Using zooplplankton community as indicator of seasonal changes in some water quality parameters in a mesoeutrophic reservoir
Conference Paper
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Overview
abstract
This research was aimed to monitor and
characterize the zooplankton community of Aguieira reservoir
(40.33 N; 8.19 W). Aguieira trophic state, nutrient concentration
(the highest amounts were observed in summer) and water
quality, can be correlated to the internal disturbances induced by
the intense water level fluctuations. These criteria indeed lead to
an increase in the suspended particulate material in the water
column. In addition, the input of allochthonous nutrients
originated from human activities in the catchment area will
increase the phytoplankton biomass (mainly Cyanobacteria)
during summer. The phytoplankton community was dominated
by the Cyanobacteria, whereas the zooplankton community by
the rotifer, Keratella cochlearis and by the caldoceran, Chydorus
sphaericus. In the absence of Cyanobacteria, the subsistence of
Copidodiaptomus numidicus, Daphnia longispina and Bosmina
coregoni was highly evident. Zooplankton community showed
similar spatial and inter-annual patterns. However, n-MDS
ordination was able to differentiate between the two identified
groups: samples obtained from December-March and from May-
September. Canonical correspondence analysis (CCA) identified
two main environmental gradients that shape zooplankton
community. One being temporal, mainly related to temperature.
The other is a trophic gradient which is associated to chlorophyll
a concentration, water transparency, nitrates and nitrites.
Variance partitioning using CCA revealed that the largest
portion (45%) of the total variation observed (70%), was
attributed to the interaction between lake and environmental
variables.
