scholarly journals Feeding aspects of Knodus heteresthes (Eigenmann, 1908) and Moenkhausia lepidura (Kner, 1858) (Characiformes, Characidae) in the Teles Pires and Juruena Rivers, southern Amazon

2020 ◽  
Author(s):  
E. Oliveira ◽  
A. R. A. Ignácio ◽  
W. L. Lázaro ◽  
C. C. Muniz ◽  
D. V. S. Campos ◽  
...  
Keyword(s):  
Stomach Contents ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Frequency Of Occurrence ◽  
Dietary Preference ◽  
Importance Index

Abstract The composition of the diet of two species of characids (Knodus heteresthes and Moenkhausia lepidura) was evaluated in the Teles Pires and Juruena Rivers, sampled in September and October 2016. We analyzed 226 stomachs of K. heteresthes and 425 of M. lepidura. The analysis of the stomach contents was based on volumetric and frequency of occurrence methods, applying the food importance index. For the similarity of the diets between the species we calculated the niche overlap with Pianka’s index. Both species in the Juruena River have a dietary preference for arthropods (IAi > 0.95). In the Teles Pires River the diet is concentrated in three sources for both species: arthropods (IAi > 0.52), vegetables (IAi > 0.33) and fish (IAi > 0.12). The diet was dissimilar when compared to environments (ANOSIM, R ≥ 0.57, p < 0.001) with high trophic niche overlap (α > 0.97), regardless of the sampled environment. In the Teles Pires River, both species were classified as omnivorous with an insectivorous tendency and in the Juruena River the insectivorous behaviour occurs.

scholarly journals Seasonal variation on diet of juvenile Elops saurus Linnaeus, 1766 (Ladyfish) in the Parnaiba River Delta

2020 ◽  
Vol 32 ◽  
Author(s):  
Tatiane Araujo Santos ◽  
Thamires Souza Gonçalves ◽  
Patricia Silva do Nascimento ◽  
Cézar Augusto Freire Fernandes ◽  
Francisca Edna de Andrade Cunha
Keyword(s):  
High Frequency ◽  
Rainy Season ◽  
Stomach Contents ◽  
Dry Season ◽  
River Delta ◽  
Frequency Of Occurrence ◽  
Relative Importance ◽  
Dry Period ◽  
Food Items ◽  
Importance Index

Abstract: Aim Identify seasonal variations in the diet of juvenile living in the estuary of the Parnaíba River Delta. Methods Food items were identified through analysis of stomach contents, and later submitted to analysis by regular methods for Frequency of Occurrence (FO), Frequency Numerical (FN), Gravimetric Frequency (FW) and Relative Importance Index (IRI). Results Juvenile diet of Elops saurus that inhabit the lagoons in the Parnaíba delta was composed in order decreasing of importance by Osteichthyes (Teleostei), Insecta and Crustacea in addition to Polychaeta and Nematoda. It was also observed a high frequency of occurrence of fragments of plastics in the diet. In the rainy season, 17 items were recorded in the diet, whereas in the dry season only 7 items were present. Relative Importance Index showed high presence of the Teleostei fish (69.93%) on diet of E. saurus during the rainy season, whereas during the dry period the insects of the families Corixidae (43.25%) and Dysticidae (39.16%). Conclusions With the study it was possible to identify that juvenile are piscivorous in the rainy season when there is a higher availability of prey in the environment and insectivores in the dry season when it reduces the supply of food, indicating feeding flexibility to environmental alterations.

scholarly journals Competition and feeding ecology in two sympatric Xenopus species (Anura: Pipidae)

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3130 ◽  
Author(s):  
Solveig Vogt ◽  
F. André de Villiers ◽  
Flora Ihlow ◽  
Dennis Rödder ◽  
John Measey
Keyword(s):  
Food Preferences ◽  
Stomach Contents ◽  
Niche Overlap ◽  
Niche Differentiation ◽  
Shannon Index ◽  
Trophic Niche ◽  
Western Cape ◽  
The South ◽  
Amphibian Species ◽  
Study Sites

