scholarly journals Trophic ecology of two piranha species, Pygocentrus nattereri and Serrasalmus marginatus (Characiformes, Characidae), in the floodplain of the Negro River, Pantanal

2014 ◽  
Vol 26 (4) ◽  
pp. 381-391 ◽  
Author(s):  
Fabiane Silva Ferreira ◽  
Wagner Vicentin ◽  
Fábio Edir dos Santos Costa ◽  
Yzel Rondon Súarez
Keyword(s):  
Trophic Ecology ◽  
Niche Breadth ◽  
Feeding Activity ◽  
Interspecific Variation ◽  
Dry Season ◽  
Ontogenetic Changes ◽  
Flood Season ◽  
Negro River ◽  
Main River ◽  
Main River Channel

AIM: This study aimed to evaluate influence of hydrological variation, ontogeny and interspecific variation in the feeding activity and diet composition for P. nattereri and S. marginatus in floodplain of Negro River, South Pantanal. METHODS: The samples were taken with the use of gillnets and cast nets of different sizes, from October/2005 to August/2008. RESULTS: We sampled 748 specimens, 442 of P. nattereri and 306 of S. marginatus. We identified 31 items in the dry and 14 in the flood season for P. nattereri, and 29 items in the dry and eight in the flood season for S. marginatus. For both species, fish was the predominant food item in both seasons. The PERMANOVA results showed that the diet varied significantly between the two species (p<0.001), during ontogenetic development (p<0.001) and seasonally (p=0.024). The ancova results suggests that the intensity of food intake was higher in the dry season (p<0.001) for both species. The niche breadth varied only between studied species with S. marginatus presenting higher niche breadth than P. nattereri. CONCLUSION: Piranhas feed more during dry season, probably because in this period food is more varied and abundant, due to the concentration of fish in the main river channel. There were ontogenetic changes in the diet, with no feeding overlap between the two species, probably because of differences in preference for some items and differences in feeding behavior displayed during hunting attacks.

scholarly journals Trophic ecology of the ichthyofauna of a stretch of the Urucu River (Coari, Amazonas, Brazil)

2013 ◽  
Vol 25 (1) ◽  
pp. 54-67 ◽  
Author(s):  
Igor David da Costa ◽  
Carlos Edwar de Carvalho Freitas
Keyword(s):  
Trophic Structure ◽  
Trophic Ecology ◽  
Fish Assemblages ◽  
Hydrological Cycle ◽  
Taxonomic Diversity ◽  
Dry Season ◽  
Water Levels ◽  
Seasonal Fluctuations ◽  
Flood Season ◽  
Wide Range

INTRODUCTION: The floodplains of the large Amazonian rivers are very productive as a result of seasonal fluctuations of water levels. This favors the fishes as they are provided with a wide range of habitats and food resources; AIM: In this study, we identified the trophic structure of fish assemblages in the upper river Urucu area (State of Amazonas - Brazil), observing seasonal changes determined by the hydrological cycle; Methods: Samples were collected with the aid of gillnets, during the flood season (April/2008) and the dry season (August/2008) in areas upstream and downstream of ports of the Urucu river within the municipality of Coari, Amazonas, Brazil; RESULTS: 902 individuals of seven orders, 23 families and 82 species were collected. Fishes were more abundant in the dry season than in the flood season, and the piscivores and carnivores (Serrasalumus rhombeus and Osteoglossum bicirrhosum) were the most significant trophic categories in the dry season whereas piscivores and insectivores (Serrasalumus rhombeus, Bryconops alburnoides and Dianema urostriatum) were more abundant in the flood season. The trophic diversity, dominance and evenness were very similar in all sampling periods and show lower values than taxonomic index patterns, except for the trophic dominance in the dry season. Taxonomic diversity and dominance were higher in the flood season if compared to the dry season, but figures were quite uniform and there were no great discrepancies between seasons. CONCLUSION: We found through our studies that the dry and flood seasons work as regulatory factors of abundance of fishes of certain trophic categories in the Urucu river, what can be possibly explained by the availability of resources and the food spectrum of each category.

scholarly journals Seasonal abundance and breeding habitat occupancy of the Orinoco Goose (Neochen jubata) in western Brazilian Amazonia

