scholarly journals Diet and niche breadth and overlap in fish communities within the area affected by an Amazonian reservoir (Amapá, Brazil)

2014 ◽  
Vol 86 (1) ◽  
pp. 383-406 ◽  
Author(s):  
JÚLIO C. SÁ-OLIVEIRA ◽  
RONALDO ANGELINI ◽  
VICTORIA J. ISAAC-NAHUM
Keyword(s):  
Community Structure ◽  
Seasonal Variation ◽  
Fish Species ◽  
Niche Breadth ◽  
Null Model ◽  
Stomach Contents ◽  
Physical Conditions ◽  
River Damming ◽  
Standard Configuration ◽  
Feeding Resources

We investigated the niche breadth and overlap of the fish species occurring in four environments affected by the Coaracy Nunes reservoir, in the Amapá Brazilian State. Seasonal samples of fishes were taken using a standard configuration of gillnets, as well as dragnets, lines, and castnets. Five hundred and forty stomach contents, representing 47 fish species were analyzed and quantified. Niche breadth and overlap were estimated using indexes of Levins and Pianka, respectively, while interspecific competition was evaluated using a null model (RA3). ANOVA and the KruskalWallis test were used, respectively, to evaluate differences in niche breadth and overlap between areas. The data indicate that the majority of the fish species belong to the piscivore, omnivore, and detritivore guilds. These species have likely colonized the environments due to the availability of suitable feeding resources, and the favorable physical conditions created by the river damming. Overall, few species have ample niches, but most of them are highly specialized. Resources seasonal variation had little effect on the feeding behavior of most species in the study areas. The null models indicated that competition was not a factor determining on community structure.

scholarly journals Diet of the ichthyofauna associated with marginal vegetation of a mangrove forest in southeastern Brazil

2007 ◽  
Vol 97 (4) ◽  
pp. 486-497 ◽  
Author(s):  
Michéle de O. D. A. Corrêa ◽  
Virgínia S. Uieda
Keyword(s):  
Seasonal Variation ◽  
Fish Species ◽  
Food Source ◽  
Niche Breadth ◽  
Animal Origin ◽  
Southeastern Brazil ◽  
Important Food ◽  
Important Food Source ◽  
Aquatic Predators ◽  
Food Niche

The objective of this study was to analyze the diet of fish species that use the mangrove vegetation for shelter and feeding in a river southeastern Brazil. The fieldwork, including collecting and underwater observations, was carried out in the dry (July and August 2004) and in the rainy season (February and March 2005) in order to assess the existence of seasonal variation in the diets. Seven kinds of food items were consumed, two of plant origin and five of animal origin. Crustaceans predominated in the diet of most species, either in the form of unidentified fragments or discriminated in eight groups. The predominance of species using mainly a single food source (crustaceans, principally Ostracoda and Tanaidacea) and the existence of seasonal variation in the diets of some species became very evident in the analysis food niche breadth, with a predominance of dietary specialists. In the Rio da Fazenda mangrove, the submersed marginal vegetation was used by the ichthyofauna as a locale for foraging, and principally as cover by bottom-feeding species. These species may be using the vegetation for protection from aerial and aquatic predators, or even from the pull of the current during the turn of the tide. In the study area, the great diversity of crustaceans constitutes an important food source for most fish species which adjusted their diet according to seasonal changes in food availability and to interactions with other species.

scholarly journals Feeding Habits of Different Fish Species in Negombo Lagoon

2019 ◽  
Vol 8 (2) ◽  
pp. 86-96
Author(s):  
Neetha Punchihewa ◽  
M.P.C. Silva
Keyword(s):  
Fish Species ◽  
Niche Breadth ◽  
Feeding Habits ◽  
Juvenile Fish ◽  
Stomach Contents ◽  
Gut Contents ◽  
Filamentous Algae ◽  
Relative Importance ◽  
Food Items ◽  
Plant Matter

To investigate the feeding habits of different fish species in Negombo lagoon, fish species were collected from Kadolkele and Liyanagemulla sites during February 2015 to July 2015 using a drag net. Collected specimens were preserved in 5% formalin. Later, the fish specimens were dissected, and stomach contents were mixed with water to make a suspension. One ml of suspension was added to the Sedgewick Rafter cell, and examined under the light microscope. The occurrence %, volume %, numbers %, and the Relative Importance Values (RIV) were calculated. The gut contents of 62 samples from 12 fish species were analyzed; 11 species were found to feed on mangroves, 10 on seagrasses, and 8 on filamentous algae. 13 food items were identified. Most of the analysed fish were categorized as omnivores and opportunistic feeders. The juvenile fish mainly feed on a combination of mangroves, seagrasses and filamentous algae. Apart from plant matter, the juvenile fish were found to feed upon Cyclops sp. and mysids. Although Hemirhamphus marginatus is an omnivore, it specially fed on mangroves, seagrasses and filamentous algae. Furthermore, H. marginatus consumed common food items in both habitats except mangroves and molluscs, and the shifting of its diet was depended on the availability of food. The broadest niche breadth was recorded by H. marginatus and the shortest niche breadth by the herbivorous fish species, Siganus vermiculatus and Liza macrolepis. Caranx sexfasciatus exhibited an ontogenetic shift in their diet. The smaller C. sexfasciatus was a carnivore and the larger individuals of the same species were herbivores.