The widespread African clawed frog (Xenopus laevis) occurs in sympatry with the IUCN Endangered Cape platanna (Xenopus gilli) throughout its entire range in the south-western Cape, South Africa. In order to investigate aspects of the interspecific competition between populations of X. laevis and X. gilli, an assessment of their niche differentiation was conducted through a comprehensive study on food composition and trophic niche structure at two study sites: the Cape of Good Hope (CoGH) and Kleinmond. A total of 399 stomach contents of X. laevis (n = 183) and X. gilli (n = 216) were obtained together with samples of available prey to determine food preferences using the Electivity index (E*), the Simpson’s index of diversity (1 − D), the Shannon index (H′), and the Pianka index (Ojk). Xenopus gilli diet was more diverse than X. laevis, particularly in Kleimond where the Shannon index was nearly double. Both species were found to consume large amounts of tadpoles belonging to different amphibian species, including congeners, with an overall higher incidence of anurophagy than previously recorded. However, X. laevis also feeds on adult X. gilli, thus representing a direct threat for the latter. While trophic niche overlap was 0.5 for the CoGH, it was almost 1 in Kleinmond, suggesting both species utilise highly congruent trophic niches. Further, subdividing the dataset into three size classes revealed overlap to be higher in small frogs in both study sites. Our study underlines the importance of actively controlling X. laevis at sites with X. gilli in order to limit competition and predation, which is vital for conservation of the south-western Cape endemic.

scholarly journals Changes in trophic characteristics of two fish species of Astyanax (Teleostei: Characidae) in response to aquatic pollution

2019 ◽  
Vol 36 ◽  
pp. 1-12 ◽  
Author(s):  
Mirella B. Alonso ◽  
Débora R. de Carvalho ◽  
Carlos B. M. Alves ◽  
Marcelo Z. Moreira ◽  
Paulo S. Pompeu
Keyword(s):  
Isotopic Composition ◽  
Fish Species ◽  
Environmental Changes ◽  
Stomach Contents ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Metropolitan Region ◽  
Trophic Plasticity ◽  
Polluted Sites ◽  
Belo Horizonte

The trophic plasticity of most fish species of Astyanax Baird &amp; Girard, 1854 in response to environmental changes and resource availability is high. This work evaluates the differences in the trophic characteristics of two congeneric species, Astyanaxtaeniatus (Jenyns, 1842) and Astyanaxlacustris (Lütken, 1875), in Rio das Velhas Basin, which is highly impacted by the discharge of sewage from the Metropolitan Region of Belo Horizonte (MRBH). Eight sites were sampled and grouped into three regions: upper course (two sites upstream of the MRBH); middle course (three sites located in the middle portion of the Rio das Velhas, region with greater influence of the MRBH), and lower course (three sites downstream of the MRBH). Samples of fish and food resources were collected from all sites to obtain the isotopic composition of nitrogen (δ15N) and carbon (δ13C), and the stomach contents of the two species was analized. The most common items in the stomach of A.lacustris and A.taeniatus, respectively, were from plants and insects, followed by algae/periphyton (especially at the low course of Rio das Velhas). In contrast, stable isotope analyses indicated that algae (in polluted sites) and periphyton (in least-disturbed sites) were best assimilated both species. Both analyses indicated that the trophic niches of the two species overlap more in more polluted sites relative to less polluted sites. Astyanaxtaeniatus and A.lacustris only presented different isotopic composition of carbon and nitrogen in the upper course of the Rio das Velhas, probably in response to the greater diversity of food items consumed by each species. In the other regions, the species presented similar isotopic signatures, with δ15N and δ13C notably enriched in the most polluted regions (middle and low course). Our results suggest that pollution acts by increasing trophic niche overlap of these species, altering the type of resources most assimilated, and promoting a greater enrichment of δ15N in fish and resources.

Spatial and trophic niche overlap between Diplodus bellottii and Diplodus vulgaris in the Tagus estuary, Portugal

2004 ◽  
Vol 84 (4) ◽  
pp. 837-842 ◽  
Author(s):  
Manuel Horta ◽  
Maria José Costa ◽  
Henrique Cabral
Keyword(s):  
Feeding Habits ◽  
Stomach Contents ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Sea Bream ◽  
Tagus Estuary ◽  
Otter Trawl ◽  
Limiting Factor ◽  
Species Competition ◽  
Competition For Space

To evaluate the consequences of the coexistence of the Senegal sea bream Diplodus bellottii with one other species of Diplodus, Diplodus vulgaris, in the Tagus estuary (Portugal), the distribution and feeding habits of juveniles and adults of both species were studied. Sampling took place between May 2001 and March 2002, in five zones, including the estuary and adjacent coastal area, using an otter trawl. Both species were abundant in the estuary and their distribution overlapped. The stomach contents analysis showed that the diet of both species was mainly composed of algae, bivalves and crustaceans. Diphodus bellottii and D. vulgaris showed a generalist feeding behaviour and were clearly omnivorous, being detected in a high trophic niche overlap between the two species. Competition for space and food may occur when densities are high and food became a limiting factor.

scholarly journals Changes in prey importance and prey niche overlap of sexes during the alpine newt breeding season

2020 ◽  
Vol 146 (2) ◽  
Author(s):  
Oldřich Kopecký
Keyword(s):  
Breeding Season ◽  
Stomach Contents ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Sexual Differences ◽  
Food Sources ◽  
Quantitative Composition ◽  
Important Prey ◽  
Alpine Newt ◽  
Prey Items