2014 ◽  
Vol 24 (4) ◽  
pp. 518-529 ◽  
Author(s):  
WHALDENER ENDO ◽  
TORBJØRN HAUGAASEN ◽  
CARLOS A. PERES
Keyword(s):  
Sandy Beaches ◽  
Dry Season ◽  
River Channel ◽  
Habitat Associations ◽  
Breeding Habitat ◽  
Seasonal Abundance ◽  
Encounter Rate ◽  
Brazilian Amazonia ◽  
Main River ◽  
Main River Channel

SummaryThe Near-threatened Orinoco Goose Neochen jubata is a poorly known South American sheldgoose with a declining population and range distribution. In this study, we surveyed the Orinoco Goose population along the middle reaches of the Rio Juruá, western Brazilian Amazonia, and its first-order tributaries. We quantified the seasonal abundance of geese, pinpointed their approximate breeding season, and examined their habitat associations and the potential effects of human activities on their abundance. Hunting by local villagers was also monitored to assess the offtake rate of this species. Orinoco Goose occurrence in the region was highly seasonal and restricted to the dry season. We estimated a mean dry-season encounter rate of 7.18 ± 2.45 adult individuals per 4-km section along this river. Immature individuals were seen along the river margins from August to December. The species showed a strong preference for sandy beaches and was primarily restricted to the main river channel, with few individuals occurring along tributaries. The encounter rate of this species was also significantly related to fluvial distance from the municipal urban centre and to the level of protection from hunting. Hunting of Orinoco Goose was reported in 12 of the 26 villages monitored. The seasonal appearance of the Orinoco Goose in the region indicates that this is a migratory population. Our study indicates that strict protection of the river margins, and sandy beaches in particular, along the main river channel is likely to be positive for the conservation of this species along the Rio Juruá. However, further knowledge of migration routes is critical for effective protection of both breeding and non-breeding populations.

scholarly journals Movements and home ranges of radio-tracked Crocodylus porosus in the Cambridge Gulf region of Western Australia

2004 ◽  
Vol 31 (5) ◽  
pp. 495 ◽  
Author(s):  
Winston R. Kay
Keyword(s):  
Habitat Preferences ◽  
Dry Season ◽  
Home Ranges ◽  
Juvenile Male ◽  
Wet Season ◽  
Gulf Region ◽  
Main River ◽  
Main River Channel ◽  
Crocodylus Porosus ◽  
Riverine Habitats

VHF radio-tags were attached to 16 estuarine crocodiles that were tracked between October 2001 and May 2003. Male (n = 12) and female (n = 4) crocodiles exhibited distinctly different patterns of movement. Females occupied a small core linear range (1.3 ± 0.9 km) on the main river channel during the dry season and moved up to 62 km to nesting habitat during the wet season, returning to the same core area the following dry season. They occasionally made excursions away from their core areas during the dry season. Males moved considerable distances along the Ord River throughout the year. The largest range recorded was 87 km for a 2.5-m juvenile male. However, ranges of males did not appear to be related to body size, with the largest two ranges being recorded for the smallest (2.5 m) and largest (4.3 m) males tagged. Rates of movement of males did not differ significantly between three size classes of males but there were significant seasonal differences, with the highest mean rates of movement occurring during the summer wet season (4.0 ± 5.4 km day–1). However, males were quite mobile during the dry season and the highest rate of movement detected was 23.3 km day–1 for a 4.3-m male at the end of July. The highest rate of sustained movement was 9.8 km day–1 for a translocated 2.6-m juvenile male, which travelled 118 km in 12 days to return to the area of its capture. Neither males nor females showed exclusive habitat preferences for any of four broad riverine habitats identified on the Ord River. However, the three largest males had activity centres that they returned to frequently despite numerous excursions throughout the year, both up- and downriver. Males had substantial range overlaps with no obvious spatial partitioning, suggesting that territoriality is not an important behavioural characteristic of free-ranging male crocodiles along the Ord River.

