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Provedor de dados:  IPB - Escola Superior Agrária
País:  Portugal
Título:  Do distinct water chemistry, reservoir age and disturbance make any difference on phosphatase activity?
Autores:  Geraldes, Ana Maria
Boavida, Maria José
Data:  2008-08-26
Ano:  2003
Palavras-chave:  Alkaline phosphatase
Orthophosphate regeneration
Phytoplankton
Zooplankton
Reservoirs
Resumo:  Alkaline phosphatase activity was assessed concomitantly with total phosphorus, orthophosphate and phosphomonoester concentrations in two meso-eutrophic reservoirs with distinct age and subjected to different kinds of environmental influence. Differences in conductivity, temperature and pH were found. However, during the study period alkaline phosphatase activity was similar in both reservoirs. Water colour was higher in S. Serrada Reservoir. This fact can be related to (1) reservoir age (2) high internal disturbance (3) large imputs of allochthonous detritus, resulting from the combined effect of grazing, fire and catchment slope. Despite the high water colour recorded in S. Serrada, alkaline phosphatase activity was apparently not inactivated by humic substances. Besides, the obtained results demonstrated that hydrolysis of phosphomonoesters by alkaline phosphatase was not important for orthophosphate regeneration in these reservoirs. Probably orthophosphate was always available to biota. In fact, in the experiments based on Selenastrum capricornutum Printz algal test, similar phytoplankton growth responses were obtained for different phosphorus concentrations. Thus, these results seem to indicate that phosphorus was not a limiting nutrient in either reservoir. Although phosphatase activity was significantly correlated with some phytoplankton genera in both reservoirs, no significant correlations were found between enzyme activity and chlorophyll-a. Significant correlations between phosphatase activity and crustacean zooplankton were only recorded in S. Serrada. In spite of these results there was some indication that the main source of phosphatase might have been bacteria involved in decomposition processes instead of phyto- and zooplankton taxa.

FCT - PRAXIS XXI/C/BIA/11012/98 4/5.3/PRODEP/2000
Tipo:  Article
Idioma:  Inglês
Identificador:  Journal of Limnology. ISSN 1723-8633. 62:2 (2003) p. 163-171

1723-8633

http://hdl.handle.net/10198/705
Editor:  Istituto Italiano di Idrobiologia
Direitos:  open access
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