STRIVE - Environmental Protection Agency

Molecular Diversity and Dynamics of Toxigenic Blue-green Algae in Irish Lakes
Figure 3.25. Chromatogram and mass spectra from the LC-MS/MS analysis of the Lough Sheelin (0246)
methanolic surface water extract collected during August 2009 indicating the presence of both microcystin-
LR (MC-LR) and microcystin-YR (MC-YR). The ion masses of the two toxins (m/z 498.30 and 523.29,
respectively) and of the characteristic -adda moiety (mm/zz 135.07) are circled in the MS and MS/MS spectra,
respectively.
3.7 Summer Dynamics of Cyanobacteria
in Lakes from the West of Ireland
(2010)
3.7.1 Variation of Selected Environmental
Variables
The physical parameters, surface temperature and
light penetration in the water column were measured
throughout summer 2010 in both Lough Corrib and
Lough Ballyquirke, along with phytoplankton biomass
estimated through chlorophyll-a level determination
(Fig. 3.26). Information on the metrics relative to
these parameters are presented in Table 3.8. The
dynamics of the three variables were compared
on a monthly basis for the two lakes. There was no
significant difference in the average temperature and
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chlorophyll-a concentration recorded in June, July and
August in Lough Corrib (ANOVA, F < 1.01, p > 0.37
n > 64), whereas the Secchi depth was significantly
lower in July than in June and August (ANOVA,
F = 3.66, p = 0.03, n = 62). In Lough Ballyquirke,
the average surface temperature, Secchi depth and
chlorophyll-a concentration were all significantly lower
in August than in June and July (ANOVA, F > 5.82,
p < 0.01, n > 43). On a comparative basis, average
temperatures and chlorophyll-a concentrations over
the course of the summer were significantly greater
in Lough Ballyquirke than in Lough Corrib (Student
t-test, p < 0.04, n = 23). Average Secchi depth was
also significantly lower in Lough Ballyquirke than in
Lough Corrib (Student t-test, p < 0.01, n = 23).