Navegando por Data de Publicação, começando com "2006-06-06"

Filtrar resultados por ano ou mês

Agora exibindo 1 - 2 de 2

Efeito das variáveis abióticas na produção primária de Egeria najas e Utricularia breviscapa da lagoa do Óleo (Estação Ecológica de Jataí, Luiz Antônio - SP)
(Universidade Federal de São Carlos, 2006-06-06) Petracco, Paula; Bianchini Júnior, Irineu; https://lattes.cnpq.br/0659731944736389
This study was developed at Oleo lagoon, an oxbow sited on Mogi Guaçu river floodplain, located in Estação Ecológica de Jataí (Luís Antônio SP Brazil). To evaluate the river level fluctuation on the metabolism of this lagoon the following activities were done: i) limnological inventories (pH, dissolved oxygen, ammonium, total nitrogen, total phosphorus, iron, magnesium, sodium, potassium, organic carbon, inorganic carbon, suspended matter, temperature, electrical conductivity and photosynthetic active radiation); ii) the lagoon batimetry; iii) in situ incubations to evaluate the primary production rates of two species of submerged aquatic macrophytes (Egeria najas Planchon and Utricularia breviscapa Wright ex Griseb); iv) simulation of levels of river overflow. In the rainy season, due to overflow of the waters of Mogi Guaçu river into the lagoon, intense modifications of abiotic variables were verified. In the dry period, when the lower values of temperature, electrical conductivity, total suspended matter, vertical light extinction coefficient, total carbon concentrations, NTK and Ptotal occurred, the E. najas stands were located in the bottom of the lagoon and the photosynthetic rates were significantly higher than in the rainy period, and the light was the main variable controlling this process. For U. breviscapa, the photosynthetic rates were higher in the rainy season, presenting possible relation to the values of temperature and inorganic carbon concentrations, which were higher in this period. From the results, it was observed that Oleo Lagoon showed three different limnological phases: dry, rainy without overflow and rainy with overflow. Considering it is a oxbow lake situated in a conservation unit, the change in limnological and biochemical characteristics were due to the overflow pulse, influencing directly or indirectly the primary production of E. najas and U. breviscapa.
Importância do prado de capim marinho (Halodule writhii Aschers) na composição da fauna de Crustacea Brachyura e na dinâmica trófica das espécies de Callinectes (Crustacea, Portunidae) na ilha de Itamaracá - Pernambuco - Brasil
(Universidade Federal de São Carlos, 2006-06-06) Moura, Noely Fabiana Oliveira de; Verani, José Roberto; https://lattes.cnpq.br/0053232138684810; https://lattes.cnpq.br/9083829606714038
With aim to know the community structure of the Crustacea Brachyura and analyze the trophic dynamics of the species Callinectes dane, C. larvatus e C. ornatus in the seagrass bed of Halodule wrightii Aschers, studies were carried out during a dry period (February, 2001 and September to December, 2001) and the wet period (March to August, 2001) in the Forno da Cal beach, Itamaraca Island, Pernambuco, Brazil. The sampling method adopted was nocturnal trawling on the seagrass using a small (2m width) bottom net with internal mesh of 5mm and external of 2mm. Additional samplings were carried out on a period of 24 hours, in February, May, July, September and December, 2001. Samplings were also carried out on the adjacent sandy flat without vegetation, in March, June, August and December, having as objective to compare the biomass, abundance and diversity of this habitat with the seagrass in this same period. To determinate the gastric evacuation rate in the Callinectes sp., experiment was carried out. The results indicate that the Portunidae family contributed with 93% of the total captures. The species Callinectes ornatus, C. danae, C. larvatus and Portunus ordwayi were the most frequent. The highest density occurred in March, positively correlating with the air temperature, and the highest biomass was observed in July, with a positive correlation to density of cast algae. The seagrass presented the highest averages of densities, biomass, number of species, richness and diversity when compared to the adjacent sandy flat. Even if the number of species observed in the sand is higher, these presented well-distributed in the environment, with equitability value higher than in the seagrass. Animal organic matter, Gastropoda and Macrophyta were the food items that most contributed in the analysis of the stomach content of the species C. danae, C. larvatus and C. ornatus. It was observed that the smallest organisms have fed of small preys and with low mobility, as in the case of highest consume of Polychaeta, Copepoda and Amphipoda by specimens of smaller carapace width. Two feeding rhythms were observed for Callinectes: a diurnal one from 4:00 to 9:00 am and a nocturnal one between 21:00 and 22:00 pm. The evacuation rate (E) obtained by the regression analysis was E = 33.26% VE h-1. The daily ration in the sampled months in the 24-hour analyses was of 798.24% SV (the stomach fullness). After transforming the stomach fullness to somatic weight a day, the observed value was 20.748%.d-1. Then, C. ornatus with weigh of 1 g may consume 0.207 g food/ day. The seagrass bed represented as an important food source to Brachyura s population, due to the diversity of preys and refuge area, not only by the vegetation of seagrass but also by the abundance of cast algae, especially for the species Callinectes danae, C. larvatus and C. ornatus.