Urodeles, including European newts, are usually sexually dimorphic predators. Among newts, the alpine newt has the most pronounced sexual size dimorphism (in favour of females). Gender is a factor that is often associated with intra-specific diet differences. Despite the significant number of dietary studies on the alpine newt, some topics such as the breadth of the trophic niche and its overlap between sexes, or inter-sexual differences in qualitative and quantitative composition of prey remain unresolved. The present study dealing with these questions was conducted at two localities (ponds at an elevation of about 450 m) in the Czech Republic. Newts were captured from the banks during the entire breeding season using a dip net, and the stomach contents were extracted using a stomach flushing technique. Altogether 190 individuals were sampled, and a total of 1,417 prey items were obtained. The available food sources differed over the course of the breeding season, as newts changed the taxa they preyed on. This reflects the ability of newts to switch between several hunting strategies. The overall food niche overlap between the sexes was relatively large (C = 0.761, resp. C = 0.797). Inter-sexual differences were detected at both localities, mainly in the number of prey items consumed from the most important prey categories such as Rana eggs or Isopoda, which were consumed in higher numbers by females. The findings of this study suggest that females are more sensitive to the trade-off between energy intake and expenditure during the breeding season.

scholarly journals Trophic analysis of the fish community in the Ciénega Churince, Cuatro Ciénegas, Coahuila

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3637 ◽  
Author(s):  
Ariana Hernández ◽  
Hector S. Espinosa-Pérez ◽  
Valeria Souza
Keyword(s):  
Fish Community ◽  
Stomach Contents ◽  
Trophic Niche ◽  
Feeding Strategies ◽  
Dietary Control ◽  
Importance Index ◽  
Linkage Method ◽  
Cuatro Ciénegas ◽  
Trophic Analysis ◽  
Feed Coefficient

Fish diets were analyzed to evaluate the dynamic trophs of the fish community in the Churince wetland system of the Cuatro Ciénegas, where the fauna consists of nine species: endemic, native and introduced. In nine sampling events (between February 2011 and May 2014) 556 specimens of all nine species were collected. Stomach contents were analyzed and the Relative Importance Index (IRI) was calculated. The feed coefficient (Q) of the diets and the accumulated trophic diversity (Hk), as well as the amplitude of the trophic niche were evaluated. Feeding strategies in the fish community were found to be eurifagic. The main foods in general were insects, crustaceans, gastropods, plants and teleosts. According to the average linkage method, four functional trophic groups were defined, with no higher consumption species; nevertheless all were regulators, mainly invertebrates. Therefore, the chain reaction in food control was higher from top to bottom, meaning a downwards dietary control.

scholarly journals Ecología trófica y reproductiva de Hemibrycon sierraensis (Characiformes: Characidae) pez endémico del río Gaira, Sierra Nevada de Santa Marta, Colombia

2017 ◽  
Vol 65 (3) ◽  
pp. 1033
Author(s):  
Eduardo J. Ibarra-Trujillo ◽  
Carlos A. García-Alzate
Keyword(s):  
Sierra Nevada ◽  
Sexual Maturity ◽  
Condition Factor ◽  
Feeding Habits ◽  
Gonadosomatic Index ◽  
Stomach Contents ◽  
Trophic Niche ◽  
Oocyte Diameter ◽  
Frequency Of Occurrence ◽  
Average Size

The study of feeding habits in fishes can give important information about their role in the fish community, their functional role in the ecosystem, and their relationships with all available resources. We studied H. sierraensis from Gaira River and performed eight bi-monthly samples between May 2014 and November 2015. We analyzed fish stomach contents by the numerical (% N), volume (% V) and frequency of occurrence (% FO) methods; we also calculated the index of food importance (IA), coefficient of emptiness (CV), trophic niche breadth (used H ') and condition factor (K). Additionally, we determined the sex ratio, gonadosomatic index (RGS), fecundity, minimum and average size at sexual maturity, and oocyte diameter by standard methods. The Gaira River has irregular meanders with clear waters, and high current velocity through its drainage; it is generally oligotrophic, with a tendency to eutrophic condition in some places. Observed dissolved oxygen values were high (5.4 mg/L), electrical conductivity was 68.63 µS/cm, and pH was found neutral. We analyzed stomach contents of 477 specimens, and found a 1.59 % coefficient of vacuity. The species was found euryphagic in its feeding habits (H'= 0.69), omnivorous tending to insectivorous; its diet consisted mainly of Trichoptera larvae (Atanatolica sp.), followed in importance by snails (Gastropoda Pomacea sp.) and dipteran larvae such as Simulium sp. Significant differences in both frequency of occurrence and the volume consumed were observed for the different size classes, as well as between different seasons of the year. The condition factor indicated that the species was well fed. Sex was determined for 424 fish, of which 241 were male and 181 female, given a ratio of 1.3: 1 (male-female) which resulted significantly different (Chi 2: 16.14; P= 0.02). The gonadosomatic index indicated that reproduction occurs during the high water river phase, fecundity was high, and oocyte diameter was relatively small. Males reached sexual maturity at an average size of 67.08 mm SL, and females at 70.68 mm SL. Their life history strategy is seasonal r. Management and conservation plans for this species are required due to human intervention in their habitat, originated by the growing tourist activity in the area.

