Artigos Científicos - FEPESCA/IECOS

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Acesso aberto (Open Access)
Influence of photoperiod on growth, uniformity, and survival of larvae of the Amazonian ornamental Heros severus (Heckel, 1840)
(Universidade Federal do Pará, 2016-07) VERAS, Galileu Crovatto; PAIXÃO, Daércio José de Macedo Ribeiro; BRABO, Marcos Ferreira; SOARES, Lourdes Marília Oliveira; SALES, Abner Dias
The objective of this work was to evaluate the influence of photoperiod on growth, uniformity, and survival of larvae of the Amazonian ornamental fish severum (Heros severus). A completely randomized study was used with five treatments (0L:24D, 6L:18D, 12L:12D, 18L:6D, 24L:0D) and four replicates, with the aquaria as the experimental unit. Two hundred severum larvae (3.20±0.16 mg and 5.60±0.00 mm) were distributed into 20 aquariums of one litre at a density of 10 larvae per litre. For a period of 15 days, feed was supplied four times daily with Artemia nauplii in a proportion of 160 nauplii/larvae/feeding. At the end of the experimental period, growth, uniformity, and survival data were subjected to analyses of variance and significance. Manipulation of the photoperiod showed no change in variables because there was no difference in the growth, uniformity, or survival of severum larvae. Thus, for larvae of this species of up to 20 days of age, the manipulation of the photoperiod is not advantageous due to the possible increase in production costs. Therefore, it is recommended to use the photoperiod close to the natural environment.
Acesso aberto (Open Access)
Estudo das diferentes formas de fósforo nas águas da plataforma continental do Amazonas
(2007-06) SANTOS, Maria de Lourdes Souza; COSTA, Katia Muniz Pereira da; FEITOSA, Fernando Antonio do Nascimento; BARROS NETO, Benício de
Hydrological samples were collected on the continental shelf of the Amazon river to determine particulate organic and inorganic matter, dissolved organic phosphorus (DOP), phosphate, total particulate phosphorus (TPP), chlorophyll a, temperature, salinity, pH, water transparency, dissolved oxygen (DO) and saturation rate. The objective was to study the forms of DOP, phosphate and TPP. In the euphotic layer, the fluvial discharge from the Amazon river favored the distribution of phosphate, TPP and DOP. In the aphotic layer, the phosphate concentration increased due to the decomposition of DOP and TPP. This increase is due to the absence of photosynthetic processes.
Acesso aberto (Open Access)
Controle alternativo de helmintos de Astyanax cf. zonatus utilizando fitoterapia com sementes de abóbora (Cucurbita maxima) e mamão (Carica papaya)
(2012-01) FUJIMOTO, Rodrigo Yudi; CORDEIRO, Helrik da Costa; RAMOS, Fabrício Menezes
The objective of this study was to evaluate the effectiveness of an alternative method with pumpkin and papaya seeds, dried and ground, for control of helminth parasites of Astyanax cf. zonatus. Sixty fish were distributed into twelve containers, with one fish/liter. The experiment consisted of four treatments and three replications: TJ = fish in fasting; TRC = fish fed with commercial diet; TSA = fish fed ad libitum with pumpkin seed, and TSM = fish fed ad libitum with papaya seeds. After seven days of feeding, all fish were weighed and blood was taken for blood smears. Efficacy was determined by checking the presence of parasites in the gills, stomach and intestine, in 40% of fishes per treatment (n=6). TJ and TSM showed 39% and 25% of weight loss respectively. The TSA showed better efficacy against the nematode in intestine and stomach (95.26% and 92.48%). The TSM promoted 72% of efficiency on monogeneans control. Hematology revealed an increase of monocyte values to treatment TSM. A decrease of eosinophil values was observed in treatments TSA, TSM and TRC. Thus, feeding fishes with pumpkin is a effective alternative method of low cost for control of nematodes in Astianax cf. zonatus.
