4. The Distribution Characteristics of Microcystis novacekii Based on 16S rDNA Sequence

Microcystis has been regarded as the most common cause of water bloom. The spatial and temporal distribution of Microcystis provides a method of bloom warning. Microcystis novacekii was the dominant cyanobacteria species in Yuqiao reservoir in recent years. Seven sampling stations were set and the phytoplankton were collected in both July and October. Comparing morphological observation with the molecular biological method, which is based on 16S rDNA sequencing, the recognizing research of M. novacekii was conducted. The results showed that the average biomass of M. novacekii was 0.92 ± 0.23 mg/L; cell density was 1833.48 ± 457.70 × 10⁴/L affected by light, temperature, nutrients, and other environmental factors. In July, the maximum biomass was 2.21 mg/L at Center station and the minimum was 0.83 mg/L at the same site; in October, the maximum was 0.18 mg/L at intake site, the minimum was 0.09 mg/L at Center West. The significant seasonal fluctuation meant that M. novacekii favored high temperature, which is the same habit with universal Microcystis algae. 30 clones of M. novacekii were collected and amplified the 16S rDNA fragments. Results proved that the molecular identification of Microcystis, which is based on the conservative fragment of 16S rDNA, was consistent with the traditional morphology judgement, we confirmed that environmental factors have a huge impact on the distribution of Microcystis and the molecular biology techniques based on 16S rDNA sequencing were reliable for Microcystis identification.