Slender naiad (Najas flexilis) habitat quality assessment

N. flexilis is a rare aquatic plant species of European conservation importance. The species is believed to be under increasing threat in its Scottish stronghold. However, the factors that affect the health of N. flexilis populations in Scotland are not fully understood, such as why does the species disappear, and where and why it fares well in some sites. In addition, more needs to be known about what actions can be taken to ensure that the habitat quality needed to support populations of N. flexilis is either maintained or restored. This report highlights that much of the sensitivity of N. flexilis to the known threats of eutrophication, competition with other plants and the mild acidification of circumneutral lakes can be related to its physiology as an obligate user of CO2; N. flexilis plants being unable to metabolise bicarbonate for photosynthesis.