Acesso aberto (Open Access)
Fotoperíodo sobre parâmetros fisiológicos relacionados ao estresse em alevinos de tilápia-do-nilo
(2013-10) VERAS, Galileu Crovatto; MURGAS, Luis David Solis; ZANGERONIMO, Márcio Gilberto; ROSA, Priscila Vieira; SOLIS DE LEON, Jonathan Antonio; SALARO, Ana Lúcia
The objective of this study was to evaluate the influence of different photoperiods on physiological parameters related to stress in Nile tilapia fingerlings (Oreochromis niloticus). A completely randomized design with five treatments (0L, 6L, 12L, 18L, 24L) and four replications was used, and the aquarium as the experimental unit. One hundred and sixty tilapia fingerlings, 3.21±0.05g and 4.35±0.07cm were distributed in 20 aquariums of 20L in a recirculation system with temperature controlled at 27 º C and density of eight fish per aquarium. Feeding was performed twice daily with extruded feed containing 40% crude protein, for a period of 75 days. At the end of experimental period, the data of survival, cortisol, glucose and hematocrit were subjected to analysis of variance and, subsequently, in case of significance (P<0.05) a Tukey test 5% was performed to compare means. Manipulation of photoperiod shows no alteration in the homeostasis of juveniles, since there is no difference in survival, blood glucose, hematocrit and plasma cortisol (P>0.05).
Acesso aberto (Open Access)
Nutrient and phytoplankton biomass in the Amazon River shelf waters
(2008-12) SANTOS, Maria de Lourdes Souza; MUNIZ, Kátia; BARROS NETO, Benício de; ARAUJO, Moacyr Cunha
The Amazon River estuary is notable at the Amazon Continental Shelf, where the presence of the large amount of water originating from the Amazon during the river's falling discharge period was made evident by the low salinity values and high nutrient levels. Even so, the presence of oceanic waters in the shelf area was significant. Dissolved organic nitrogen was the predominant species of the nitrogen cycle phases, followed by total particulate nitrogen, nitrate, ammonium and nitrite. The chlorophyll a data in the eutrophic area indicated that there is sufficient nitrogen in the area to withstand productivity, though dissolved inorganic nitrogen removal processes are faster than regeneration or mineralization. The anomalous amounts of inorganic dissolved nitrogen showed more removal than addition. The simulations with the bidimensional MAAC-2D model confirmed that high nutrient waters are displaced northwest-ward (two cores at 2.5ºN-50ºW and 4ºN-51ºW) by the stronger NBC during falling river discharge. During high river flow period these nutrient-rich lenses are distributed around 0.5ºN-48.5ºW as well as along the shallow Amazonian shelf (20m-50m depth, 1ºN-3.5ºN), as a result of the spreading of Amazon freshwater outflow.
Acesso aberto (Open Access)
Acute toxicity and histopathology in ornamental fish amazon bluespotted corydora (Corydoras melanistius) exposed to formalin
(2012-12) SANTOS, Rudã Fernandes Brandão; DIAS, Henrique Malta; FUJIMOTO, Rodrigo Yudi
The objective of this work was to evaluate the acute toxicity of formalin and histopathological effects on the Amazon ornamental fish, bluespotted coridora (Corydoras melanistius). A randomized design was used, with ten concentrations of formalin (40%) (0, 3, 6, 12, 25, 50, 100, 150, 200 and 250mg.L-1) with four replicates and five fish per container (3L) in static system for 96 hours. The moribund fish were killed and fixed in 10% formalin to proceed the histopathological analysis of gill, liver and kidney. At the end of this experiment the following mortality rates (%) were obtained in increasing order of exposure: 0, 0, 0, 0, 0, 65, 85, 100, 100 and 100%. The lethal concentration 50% (LC50-96h (I)) estimated was 50.76 mg.L-1 with regression of y = 0.51x, and r² = 0.80. Further, in higher concentrations morphological changes as gill hyperplasia, with filling of interlamellar spaces, disorganization of liver arrangement, and necrosis in kidney were observed. In this study, the formalin can be considered slightly toxic to bluespotted corydora, and cause morphological changes when exposed to high concentrations. The use of formalin to treat of ornamental fish in the inner river of capture with wrong concentration can provoke negative environmental and biological effects.
