Algae Genera Cell Density and Cell Volumes
As part of the IEPA’s ALMP program, Zahniser staff collected water samples to be tested
for genera, cell density and cell volumes. Phytoplankton analysis was conducted at
Western Illinois University in the lab of Dr. Larry M. O’Flaherty. The report is as
Lake Glenn Shoals Report
Lake Glenn Shoals was sampled at three sites on 9 May, 18 June, 20 July, 24
August and 17 October, 2001 (Appendix A: List of Taxa; Summary of Numbers and
Biovolumes). No record of sampling in previous years was available. Peak production
of phytoplankton occurred on 20 July at Site 1 (16,124/mL), 9 May at Site 2 (20,180/mL)
and 24 August at Site 3 (22,748/mL) (Table: Phytoplankton Totals; Graph: Total
Phytoplankton). Blue-greens (Cyanophyta) dominated the phytoplankton at every site on
every date in 2001 (Graph: Cyanophyta).
Diatoms (Bacillariophyta) reached their maximum densities at sites 2 and 3 on 9
May (1080/mL-Site 2; 4810/mL-Site 3) and at Site 1 on 18 June (1590/mL) (Appendix
A: Phytoplankton Totals; Graph: Bacillariophyta). Diatom densities were 100 or
more/mL on all dates in 2001. Densities of Cyclotella meneghiniana accounted for most
of the diatom totals at each site on each date except for 18 June at Site 3 when Nitzschia
palea was in the majority (Appendix A: Numbers and Biovolumes of Individual Taxa-
Site1; Site 2; Site 3). The only other diatoms in densities of 100 or more/mL at each site
were Cyclotella chaetoceros, Nitzschia acicularis, N. linearis and N. palea. C.
chaetoceros was at this level only at Site 1 on 18 June (122/mL) and Site 2 (173/mL)
after which it was not seen. N. acicularis was at 153/mL at Site 1 and 112/mL at Site 2
on 24 August. It was in a density of 214/mL on 9 May and 173/mL on 24 August at Site
3. N. linearis was in a density of 100 or more/mL only on 24 August at Site 3 (173/mL).
Of the three species of Nitzschia, N. palea was at this density at Site 3 on 9 May
(601/mL), at sites 1 and 3 on 18 June (326/mL-Site 1; 703/mL-Site 3), at sites 2 and 3 on
20 July (122/mL-Site 2; 897/mL-Site 3) and at all three sites on 24 August (296/mL-Site
1; 183/mL-Site 2; 255/mL-Site 3) (Appendix A: Numbers and Biovolumes of
Individual Taxa-Site1; Site 2; Site 3). These three species of
Nitzschia are tolerant of high concentrations of organic materials. They often develop on
the bottom in shallow areas and enter the phytoplankton from there or they are brought in
from tributaries of a lake following rainfall. They and the rest of the diatoms found in the
samples from Lake Glenn Shoals are indicative of eutrophic conditions (Appendix A:
List of Taxa).
Green algae (Chlorophyta) reached their peak production at sites 1 and 2 on 18
(1468/mL-Site 1; 1091/mL-Site 2) and at Site 3 on 9 May (4229/mL) (Appendix A:
Phytoplankton Totals; Graph: Chlorophyta). Except for the density of 51/mL observed
on 9 May at Site 1, all of the densities at the three sites exceeded 100/mL on each date.
In fact, except for that date and 17 October, the densities at Site 1 exceeded those at sites
2 and 3 on every date and total production of greens at Site 3 exceeded those at Site 2 on
all dates except 17 October. The number of different taxa at each site was fairly similar
with 32 at Site 1, 37 at Site 2 and 38 at Site 3 and all were indicative of eutrophic
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