RESUMO
The aim of this work was to evaluate the microbial activity of the surface sediments (0-10 cm) of the Chacopata-Bocaripo lagoon axis (Ch-BLA) through microbiological parameters: microbial biomass (Cmic) dehydrogenase activity (DHS), fluorescein diacetate hydrolysis (HFDA), arginine ammonification (AA) and biochemical parameters: phosphatase (PHa) and urease (URa) activity. They were determined during transition (July 2010) and upwelling (March 2011) periods. Total organic carbon (TOC) did not vary significantly (p⩾0.05) between climatic periods. All the parameters studied were higher in upwelling season: Cmic (191.79 mg Cmic kg(-1)), DHS (228.70 µg TFF g(-1) 24 h(-1)), HFDA (204.09 µg fluorescein g(-1) 24 h(-1)), AA (13.09 µg NH4-N g(-1) h(-1)), PHa (132.31 µg pNF g(-1) h(-1)), URa (12.90 µg NH4-N g(-1) h(-1)). They appear to be controlled by the availability and quality of nutrients in each climatic period, and were useful tools for evaluating changes in microbial activity in marine sediments.
Assuntos
Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Biomassa , Carbono/análise , Fluoresceínas/metabolismo , Hidrólise , Monoéster Fosfórico Hidrolases/metabolismo , Estações do Ano , Urease/metabolismo , Venezuela , Microbiologia da ÁguaRESUMO
Perna viridis was used as biomonitor to assess heavy metal levels in the Chacopata-Bocaripo lagoon axis, Venezuela, during rain and drought seasons. The mussels were weighed and measured. The metal concentrations were determined by atomic absorption spectrophotometry. For rain period, the order of bioavailability was: Cu>Ni>Mn>Co>Cd>Pb, and for drought: Cu>Mn>Ni>Co>Pb>Cd. The concentrations of Ni, Co, Cd and Pb showed significant differences (P<0.05) in both periods. There was higher metal accumulation during drought season, possibly related to upwelling, since it produces an increase in primary productivity, which translates more food into organisms, making metals bioavailable for mussels. Only Cu and Mn showed significant relationships between the size and metal concentration, during drought period, it may be because of the organisms need for these essential metals in different physiological processes.
Assuntos
Monitoramento Ambiental/estatística & dados numéricos , Poluentes Ambientais/análise , Metais Pesados/análise , Perna (Organismo)/metabolismo , Animais , Secas , Monitoramento Ambiental/métodos , Chuva , Estações do Ano , Espectrofotometria Atômica , VenezuelaRESUMO
The aim of this work was to determine the frequency of different reproductive phases and to induce the germination of spores from tetrasporic and cystocarpic Gracilariopsis tenuifrons from Chacopata and La Peña, Venezuela, under controlled laboratory conditions (temperature 22 +/- 1 degree C, 12L:12D photoperiod, salinity of 36 +/-1 PSU and irradiance of 269 microE m(-2) s(-1)). Tetrasporic individuals dominated numerically over gametophitic individuals. The proportion of vegetative algae was very low. Only cystocarpic algae were collected and the spermatangia were absent. Sporulation, germination and formation of algae suggest that they present a Polysiphonia-type life cycle. Algae with reproductive structures were not obtained in the laboratory,
Assuntos
Estágios do Ciclo de Vida/fisiologia , Rodófitas/crescimento & desenvolvimento , Esporos/fisiologia , Animais , Fotoperíodo , Dinâmica Populacional , Reprodução/fisiologia , Cloreto de Sódio/análise , Fatores de Tempo , VenezuelaRESUMO
The marine algal flora from the eastern coast of Mochima National Park, Sucre, Venezuela was studied with a total of 51 taxa identified, including eight new additions of red algae which are Erythrotrichia carnea (Dillwyn) J. Agardh, Sahlingia subintegra (Rosenvinge) Kornmann, Liagora ceranoides Lamouroux, Asparagopsis taxiformis (Delile) Trevisan, Dasya corymbifera J. Agardh, Chondria dasyphylla (Woodward) C. Agardh, Herposiphonia secunda f. tenella (C. Agardh) M.J. Wynne and Polysiphonia subtilissima Montagne. Morphological and anatomical aspects of the specimens are described and illustrated.
Assuntos
Alga Marinha , VenezuelaRESUMO
The marine algal flora from the eastern coast of Mochima National Park, Sucre, Venezuela was studied with a total of 51 taxa identified, including eight new additions of red algae which are Erythrotrichia carnea (Dillwyn) J. Agardh, Sahlingia subintegra (Rosenvinge) Kornmann, Liagora ceranoides Lamouroux, Asparagopsis taxiformis (Delile) Trevisan, Dasya corymbifera J. Agardh, Chondria dasyphylla (Woodward) C. Agardh, Herposiphonia secunda f. tenella (C. Agardh) M.J. Wynne and Polysiphonia subtilissima Montagne. Morphological and anatomical aspects of the specimens are described and illustrated.