Acesso aberto (Open Access)
Morphological deformities in the osseous structure in spotted sorubim Pseudoplatystoma coruscans (agassiz & spix, 1829) with vitamin c deficiency
(2013-03) FUJIMOTO, Rodrigo Yudi; SANTOS, Rudã Fernandes Brandão; CARNEIRO, Dalton José
Vitamin C is essential for fish diets because many species cannot syntethize it. This vitamin is needed for bone and cartilage formation. Moreover, it acts as antioxidant and improve the immunological system. The present work investigated the effects of vitamin C diet supplementation to spotted sorubim (Pseudoplatystoma coruscans) fingerlings by frequency of bone and cartilage deformation. Ascorbyl poliphosphate (AP) was used as source of vitamin C in the diets for spotted sorubim fingerlings during three months. Six diets were formulated: one diet control (0 mg/kg of vitamin C) and 500, 1,000, 1,500, 2,000 and 2,500 mg AP/kg diets. Fishes fed without vitamin C supplementation presented bone deformation in head and jaws, and fin fragilities. Thus, 500 mg AP/kg diet was enough to prevent deformation and the lack of vitamin C supplementation worsening the development of fingerlings.
Acesso aberto (Open Access)
Observações hidrológicas e resultados de modelagem no espalhamento sazonal e espacial da pluma de água Amazônica
(Instituto Nacional de Pesquisas da Amazônia, 2009) SILVA, Alex Costa da; SANTOS, Maria de Lourdes Souza; ARAUJO, Moacyr Cunha; BOURLÈS, Bernard
In this study, we present surface synoptic data collected during four oceanographic cruises undertaken in March-April 1995, October-November 1997, April-May 1999 and August-September 2001 in the Brazilian Program “REVIZEE/SCORE-NO” and a combination of model results (1/6 deg.). The emphasis of this paper is to point out the monthly changes on the spreading of the Amazon plume over the external Amazon shelf area and the eastern region of the Amazon River. Hydrographic data and model results demonstrated that during March-May, the Amazon plume moved southwestward along the northern coast of Brazil, decreasing during August-September; but this was not observed during October-November. Model results revealed ring signatures shedding from the North Brazil Current (NBC). Results also showed that during August the Amazon plume encircling the NBC retroflection was around 7º N.
Acesso aberto (Open Access)
First occurrence of Quadrigyrus nickoli (Acanthocephala) in the ornamental fish Hyphessobrycon eques
(2013-03) FUJIMOTO, Rodrigo Yudi; SARMENTO, Aline de Melo Braun; DINIZ, Daniel Guerreiro; EIRAS, Jorge Costa; MARTINS, Maurício Laterça
The objective of this work was to report the first seasonal occurrence of the acanthocephalan Quadrigyrus nickoli Schmidt & Hugghins, 1973 (Quadrigyridae), in the “Mato Grosso” Hyphessobrycon eques (Characidae) (Steindachner, 1882), collected from the Chumucuí River, state of Pará, Brazil. The fish were collected between July 2006 (rainy season) and June 2007 (dry season) and were examined for parasites using pattern techniques. A total of 75 parasites were found in the stomach and intestine. Among 83 fish examined (50 in the dry season and 33 in the rainy season), 22 were parasitized by cystacanths of Q. nickoli. The importance of H. eques as a paratenic host for Q. nickoli is discussed. This is the first study on the biology of and infection by Q. nickoli occurring in the eastern Amazon region.
