E. Masseret et al., CHANGES IN THE STRUCTURE AND METABOLIC-ACTIVITIES OF PERIPHYTIC COMMUNITIES IN A STREAM RECEIVING TREATED SEWAGE FROM A WASTE STABILIZATIONPOND, Water research (Oxford), 32(8), 1998, pp. 2299-2314
In order to determine the impact of the treated water discharge of a w
aste stabilization pond on the periphyton in the stream receptor, the
structure and the metabolic activities of the periphytic communities w
ere studied above and below the outflow. Only slight changes were obse
rved in the bacterial community. The Diatom abundance and biomass and
the relative abundance of the different species differed between upstr
eam and downstream stations. The heterotrophic index was generally low
er in the upstream control station than in the downstream stations, wh
ereas periphytic chlorophyll a concentrations decreased downstream of
the stabilization pond. This implied an increase in heterotrophic micr
oorganisms and/or an adaptation by autochthonous periphytic microorgan
isms. Photosynthetic carbon fixation decreased beyond the pond outflow
maybe because of the disappearance of sensitive species, while the ap
pearance of other resistant species led to an increase iii productivit
y (autotrophic assimilation/chl a concentrations). Finally, potential
chemoheterotrophic activity increased in the downstream stations, whil
e the potential photoheterotrophic activity decreased. On the whole, t
he pond effluent preferentially favoured the development of chemoheter
otrophic microorganisms to the detriment of photosynthetic microorgani
sms. (C) 1998 Elsevier Science Ltd. All rights reserved.