scholarly journals Non-random seasonal variation in the structure of a Mediterranean snake community

Web Ecology ◽  
2007 ◽  
Vol 7 (1) ◽  
pp. 40-46
Author(s):  
E. Filippi ◽  
L. Luiselli
Keyword(s):  
Monte Carlo ◽  
Community Structure ◽  
Seasonal Variation ◽  
Central Italy ◽  
Habitat Type ◽  
Null Model ◽  
Niche Overlap ◽  
Null Models ◽  
Habitat Niche ◽  
Mediterranean Community

Abstract. The community structure in relation to habitat type was studied in a Mediterranean community of snakes from Canale Monterano, central Italy. Habitat data for snakes were analysed both overall and divided by season, i.e. spring (April–June) and summer (July–September). Community analyses were performed using null models (RA2 and RA3 algorithms) and Monte Carlo simulations on habitat niche overlap estimates. Null models suggested that the community was assembled non-randomly (according to RA2 but not RA3), indicating that the generalist-specialist nature (the number of resource states, but not necessarily the types) used by each species in the assemblage reduced ecological similarity. Similar results were reached also performing the same null model procedures on the spring datasets, whereas no structure emerged during summer either by RA2 or RA3 algorithms. In general, this study suggests that the community structure of snakes during spring may be shaped by the different eco-physiological needs of the various species (probably, the differential tolerance to cold and the consequent needs of finding suitable hibernacula), whereas the lack of structure during summer may be caused by the between-species similar foraging needs.

scholarly journals Seasonal variation and community structure of fishes in the Mahananda River with special reference to conservation issues

2016 ◽  
Vol 4 (1) ◽  
pp. 325 ◽  
Author(s):  
Shams Muhammad Galib ◽  
Md Abdur Rashid ◽  
Nipa Chaki ◽  
ABM Mohsin ◽  
Md Abdur Razzaq Joadder
Keyword(s):  
Community Structure ◽  
Seasonal Variation ◽  
Fish Species ◽  
Legal Protection ◽  
Hypophthalmichthys Molitrix ◽  
Exotic Fish ◽  
Meristic Characters ◽  
Analysis Of Similarity ◽  
Fishing Gears ◽  
Traditional Fishing

This study was carried out in the Mahananda River from January to December 2013 with a view to determining the seasonal variation and community structure of fishes along with some conservation issues. Monthly sampling was carried out using traditional fishing gears and fishes were identified based on morphometric and meristic characters. A total of 4082 individuals of native fish species were captured, analyzed and classified into 62 species belonging to 46 genera, 25 families and 9 orders. Cypriniformes and Siluriformes were the dominant fish orders represented by 19 species each and the most abundant family was Cyprinidae (14 species). In addition to indigenous individuals, 9 individuals of 2 exotic fish species (Hypophthalmichthys molitrix and Pangasius hypophthalmus) were also recorded. Among three sampling sites, S-1 was the most diversified in terms of not only the number of individual fish but also the number of species present represented by mean (±SE) individuals of 151.50±25.22 and species of 25.58±3.91. Three distinct fish groups of fish families were revealed from the cluster analysis of similarity. To improve the situation, control of illegal fishing gears, establishment of sanctuaries and legal protection for threatened species are recommended.

scholarly journals Effect of the Human Utilization of Northern Snakehead (Channa argus Cantor, 1842) on the Settlement of Exotic Fish and Cladoceran Community Structure

2021 ◽  
Vol 13 (5) ◽  
pp. 2486
Author(s):  
Jong-Yun Choi ◽  
Seong-Ki Kim
Keyword(s):  
Community Structure ◽  
Fish Species ◽  
Micropterus Salmoides ◽  
Lepomis Macrochirus ◽  
Nakdong River ◽  
Exotic Fish ◽  
Carnivorous Fish ◽  
Channa Argus ◽  
The Nakdong River ◽  
Exotic Fish Species

