356 resultados para Amazon islands
Resumo:
Larval development of the freshwater palaemonid shrip Pseudopalaemon chryseus Kensley & Walker, 1982 was studied in the laboratory from the offspring oof females collected in a lake of the lower Negro River system. Females carry few (14 to 43), large (1.86 + 0.13 x 1.29 + 0.06 mm), yolk-rich eggs. The species goes throught three larval stages without feeding and the main feature of its larval development is the presence of functional walking legs on hatching. Descriptions and illustrations of the three larval and first juvenile stages are presented.
Resumo:
The two especies of Lophopidae found in the lowland Amazon Basin, Hesticus rufimanus, (walker) and H. sanguinifrons Muir, are redescribed and their geographical distributions given. Keys are provided to genera of New World lophopidae, and to species of Hesticus .
Resumo:
Recent studies have described widespread statigraphic units of Late Pleistocene and Holocene age in the western part of the Amazon Basin. The recognition of deltaic sedimentation in the uppermost these units near Rio Branco, Brazil, at a modern elevation of approximately 500 feett leads to the conclusion that this area was situated on the edge of a large Amazonian lake that existed in the recent past when Andean tectonism caused active downwarping of the western edge of the Amazon Basin. The ramifications of this "Lago Anazonas" hypothesis extend into every area of modern Amazonian geology and biology.
Resumo:
Evapotranspiration rates for a eight month old tropical pasture were estimated using the Penman-Monteith equation. Transpiration rates for several woody secondary successional species and stump sprous in the pasture and conucos (farm sites) were measured using the tritiated water technique.The stuty area was located near the village of San Carlos de Rio Negro (1° 56' N, 67° 03' W) in southern Venezuela, near the confluence of the Casiquiare and the Rio Guania wich forms the Rio Negro. The terrain was gently rolling with the areas between the small ridges supporting Amazon caatina forests on spodosols, and higher never flooded areas (tierra firma) supporting a mixed species forest.Results indicated that for a one month period, ET loss (0.46 cm/day) from the pasture, including soil and root mat evaporation, was about 0.43 cm/day less than estimated from the adjacent undisturbed forest (0.89 cm/day). Pan A evaporation for the same time period was 0.64 cm/day. Transpiration rates for seed established species were significantly less (0.38 cm/day) than for stump sprouts (1.09 cm/day) of the primary forest in the pasture.
Resumo:
The work conelete of a survey of the mvaewe plants which appeared during the first six months of seedling stage in foreet plantations of second and third rotation, in the Jari area, Brazil. The resulting list showed two types of invasives: (1) true weeds - those cosmopolitan species that are typical of disturbed habitats; and (2) pioneer species - those which were probably remnants from the original natural vegetation of the studied area.
Resumo:
A large-scale inventory of trees > 10cm DBH was conducted in the upland "terra firme" rain forest of the Distrito Agropecuário da SUFRAMA (Manaus Free Zone Authority Agricultural District) approximately 65Km north of the city of Manaus (AM), Srasil. Thegeneral appearance and structure of the forest is described together with local topography and soil texture. Thepreliminary results of the Inventory provide a minimum estimate of 698 tree species in 53 families in the 40Km radius sampled, including 17 undescribed species. Themost numerically abundant families, Lecythidaceae, Leguminosae, 5apotaceae and Burseraceae as also among the most species rich families. One aspect of this diverse assemblage is the proliferation of species within certain genera, Including 26 genera In 17 families with 6 or more species or morphospecies. Most species have very low abundances of less than 1 tree per hectare. While more abundant species do exist at densities ranging up to a mean of 12 trees per ha, many have clumped distributions leading to great variation in local species abundance. The degree of similarity between hectare samples based int the Coefficient of Community similarity Index varies widely over different sample hectares for five ecologically different families. Soil texture apparently plays a significant role In determining species composition in the different one hectare plots examined while results for other variable were less consistent. Greater differences in similarity indices are found for comparisons with a one hectare sample within the same formation approximately 40Km to the south. It is concluded that homogeneity of tree community composition within this single large and diverse yet continuous upland forest formation can not be assumed.
Resumo:
Two new genera and species of Paramphistomidae (Tremadota, Digenea) are described from freshwater fish of the Brazilian Amazon. Anavilhanatrema robustagen. et sp. nov. is characterized as having a cylindrical body with an anterior expansion, small suckers, a small cirrus sac, large lobate testes, a lobate ovary, long ceca and extensive vitellaria. Pacudistoma turgidagen. et sp. nov., on the other hand, is distinguished by having a stout, cylindrical body, a large oral sucker with internal diverticula, a large genital sucker, smaller lobate testes, a spherical ovary, long ceca and relatively extensive vitellaria. Both species appear to be host specific with A. robustafound in Pristobrycon striolatus(STEINDACHNER) while P. turgidaoccurus in Hyleus pacu(SCHOMBURCK).
