Anatomical Changes during Rooting of Mangroves - Avicennia officinalis and Excoecaria agallocha.

Mangrove forests continue to disappear all over the world due to a number of reasons. This is the study made to screen the anatomical and biochemical changes during the rooting process. Two important mangrove species have been examined based on their salt relationship natures: Avicennia officinalis subsp. australasica (salt excreting plant) and Excoecaria agallocha L (salt accumulating plant). The plants were treated with different root promoting hormones like IBA, IAA and NAA at different concentrations for three minutes each. After 45 days of the growth period root growth and anatomical changes were observed. The roots originated from the deeper zone of the secondary xylem after several anatomical variations in the hormone treated plants. This is the first trial which may help to determine the mass propagation of these commercial and medicinally important mangroves.

Mangrove forest composition and structure in Las Perlas Archipelago, Pacific Panama

Mangrove forest is an important ecosystem that provides many services, but in Panama, as in other countries, they are under threat due to a variety of human activities. Nowadays, large areas of mangroves continue to be lost without been described and lack of management strategies. This study focused on the mangrove structure in the two largest islands, Isla del Rey and Isla San Jose, of Las Perlas Archipelago (LPA), Pacific Panama. Assessment of Landsat satellite imagery revealed loss of mangroves in the LPA of 965ha in the period 1974-1986, and 248ha in the period 1986-2000. The majority of the loss (>77%) from the two study islands was due to timber extraction and agricultural development. In May 2006, permanent plots following the CARICOMP protocol were established at two sites on Isla del Rey (R1 and R2) and one site on Isla San Jose (SJ) where standardized metrics such as species, height and diameter at breast height of adult trees and seedlings were recorded. Forest structure differed at the three sites, although R1 and R2 were most similar. At R1, Laguncularia racemosa was the important species and R2 was dominated by Pelliciera rhizophorae. Examination of the forest structure and classified imagery indicated that these sites are spatially dynamic and appear to be rejuvenating. The forest structure would indicate that the sites have been growth-limited previously by human activities and possibly by other factors. SJ was dominated by Rhizophora mangle and appears to have a mature forest with large adult trees and few seedlings. It does not appear to have shown the same extent of spatial regrowth as the other two sites between 1986 and 2000 and is relatively static. The establishment of permanent plots and monitoring will be useful as part of the management plan, as the LPA shows a variety of mangrove structures and could be subject to further coastal development. Rev. Biol. Trop. 58 (3): 857-869. Epub 2010 September 01.

Los bosques de manglar son ecosistemas importantes que proveen muchos servicios, pero éstos están bajo la amenaza de una variedad de actividades humanas y grandes áreas de manglar continúan perdiéndose en Panamá. Este estudio está enfocado en la estructura de manglar de las dos islas más grandes del Archipiélago de Las Perlas en el Pacifico Panameño (LPA), la Isla del Rey y la Isla San José. La evaluación de las imágenes del satélite Landsat revela la pérdida de manglares en LPA de 965ha en el periodo entre 1974-1986, y de 286ha en el periodo 1986-2000. La mayor parte de la pérdida (>77%) en las dos islas estudiadas fue debida a la extracción de madera y al desarrollo agrícola. En mayo de 2006, se establecieron parcelas permanentes siguiendo el protocolo de CARICOMP en dos sitios en la isla del Rey (R1 y R2) y un sitio en la Isla San José (SJ) donde especies, altura y diámetro a la altura de la copa de árboles adultos y jóvenes fueron registradas. La estructura del bosque difirió en los tres sitios, sin embargo R1 y R2 fueron los más similares. En R1, Laguncularia racemosa fue la especie más dominante y Pelliceria rhizophora en R2. El análisis de la estructura del bosque y de imágenes clasificadas indicó que estos sitios son espacialmente dinámicos y parecen estar regenerándose. La estructura del bosque indica que el crecimiento en los sitios ha estado limitado por las actividades humanas y posiblemente por otros factores. SJ fue dominado por Rhizophora mangle y parece tener un bosque maduro con árboles adultos grandes y pocos jóvenes. Éste sitio no parece mostrar la misma extensión de rebrote espacial de los otros dos sitios entre 1986-2000 y es relativamente estático. El establecimiento de parcelas permanentes y el monitoreo serán útiles en la implementación del plan de manejo, ya que los manglares del LPA tienen una variedad estructural y podrían estar sujetos a un mayor desarrollo costero.

Population densities and genetic diversity of actinomycetes associated to the rhizosphere of Theobroma cacao / Densidades populacionais e diversidade genética de actinomicetos associados a rizosfera de Theobroma cacao

In spite of the acknowledged importance of growth-promoting bacteria, only a reduced number of studies were conducted with these microorganisms on Theobroma cacao. The objectives of this work were to study the population densities and genetic diversity of actinomycetes associated with the rhizosphere of cacao as a first step in their application in plant growth promotion and biological control. The populations densities of actinomycetes in soil and cacao roots were similar, with mean values of 1,0 x 10(6) CFU/g and 9,6 x 10(5) CFU/g, respectively. All isolates selected and used in this study were identified through sequencing analyses of a fragment of the rpoB gene that encodes the [beta]-subunit of the RNA polymerase as species of the genus Streptomyces. In vitro cellulolytic, xilanolytic and chitinolytic activity, indolacetic acid production and phosphate solubilization activities were observed in most of the isolates tested. The data obtained in this study demonstrate that actinomycetes account for a higher percentage of the total population of culturable bacteria in soil than on cacao roots. Additionally, actinomycetes from the cacao rhizosphere are genetically diverse and have potential applications as agents of growth promotion.