Spatial trophic variability of a coastal apex predator, the giant trevally Caranx ignobilis, in the western Indian Ocean

2020 ◽  
Vol 641 ◽  
pp. 195-208
Author(s):  
JR Glass ◽  
R Daly ◽  
PD Cowley ◽  
DM Post
Keyword(s):  
Indian Ocean ◽  
Trophic Ecology ◽  
Niche Breadth ◽  
Trophic Position ◽  
Western Indian Ocean ◽  
Trophic Niche ◽  
Niche Width ◽  
Apex Predator ◽  
Ontogenetic Changes ◽  
Top Predators

Top predators have substantial downstream effects on the structure, function, and resilience of ecosystems. The influence of top predators on an ecosystem can vary if they occur within multiple habitat types and have a wide niche breadth due to spatiotemporal changes in diet. We examined spatial patterns in trophic position and niche width for an economically important reef-associated fishery species, the giant trevally Caranx ignobilis. We sampled 4 localities in the western Indian Ocean representing different habitats: coral atolls, coastal reefs, and granitic islands. We analyzed isotopic ratios of carbon (13C/12C) and nitrogen (15N/14N), and performed compound-specific amino acid stable isotope analysis (AA-CSIA) to control for baseline nitrogen variation. Our analysis of 12 juveniles and 43 adults revealed wide variation in trophic niche breadth between sampling sites and an offshore to coastal gradient in carbon that drove niche distinctiveness between localities. We observed niche width patterns suggestive of ontogenetic changes in diet and habitat utilization and larger niche sizes at the oceanic island sites than the coastal site. Trophic position estimates ranged from 3.5-5, expanding the trophic range of C. ignobilis relative to previous studies using AA-CSIA and placing it at the equivalent trophic level as many predatory sharks. Our study corroborates prior evidence that C. ignobilis is an important apex predator in reef and island ecosystems. Additionally, we show how evaluating spatiotemporal components of trophic ecology of marine predators is critical for characterizing their functional role and ecosystem influence, allowing for targeted conservation efforts.

scholarly journals Chaco Chachalaca (Ortalis canicollis, Wagler, 1830) feeding ecology in a gallery forest in the South Pantanal (Brazil)

2015 ◽  
Vol 75 (1) ◽  
pp. 49-57
Author(s):  
J. Ragusa-Netto
Keyword(s):  
Niche Breadth ◽  
Feeding Habits ◽  
Feeding Activity ◽  
Habitat Type ◽  
Food Resources ◽  
Dry Season ◽  
Gallery Forest ◽  
Wet Season ◽  
Feeding Niche ◽  
The Impact

Cracids are generalist frugivores, which often exploit plant food resources such as flowers and leaves, mainly when fruit production declines. The Chaco chachalaca (Ortalis canicollis) is the most abundant cracid in the Pantanal (Brazil), and particularly common in the gallery forests. However, the factors related to their occurrence in this habitat type are unclear. In this study I describe the feeding habits and feeding niche breadth fluctuations of the Chaco chachalaca in relation to food resources abundance and diversity at the Miranda river gallery forest (Southern Pantanal). I also analyzed the relationships between Chaco chachalacas feeding activity and food resources abundance. This parameter (flowers and fruits) exhibited significant seasonal differences of abundance in which flowers were plentiful at the end of the dry, while fruits were abundant during the early wet season. However, food resources diversity to Chaco chachalacas exhibited no seasonal difference. Their feeding activity paralleled the availability of food resources, so that when some items were massively available an enhanced number of Chaco chachalacas foraged in the gallery forest, particularly during the prolonged dry season when they extensively used flowers and Genipa americana fruits. In fact, the Chaco chachalaca feeding niche breadth value presented low values in this period, while high values were common in the rest of the year. The flexible diet of this cracid, potentially favors their year round presence in the gallery forest, mainly during the prolonged dry season when the propensity for famine might be high. Since the Chaco chachalaca is among the largest and most abundant canopy frugivores in the gallery forest, it may contribute to forest regeneration, an underscored role due to the impact of annual floods and meandering dynamics on tree loss.

scholarly journals Feeding ecology of Serrasalmus gouldingi (Characiformes: Serrasalmidae) in the lower Anapu River region, Eastern Amazon, Brazil

2016 ◽  
Vol 46 (3) ◽  
pp. 259-270 ◽  
Author(s):  
Bruno da S. PRUDENTE ◽  
Pedro CARNEIRO-MARINHO ◽  
Roberta de M. VALENTE ◽  
Luciano F. de A. MONTAG
Keyword(s):  
Feeding Ecology ◽  
Diet Composition ◽  
Niche Breadth ◽  
Life Stage ◽  
Flood Pulse ◽  
Feeding Intensity ◽  
High Tendency ◽  
Flood Season ◽  
River Region ◽  
The Relationship

