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Use of a generalized additive model to investigate key abiotic factors affecting microcystin cellular quotas in heavy bloom areas of Lake Taihu.

Tao M, Xie P, Chen J, Qin B, Zhang D, Niu Y, Zhang M, Wang Q, Wu L - PLoS ONE (2012)

Bottom Line: So far, most studies on MCs have been limited to two small bays, while systematic research on the whole lake is lacking.To explain the variations in MC concentrations during cyanobacterial bloom, a large-scale survey at 30 sites across the lake was conducted monthly in 2008.The health risks of MC exposure were high, especially in the northern area.

View Article: PubMed Central - PubMed

Affiliation: Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, People's Republic of China.

ABSTRACT
Lake Taihu is the third largest freshwater lake in China and is suffering from serious cyanobacterial blooms with the associated drinking water contamination by microcystin (MC) for millions of citizens. So far, most studies on MCs have been limited to two small bays, while systematic research on the whole lake is lacking. To explain the variations in MC concentrations during cyanobacterial bloom, a large-scale survey at 30 sites across the lake was conducted monthly in 2008. The health risks of MC exposure were high, especially in the northern area. Both Microcystis abundance and MC cellular quotas presented positive correlations with MC concentration in the bloom seasons, suggesting that the toxic risks during Microcystis proliferations were affected by variations in both Microcystis density and MC production per Microcystis cell. Use of a powerful predictive modeling tool named generalized additive model (GAM) helped visualize significant effects of abiotic factors related to carbon fixation and proliferation of Microcystis (conductivity, dissolved inorganic carbon (DIC), water temperature and pH) on MC cellular quotas from recruitment period of Microcystis to the bloom seasons, suggesting the possible use of these factors, in addition to Microcystis abundance, as warning signs to predict toxic events in the future. The interesting relationship between macrophytes and MC cellular quotas of Microcystis (i.e., high MC cellular quotas in the presence of macrophytes) needs further investigation.

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Temporal variation of phytoplankton density composition in the northern area of Lake Taihu.
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pone-0032020-g003: Temporal variation of phytoplankton density composition in the northern area of Lake Taihu.

Mentions: A total of 87 phytoplankton taxa were recorded, with Microcystis spp. being the absolute dominant species in most months of the year. Temporal variation in phytoplankton abundance of various groups in the northern area was shown in Figure 3. Diatoms (Bacillariophyceae, mainly Cyclotella spp.), Cryptophyta and Chrysophyta jointly prevailed over the other groups only in winter and early spring. As the flourish of non-N-fixing Microcystis spp. in May, cyanobacteria became the absolutely advantageous taxa and maintained the superiority status in the remaining seasons. Microcystis spp. mainly contained M. aeruginosa, M. flos-aquae, M. viridis and M. wesenbergii in the study period. Spatial distribution of Microcystis biomass of Sites 1–30 from spring to autumn were demonstrated in Figure 4. Microcystis was abundant in the three northern bays and west littoral zones. Of which Meiliang bay was the most severely polluted area in Lake Taihu. Since spatial distribution of Microcystis revealed high risks in the northern area of Lake Taihu (Fig. 4), the present study is mainly focused on this area. Other potential MC-producing cyanobacteria (such as Anabaena spp. and Oscillatoria spp.) also multiplied during periods of Microcystis spp. dominance but accounted for a marginal part of cyanobacteria biomass (Fig. 3). Seasonal changes of Microcystis abundance in the northern area were shown in Figure 2C. Dramatic increase of Microcystis spp. gave rise to explosion of cyanobacteria density in May.


Use of a generalized additive model to investigate key abiotic factors affecting microcystin cellular quotas in heavy bloom areas of Lake Taihu.

Tao M, Xie P, Chen J, Qin B, Zhang D, Niu Y, Zhang M, Wang Q, Wu L - PLoS ONE (2012)

Temporal variation of phytoplankton density composition in the northern area of Lake Taihu.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3285656&req=5

pone-0032020-g003: Temporal variation of phytoplankton density composition in the northern area of Lake Taihu.
Mentions: A total of 87 phytoplankton taxa were recorded, with Microcystis spp. being the absolute dominant species in most months of the year. Temporal variation in phytoplankton abundance of various groups in the northern area was shown in Figure 3. Diatoms (Bacillariophyceae, mainly Cyclotella spp.), Cryptophyta and Chrysophyta jointly prevailed over the other groups only in winter and early spring. As the flourish of non-N-fixing Microcystis spp. in May, cyanobacteria became the absolutely advantageous taxa and maintained the superiority status in the remaining seasons. Microcystis spp. mainly contained M. aeruginosa, M. flos-aquae, M. viridis and M. wesenbergii in the study period. Spatial distribution of Microcystis biomass of Sites 1–30 from spring to autumn were demonstrated in Figure 4. Microcystis was abundant in the three northern bays and west littoral zones. Of which Meiliang bay was the most severely polluted area in Lake Taihu. Since spatial distribution of Microcystis revealed high risks in the northern area of Lake Taihu (Fig. 4), the present study is mainly focused on this area. Other potential MC-producing cyanobacteria (such as Anabaena spp. and Oscillatoria spp.) also multiplied during periods of Microcystis spp. dominance but accounted for a marginal part of cyanobacteria biomass (Fig. 3). Seasonal changes of Microcystis abundance in the northern area were shown in Figure 2C. Dramatic increase of Microcystis spp. gave rise to explosion of cyanobacteria density in May.

Bottom Line: So far, most studies on MCs have been limited to two small bays, while systematic research on the whole lake is lacking.To explain the variations in MC concentrations during cyanobacterial bloom, a large-scale survey at 30 sites across the lake was conducted monthly in 2008.The health risks of MC exposure were high, especially in the northern area.

View Article: PubMed Central - PubMed

Affiliation: Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, People's Republic of China.

ABSTRACT
Lake Taihu is the third largest freshwater lake in China and is suffering from serious cyanobacterial blooms with the associated drinking water contamination by microcystin (MC) for millions of citizens. So far, most studies on MCs have been limited to two small bays, while systematic research on the whole lake is lacking. To explain the variations in MC concentrations during cyanobacterial bloom, a large-scale survey at 30 sites across the lake was conducted monthly in 2008. The health risks of MC exposure were high, especially in the northern area. Both Microcystis abundance and MC cellular quotas presented positive correlations with MC concentration in the bloom seasons, suggesting that the toxic risks during Microcystis proliferations were affected by variations in both Microcystis density and MC production per Microcystis cell. Use of a powerful predictive modeling tool named generalized additive model (GAM) helped visualize significant effects of abiotic factors related to carbon fixation and proliferation of Microcystis (conductivity, dissolved inorganic carbon (DIC), water temperature and pH) on MC cellular quotas from recruitment period of Microcystis to the bloom seasons, suggesting the possible use of these factors, in addition to Microcystis abundance, as warning signs to predict toxic events in the future. The interesting relationship between macrophytes and MC cellular quotas of Microcystis (i.e., high MC cellular quotas in the presence of macrophytes) needs further investigation.

Show MeSH
Related in: MedlinePlus