Acesso aberto (Open Access)
Nematode parasites of Pescada Gó, Macrodon ancylodon Bloch and Schneider, 1801 (Osteichthyes, Sciaenidae), from Vila dos Pescadores, Bragança-PA, Brazil
(2012-12) FUJIMOTO, Rodrigo Yudi; SARMENTO, Aline de Melo Braun; DINIZ, Daniel Guerreiro; EIRAS, Jorge Costa
The objective of this work was to evaluate the host/parasite relationship of nematodes in Macrodon ancylodon. Ninety seven fishes (50 in wet season and 47 in dry season) were weighed (167.1 ± 109.9g) and measured (28.3 ± 5.2cm). Only twelve specimens were not infected by any parasites and the prevalence of infection was 87.6%. The highest prevalence values were observed in August and September (dry season, 100%). The stomach was the most infected organ during the whole months (prevalence of 64.2%, and mean intensity of 4.6±7.8 parasites/fish), and the medium intestine showed the lowest infection (prevalence 27.3% and mean intensity 2.5±2.1 parasites/fish). The nematodes were identified as Raphidascaris sp., Goezia sp. and Cucullanus sp. Only the male and juvenile fishes could be presented different values of infection according to rainfall, being more infected in August to October. The female hosts presented higher values of abundance and mean intensity of infection (p<0.01) throughout the year.
Acesso aberto (Open Access)
Influência da biomassa inicial sobre o crescimento e a produtividade de peixes em sistema de policultivo
(2006-12) NUNES, Zélia Maria Pimentel; LAZZARO, Xavier; PERET, Alberto Carvalho
The analysed species composition, fish growth, and productivity of four polycultures (P75, P78, P87, and P207) with the objective to improve the small reservoir (0.1–5 ha) fishery management and productivity in the Brazilian semiarid region were conducted a experiment. To mimic reservoir conditions, we used 120 and 5,000m2 ponds and evaporation and infiltration water loss was replaced. In addition, manure and fertilizers were used only moderately. The initial biomass of Nile tilapia Oreochromis niloticus, 'tambaqui' Colossoma macropomum, 'curimatã pacu' Prochilodus argenteus, common carp Cyprinus carpio, and 'tucunaré' Cichla ocellaris ranged from 75 to 207kg ha–1. The fish showed low growth rates (<0.01g g–1 d–1) after 75 days of culture (P78 and P87). Tambaqui, tilapia, and curimatã growth decreased after 53 days (P75). In moderate biomass, tambaqui grew less than carp and curimatã did (P207). Tilapia productivity reached 720kg ha–1yr–1 (P78) and fell to 220kg ha–1yr–1 because of the reproductive process (P75 and P207). The carp productivity of 1,600kg.ha–1yr–1 was higher than those of the other fish (P87). The 75kg.ha–1 biomass level (60:30:4:3:3% of tilapia, tambaqui, carp, curimatã, and tucunaré, respectively) optimized fish growth and productivity. The use of monosexed tilapia and tambaqui feed supplementation was indispensable for the success of polyculture.
Acesso aberto (Open Access)
Parasites of four ornamental fish from the Chumucuí River (Bragança, Pará, Brazil)
(2013-03) FUJIMOTO, Rodrigo Yudi; BARROS, Zaira Monik Nunes de; MARINHO FILHO, Adjalbas Nunes; DINIZ, Daniel Guerreiro; EIRAS, Jorge Costa
The objective of the present study was to evaluate the parasite fauna of four species of ornamental fish collected in the Chumucuí River, municipality of Bragança, Pará, Brazil. From June 2006 to December 2007. Fishes (n=307) belonging to four species were collected, including 23 specimens of Moenkhausia sanctaefilomenae (redeye tetra), 37 Carnegiella strigata (marbled hatchetfish), 7 Chilodus punctatus (spotted headstander), and 240 Astyanax bimaculatus (twospot astyanax). The parasites found belonged to three taxa: monogeneans in the gills, nematodes (larvae of Capillaria sp. and Contracaecum sp.) in the digestive tract and liver and acanthocephalans (Quadrigyrus torquatus, Q. brasiliensis and Q. nickoli) in the stomach and intestine. Astyanax bimaculatus presented higher prevalence of acanthocephalans in the wet season, and lower prevalence of nematodes in the dry season. The possible importance of these parasites in the exportation of ornamental fish is discussed.
