinbao Liao ◽  
Daniel Bearup ◽  
Bernd Blasius
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Trophic Position ◽  
Biodiversity Loss ◽  
Habitat Destruction ◽  
Trophic Levels ◽  
Food Web Structure ◽  
Spatially Extended ◽  
Biodiversity Maintenance ◽  
Patch Connectivity

Habitat destruction, characterized by patch loss and fragmentation, is a key driver of biodiversity loss. There has been some progress in the theory of spatial food webs; however, to date, practically nothing is known about how patch configurational fragmentation influences multi-trophic food web dynamics. We develop a spatially extended patch-dynamic model for different food webs by linking patch connectivity with trophic-dependent dispersal (i.e. higher trophic levels displaying longer-range dispersal). Using this model, we find that species display different sensitivities to patch loss and fragmentation, depending on their trophic position and the overall food web structure. Relative to other food webs, omnivory structure significantly increases system robustness to habitat destruction, as feeding on different trophic levels increases the omnivore's persistence. Additionally, in food webs with a dispersal–competition trade-off between species, intermediate levels of habitat destruction can enhance biodiversity by creating refuges for the weaker competitor. This demonstrates that maximizing patch connectivity is not always effective for biodiversity maintenance, as in food webs containing indirect competition, doing so may lead to further species loss.

Trophic position and individual feeding histories of fish from Lake Okeechobee, Florida

1999 ◽  
Vol 56 (4) ◽  
pp. 590-600 ◽  
Author(s):  
Brian Fry ◽  
Patricia L Mumford ◽  
Franklin Tam ◽  
Don D Fox ◽  
Gary L Warren ◽  
...  
Keyword(s):  
Fish Species ◽  
Trophic Position ◽  
Trophic Levels ◽  
Small Fish ◽  
Lake Okeechobee ◽  
Isotopic Analyses ◽  
Marsh Site ◽  
C And N ◽  
Almost All

We used C and N stable isotope measurements to identify trophic position and feeding histories of fish from Lake Okeechobee, one of the largest lakes in North America. When δ15N values were used to estimate trophic levels, analyses of about 500 individual fish collected in two seasons at five sites showed that trophic level varied from 2 (herbivore) to 4.3 (second-level carnivore) among the 29 fish species examined. Lower trophic levels predominated among small fish caught at a littoral marsh site, and highest trophic levels were found among larger offshore fish. Marsh fish showed about three times the C isotope variation than did offshore fish, consistent with the wider array of foods in the marsh versus offshore food web. In addition to these community-level results, there were often unexpected large isotopic differences between individuals in almost all fish species examined, suggesting large differences in individual feeding behavior. Isotopic analyses indicate long-term differences in feeding among individuals, in addition to the short-term differences often observed in stomach content studies. Long-term individual variation in fish foraging may be important in understanding variation in other biochemical parameters measured in fish, such as Hg or PCB contents.

Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea

1998 ◽  
Keyword(s):  
Rainbow Trout ◽  
Atlantic Salmon ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Lake Trout ◽  
Maternal Diet ◽  
Life Stage ◽  
Maternal Weight ◽  
Thermal Habitat ◽  
Finger Lakes

<em>Abstract</em>.—A lethal thiamine deficiency afflicting larval landlocked Atlantic salmon <em>Salmo salar </em>in several of New York’s Finger Lakes has been linked to a maternal diet of the exotic, thiaminase-rich alewife <em>Alosa pseudoharengus</em>. To evaluate why trout and char species in the Finger Lakes are apparently not affected by this “Cayuga syndrome,” levels of thiamine in the whole blood of syndromepositive and syndrome-negative stocks of Atlantic salmon were compared with levels in lake trout <em>Salvelinus namaycush</em>, brown trout <em>Salmo trutta</em>, and rainbow trout <em>Oncorhynchus mykiss </em>from Cayuga and/or Seneca lakes. Thiamine levels did not differ between sexes within any species or stock. Consistent with the hypothesis that thermal habitat partitioning may predispose the salmon to more dietary thiaminase than other Finger Lakes salmonids, thiamine levels in the salmon that produced syndrome-positive sac fry were significantly lower than levels measured in Finger Lakes brown trout and rainbow trout. In contrast, there was no difference between the syndrome-positive salmon and Finger Lakes lake trout, possibly because the male char were in starved (postspawned) condition. Regressions of maternal blood or egg thiamine versus maternal weight and length were not significant for salmon that produced syndrome-positive sac fry; yet, a significant inverse relationship was detected for the syndrome-negative salmon from the Adirondack progenitor stock. These findings may reflect the transition of these reference control salmon from a thiaminase-poor invertebrate diet to a piscivorous diet of thiaminase-active smelt <em>Osmerus mordax</em>.

