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  • tropical biogeochemical processes  (2)
  • ASFA15::M::Mangroves  (1)
  • 1
    ISSN: 1573-515X
    Keywords: anthropogenic impact ; interamerican seas ; nitrogen cycling ; nutrient limitation ; tropical biogeochemical processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We discuss the mechanisms leading to nutrient limitation in tropical marine systems, with particular emphasis on nitrogen cycling in Caribbean ecosystems. We then explore how accelerated nutrient cycling from human activities is affecting these systems. Both nitrogen and phosphorus exert substantial influence on biological productivity and structure of tropical marine ecosystems. Offshore planktonic communities are largely nitrogen limited while nearshore ecosystems are largely phosphorus limited. For phosphorus, the ability of sediment to adsorb and store phosphorus is probably greater for tropical carbonate sediments than for most nearshore sediments in temperate coastal systems. However, the ability of tropical carbonate sediments to take up phosphorus can become saturated as phosphorus loading from human sources increases. The nature of the sediment, the mixing rate between nutrient-laden runoff waters and nutrient-poor oceanic waters and the degree of interaction of these water masses with the sediment will probably control the dynamics of this transition. Nearshore tropical marine ecosystems function differently from their temperate counterparts where coupled nitrification/denitrification serves as an important mechanism for nitrogen depuration. In contrast, nearshore tropical ecosystems are more susceptible to nitrogen loading as depurative capacity of the microbial communities is limited by the fragility of the nitrification link. At the same time, accumulation of organic matter in nearshore carbonate sediments appears to impair their capacity for phosphorus immobilization. In the absence of depurative mechanisms for either phosphorus or nitrogen, limitation for both these nutrients is alleviated and continued nutrient loading fuels the proliferation of nuisance algae.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-515X
    Keywords: anthropogenic impact ; interamerican seas ; nitrogen cycling ; nutrient limitation ; tropical biogeochemical processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We discuss the mechanisms leading to nutrient limitation in tropical marine systems, with particular emphasis on nitrogen cycling in Caribbean ecosystems. We then explore how accelerated nutrient cycling from human activities is affecting these systems. Both nitrogen and phosphorus exert substantial influence on biological productivity and structure of tropical marine ecosystems. Offshore planktonic communities are largely nitrogen limited while nearshore ecosystems are largely phosphorus limited. For phosphorus, the ability of sediment to adsorb and store phosphorus is probably greater for tropical carbonate sediments than for most nearshore sediments in temperate coastal systems. However, the ability of tropical carbonate sediments to take up phosphorus can become saturated as phosphorus loading from human sources increases. The nature of the sediment, the mixing rate between nutrient-laden runoff waters and nutrient-poor oceanic waters and the degree of interaction of these water masses with the sediment will probably control the dynamics of this transition. Nearshore tropical marine ecosystems function differently from their temperate counterparts where coupled nitrification/denitrification serves as an important mechanism for nitrogen depuration. In contrast, nearshore tropical ecosystems are more susceptible to nitrogen loading as depurative capacity of the microbial communities is limited by the fragility of the nitrification link. At the same time, accumulation of organic matter in nearshore carbonate sediments appears to impair their capacity for phosphorus immobilization. In the absence of depurative mechanisms for either phosphorus or nitrogen, limitation for both these nutrients is alleviated and continued nutrient loading fuels the proliferation of nuisance algae.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2021-05-19
    Description: Se presenta el estado de cambio (1992-2000) de indicadores ecológicos seleccionados como medidas de éxito del proyecto de rehabilitación de bosques de manglar en la Ciénaga Grande de Santa Marta (CGSM), Colombia, en respuesta a cambios hidrológicos iniciados en 1995. Existe una reducción significativa de la salinidad del agua y del suelo en todas las estaciones de muestreo como resultado de la reconexión hidráulica de los caños Clarín y Aguas Negras con el Río Magdalena. La salinidad del agua intersticial del suelo (profundidad 0,5 m) (7 estaciones) y de la columna de agua (0,5 m) (10 estaciones) se redujo (suelo 〈30 g kg-1; agua 〈10 g kg-1) significativamente de 1994 al 2000. Durante 1994 los valores de salinidad del agua intersticial del suelo fluctuaron entre 40 g kg-1 (Rinconada) y 100 g kg-1 (KM 13), mientras que la salinidad en la columna de agua fluctuó entre 25-35 g kg-1 para la mayoría de las estaciones muestreadas. Esta reducción de la salinidad facilitó la regeneración del bosque de manglar con una ganancia neta de 99 km2 de 1995 a 1999. La alta precipitación registrada en los años 1995 y 1999 como resultado del fenómeno El Niño-La Niña (ENSO), y coincidente con la apertura de los caños, influyó significativamente en la rápida regeneración del bosque de manglar. La falta de inversión económica para el mantenimiento de las obras hidráulicas a partir de 2001 y hasta 2004 causó un incremento gradual de la salinidad y el deterioro de la vegetación regenerada. Se requiere de un esfuerzo internacional y del Gobierno Colombiano para mantener en forma sostenida los beneficios sociales y económicos estratégicos alcanzados hasta 2000 en la región de la CGSM.
    Description: We describe trajectories of selected ecological indicators used as performance measures to evaluate the success of a mangrove rehabilitation project in the Ciénaga Grande de Santa Marta (CGSM) Delta-Lagoon complex, Colombia, as result of freshwater diversions initiated in 1995. There is a significant reduction in soil and water column salinity in all sampling stations follo wing the hydraulic reconnection of the Clarín and Aguas Negras channels to the Magdalena River. Soil intersticial water salinity (depth: 0.5 m) (7 stations) and water column salinity (0.5 m) (10 stations) values declined significantly (soil 〈30 g kg -1 ; water 〈10 g kg -1 ) from 1994 to 2000. During 1994 soil interstitial water salinity ranged from 40 g kg -1 (Rinconada) to 100 g kg -1 (KM 13), while water column salinity fluctuated between 25-35 g kg -1 for most of the sampling stations. This salinity reduction increased mangrove forest regeneration promoting a net gain of 99 km 2 from 1995 to 1999. The high precipitation recorded in 1995 and 1999 caused by El Niño-La Niña (ENSO), coinciding with the channels rehabilitation, influenced rapid mangrove regeneration. The lack of economic investment in the maintenance of the diversion structures from 2001 to 2004 caused a salinity increase affecting negatively already restored vegetation. A sustainable effort from the international community and t he Colombian government is needed to maintain the strategic social and economic benefits reached until 2000 in the CGSM region
    Description: Published
    Keywords: Rehabilitation ; ASFA15::M::Mangroves ; ASFA15::M::Mangrove swamps ; ASFA15::S::Salinity
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.72-93
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