Appearance of Cylindrospermopsis raciborskii in winter in an artificial pond in northern Taiwan

¹ Research Center for Environmental Changes, Academia Sinica, 128, Section 2, Academia Road, Taipei 11529, Taiwan
² Present address: euglena Co., Ltd., 287-14 Shiraho, Ishigaki, Okinawa 907-0242, Japan

^* Corresponding author: yamamoto@euglena.jp

Received: 17 April 2016
Accepted: 24 August 2016

Abstract

The seasonal dynamics of Cylindrospermopsis raciborskii was investigated from June 2011 to December 2013 in a small artificial pond in northern Taiwan. The abundance of C. raciborskii increased from late February to early April 2012 when the water temperature ranged from 16.4 to 21.7°C and from mid-August 2012 to mid-February 2013 as the water temperature decreased from about 27°C to below 20°C; it peaked in mid-February 2013 when the water temperature was 16.3°C. In the summer months, the abundance of C. raciborskii was very low and sometimes undetectable. A laboratory experiment using a strain that was isolated from the pond suggested that the dominance of C. raciborskii in low-temperature seasons could be attributed to its tolerance of, not preference for, low temperatures. Contrary to the results of this study, our earlier survey conducted in the same pond from August 2009 to January 2011 showed that the abundance of C. raciborskii was low in winter and increased in summer. Environmental changes in the study pond and/or the appearance of a different ecotype was assumed to be responsible for the change in the dynamics of C. raciborskii.