scholarly journals Dynamics of a toxic cyanobacterial bloom (Cylindrospermopsis raciborskii) in a shallow reservoir in the semi-arid region of northeast Brazil

1999 ◽  
Vol 20 ◽  
pp. 285-297 ◽  
Author(s):  
M Bouvy ◽  
R Molica ◽  
S De Oliveira ◽  
M Marinho ◽  
B Beker
Keyword(s):  
Arid Region ◽  
Cyanobacterial Bloom ◽  
Cylindrospermopsis Raciborskii ◽  
Northeast Brazil ◽  
Shallow Reservoir ◽  
Semi Arid Region ◽  
Semi Arid

Macroalgae Mariculture as a Social and Environmental Alternative for Coastal Traditional Communities of the Semi-Arid Region of Northeast Brazil

2020 ◽  
pp. 91-98
Author(s):  
Ivanilson de Souza Maia ◽  
Dárlio Inácio Alves Teixeira ◽  
Vigínia Maria Cavalari Henriques ◽  
Maulori Curié Cabral
Keyword(s):  
Arid Region ◽  
Northeast Brazil ◽  
Semi Arid Region ◽  
Semi Arid ◽  
Traditional Communities

scholarly journals Helminths infecting the cat-eyed snake Leptodeira annulata Linnaeus 1758 (Squamata: Dipsadidae) in a semiarid region of Brazil

2018 ◽  
Vol 55 (4) ◽  
pp. 281-285
Author(s):  
E. F. Fernandes De Carvalho ◽  
A. Ferreira Da Silva-Neta ◽  
C. De Sousa Silva ◽  
C. R. De Oliveira ◽  
J. Da Cunha Xavier Nunes ◽  
...  
Keyword(s):  
Arid Region ◽  
Paratenic Host ◽  
Nematode Species ◽  
Helminth Fauna ◽  
Semiarid Region ◽  
Northeast Brazil ◽  
Semi Arid Region ◽  
Semi Arid

Abstract Snakes have diverse feeding and living habits, being exposed to a variety of endoparasite communities. However, more studies are still necessary to document these relationships. We examined 18 specimens of the cat-eyed snake Leptodeira annulata from a semi-arid region in Northeast Brazil. Eight taxa of parasites were found, with higher prevalence of cystacanths (Acanthocephala). Five nematode species (Hexametra boddaertii, Oswaldocruzia sp., Oxyascaris sp., Physaloptera sp. and Raillietnema spectans) and the pentastome Raillietiella furcocerca represent a new parasitism record for the host studied. Our results also showed that L. annulata could act as paratenic host for acanthocephalans. These results contribute to the knowledge of the helminth fauna of L. annulata.

scholarly journals Spatial-temporal variation in coiled and straight morphotypes of Cylindrospermopsis raciborskii (Wolsz) Seenayya et Subba Raju (Cyanobacteria)

2010 ◽  
Vol 24 (2) ◽  
pp. 585-591 ◽  
Author(s):  
Ênio Wocyli Dantas ◽  
Maria do Carmo Bittencourt-Oliveira ◽  
Ariadne do Nascimento Moura
Keyword(s):  
Arid Region ◽  
Thermal Stratification ◽  
Cylindrospermopsis Raciborskii ◽  
Temporal Behavior ◽  
Mixed Condition ◽  
Ecological Success ◽  
Main Factors ◽  
Semi Arid Region ◽  
Sampling Times ◽  
Semi Arid

This study reports the spatial and temporal behavior of straight and coiled morphotypes of C. raciborskii in a reservoir in Brazil's semi-arid region as well as the main factors responsible for the variability. Two set of samples were collected from the subsurface and bottom in the central region of a reservoir in two seasonal periods (dry - January 2005; rainy - June 2005) over 20-hour sampling periods during daylight (8 am, 12 pm and 4 pm) and dark (8 pm, 12 am and 4 am) hours. Measurements of abiotic parameters were determined concurrently to the sampling of biotic variables. Two C. raciborskii morphotypes were found in the reservoir: straight and coiled. There was no difference in density of the straight and coiled C. raciborskii morphotypes between the different sampling times for either season. Vertical differences were found in the distribution of both morphotypes in both seasons, with greater densities recorded at the subsurface. Densities of the two C. raciborskii morphotypes were greater in the dry season, with the density of the coiled morphotype at the surface two-fold greater than that of the straight morphotype and that found in the rainy season. The ecological success of the coiled morphotype was due to thermal stratification, whereas a mixed condition was determinant in the success of the straight morphotype.