Acesso aberto (Open Access)
Experimental infection in Notodiaptomus sp. (Crustacea: Calanoida) with larvae of Camallanus sp. (Nematoda: Camallanidae)
(2007-04) MARTINS, Maurício Laterça; GHIRALDELLI, Luciana; GARCIA, Fabiana; ONAKA, Eduardo Makoto; FUJIMOTO, Rodrigo Yudi
This trial registered the experimental infection viability with nematode larvae Camallanus sp. in Notodiaptomus sp., a crustacean, which can be an intermediate host. Adult females of nematode were dissected from the intestines of Xiphophorus maculatus (Osteichthyes: Poeciliidae), at a fish farm in the State of São Paulo. Females were slightly compressed for larvae release, collected with Pasteur pipette and separated on Petri dishes with 9ml filtered water at 28.1ºC, from zooplankton culture. Treatments consisted of Petri dishes with 60 and 105 copepods, in which 120, 150 and 210 larvae of nematode were added in four replications. Twenty-four and 36h after exposition to the larvae, the copepods were fixed in 70% alcohol to record the amount of fixed larvae. Twenty four hours after exposition, 60 copepods group with 120 larvae showed significantly higher prevalence (46.5%) when compared to 105 copepods and 120 larvae (33.2%). Thus, these answers suggested that 120 larvae were enough for a successful infectivity. Experimental infection was available and so, it was used as a pattern to life cycle studies of camallanid nematodes and hosts susceptibility tests.
Acesso aberto (Open Access)
Characterization of the acute inflammatory response in the hybrid tambacu (Piaractus mesopotamicus male × Colossoma macropomum female) (Osteichthyes)
(2009-08) MARTINS, Maurício Laterça; Myiazaki, DMY; DIAS, Marcos Tavares; FENERICK JÚNIOR, Jaime; ONAKA, Eduardo Makoto; BOZZO, Fabiana Rizzi; FUJIMOTO, Rodrigo Yudi; MORAES, Flávio Ruas de
This work evaluated the acute inflammatory response induced by injections of 0.5 mL saline solution (control), 500 µg carrageenin and 0.5 mL thioglycollate 3% in the swim bladder of juvenile tambacu hybrid. Fish were distributed in three treatments, three replications and acclimated for a period of 10 days before assay. The cell characterization from the inflammatory exudate was performed in Giemsa and PAS stained smears. Carrageenin, injected in fish, showed an increase on the total number of cells in the inflammatory exudate when compared to saline and thioglycollate injected. Whereas, for carrageenin-injected fish, the percentage of thrombocyte was higher than thioglycollate. On the other hand, granulocyte percentage in thioglycollate-injected fish was higher than the ones injected using carrageenin. Carrageenin provoked the highest migration of macrophage to the inflammatory site. The PAS method confirmed the presence of three types of granulocytes: eosinophilic granular cell (EGC) type 1 with the characteristics of a special granulocytic cell commonly found in the circulating blood; EGC type 2 shorter than the last one and neutrophil. This study contributes to a better understanding of the inflammatory response and infectious processes in native fish.
