1.0 Introduction: Scottish Natural Heritage has identified the need to monitor freshwater habitats. The Lake of Menteith, where Slender Naiad was discovered in 1994, is a priority site in view of this species listing in Annex II, Habitats and Species Directive (92/43/EEC) and in the Red Data Book.
2.0 Aim and Objectives: The aim of this survey was to assess the distribution and status of the Slender Naiad (Najas flexilis) in the Lake of Menteith. In order to meet this aim four objectives were identified:
1. To map the location and extent of Najas populations in the lake;
2. To provide a written assessment of its distribution within the lake and a semi-quantitative assessment of its abundance;
3. On the basis of its distribution within the lake, describe the Slender Naiad's habitat associations e.g. depth, substrate, water clarity, associated macrophyte species and water chemistry.
4. To provide recommendations for future monitoring of this species within the lake e.g. location(s), frequency, methodology.
3.0 Methodology: Previous surveys, Keymer (1980) and Lassiere (1994 & 1995), had followed a stratified sampling approach where the best situations for macrophytes were visited and sampled or, indeed, different techniques tested. As a result, there has been no baseline survey covering all areas of the lake including the less favoured areas and the true status of macrophytes was still unknown. A full systematic baseline survey was therefore undertaken on a 100 metre grid system.
4.0 Results
5.0 Discussion of Results
6.0 Recommendations
Appendix 1. Baseline Survey Summary Sheet
(a) Transect Summary
(b) Table of Relative Species Abundance
Appendix 2. Submerged and Floating Species List for Lake of Menteith with Trophic Ranking Scores (TRS) and overall perceived abundance on DAFOR Scale.
Appendix 3. Bibliography
Appendix 4. All Field Records
MAP 1 Location of Sub-Sample Transects
All Records of Najas on this Survey
Recommended Areas for Future Survey