Apesar da reconhecida importância das bactérias promotoras de crescimento, apenas um reduzido número de estudos foi conduzido com este grupo de microrganismos na cultura do cacaueiro. Os objetivos deste trabalho foram o estudo da densidade populacional e da diversidade genética de actinomicetos associados à rizosfera do cacaueiro como o primeiro passo para sua utilização na promoção de crescimento de mudas desta cultura e no controle biológico de doenças. As densidades populacionais de actinomicetos em amostras de solo e de raízes de cacaueiro foram semelhantes, com valores médios de 1,0 x 10(6) UFC/g e de 9,6 x 10(5) UFC/g, respectivamente. Todos os isolados selecionados para este estudo foram identificados através de análises de seqüências de um fragmento do gene rpoB, que codifica a beta-subunidade da RNA polimerase, como pertencentes ao gênero Streptomyces. Dentre os isolados testados, constatou-se in vitro, a produção de celulase, xilanase, quitinase, ácido indolacético e a capacidade de solubilização de fosfato. Os dados obtidos demonstram que os actinomicetos representam uma maior proporção da população total de bactérias cultiváveis em solo do que em raízes. Adicionalmente, os actinomicetos da rizosfera do cacaueiro são geneticamente diversos e apresentam potencial para atuarem como agentes de promoção de crescimento.

Growth of Avicennia marina and Ceriops decandra seedlings inoculated with halophilic azotobacters.

Inoculation of azotobacter has significant positive effects on the growth characteristics and pigments in mangrove seedlings of Avicennia marina and Ceriops decandra. The bacterial inoculation significantly increased the root dry biomass at the maximum of 75.8% at 30 gl(-1) salinity in Ceriops decandra. But in Avicennia marina, the shoot dry biomass was increased significantly at the maximum of 56.12% at 30 gl(-1) salinity in general, the Azotobacter beijerinkii improved the growth characteristics better in both species of mangroves preferably at higher salinity levels in A. marina and at a range of salinity in C. decandra. The results recommend this forraising vigorous seedlings under nursery conditions.

Biomass, litterfall and decomposition rates for the fringed rhizophora mangle forest lining the Bon Accord Lagoon, Tobago

The mangrove forest that fringes the Bon Accord Lagoon measures 0.8 km(2) and is dominated by red mangrove (Rhizophora mangle). This forest forms the landward boundary of the Buccoo Reef Marine Park in Southwest Tobago, and is part of a mangrove-seagrass-coral reef continuum. Biomass and productivity, as indicated by litterfall rates, were measured in seven 0.01 ha monospecific plots from February 1998 to February 1999, and decomposition rates were determined. Red mangrove above-ground biomass ranged between 2.0 and 25.9 kg (dry wt.) m(-2). Mean biomass was 14.1+/-8.1 kg (dry wt.) m(-2) yielding a standing crop of 11 318+/-6 488 t. Litterfall rate varied spatially and seasonally. It peaked from May to August (4.2-4.3 g dry wt. m(-2) d(-1)) and was lowest from October to December (2.3-2.8 g dry wt. m(-2) d(-1)). Mean annual litterfall rate was 3.4+/-0.9 g dry wt. m(-2) d(-1). Leaf degradation rates ranged from 0.3% loss d(-1) in the upper intertidal zone to 1% loss d(-1) at a lower intertidal site flooded by sewage effluent. Mean degradation rate was 0.4+/-1% loss d(-1) . The swamp produces 2.8 t dry wt. of litterfall and 12 kg dry wt. of decomposed leaf material daily. Biomass and litterfall rates in Bon Accord Lagoon were compared to five similar sites that also participate in the Caribbean Coastal Marine Productivity Programme (CARICOMP). The Bon Accord Lagoon mangrove swamp is a highly productive fringed-forest that contributes to the overall productivity of the mangrove-seagrass-reef complex

The structure and productivity of the Thalassia testudinum community in Bon Accord Lagoon, Tobago

The Thalassia testudinum dominated seagrass community in the Buccoo Reef/ Bon Accord Lagoon Marine Park, measures 0.5 km(2) and is part of a contiguous coral reef, seagrass bed and mangrove swamp system in southwest Tobago. 7 testudinum coverage, productivity and percent turnover rates were measured from February 1998 to February 1999 at four sample locations, while total T. testudinum biomass was measured at two locations in the lagoon from 1992-2002. Productivity and turnover rates varied spatially and seasonally. They were higher in the back-reef area than in the mangrove-fringed lagoon, and were lowest at locations near to a sewage outfall. 7 testudinum coverage ranged from 6.6% in the lagoon to 68.5% in the back-reef area while productivity ranged from 3.9 to 4.9 g dry wt m(-2) d(-1) . Productivity and percentage turnover rates were higher in the dry season (January-June) than in the wet season (July-December). Productivity ranged from 3.0 in the wet season to 5.0 g dry wt m2 d-' in the dry season while percentage turnover rates ranged from 4.2% to 5.6%. Total Thalassia biomass and productivity in Bon Accord Lagoon were compared to six similar sites in the Caribbean that also participate in the Caribbean Coastal Marine Productivity Program (CARICOMP). This seagrass community is being negatively impacted by nutrient-enriched conditions

How to alleviate degradation of mangroves?

This work has experimentally proved that hyper salinity, a major cause for degradation of coastal mangrove habitats, can be alleviated by flushing of hyper saline soil with tidal water and/or with rainwater. Over a period of three years after digging the creeks to flush hyper saline soil with tidal water, an appreciable reduction in soil salinity and a moderate increase in colonization of mangroves are observed. Soil analysis showed a significant reduction in salinity after 2 months of storage of rainwater with a significant and concomitant increase of heterotrophic bacterial counts and nutrients. This study raises the possibility of converting degrading mangrove habitats to luxuriant ones through man-made efforts.