Trophic niche overlap in two syntopic colubrid snakes (Hierophis viridiflavus and Zamenis longissimus) with contrasted lifestyles

2012 ◽  
Vol 33 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Hervé Lelièvre ◽  
Pierre Legagneux ◽  
Gabriel Blouin-Demers ◽  
Xavier Bonnet ◽  
Olivier Lourdais
Keyword(s):  
Diet Composition ◽  
Feeding Rate ◽  
Species Coexistence ◽  
Niche Partitioning ◽  
Stomach Contents ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Temperate Climate ◽  
Feeding Strategies ◽  
Mean Body Temperature

In many organisms, including snakes, trophic niche partitioning is an important mechanism promoting species coexistence. In ectotherms, feeding strategies are also influenced by lifestyle and thermoregulatory requirements: active foragers tend to maintain high body temperatures, expend more energy, and thus necessitate higher energy income. We studied diet composition and trophic niche overlap in two south European snakes (Hierophis viridiflavus and Zamenis longissimus) in the northern part of their range. The two species exhibit contrasted thermal adaptations, one being highly mobile and thermophilic (H. viridiflavus) and the other being elusive with low thermal needs (Z. longissimus). We analyzed feeding rate (proportion of snakes with indication of a recent meal) and examined more than 300 food items (fecal pellets and stomach contents) in 147 Z. longissimus and 167 H. viridiflavus. There was noticeable overlap in diet (overlap of Z. longissimus on H. viridiflavus = 0.62; overlap of H. viridiflavus on Z. longissimus = 0.80), but the similarity analyses showed some divergence in diet composition. Dietary spectrum was wider in H. viridiflavus, which fed on various mammals, birds, reptiles, and arthropods whereas Z. longissimus was more specialized on mammals and birds. The more generalist nature of H. viridiflavus was consistent with its higher energy requirements. In contrast to our expectation, feeding rate was apparently higher in Z. longissimus than in H. viridiflavus, but this could be an artifact of a longer transit time in Z. longissimus, given its lower mean body temperature. These results allow a better understanding of the ability to coexist in snakes belonging to temperate climate colubrid communities.

scholarly journals The food web in a subterranean ecosystem is driven by intraguild predation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andrea Parimuchová ◽  
Lenka Petráková Dušátková ◽  
Ľubomír Kováč ◽  
Táňa Macháčková ◽  
Ondřej Slabý ◽  
...  
Keyword(s):  
Food Web ◽  
Trophic Interactions ◽  
Intraguild Predation ◽  
Linear Models ◽  
Niche Overlap ◽  
Trophic Niche ◽  
High Availability ◽  
Large Prey ◽  
Arthropod Predators ◽  
Body Sizes

AbstractTrophic interactions of cave arthropods have been understudied. We used molecular methods (NGS) to decipher the food web in the subterranean ecosystem of the Ardovská Cave (Western Carpathians, Slovakia). We collected five arthropod predators of the species Parasitus loricatus (gamasid mites), Eukoenenia spelaea (palpigrades), Quedius mesomelinus (beetles), and Porrhomma profundum and Centromerus cavernarum (both spiders) and prey belonging to several orders. Various arthropod orders were exploited as prey, and trophic interactions differed among the predators. Linear models were used to compare absolute and relative prey body sizes among the predators. Quedius exploited relatively small prey, while Eukoenenia and Parasitus fed on relatively large prey. Exploitation of eggs or cadavers is discussed. In contrast to previous studies, Eukoenenia was found to be carnivorous. A high proportion of intraguild predation was found in all predators. Intraspecific consumption (most likely cannibalism) was detected only in mites and beetles. Using Pianka’s index, the highest trophic niche overlaps were found between Porrhomma and Parasitus and between Centromerus and Eukoenenia, while the lowest niche overlap was found between Parasitus and Quedius. Contrary to what we expected, the high availability of Diptera and Isopoda as a potential prey in the studied system was not corroborated. Our work demonstrates that intraguild diet plays an important role in predators occupying subterranean ecosystems.

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