Acesso aberto (Open Access)
Protozoan parasites of Xiphophorus spp. (Poeciliidae) and their relation with water characteristics
(2009-02) GARCIA, Fabiana; FUJIMOTO, Rodrigo Yudi; MARTINS, Maurício Laterça; MORAES, Flávio Ruas de
This work investigated the relationship between water characteristics and infestation of protozoan parasites, Icthyophthirius multifiliis and Trichodina sp., in swordtails (Xiphophorus helleri) and platy (Xiphophorus maculates) collected in an ornamental fish farm in São Paulo, Brazil. Fish were monthly collected from ponds and tanks for one year. The prevalence rates in fish from tanks and ponds were, respectively, 34.2% and 22.5% for I. multifiliis, and 13% and 54.2% for Trichodina sp. Increased electric conductivity and pH provoked reduction of I. multifiliis infestation. Low oxygen concentration increased Trichodina sp. infestation. The use of salt to increase the electric conductivity of water was a method to control I. multifiliis. Low dissolved oxygen and the addition of organic fertilizer favored the reproduction of Trichodina sp.
Acesso aberto (Open Access)
Effects of chromium supplementation on the infrapopulations of Anacanthorus penilabiatus (Monogenoidea) and Piscinoodinium pillulare (Dinoflagellida) parasites of Piaractus mesopotamicus (Characidae)
(2010-08) FUJIMOTO, Rodrigo Yudi; CASTRO, Marcello Pardi de; MARTINS, Maurício Laterça; MORAES, Flávio Ruas de; VARELLA, Jamille Elzira de Almeida; DINIZ, Daniel Guerreiro
This study evaluated the parasitism by Anacanthorus penilabiatus (Monogenoidea) and Piscinoodinium pillulare (Dinoflagellida) in the gills of "pacu", Piaractus mesopotamicus supplemented with chromium in the diet. Randomised delineation by using factorial scheme (4x2x2) for Monogenoidea and 4x2x3 for Dinoflagellate with four levels of chromium (0, 6, 12, 18mg/kg diet), two stocking densities (4kg/m3 and 20kg/m3), two classes of length (higher and lower than 17 cm) for a period of 7, 60 and 90 days, and four replicates was used. The fishes in low density which received 12 and 18mg/kg showed decreased monogeneoidea values, seven days after the experiment begin. Six, 12 and 18 mg/kg caused reduction in the dinoflagellate number in the fishes maintained at 20kg/m3. It was possible that chromium supplementation (12 e 18mg/kg) favoured the fishes health by reducing Monogenoidea and Dinoflagellida number in lower and higher densities, respectively.
Acesso aberto (Open Access)
Seasonality of nematode larvae in Iguanodectes spilurus (Characidae) an ornamental fish from northeastern Para, Brazil
(Instituto Nacional de Pesquisas da Amazônia, 2013-12) FUJIMOTO, Rodrigo Yudi; ANJOS, Ellem Cristina Silva dos; RAMOS, Fabrício Menezes; MARTINS, Maurício Laterça
The current study presents a parasitological survey of larval nematodes from freshwater ornamental fish Iguanodectes spilurus caught in the watercourse of the Caete River, in the northeast region of the State of Para, Brazil. A total of 176 specimens, 1.36±0.75 g weight and 5.53±0.98 cm total length, were analyzed. Nematode larvae were identified as Capillaria sp., Procamallanus sp. and Anisakidae, with prevalence of 70.45% and infection intensity ranging from 1.81 to 4.70 larvae. The highest prevalence 57.38% occurred in the liver, but no seasonality was observed, indicating high infection throughout the year. Seasonality was observed in fish parasitized in the stomach, intestine and caecum, with prevalence and mean intensity of 17.61% and 2.32 parasites, 12.5% and 1.81 parasites, 10.79% and 2.21 parasites, respectively. The highest degree of infection was observed in the rainy season, probably due to increased availability of intermediate hosts or food.
