N2-fixation along a gradient of long-term disturbance in tropical mangroves bordering the gulf of Mexico

Vovides, A. G. , López-Portillo, J. and Bashan, Y. (2011) N2-fixation along a gradient of long-term disturbance in tropical mangroves bordering the gulf of Mexico. Biology and Fertility of Soils, 47(5), pp. 567-576. (doi: 10.1007/s00374-011-0562-4)

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Microbial processes are key elements in determining the productivity of mangroves, and reductions in these processes reflect the loss of microbial biodiversity and function due to fabricated disturbances. Because nitrogen is a major limiting nutrient for the productivity of these ecosystems, the goal of this study was to determine profiles of inorganic nitrogen combined with several environmental parameters, all in relation to the degree of long-term hydraulic impairment of a tropical, monospecific black mangrove (Avicennia germinans) forest that showed degradation ranging from total loss of mangrove cover to no disturbance. N2-fixation, oxygen levels, and nitrite contents decreased significantly with the severity of the disturbance, and almost null levels were reached in the completely degraded zone, whereas salinity achieved very high values. Concomitantly, total N, ammonium, and P contents and ammonia volatilization increased significantly. Pore-water temperature and pH increased moderately. Other soil physical properties (sand, silt, clay, organic matter, and total C), which varied among the sampling sites, were not correlated with the level of disturbance. Principal component analyses, including environmental and biological parameters, suggested that the most significant finding was the considerable loss of N2-fixation with increasing impairment, which was concomitant with significant increases in volatilization of ammonia and salinity. The results show that microbial N-cycling processes are highly sensitive to salinity and to man-made disturbances that modify the water level and flow.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Vovides, Dr Alejandra
Authors: Vovides, A. G., López-Portillo, J., and Bashan, Y.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Biology and Fertility of Soils
ISSN (Online):1432-0789
Published Online:12 April 2011

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