Recycling of Elements Transported Upstream by Runs of Pacific Salmon: I, δ15N and δ13C Evidence in Sashin Creek, Southeastern Alaska

1990 ◽  
Vol 47 (1) ◽  
pp. 136-144 ◽  
Author(s):  
Thomas C. Kline Jr. ◽  
John J. Goering ◽  
Ole A. Mathisen ◽  
Patrick H. Poe ◽  
Patrick L. Parker
Keyword(s):  
Rainbow Trout ◽  
Food Webs ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Oncorhynchus Gorbuscha ◽  
Organic C ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Control Section ◽  
The Difference ◽  
Δ15n And Δ13c

Values of δ15N and δ13C (the per mil deviation from the recognized isotope standard) from biota of a southeastern Alaska stream (Sashin Creek) that receives an annual run of 30 000 anadromous pink salmon (Oncorhynchus gorbuscha) were measured to determine sources of nitrogen (N) and carbon (C). Marine-derived nitrogen (MDN) is the predominant source of N for food webs found in the lower 1200 m of the stream which, due to a waterfall, is the only portion of the stream available to salmon returning to spawn. Comparable spawning section biota were enriched by about 5 per mil relative to the salmon-free control section, corresponding to the difference between 0 and 100% MDN in a mixing model. Food webs of resident rainbow trout (O. mykiss), at the outlet of one of the source lakes, Sashin Lake, have very low δ13C, suggesting the importance of a respired C pool in the lake. The source of C in the remainder of the stream is C fixation by autochthonous producers and marine organic C (within the salmon spawning section). Resident fishes in the salmon spawning section depend on MDN and some of the C delivered by the annual run of returning salmon.

scholarly journals Multiple species drive flexible lake food webs with warming

2018 ◽  
Author(s):  
Timothy J. Bartley ◽  
Tyler D. Tunney ◽  
Nigel P. Lester ◽  
Brian J. Shuter ◽  
Robert H. Hanner ◽  
...  
Keyword(s):  
Climate Change ◽  
Temperature Gradient ◽  
Food Webs ◽  
Lake Trout ◽  
Trophic Levels ◽  
Forage Fish ◽  
Food Web Structure ◽  
Web Structure ◽  
Nearshore Habitat ◽  
Multiple Species

AbstractClimate change is rewiring the food webs that determine the fate of diverse ecosystems. Mobile generalist consumers are responding to climate change by rapidly shifting their behaviour and foraging, driving food webs to flex. Although these responsive generalists form a key stabilizing module in food web structure, the extent to which they are present throughout whole food webs is largely unknown. Here, we show that multiple species comprising key trophic roles drive flexible lake food webs with warming. By examining lakes that span a 7°C air temperature gradient, we found significant reductions in nearshore derived carbon and nearshore habitat use with increased temperature in three of four fish species. We also found evidence that the response of lake trout to increased temperatures may reduce their biomass and cascade to release their preferred prey, the pelagic forage fish cisco. Our results suggest that climate warming will shift lake food webs toward increased reliance on offshore habitats and resources. We argue that species across trophic levels broadly couple lake macrohabitats, suggesting that potentially stabilizing responsive consumers are present throughout food webs. However, climate change appears to limit their ability to responsively forage, critically undermining a repeated stabilizing mechanism in food webs.

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