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RESEARCH PRODUCT

Survival and growth of transplantedFontinalis dalecarlica (Bryophyta) in controlled flow and short-term regulated flow sites in the Perhonjoki River, Western Finland

subject

description

Impoundment, channelisation and short-term regulation of the Perhonjoki river have caused changes in the distribution and abundance of aquatic mosses. While some moss species have colonised the beds in the channelised and short-term regulated part of the river, Fontinalis spp. are mainly restricted to the sites above the power plant where flow variability is low. Therefore, as a first step towards gaining a better understanding of the factors contributing to the distribution and abundance of Fontinalis dalecarlica (Bruch & Schimp, Fontinalaceae) in the Perhonjoki, a transplant experiment was conducted to test whether short-term flow regulation restricts the survival and growth of this species. Artificial substrates with tufts of F. dalecarlica were transplanted in July 1993 to controlled flow and short-term regulated flow riffles, above and below the Kaitfors power plant, respectively. Survival and growth were monitored for 1 year. F. dalecarlica survived the winter and grew well during the summer in the short-term regulated flow site. Mosses did not grow at the controlled flow site. Effects of channelisation are partly seen in the fate of the substrates. At the controlled flow site, ten of the 30 substrates were lost during the winter, and 67% of the substrates in the mid-channel sub-area and 40% of the substrates in the sub-area near the bank had suffered severely during this experiment. At the short-term regulated flow site, the equivalent percentages were 17, 13 and 27%, respectively. Hygrohypnum spp. attached to the substrates during the summer of 1994. The results indicate that short-term regulation does not prevent the survival and growth of F. dalecarlica and thus does not prevent this species from surviving in the areas below the power plant. Present environmental conditions seem to contribute to the poor colonising capability of this species and thus limit colonisation. However, we suggest that the recovery of F. dalecarlica could be enhanced by moss transplant. Copyright © 1999 John Wiley & Sons, Ltd.