FLORISTIC AND VEGETATIONAL ASPECTS OF AN INSELBERG IN THE SEMI-ARID REGION OF NORTHEAST BRAZIL

2009 ◽  
Vol 66 (2) ◽  
pp. 329-346 ◽  
Author(s):  
P. Gomes ◽  
M. Alves
Keyword(s):  
Species Richness ◽  
Arid Region ◽  
Floristic Composition ◽  
Northeastern Brazil ◽  
Northeast Brazil ◽  
Surrounding Area ◽  
Floristic Inventory ◽  
Exposed Rock ◽  
Semi Arid Region ◽  
Semi Arid

Inselbergs are rocky environments that support a unique flora distinct from that of the surrounding area. The objectives of this work were to conduct a floristic inventory of an inselberg in the semi-arid region of Northeast Brazil, and to investigate the relationship between its flora and the flora of the surrounding area. The following questions were addressed: is the species richness comparable to other inselbergs in northeastern Brazil; is the floristic composition of the inselberg more similar to other inselbergs or to the surrounding Caatinga vegetation; and do the similarities in the floristic composition of inselbergs depend on the distance between them? This work documents 201 species in 62 families. Cyperaceae (28 spp.), Euphorbiaceae (19), Poaceae (15), Orchidaceae (11) and Bromeliaceae (9) are the most species-rich families. On the inselberg the plants are distributed in islands found on exposed rock, in fissures and in depressions in the rock. Variations in species richness in the region were assessed by comparison of floristic inventories conducted in other inselbergs of the semi-arid region with those of this study. The flora of the inselberg under investigation is more similar to the flora of other nearby inselbergs than to the vegetation of the surrounding semi-arid region.

scholarly journals Analysis of the NDVI Temporal Dynamics in Semi-arid Ecosystems: Brazilian Caatinga and African Western Sahel (Análise da Dinâmica Temporal do NDVI nos Ecossistemas Semi-áridos: Caatinga Brasileira e Sahel Ocidental Africano)

2011 ◽  
Vol 4 (2) ◽  
pp. 300 ◽  
Author(s):  
Humberto Alves Barbosa ◽  
T.V. Lakshimi Kumar ◽  
Ivon Wilson da Silva Junior
Keyword(s):  
El Niño ◽  
Arid Region ◽  
Temporal Dynamics ◽  
El Nino ◽  
Arid Ecosystems ◽  
Northeast Brazil ◽  
Vegetation Types ◽  
Semi Arid Region ◽  
Semi Arid ◽  
African Sahel

Os resultados indicaram que o efeito causado pelo evento El Niño, nos vários tipos de vegetação na região semi-árida do Nordeste do Brasil, durante as duas últimas décadas do século passado, apresentou diferentes padrões sazonais e interanuais dos tipos de vegetação no Sahel africano. A amplitude sazonal na variação do Índice de Vegetação Diferença Normalizada – NDVI, no Sahel Africano não foi alterada pelo efeito climático do El Niño, no entanto, na região semi-árida do Nordeste do Brasil, os tipos de vegetação foram afetados durante os eventos El Niño. Além disso, observou-se que o NDVI varia de acordo com as condições climáticas locais, apresentando uma lacuna temporal entre a ocorrência de precipitação e absorção de água disponível na vegetação. Esta informação é importante para mostrar condições de contorno para os modelos climáticos e também para a previsão numérica de tempo.  Palavras-chave: Vegetação, Aridez . Satelite  Análise da Dinâmica Temporal do NDVI nos Ecossistemas Semi-áridos: Caatinga Brasileira e Sahel Ocidental Africano   ABSTRACT The results indicated that the effect caused by the El Niño event in the various types of vegetation in the semi-arid region of Northeast Brazil during the last two decades of the last century, presented a differing seasonal and interannual patterns from the vegetation types in the African Sahel. The seasonal amplitude of Normalized Difference Vegetation Index - NDVI variation in the African Sahel was not altered by the climatic effect of El Niño, however, in the semi-arid region of Northeast Brazil, the vegetation types were affected during the El Niño events. Furthermore, it was observed that the NDVI varies according to the local climatic conditions, presenting a temporal gap between the precipitation occurrence and water absorption available from the vegetation. This information is important to show contour conditions for climatic models and also for the weather numerical forecasting.   Keywords: Vegetation, drought, satellite.

