Figure 3 B-I from Knysak and Żelazna-Wieczorek 2017. Pleodorina indica (Iyengar) H. Nozaki 400x.

A new paper in Oceanological and Hydrobiological Studies reports a massive bloom of Pleodorina indica in a reservoir in central Poland. Piotr Knysak and Joanna Żelazna-Wieczorek sampled the reservoir on the Olechówka River in Łódź during the summer of 2015 and found that P. indica made up ~95% of the algae collected.

The authors suggest that the bloom was caused by exceptionally high temperatures. The article is paywalled, but lead author Piotr Knysak was kind enough to a full-text request on ResearchGate.

Pleodorina indica is a repeat offender, having been responsible for a 2003 bloom in the River Malše in the Czech Republic:

Figure 2 A-G from Znachnor and Jezberová 2005. (A-D) Accumulated colonies of P. indica formed scums in the River Malše (Czech Republic). The dense scums redispersed into optically homogenous suspension . (E-G) Microscopic views of the cenobial colonies of P. indica.

Stable links:

Knysak P, Żelazna-Wieczorek J (2017) Massive occurrence of the alien invasive species Pleodorina indica (Volvocales, Chlorophyta) in a reservoir located in urban areas of Central Poland. Oceanological and Hydrobiological Studies, 46: 116–122.

Znachor P, Jezberová J (2005) The occurrence of a bloom-forming green alga Pleodorina indica (Volvocales) in the downstream reach of the River Malše (Czech Republic). Hydrobiologia, 541: 221–228.