Abstract Studies on feeding ecology of fishes are important to understand the relationship between species and environmental seasonal variations. In tropical rivers, these relationships are mainly modeled by hydrological patterns. Thereby, this study aimed to assess the influence of fluviometric variation and life stage (juveniles and adults) in the feeding ecology of Serrasalmus gouldingi in the lower Anapu River region, located in Eastern Amazon, Pará, Brazil. Specimens were collected bimonthly, considering four different hydrological periods. We assessed the diet composition, feeding intensity and niche breadth of the species. Thirty-two dietary items were identified and grouped into ten categories. A total of 279 stomachs were analyzed, showing a predominance of fish fragments, followed by fruits and seeds. The diet composition of S. gouldingi differed only between drought and flood season, although it did not differ between juveniles and adults. An increase in feeding intensity was recorded during the rise in the water level, with a lower feeding intensity observed during transitional season. Serrasalmus gouldingi showed lower niche breadth during flood season, attributed to the high consumption of fruits and seeds, presenting an omnivorous diet with high tendency towards piscivory. Although less evident than in other Amazon watersheds, the flood pulse in the lower Anapu River region is an important factor influencing the feeding ecology of the species.

scholarly journals Crevasse splays within a lignite seam at the Tomisławice opencast mine near Konin, central Poland: architecture, sedimentology and depositional model

Geologos ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 25-37 ◽  
Author(s):  
Lilianna Chomiak
Keyword(s):  
Middle Miocene ◽  
Structural Features ◽  
Fine Grained ◽  
Opencast Mine ◽  
Main River ◽  
Main River Channel ◽  
Lignite Mine ◽  
Flooding Event ◽  
Crevasse Splay ◽  
Sandy Sediments

AbstractThe present article focuses predominantly on sandy deposits that occur within the Middle Miocene lignite seam at the Tomisławice opencast mine, owned by the Konin Lignite Mine. As a result of mining activity, these siliciclastics were available for direct observation in 2015–2016. They are situated between two lignite benches over a distance of ~500 m in the lower part and ~200 m in the higher part of the exploitation levels. The maximum thickness of these sandy sediments, of a lenticular structure in a S–N cross section, is up to 1.8 m. With the exception of a thin lignite intercalation, these siliciclastics comprise mainly by fine-grained and well-sorted sands, and only their basal and top layers are enriched with silt particles and organic matter. Based on a detailed analysis of the sediments studied (i.e., their architecture and textural-structural features), I present a discussion of their genesis and then propose a model of their formation. These siliciclastics most likely formed during at least two flood events in the overbank area of a Middle Miocene meandering or anastomosing river. Following breaching of the natural river levee, the sandy particles (derived mainly from the main river channel and levees) were deposited on the mire (backswamp) surface in the form of crevasse splays. After each flooding event, vegetation developed on the top of these siliciclastics; hence, two crevasse-splay bodies (here referred to as the older and younger) came into existence. As a result, the first Mid-Polish lignite seam at the Tomisławice opencast mine is currently divided in two by relatively thick siliciclastics, which prevents a significant portion of this seam from being used for industrial purposes.

scholarly journals Seed Functional Traits Provide Support for Ecological Restoration and ex situ Conservation in the Threatened Amazon Ironstone Outcrop Flora

2020 ◽  
Vol 11 ◽  
Author(s):  
Marcilio Zanetti ◽  
Roberta L. C. Dayrell ◽  
Mariana V. Wardil ◽  
Alexandre Damasceno ◽  
Tais Fernandes ◽  
...  
Keyword(s):  
High Temperatures ◽  
Functional Traits ◽  
Niche Breadth ◽  
Seed Storage ◽  
Interspecific Variation ◽  
Ex Situ ◽  
Seed Traits ◽  
Physical Dormancy ◽  
Apparent Lack ◽  
Germination Traits

