Navegando por Autor "CAMARGO-ZORRO, Mauricio"

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Acesso aberto (Open Access)
Biologia e estrutura populacional das espécies da família sciaenidae (Pisces : Perciformes), no estuário do rio Caetê município de Bragança, Pará-Brasil
(Universidade Federal do Pará, 1999-03) CAMARGO-ZORRO, Mauricio; ISAAC, Victoria Judith; http://lattes.cnpq.br/3696530797888724
This study aimed to assess the average biomass and spatial and temporal distribution of the family Sciaenidae fishes in the estuary of the Caeté River, northern of Brazil, with special reference to the species Stellifer rastrifer, Stellifer naso, Macrodon ancylodon and Cynoscion microlepidotus. Age at first sexual maturity (L50), spawning season, the length-weight relationships, food diet, population consumption by biomass (Q/B), population structure and dynamics were estimated. 6 Bimonthly samples were taken in the estuarine area of the Caeté River, from October 1996 to August 1997. The average biomass of the family Sciaenidae was 0,840g/m². The spatial distribution in the system was related to spawning and recruitment. Juveniles of S. rastrifer, S. naso e M. ancylodon occurred inside some areas in the estuary, although larger individuals were abundant outside where salinity is higher. The L50 values were 10cm, 10,7cm e 21,5cm respectively. Two spawning periods in a year were found, which determine the recruitment of two cohorts, with different growth parameters. The length-weight relations were allometric and no differences were found by sex. An ontogenetic change was found in the diet composition of these species; young prey zooplancton and adults feed predominantly on larval stages of decapodes and poliquetes, and juveniles of fishes. Diet overlaps changed during the ontogenic development of each species. The relation Q/B indicated that S. rastrifer and S. naso consume more food in relation to the body size, in opposite to the larger species like M. ancylodon and C. microlepidotus. The fishes of the Caeté River presented higher growth and low longevity when compared to the same species inhabit the higher latitudes.
Acesso aberto (Open Access)
A comunidade ictica e suas interrelacões tróficas como indicadores de integridade biológica na área de influencia do projeto hidrelétrico Belo Monte-Rio Xingu, PA
(Universidade Federal do Pará, 2004-04) CAMARGO-ZORRO, Mauricio; ISAAC, Victoria Judith; http://lattes.cnpq.br/3696530797888724
This study presents applied methodologies to better understand the dynamics of mechanisms characterizing a portion of the Xingu River, with respect to fish communities living in that environment. Through the study of the ichthyofauna it is aimed to verify various environmental standard patterns, in order to assess the current conservation state of a part of the Xingu River. Based on surveys of the local ichthyofauna conducted over seasonal variations, analyses were conducted at the specieS, population and trophic guild levels. With regards to the ecological population level, study of biological parameters such as individual growth rates, asymptotic body length, mortality rates and size at first maturity were good indicators for a better understanding of the life history of those fish groups. Therefore a trend was observed in which species of relatively small body size to followed a "r" type strategy, whilw species of larger body sizes would follow the "k" strategy tactics. From a functional point of view, it was verified that guild community structure is not only a good indicator of convergence patterns to similar ecosystems as like the Xingu River studied stretch, but also a tool to assess its conservation status. A steady- state ecosystem model for the medium Xingu River sector indicated that it is a system highly instable, and simultaneusly look like a mature seasonal system. An apparent seasonal restriction of food availability observed in the studied river section could imply optimum use efficiency and transfer of the trophic resources. A biogeographic study was undertaken based on species occurrence in order to conceptualise the River stretch comprised between the confluences of the Iriri and Xingu Rivers up to the vicinity of of the village Senador José Porfirio, in the Xingu basin. By means of this analysis, it was possible to demonstrate that the medium upstream of waterfalls) and lower (downstream) courses of the Xingu River are parts of two endemic areas. The low affinity of species composition observed in these two sectors is attributed to geographic variations in the landscape. Therefore, the boundaries of the waterfalls around the village of Belomonte and the influence of the Amazon River in the lower Xingu course could trigger differences in ichthyofaunal composition and species abundance when compared to the medium course of that river. Finally, the importance of maintaining all hydrologic connectivity is pointed out in order to maintan the unity of the system, from the headwaters to the mouth. Impacts on environmental processes and fish populations in the medium course of the Xingu River as a result of the eventual construction of the Belemonte hydroelectric dam are discussed.
Acesso aberto (Open Access)
Effect of seasonal flooding cycle on litterfall production in alluvial rainforest on the middle Xingu River (Amazon basin, Brazil)
(Universidade Federal do Pará, 2015-08) CAMARGO-ZORRO, Mauricio; GIARRIZZO, Tommaso; JESUS, Allan Jamesson Silva de
The assumption for this study was that litterfall in floodplain environments of the middle Xingu river follows a pattern of seasonal variation. According to this view, litterfall production (total and fractions) was estimated in four alluvial rainforest sites on the middle Xingu River over an annual cycle, and examined the effect of seasonal flooding cycle. The sites included two marginal flooded forests of insular lakes (Ilha Grande and Pimentel) and two flooded forests on the banks of the Xingu itself (Boa Esperança and Arroz Cru). Total litterfall correlated with rainfall and river levels, but whereas the leaf and fruit fractions followed this general pattern, the flower fraction presented an inverse pattern, peaking in the dry season. The litterfall patterns recorded in the present study were consistent with those recorded at other Amazonian sites, and in some other tropical ecosystems.
