193
14 Phytoplankton Assemblages as an Indicator of Water Quality in Seven Temperate Estuarine Lakes in South-East Australia
and Humphrey 1975). Chl a was extracted from filters using
90 % acetone in the dark for 24 h at 4 °C, cleaned up by centrifugation, and then measured using a spectrometer (Shimadzu UV 1700). Phytoplankton species were identified
under a microscope (Olympus, CKX31) in the laboratory.
Taxonomy and nomenclature were assessed by reference
to Fenner et al. (1976), Hasle (1976), Hasle and Syvertsen
(1997).
14.2.3 Data Analysis
Data analysis included species similarity analysis on the species composition data (PRIMER Version 5), and multilinear
regression analyses between the phytoplankton biomass and
environmental factors (SPSS 13.0).
14.3 Results
14.3.1 Spatial Variation of Physical
Environmental Factors in the Studied
Estuaries
During the sampling period, the studied estuaries displayed
typical warm-temperate waters characteristics (Fig. 14.2a).
Water temperature did not show any obvious geographical differences between lakes, average water temperatures
were about 19.4 °C in spring (October), 23.3 °C in summer
(December), 20.3 °C in autumn (April), and 13.2 °C in winter
(June) in this region.
Salinity exhibited some differences in the studied estuaries
(Fig. 14.2b). Lakes can be classified into three types based on
the range in salinity, namely mesohaline (5–18 psu), polyhaline (18–30 psu), and euhaline (30–40 psu). Swan Lake was
found to be mesohaline and ranged from 12 to 23 psu with a
mean value of 17.1 psu; Conjola Lake, Coila Lake, and Lake
Illawarra are defined as polyhaline with mean values of 19.0,
27.1, and 26.7 psu, respectively; St. Georges Basin, Durras
Lake, and Burrill Lake can be classified as euhaline because
salinity ranged from 30 to 35 psu on most occasions.
The mean pH in most of the studied estuaries varied within the normal range for coastal water bodies (pH = 7.5–8.0),
except for Swan Lake (Fig. 14.2c). High pHs were observed
in Swan Lake with a mean of 8.6 during the sampling period.
High pH values (about 9.0) have been previously noted for
this lake (Sullivan 2003). Turbidity also showed a gradient in
the studied estuaries during the sampling period (Fig. 14.2d).
The highest turbidities generally occurred in Lake Illawarra,
where most values were greater than 5.0 NTU. Low turbidities were found in Swan Lake and Conjola Lake with most
values below 2 NTU. Other lakes (St. Georges Basin, BurTable 14.1 General information for the studied estuaries. (Data from NSW Office of Environment and Heritage)
Items
Catchment area (km 2 ) Waterway area (km 2 ) Entrance characteristics Resident population
(2001 Census)
Seagrassarea (km 2 )
Lake Illawarra
270
36.3
Mostly open and
untrained
~90,000
5.142
St. Georges Basin
32
11
Intermittently or
mechanically opened
and untrained
11,880
8.538
Swan Lake
34
4.5
Intermittently open and
untrained
580
0.587
Burrill Lake
78
4.1
Generally open and
untrained
1,410
0.508
Conjola Lake
145
5.9
Mostly open and
untrained
940
0.527
Durras Lake
55
3.5
Intermittently open and
untrained
330
0.509
Coila Lake
48
6.3
Closed except when
artificially opened
1,050
1.86
Table 14.2 The GPS positions of sampling sites in the seven lakes
Site 1
Site 2
Site 3
Lake Illawarra
34.31°S
34.31°S
34.30°S
150.51°E
150.50°E
150.50°E
Burrill Lake
35.38°S
35.37°S
35.35°S
150.44°E
150.43°E
150.44°E
St. Georges Basin
35.15°S
35.12°S
35.10°S
150.59°E
150.60°E
150.57°E
Swan Lake
35.19°S
35.18°S
35.17°S
150.56°E
150.55°E
150.54°E
Durras Lake
35.65°S
35.64°S
35.62°S
150.29°E
150.27°E
150.27°E
Conjola Lake
35.26°S
35.25°S
35.23°S
150.48°E
150.45°E
150.45°E
Coila Lake
36.05°S
36.03°S
36.01°S
150.14°E
150.13°E
150.11°E
14 Phytoplankton Assemblages as an Indicator of Water Quality in Seven Temperate Estuarine Lakes in South-East Australia
and Humphrey 1975). Chl a was extracted from filters using
90 % acetone in the dark for 24 h at 4 °C, cleaned up by centrifugation, and then measured using a spectrometer (Shimadzu UV 1700). Phytoplankton species were identified
under a microscope (Olympus, CKX31) in the laboratory.
