Dinámica de las propiedades del suelo en bosques de Rhizophora mangle L. (Rhizophoraceae) en Isla de Margarita, Venezuela

Abstract

Dynamics of soil properties in forests of Rhizophora mangle L. (Rhizophoraceae) in Margarita Island, Venezuela. Biochemical and microbiological properties of soils can provide information related to ecosystems environmental status. With the aim to determine the response of microbial biomass, and enzymatic and microbial activity in hypersaline (IS≥55ups) and saline (IS<55ups) mangrove soils exposed to interstitial salinities (IS) greater than 36ups, these properties were measured in mono-specific forests of Rhizophora mangle at Laguna de la Restinga National Park (Margarita Island, Venezuela). During three seasons (dry, wet and transition), a total of 120 soil samples were collected from ten (5 hypersaline and 5 saline) randomly-selected sites of 1000m 2 each. Four soil samples (400-500g) per plot were randomly collected with a corer at a depth of 10cm using a 1m 2 quadrat; each sample consisted in the combination of 8 sub-samples (50-60g ea.). Physical, chemical, enzymatic, biochemical and microbiological properties of soil samples were determined using standard laboratory protocols. The response of microbial biomass and microbial and enzymatic activity was analyzed taking into account spatial and climatic factors and interstitial salinity. Microbial biomass was linked to each locality conditions, and was not sensitive to seasonal or salinity differences. Microbial activity remained functionally active during the study period and presented variable responses. Dehydrogenase activity proved to be a good indicator for flooded and anoxic environments, and arginine ammonification resulted to be the more sensitive microbial activity to changes in salinity. Regarding enzyme activities, spatial variability was the most widespread response. We did not find a unique general pattern between enzymatic activities and spatio-temporal variation; and only the enzyme phosphatase was negatively affected by salinity. We conclude that microbial populations of mangrove soils and their activities have functional adaptations to flooded and highly-saline environments typical of a negative estuary, subjected to drastic changes due to weather and water dynamics. Future studies are needed to determine the relation between the "health" of mangrove forest and microbial populations, and their activities in mangroves soils.

Estructura comunitaria de bivalvos y gasterópodos en raíces del mangle rojo Rhizophora mangle (Rhizophoraceae) en isla Larga, bahía de Mochima, Venezuela

“…Existen reportadas seis especies de mangle: Rhizophora mangle, R. racemosa, R. harrisoni, Laguncularia racemosa, Avicennia germinans y Conocarpus erectus (Conde & Alarcon, 1993). En nuestro país, se han realizado estudios donde se han caracterizado estos ambientes en diferentes zonas, destacándose los de Medina & Barboza (2003), Lacerda, Conde, Kjerfve, Álvarez-León, Alarcón & Polanía (2001), Conde & Suárez (2003), Barreto (2008), Sánchez-Arias, Paolini & Rodríguez (2010), López, Barreto & Conde (2011) y Del Mónaco, Jiménez, Narciso, Alfonso & Bustillos (2010). Sin embargo, desde el punto de vista ecológico, son pocos los trabajos que se han realizado, particularmente sobre organismos asociados a las raíces de R. mangle, destacándose los de Morao (1983), Ordosgoitti (1985), Montes (1992), Marcano (1996), Márquez & Jiménez (2002), Barrios, Márquez & Jiménez (2003), Márquez-Rojas, Blanco-Rabla, Jiménez & Allen (2006), Villafranca (2007), Cedeño, Jiménez, Pereda & Allen (2010), López et al (2011) y Guerra-Castro, Cruz-Motta & Conde (2011).…”

Bioprospecting from marine coastal sediments of Colombian Caribbean: screening and study of antimicrobial activity

“…The counting of cultivable bacteria was higher in CAN than in PBE, probably because CAN is a mangrove swamp ecosystem which favours microbial growing by the rapid decay of trash, detritus that is the base of the food chain in marine coastal environments and the radical exudates, a nutrient font for the micro‐organisms (Sánchez‐Arias et al . ). A high quantity of isolates were obtained with the culture media TSA and MA, most of the colonies formed were slightly humid and somewhat shiny, circular and irregular forms were predominant although some isolates were rhizoids.…”

Preferencia de microhábitat de Pseudoscorpiones (Arachnida) en bosques de mangle del sur del golfo de Morrosquillo, Caribe colombiano

“…Se analizaron 4 variables fisicoquímicas: humedad de la hojarasca, humedad de la corteza, humedad del suelo y salinidad del suelo, las cuales, se consideraron las más importantes y que podrían influir en la comunidad de pseudoescorpiones en cada uno de los fragmentos de bosque de mangle evaluados (Weygodlt, 1969). Para determinar la humedad del suelo se utilizó un nucleador o cilindro de 50 mm de diámetro y 100 mm de longitud, a una profundidad de 0-10 cm para la obtención de las muestras de cada monolito donde se colectó la hojarasca (Sánchez et al, 2010). Las muestras fueron llevadas y procesadas en el laboratorio, donde se sometieron a procesos de secado en un horno a 115 °C por un tiempo de 24 horas.…”