Cangas (ironstone outcrops) host a specialized flora, characterized by high degree of edaphic endemism and an apparent lack of natural history knowledge of its flora. Due to intense pressure from iron ore mining this ecosystem is under threat and in need of restoration. We studied seed functional traits that are relevant for restoration, translocation and ex situ conservation in 48 species from cangas in eastern Amazon. Were determined the thermal niche breadth, classified seed dormancy and determined methods to overcome it, determined the effect of seed storage on germination, tested the association between germination traits and functional groups, and tested whether seed traits are phylogenetically conserved. We found a broad interspecific variation in most seed traits, except for seed water content. Large interspecific variation in the temperature niche breadth was found among the studied species, but only four species, showed optimum germination at high temperatures of 35–40°C, despite high temperatures under natural conditions. Only 35% of the studied species produced dormant seeds. Mechanical scarification was effective in overcoming physical dormancy and application of gibberellic acid was effective in overcoming physiological dormancy in five species. For the 29 species that seeds were stored for 24 months, 76% showed decreases in the germination percentage. The weak association between germination traits and life-history traits indicate that no particular plant functional type requires specific methods for seed-based translocations. Exceptions were the lianas which showed relatively larger seeds compared to the other growth-forms. Dormancy was the only trait strongly related to phylogeny, suggesting that phylogenetic relatedness may not be a good predictor of regeneration from seeds in cangas. Our study provides support to better manage seed sourcing, use, storage and enhancement techniques with expected reduced costs and increased seedling establishment success.

scholarly journals Habitat factors differentiating the occurrence of Ostracoda (Crustacea) in the floodplain of a small lowland River Krąpiel (N-W Poland)

2020 ◽  
pp. 23
Author(s):  
Agnieszka Szlauer-Łukaszewska ◽  
Vladimir Pešić
Keyword(s):  
Abiotic Factors ◽  
River Channel ◽  
Water Bodies ◽  
Oxbow Lakes ◽  
Factors Associated ◽  
Main River ◽  
Main River Channel ◽  
Habitat Factors ◽  
Sediment Sorting ◽  
Physical And Chemical

We analysed the occurrence of ostracods in a small river, taking into account all the types of water bodies in the floodplain − these included helocrenes, oxbow lakes, and ponds, as well as the main river channel. The objective of the study was to investigate the variation in ostracod communities and identify those factors determining species distribution. The environmental factors considered were the type of water body, responsible for 17% of the variance, the physical and chemical water properties (29%), and the biotic and abiotic factors associated with the substrate type (23%). Among the factors associated with the substrate, sediment sorting, plant coverage and insolation were the most important. The ostracod fauna of the helocrenes differed from that of the other water bodies in the floodplain. In the water bodies of the Krąpiel valley and in the main river channel, 33 ostracod species were recorded, of which 26 were found in the main river channel. Refugia in the floodplain were the main source of the diversity and abundance of ostracods in the main river channel. The mean density in the main river channel was very low, at 330 indiv. m−2, while in the water bodies of the floodplain it was the greatest, reaching up to 5568 indiv. m−2.

scholarly journals Variation of the Water Level in the Yangtze River in Response to Natural and Anthropogenic Changes

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2594 ◽  
Author(s):  
Jinxin Liu ◽  
Jinyun Deng ◽  
Yuanfang Chai ◽  
Yunping Yang ◽  
Boyuan Zhu ◽  
...  
Keyword(s):  
Water Level ◽  
Yangtze River ◽  
Dry Season ◽  
Climate Variation ◽  
Dominant Factor ◽  
The Yangtze River ◽  
Flood Season ◽  
Dam Operation ◽  
Adjustment Mechanisms ◽  
Measured Water

The water level in the Yangtze River has significantly changed due to the effects of varied precipitation and dam operations, which have exerted significant effects on irrigation, navigation, and ecosystems. Based on the measured data and the proposed calculation method, we analyzed the adjustment mechanisms of the seasonal water level in the whole Yangtze River. The results were as follows. During the dry season, the rising precipitation and dam operation both increased the water level in the upper reaches and in the reaches from the Jianli to Datong stations during 1981–2014. Moreover, dam operations were the dominant factor (except at Datong station). In the reaches from the Yichang to Shashi stations, dam operations are the reason for the reduction of the measured water level in the dry season, while the rising precipitation had an opposite influence. During the flood season, dam operations helped to reduce the water level from the upper reaches to the estuary during 1981–2014, while climate variation stresses adversely affected the entire river basin. In the reaches between the Luoshan and Jianli stations, climate variation is the dominant factor for the increased water level during the flood season, while dam operation is the reason for the reduced water level at the other six hydrological stations.

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