Influence of Some Environmental Variables on the Zooplankton Community of Aguieira Reservoir (Iberian Peninsula, Portugal): Spatial and Temporal Trends
This research was aimed to assess the spatial and temporal trends in the zooplankton community of
Aguieira reservoir at the Mondego catchment (Iberian Peninsula, Portugal) in response to some
environmental variables. A total of 24 zooplankton as well as water samples were collected in the
months of March (spring), May (early summer), September (late summer) and December (winter) of
2010 and 2011. The data from these samples was obtained by the Descriptive (range, percentage)
and multivariate statistics (Non-metric Dimensional Scaling (n-MDS), Bray-Curtis distance, Canonical Correspondence Analysis (CCA). Altogether twenty-three zooplankton species were
recorded which included Rotifera (12), Cladocera (8) and Copepoda (3). In terms of abundance,
Rotifera (Keratella spp. and Polyarthra sp.) dominated in May and September, while Copepoda
(Copidodiaptomus numidicus and Tropocyclops prasinus) overtook in December and March.
Cladocera was the least abundant taxon of which Daphnia longispina and Bosmina coregoni has
shown abundance from December-March whereas Chydorus sphaericus, Ceriodaphnia pulchella
and Diaphanosoma brachyurum from May-September. Results of n-MDS exhibited similar spatial
and inter-annual patterns with environmental variables and zooplankton community. However, there
were differences between the samples collected in the months of March/December and
May/September in both the years. Results of CCA revealed water temperature and algal biomass as
the main environmental gradients that influenced the zooplankton community. Since some of the
observed changes in the zooplankton composition might be influenced by other complex
abiotic/biotic interactions. Therefore this study suggests further research to understand the
complexity of the interactions between biological, environmental and climatic parameters of the
reservoir. Neverthless, understanding the dynamics and nature of zooplankton communities is
crucial for the implementation of good management practices for reservoirs.
