Fringed Water Lilly Lochmaben Lochs Ewan Lawrie Freshwater Advisor - PowerPoint PPT Presentation

Fringed Water Lilly Lochmaben Lochs Ewan Lawrie Freshwater Advisor SNH

Lochmaben

Mill Loch

Mill Loch Source: Lochmaben and District Community Initiative

Fringed Water Lily Source: Wikipedia

Source: https://scotland-species.nbnatlas.org/

Dense floating mats can form on the waters surface

Dense floating mats can form on the waters surface • Affecting recreational activities

Dense floating mats can form on the waters surface • Affecting recreational activities • Restricting light to the exclusion of native plants

Dense floating mats can form on the waters surface • Affecting recreational activities • Restricting light to the exclusion of native plants • Decreasing oxygen exchange

Dense floating mats can form on the waters surface • Affecting recreational activities • Restricting light to the exclusion of native plants • Decreasing oxygen exchange • Increasing sediment levels

Potential coverage based on depth

Mat Forming Vegetation

Control Options Reducing Nutrient Levels Dewatering Shading Physical Control Chemical Control

Control Options Reducing Nutrient Levels • Reducing the nutrient levels would not only help control Fringed Water Lily but other invasive species as well • Achieving this is challenging

Control Options Dewatering • Fringed Water Lily is resistant to dehydration so dewatering is unlikely to be successful.

Control Options Shading • Some areas were shaded using tarpaulin in the late 2000s • There were difficulties with this due to wave action. • It impacted recreational use of the loch • People interfered with the trial plots

Control Options Physical Control • Removal of cut material would reduce the nutrient levels in the loch • Cutting risks spreading the plant. • Cutting would probably be required more than once a year. • The plant is intergrown with the swamp and eradication would be difficult

Control Options Chemical Control Dichlobenil granulate was trialed in 2008/09 • Dichlobenil was used for general annual and perennial weed control It has low solubility. It is moderately persistent in soils and very persistent in water. It is moderately toxic to mammals, aquatic organisms, honeybees and earthworms • It was banned in March 2010

Control Options Chemical Control • Spraying with Glyphosate has taken place for a number of years. • Use of a sticking agent improved its effectiveness • Working with partners

Spraying with Glyphosate 1998- 2001 Centre for Aquatic Plant Management 2002-2005 Dumfries and Galloway Rangers Source: Lochmaben and District Community Initiative 2006-2009 Lochmaben and District Community Initiative 2011-2017 Dumfries and Galloway Rangers

Spraying with Glyphosate • Has probably helped reduce the extent of Fringed Water Lily but has not eradicated it

Spraying Issues Spraying from the bank using a boom did not reach all areas

Spraying Issues The target plant was intergrown with non target species.

Spraying Issues It grows from relatively small seedlings which can be hard to spot. Particularly amongst tall vegetation.

Spraying Issues Dead material rots down and becomes part of the internal nutrient loading of the loch

Spraying Issues Increased public concern over use of pesticides.

Next Steps We are currently in discussions with SEPA about ways forward.

Thank you

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