59
5 Eutrophication of Lakes
5.7.2 Macroinvertebrate Sampling
Macroinvertebrate samples were collected from 90 sites in
the littoral zone of the three reservoirs. Samples were collected quarterly over a period of 2 years (in March, June,
September, and December of 2008 and 2009) with an Ekman-Birge dredge (0.0225 m
2
). The material collected was
fixed in 70 % formaldehyde and subsequently identified to
the family or genus level, as was the case of Chironomidae
(Peterson 1960; Merritt and Cummins 1996; Mugnai et al.
2010; Trivinho-Strixino 2011).
5.7.3 Abiotic Data
The following physical and chemical parameters of the surface water were measured using a YIS model Multiprobe for
each sampling occasion at each sampling site: electrical conductivity, turbidity, total nitrogen (TN), and pH. Additionally, groundwater samples were collected with a Van Dorntype cylinder for subsequent measurement of total phosphorus (TP) and orthophosphates (PO 4 ) for use in the trophic
state index (TSI), following the “Standard Methods for the
Examination of Water and Wastewater” (APHA 1992). The
Fig 5.1 Location of the Vargem das Flores, Serra Azul, and Ibirité reservoirs in the catchment of the Paraopeba River, Minas Gerais, Brazil and
the distribution of the sampling sites ( black dots) within the reservoirs
5 Eutrophication of Lakes
5.7.2 Macroinvertebrate Sampling
Macroinvertebrate samples were collected from 90 sites in
the littoral zone of the three reservoirs. Samples were collected quarterly over a period of 2 years (in March, June,
September, and December of 2008 and 2009) with an Ekman-Birge dredge (0.0225 m
2
). The material collected was
fixed in 70 % formaldehyde and subsequently identified to
the family or genus level, as was the case of Chironomidae
(Peterson 1960; Merritt and Cummins 1996; Mugnai et al.
2010; Trivinho-Strixino 2011).
5.7.3 Abiotic Data
The following physical and chemical parameters of the surface water were measured using a YIS model Multiprobe for
each sampling occasion at each sampling site: electrical conductivity, turbidity, total nitrogen (TN), and pH. Additionally, groundwater samples were collected with a Van Dorntype cylinder for subsequent measurement of total phosphorus (TP) and orthophosphates (PO 4 ) for use in the trophic
state index (TSI), following the “Standard Methods for the
Examination of Water and Wastewater” (APHA 1992). The
Fig 5.1 Location of the Vargem das Flores, Serra Azul, and Ibirité reservoirs in the catchment of the Paraopeba River, Minas Gerais, Brazil and
the distribution of the sampling sites ( black dots) within the reservoirs