Empirical studies suggest that changes in the density of top predators, such as carnivorous fish, in freshwater food webs, strongly affect not only fish communities but also various primary and secondary consumers. Based on these findings, we explored how differences in the utilization of carnivorous fish (i.e., Northern Snakehead, Channa argus) by humans affected the fish and cladoceran community structure as well as the settlement of exotic fish species (i.e., Lepomis macrochirus and Micropterus salmoides) in 30 wetlands located in the upper and lower reaches of the Nakdong River. Our results show that in the mid–lower reaches of the Nakdong River, the density of C. argus was low, while high densities of L. macrochirus and M. salmoides were observed. Exotic fish species are frequently consumed by C. argus, leading to a low density of L. macrochirus and M. salmoides in the upper reaches, which supported a high density of C. argus. However, in the mid–lower reaches, the density of L. macrochirus was high because of the frequent collection of C. argus by fishing activities. The dominance of L. macrochirus significantly changed the structure of cladoceran communities. L. macrochirus mainly feeds on pelagic species, increasing the density of epiphytic species in the mid–lower reaches. The continued utilization of C. argus by humans induced a stable settlement of exotic fish species and strongly affected the community structures of primary consumers in the 30 wetlands. The frequency of C. argus collection has to be reduced to secure biodiversity in the mid–lower reaches of the Nakdong River, which will reduce the proportion of exotic fish species and increase the conservation of native fish.

scholarly journals Seasonal feeding plasticity can facilitate coexistence of dominant omnivores in Neotropical streams

2021 ◽  
Author(s):  
Mayara P. Neves ◽  
Pavel Kratina ◽  
Rosilene L. Delariva ◽  
J. Iwan Jones ◽  
Clarice B. Fialho
Keyword(s):  
Seasonal Variation ◽  
Fish Species ◽  
Resource Availability ◽  
Seasonal Changes ◽  
Dry Season ◽  
Diet Overlap ◽  
Isotopic Niche ◽  
Neotropical Streams ◽  
Feeding Plasticity ◽  
The Impact

AbstractCoexistence of ecomorphologically similar species in diverse Neotropical ecosystems has been a focus of long-term debate among ecologists and evolutionary biologists. Such coexistence can be promoted by trophic plasticity and seasonal changes in omnivorous feeding. We combined stomach content and stable isotope analyses to determine how seasonal variation in resource availability influences the consumption and assimilation of resources by two syntopic fish species, Psalidodon aff. gymnodontus and P. bifasciatus, in the Lower Iguaçu basin. We also tested the impact of seasonality on trophic niche breadth and diet overlap of these two dominant omnivores. Seasonal changes in resource availability strongly influenced the consumption and assimilation of resources by the two fish species. Both species exhibited high levels of omnivory, characterized by high diversity of allochthonous resources in the wet season. Terrestrial invertebrates were the main component of diet during this season. However, in the dry season, both species reduced their isotopic niches, indicating diet specialization. High diet overlap was observed in both seasons, but the isotopic niche overlap was smaller in the dry season. Substantial reduction in the isotopic niche of P. bifascistus and a shift toward aquatic invertebrates can facilitate coexistence during this season of resource shortage. Feeding plasticity allows omnivorous fish to adjust their trophic niches according to seasonality, promoting the exploitation of different resources during periods of greater resource diversity. This seasonal variation could be an important mechanism that contributes to the resource partitioning and coexistence of dominant omnivores in Neotropical streams.

A null model to study community structure of microcrustacean assemblages in north Patagonian urban wetlands (39-41°S, Chile)

Crustaceana ◽  
2014 ◽  
Vol 87 (11-12) ◽  
pp. 1377-1385
Author(s):  
Patricio De los Ríos-Escalante ◽  
Andrés Muñoz-Pedreros ◽  
Patricia Möller
Keyword(s):  
Community Structure ◽  
Trophic Status ◽  
Null Model ◽  
Model Analysis ◽  
Jaccard Index ◽  
Field Observations ◽  
Urban Wetlands ◽  
Community Similarity ◽  
Chilean Patagonia ◽  
Inland Water Bodies

The inland water bodies of northern Chilean Patagonia (38-41°S) have many lakes, wetlands and ponds with different littoral and zooplanktonic crustacean assemblages. This study presents field observations of species associations sampled from shallow wetlands located in the urban zones of Valdivia (39°S) and Puerto Montt (41°S). A species presence-absence matrix was created for calculating the Jaccard Index of community similarity and for testing null models of species associations, with the aim of determining whether species associations are random or not. The results of the Jaccard Index calculations indicated the existence of non-defined groups. The results of the null model analysis denoted the presence of regulating factors for Valdivia wetlands, whereas for Puerto Montt wetlands no such factors could be demonstrated. The outcomes of both the Jaccard Index and the significant null model analysis agree with previous ecological descriptions of changes in trophic status as a consequence of changes in the surrounding basin as a determinant of species associations. The ecology of these communities is also discussed.

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