scholarly journals Cyanobacterial blooms in stratified and destratified eutrophic reservoirs in semi-arid region of Brazil

2011 ◽  
Vol 83 (4) ◽  
pp. 1327-1338 ◽  
Author(s):  
Ênio W. Dantas ◽  
Ariadne N. Moura ◽  
Maria do Carmo Bittencourt-Oliveira
Keyword(s):  
Arid Region ◽  
Cyanobacterial Blooms ◽  
Cylindrospermopsis Raciborskii ◽  
Dissolved Phosphorus ◽  
Phytoplankton Communities ◽  
Thermal Changes ◽  
Environmental Instability ◽  
Semi Arid Region ◽  
Eutrophic Reservoirs ◽  
Semi Arid

This study investigated the dynamics of cyanobacteria in two deep, eutrophic reservoirs in a semi-arid region of Brazil during periods of stratification and destratification. Four collections were carried out at each reservoir at two depths at three-month intervals. The following abiotic variables were analyzed: water temperature, dissolved oxygen, pH, turbidity, water transparency, total phosphorus, total dissolved phosphorus, orthophosphate and total nitrogen. Phytoplankton density was quantified for the determination of the biomass of cyanobacteria. The data were analyzed using CCA. Higher mean phytoplankton biomass values (29.8 mm³.L-1) occurred in the period of thermal stratification. A greater similarity in the phytoplankton communities also occurred in this period and was related to the development of cyanobacteria, mainly Cylindrospermopsis raciborskii (>3.9 mm³.L-1). During the period of thermal destratification, this species co-dominated the environment with Planktothrix agardhii, Geitlerinema amphibium, Microcystis aeruginosa and Merismopedia tenuissima, as well as with diatoms and phytoflagellates. Environmental instability and competition among algae hindered the establishment of blooms more during the mixture period than during the stratification period. Thermal changes in the water column caused by climatologic events altered other physiochemical conditions of the water, leading to changes in the composition and biomass of the cyanobacterial community in tropical reservoirs.

scholarly journals Selectivity of Pre and Postemergence Herbicides in Single or Combined Applications in Castor Crop

Agronomy ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 19
Author(s):  
Augusto G. F. Costa ◽  
Valdinei Sofiatti ◽  
Cleber D. G. Maciel ◽  
Jalmi G. Freitas ◽  
Gleibson D. Cardoso ◽  
...  
Keyword(s):  
Weed Management ◽  
Arid Region ◽  
Field Experiments ◽  
Ricinus Communis ◽  
Northeast Brazil ◽  
Ricinus Communis L ◽  
Chlorimuron Ethyl ◽  
Semi Arid Region ◽  
Postemergence Herbicides ◽  
Semi Arid

One of the main challenges in castor crop (Ricinus communis L.) production is efficient weed management mainly due to limited options of selective herbicides. This study evaluated the selectivity of herbicides applied alone or in combination in pre- and postemergence applications in castor crop. Two field experiments were carried out under irrigation conditions in a semi-arid region of Northeast Brazil. It was found that the visual symptoms of phytointoxication of the herbicides used on castor were mild in both experiments. Consequently, there were no significant interferences on plant height, number of racemes, and grain (seed) yield. Pre-emergence applications (g ha−1) of trifluralin (1800), pendimethalin (1500), clomazone (750), clomazone + trifluralin (750 + 1800), and clomazone + pendimethalin (750 + 1500) followed by chlorimuron-ethyl in postemergence (15 g ha−1) are selective to castor. The application (g ha−1) of pendimethalin + clomazone (1000 + 500) in pre-emergence, associated with chlorimuron-ethyl (10 and 15), metamitron (2800 and 4200), ethoxysulfuron (60 and 80), or halosulfuron-methyl (75 and 112.5) in one or two applications in postemergence, as single or split applications, in an interval of 14 days, are selective to castor crop.

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