Resumo:
Studies were made of the intestinal parasites of Amerindian populations of the Uaupes River basin of Brazil. Three groups were sampled: 1) Tukano fisher-agriculturalists who live in permanent riverine villages; 2) Maku hunter-horticulturalists who live in close contact with the Tukano fishing villages; and 3) Maku who inhabit the forest interior and have little contact with permanent settlements. Fecal samples were collected from 498 individuals of which 220 were from the first group, 135 from de second and 143 from the third. The samples were analyzed by means of microflotation and centrifugal sedimentation. A total of 18 protozoan and helminth species were recorded based on the presence of cysts or eggs. These included five nematode species that could not be identified. The three common pathogenic nematodes were found to be prevalent: the hookworm, Necator americanus(96%); the whipworm, Trichuris trichiura(77%) and the large roundworm, Ascaris lumbricoides(75%). The prevalence of Ascarisamong the villages was found to vary from 56 to 100%. Individuals living in, or associated with, permanent settlements had higher prevalence and intensity rates than those living in the nomadic hunter-gatherer way. This is shown to be directly related to fecal contamination of the environment in and around permanent settlements. The prevalence of Ascarisin a population can be used as an indicator of such environmental contamination.
Resumo:
Miracetyma etimaruyagen. et sp. n. is proposed from the gills filaments of Curimata cyprinoides(Linnaeus, 1758), Potamorhina latior(Spix, 1829) and Psectrogaster essequibensis(Gunther, 1864). The species of the new genus is characterized by having a more complex latching antenna. The claw is greatly reduced and has a groove; the third segment has one or two grooves; the first, second and third segments have one or two cuticular extensions. The legs have pectinate setae and the first endopod is greatly modified, very long, and without setae. The first segment of the first endopod is large, strong and elongate and the second segment is subcylindrical, slender and elongate. These modifications imply in a loss of swimming capacity which is linked to secure fixation on the gill filament. As a result, the leg morphology has evolved other functions.
Resumo:
A new species of Calanoid copepod, Rhacodiaptomus besti,is described from material collected in the Igarapé São Pedro, Rio Jamari, State of Rondônia, and Lago Amanã, Rio Japurá, State of Amazonas, in Western Amazonia. A detailed morphological analysis of the species was undertaken in order to provide a basis for future studies on inter and intrageneric relationships.
Resumo:
Anphira branchialisgen. et sp. nov. (Crustacea, Isopoda, Cymothoidae) is described from the dorsal areas of the gill chambers of three species of piranhas (Serrasalmusspp.). The fishes were caught in rivers near Manaus, Amazonas State and on Maracá island, Federal Territory of Roraima, Brasil. The new genus and species is characterized by having large, flat coxal plates on ail 7 pereonites. These plates usually extend beyond the margins of the following segments and the 7th ones extend nearly to the pleotelson and cover the lateral margins of the pleonites. The mandible of this species is rounded, "foot shaped" and without incisor. The mandibular palp is short and stout. The maxillules have 3 terminal and 2 subterminal spines. The pleopods are simple lamellar structures with rounded tips. Evidence is presented that these parasites feed on gill filaments.
Resumo:
Of eleven proteins analyzed in four Amazonian populations, the esterases showed the greatest variation, with five activity zones. EST1, EST2 and EST5 showed variation in each of the populations studied. EST1 and EST2 are each controlled by two, and EST5 by four, codomi-nant alleles. LAP presented six activity zones, with codominant variation in LAP5and LAP6.oc—GPDH was monomorphic with one activity band on starch gel and two on polyacrylamide gel. 1DH presented two activity zones, with variation in the IDHl region. PGM had a single activity zone, with variation in all populations. The Ariquemes populations showed five alleles and the other populations three, all of then codominant. Three activity zones with two codominant alleles were observed for ODH. Aldehyde Oxidase showed two activity zones, with variation in AOl only in the Ariquemes and Porto Velho/Samuel populations. 6-PGDH showed only one activity zone and variation only in the Ariquemes population. The remaing systems - XDH, G-6-PDH and GDH. was monomorphic.
Resumo:
The alimentary preferences of five species of wood-feeding termites of the genus Nasutitermes that coexist in the inundated forests of the floodplains of the Amazon river várzea for species of fresh wood and for wood in different stages of decomposition was evaluated in laboratory tests. Wood of low density was generally preferred; the decay stages were preferred over fresh wood. The five termite species differ in the amplitude of their choices, indicating a strong differentiation in food choice among them. Differences in feeding preferences may be a niche-separating factor for these five Nasutitermes species of the floodplains.
Resumo:
Larval development of the freshwater shrimp Pseudopalaemon amazonensis Ramos-Porto was studied in the laboratory based on the offspring of ovigerous females collected in a small “terra-firme” forest stream near Manaus, Brazil. Ovigerous females with a mean total length of 36.5 ± 1.9 mm carried 13-19 eliptical, yolk-rich eggs measuring 2.55 ± 0.16 x 1.64 ± 0.11 mm. The larval period consisted of 3 benthie stages and the larvae accomplished metamorphosis after 7-8 days without feeding. The newly-hatched larva had sessile eyes and all appendages, except for the uropods; chelipeds were present as uniramous buds, but walking legs were fully developed and functional. Descriptions and illustrations of the 3 larval and first juvenile stages are presented.