Acesso aberto (Open Access)
Food categories reconstruction and feeding consumption estimates for the Sciaenid Macrodon ancylodon (Bloch & Schneider), and the congeneric fishes Stellifer rastrifer (Jordan) and Stellifer naso (Jordan) (Pisces, Perciformes) in the Caeté Estuary, Northern Coast of Brazil
(2004-03) CAMARGO-ZORRO, Mauricio; ISAAC, Victoria Judith
A quantitative method to estimate fish feeding consumption and energy intake from different food categories through the reconstruction of ingested preys based on hard not digestible body structures is presented. In order to establish the equations of the functional relationships between preys weight and body structures, stomachs of 1.086 specimens of Macrodon ancylodon (Bloch & Schneider, 1801), Stellifer rastrifer (Jordan, 1889), and Stellifer naso (Jordan, 1889) fish species were dissected. Consequently, preys reconstruction enabled a quantitative evaluation of food categories consumption. Results indicate a marked difference in diet composition and energy requirements according to fish species ontogenetic development.
Acesso aberto (Open Access)
Population and biological parameters of selected fish species from the middle Xingu River, Amazon Basin
(Universidade Federal do Pará, 2015-08) CAMARGO-ZORRO, Mauricio; GIARRIZZO, Tommaso; NAHUM, Victoria Judith Isaac
This study estimates the main biological parameters, including growth rates, asymptotic length, mortality, consumption by biomass, biological yield, and biomass, for the most abundant fish species found on the middle Xingu River, prior to the construction of the Belo Monte Dam. The specimens collected in experimental catches were analysed with empirical equations and length-based FISAT methods. For the 63 fish species studied, high growth rates (K) and high natural mortality (M) were related to early sexual maturation and low longevity. The predominance of species with short life cycles and a reduced number of age classes, determines high rates of stock turnover, which indicates high productivity for fisheries, and a low risk of overfishing.
Acesso aberto (Open Access)
Reproductive biology and spatio-temporal distribution of Stellifer rastrifer, Stellifer naso and Macrodon ancylodon (Sciaenidae) in the Caeté estuary, northern Brazil
(2005-06) CAMARGO-ZORRO, Mauricio; ISAAC, Victoria Judith
This study analyses the spatial and temporal distribution of the dominant Sciaenids in the Caeté estuary on the northern coast of Brazil. Samples were taken by otter trawls in four areas of the Caeté estuary between October 1996 and August 1997 six bimonthly. Stellifer rastrifer, Stellifer naso and Macrododon ancylodon presented the highest biomass out of eleven species of Sciaenidae caught. Minimum and mean length at first maturity were calculated and the main spawning periods determined. Changes in the spatio-temporal distribution of the three species were related to seasonal changes in estuarine salinity and spawning pulses. Larvae and juveniles of S. rastrifer, S. naso and M. ancylodon were found in the inner estuary while larger specimens were more abundant in the outer estuary with higher salinities. M. ancylodon spawned from October to February and rested from April to August whereas S. rastrifer and S. naso spawned throughout the year, though with two peaks, in October-December and June.
Acesso aberto (Open Access)
Spatial distribution of southern brown shrimp (Farfantepenaeus subtilis) on the Amazon continental shelf: a fishery, marine geology and GIS integrated approach
(Universidade Federal do Pará, 2015-12) MARTINS, Déborah Elena Galvão; CAMARGO-ZORRO, Mauricio; SOUZA FILHO, Pedro Walfir Martins e; CINTRA, Israel Hidenburgo Aniceto; SILVA, Kátia Cristina de Araújo
The spatial distribution of the southern brown shrimp Farfantepenaeus subtilis (Pérez-Farfante, 1967) was studied based on industrial fishing fleet activities and is associated with geological and oceanographic characteristics of the benthonic environments on the Amazon continental shelf. Using a geographical information system (GIS) this paper sought to calculate the relative abundance of brown shrimp based on catch per unit effort (CPUE) and compare it with bathymetry, type of sedimentary structure, sedimentation rate and bottom salinity. As a result, we have concluded that the relative abundance (in terms of CPUE) is not uniformly distributed in space. Spatial analysis indicates that commercial trawling efforts were made in the (foreset) region of the subaqueous Amazon delta at depths of 40 to 60 m. In this region, prawn are responsible for the bioturbation of the sediments and the creation of a sedimentary structure called mottled mud. In the foreset region, sedimentation rates progressively increased up to 10 cm.yr-1; re-suspension was reduced and bottom salinity was high (~ 36). It appears that all of these factors define a stable muddy area with intense bioturbation. This notable biological activity is to be explained by the occurrence of a high F. subtilis abundance that appears to originate in a microbial loop. We concluded that by combining fishery information with environmental data from a GIS, it was possible to identify abundance distribution patterns for southern brown shrimp and other economically important fishery resources and to understand how they change on a large spatial-scale.