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Advisor(s)
Abstract(s)
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.
Description
Keywords
Alkaline phosphatase Orthophosphate regeneration Phytoplankton Zooplankton Reservoirs
Citation
Geraldes, Ana Maria; Boavida, Maria José (2003). Do distinct water chemistry, reservoir age and disturbance make any difference on phosphatase activity? Journal of Limnology. ISSN 1723-8633. 62:2, p. 163-171
Publisher
Istituto Italiano di Idrobiologia