Taxonomy and nomenclature were assessed by reference
to Fenner et al. (1976), Hasle (1976), Hasle and Syvertsen
(1997).
14.2.3 Data Analysis
Data analysis included species similarity analysis on the species composition data (PRIMER Version 5), and multilinear
regression analyses between the phytoplankton biomass and
environmental factors (SPSS 13.0).
14.3 Results
14.3.1 Spatial Variation of Physical
Environmental Factors in the Studied
Estuaries
During the sampling period, the studied estuaries displayed
typical warm-temperate waters characteristics (Fig. 14.2a).
Water temperature did not show any obvious geographical differences between lakes, average water temperatures
were about 19.4 °C in spring (October), 23.3 °C in summer
(December), 20.3 °C in autumn (April), and 13.2 °C in winter
(June) in this region.
Salinity exhibited some differences in the studied estuaries
(Fig. 14.2b). Lakes can be classified into three types based on
the range in salinity, namely mesohaline (5–18 psu), polyhaline (18–30 psu), and euhaline (30–40 psu). Swan Lake was
found to be mesohaline and ranged from 12 to 23 psu with a
mean value of 17.1 psu; Conjola Lake, Coila Lake, and Lake
Illawarra are defined as polyhaline with mean values of 19.0,
27.1, and 26.7 psu, respectively; St. Georges Basin, Durras
Lake, and Burrill Lake can be classified as euhaline because
salinity ranged from 30 to 35 psu on most occasions.
The mean pH in most of the studied estuaries varied within the normal range for coastal water bodies (pH = 7.5–8.0),
except for Swan Lake (Fig. 14.2c). High pHs were observed
in Swan Lake with a mean of 8.6 during the sampling period.
High pH values (about 9.0) have been previously noted for
this lake (Sullivan 2003). Turbidity also showed a gradient in
the studied estuaries during the sampling period (Fig. 14.2d).
The highest turbidities generally occurred in Lake Illawarra,
where most values were greater than 5.0 NTU. Low turbidities were found in Swan Lake and Conjola Lake with most
values below 2 NTU. Other lakes (St. Georges Basin, BurTable 14.1 General information for the studied estuaries. (Data from NSW Office of Environment and Heritage)
Items
Catchment area (km 2 ) Waterway area (km 2 ) Entrance characteristics Resident population
(2001 Census)
Seagrassarea (km 2 )
Lake Illawarra
270
36.3
Mostly open and
untrained
~90,000
5.142
St. Georges Basin
32
11
Intermittently or
mechanically opened
and untrained
11,880
8.538
Swan Lake
34
4.5
Intermittently open and
untrained
580
0.587
Burrill Lake
78
4.1
Generally open and
untrained
1,410
0.508
Conjola Lake
145
5.9
Mostly open and
untrained
940
0.527
Durras Lake
55
3.5
Intermittently open and
untrained
330
0.509
Coila Lake
48
6.3
Closed except when
artificially opened
1,050
1.86
Table 14.2 The GPS positions of sampling sites in the seven lakes
Site 1
Site 2
Site 3
Lake Illawarra
34.31°S
34.31°S
34.30°S
150.51°E
150.50°E
150.50°E
Burrill Lake
35.38°S
35.37°S
35.35°S
150.44°E
150.43°E
150.44°E
St. Georges Basin
35.15°S
35.12°S
35.10°S
150.59°E
150.60°E
150.57°E
Swan Lake
35.19°S
35.18°S
35.17°S
150.56°E
150.55°E
150.54°E
Durras Lake
35.65°S
35.64°S
35.62°S
150.29°E
150.27°E
150.27°E
Conjola Lake
35.26°S
35.25°S
35.23°S
150.48°E
150.45°E
150.45°E
Coila Lake
36.05°S
36.03°S
36.01°S
150.14°E
150.13°E
150.11°E