Scottish Environment Protection Agency Control of invasive non-native species in priority mesotrophic lochs R80014PUR Final Report March 2009 Revision Schedule Control of Invasive Non-Native Macrophytes in Mesotrophic Lochs Elodea canadensis and Elodea nuttallii March 2009 Rev Date Details Prepared by Reviewed by Approved by 01 14/08/08 Draft Report Carolyn Cowan Sue Bell Graduate Ecologist Associate Environmental Specialist 02 16/12/08 Draft Report Stephen Clark Sue Bell Assistant Ecologist Associate Environmental Specialist 03 11/03/2009 Final Stephen Clark Sue Bell Sue Bell Assistant Ecologist Associate Environmental Associate Environmental Specialist Specialist Scott Wilson 23 Chester Street EDINBURGH EH3 7EN Tel 0131-225-1230 Fax 0131-225-5582 www.scottwilson.com This document has been prepared in accordance with the scope of Scott Wilson's Table of Contents 1 Introduction ....................................................................................... 4 1.2 Aims...........................................................................................................................................4 1.3 Lochs reviewed.........................................................................................................................4 1.4 Structure of the document .......................................................................................................5 2 Methodology ...................................................................................... 6 2.2 Desk Based Research .............................................................................................................6 2.3 Site Visits ..................................................................................................................................6 2.4 Site Survey Loch Grogary .......................................................................................................7 3 Literature Review .............................................................................. 8 3.1 Ecology of Elodea canadensis and Elodea nuttallii...............................................................8 Identification ..................................................................................................................................................8 Ecology ..........................................................................................................................................................8 Habitat ............................................................................................................................................................9 Method of dispersal ......................................................................................................................................9 3.2 Ecology of priority conservation species ................................................................................9 Slender Naiad (Najas flexilis) – from Wingfield et al.. (2004) ............................................................. 10 Shetland Pondweed (Potamogeton rutilis) ............................................................................................ 11 Stoneworts.................................................................................................................................................. 12 3.3 Interaction between Elodea species and priority species .................................................. 13 4 Control methods .............................................................................. 16 4.2 Mechanical ............................................................................................................................. 16 4.3 Chemical ................................................................................................................................ 18 4.4 Biological ................................................................................................................................ 20 Beavers as Biological Control for Elodea .............................................................................................. 21 4.5 Environmental ........................................................................................................................ 21 5 SWOT Analysis ............................................................................... 23 5.2 Mechanical ............................................................................................................................. 23 Strengths .................................................................................................................................................... 23 Weaknesses ............................................................................................................................................... 23 Opportunities .............................................................................................................................................. 23 Threats ........................................................................................................................................................ 24 5.3 Chemical ................................................................................................................................ 24 Strengths .................................................................................................................................................... 24 Weaknesses ............................................................................................................................................... 24 Opportunities .............................................................................................................................................. 24 Threats ........................................................................................................................................................ 25 5.4 Biological ................................................................................................................................ 25 1 Strengths .................................................................................................................................................... 25 Weaknesses ............................................................................................................................................... 25 Opportunities .............................................................................................................................................. 25 Threats ........................................................................................................................................................ 25 5.5 Environmental ........................................................................................................................ 25 Strengths .................................................................................................................................................... 25 Weaknesses ............................................................................................................................................... 26 Opportunities .............................................................................................................................................. 26 Threats ........................................................................................................................................................ 26 5.6 “Do nothing” ........................................................................................................................... 26 Strengths .................................................................................................................................................... 26 Weaknesses ............................................................................................................................................... 26 Opportunities .............................................................................................................................................. 26 Threats ........................................................................................................................................................ 27 5.7 Conclusions ........................................................................................................................... 27 Methods to control Elodea ....................................................................................................................... 27 Methods to promote Najas flexilis and Potamogeton rutilus ............................................................... 27 Options for review at the thirteen priority sites ...................................................................................... 28 6 Control options ................................................................................ 34 6.1 Introduction ............................................................................................................................ 34 6.2 Scaraidh ................................................................................................................................. 35 6.3 Croghearraidh ........................................................................................................................ 37 6.4 Grogary .................................................................................................................................. 39 6.5 Nan Gad ................................................................................................................................