Acesso aberto (Open Access)
Composição corporal e eficiência de utilização de nutrientes por pacus alimentados com ração suplementada com cromo trivalente
(2007-12) FUJIMOTO, Rodrigo Yudi; CASTRO, Marcello Pardi de; HONORATO, Claucia Aparecida; MORAES, Flávio Ruas de
The objective of this work was to evaluate body composition as well as nutrient efficiency use by pacus fed on diet supplemented with chromium at two stocking densities. The experimental design was completely randomized with 24 treatments, in factorial scheme: four levels of chromium in the diet (0, 6, 12, and 18 mg kg-1), two stocking densities (4 and 20 kg m-3) and three periods (30, 60 and 90 days). Increases in efficiency of crude protein retention and in percentage of crude protein and decrease in efficiency of fat retention and smaller values of fat percentage in the carcass were observed. In the smallest density, the level of 6 mg kg-1 of chromium was enough to make possible the higher accumulation of protein and smaller fat concentration in the carcass. In the density of 20 kg m-3, the need of chromium was higher, 12 mg kg-1, to obtain similar results. Pacus fed on diet supplement with chromium present lean meat, with smaller fat concentration, until 60 days of experiment.
Acesso aberto (Open Access)
Efeitos do tratamento com formalina e sulfato de cobre sobre os parâmetros hematológicos e parasitos monogenéticos em juvenis de Hemigrammus sp. (Osteichthyes: Characidae)
(Instituto Nacional de Pesquisas da Amazônia, 2013-06) PAIXÃO, Luciana Farias; SANTOS, Rudã Fernandes Brandão; RAMOS, Fabrício Menezes; FUJIMOTO, Rodrigo Yudi
The objective of this study was to evaluate the effectiveness of formalin and copper sulphate to controlm onogeneans injuvenile Hemigrammus spand its effect on leukocyte count. We used acompletely randomized design with five treatments and three replications. All treatments lasted for three days and consisted of: T1, control; T2 and T3 immersion bath for one hour in formalin, an of two concentrations of 0.25ml formalin and the other 0.1mlL-1; the T4 bath for 24 hours with 0,025 ml of formalin-L -1; and T5, bath 24 hours with copper sulphate (0.3 mgL-1). After the experimental period was observed that T2, 100% mortality. The T3 and T5 provided 100% efficiency, however, fish presented mortalities and intoxication of the 66 and 80% respectively. T4 showed an efficacy of 77.7% and decrease in parasitological indices: total number of parasites of 11, 3 ± 9, mean infection intensity of 3.2 ± 2 and a prevalence of 47.1%. As the leukocytes was observed that at T3, T4 and T5 occurred differences in the proportionof lymphocytes, monocytes and neutrophilsas compared to control. The CuSO4 and formalin reduce the parasite load, but presented to be toxicat higher concentrations.
Acesso aberto (Open Access)
Características sedimentares fluviais associadas ao grau de preservação da mata Ciliar - Rio Urumajó, Nordeste Paraense
(Instituto Nacional de Pesquisas da Amazônia, 2009-03) BRITO, Roney Nonato Reis de; ASP NETO, Nils Edvin; BEASLEY, Colin Robert; SANTOS, Helane Súzia Silva dos
Rivers are the main ways of sediment transport from inland to the coastal zone and oceans. Despite direct influence of climate, the vegetation coverage plays a central role in liquid and solid fluvial discharge. In this context, the present work aimed to study the fluvial sedimentology of the Urumajó River (Pará, Brazil) in relation to the preservation state of riparian vegetation. Sediment samples were collected at five sites (A to E), including a five-sample transversal profile at each site. The sites were distributed from the source to the estuarine area. The characteristics and preservation state of the riparian vegetation were analyzed at each site as well. The collected sediments were submitted to grain size analysis, where mean grain size, median, asymmetry, selection and kurtosis were obtained. The results made it possible to recognize the regular characteristics (sites A and C), which included median sand as the main sediment class and well-sorted and approximate symmetric grain size distribution, directly related to the well-preserved riparian vegetation at sites A and C. On the other hand, sites B, D and E showed substantial differences in relation to the regular pattern. This fact could be associated to the vegetation degradation at those sites, resulting in margin erosion. Furthermore, at site E, reflexes of tide influence on the sediment characteristics could be observed, subsidizing the estuary delimitation.