Invasive non-native aquatic weeds: an often underestimated problem

Transcription

1 Invasive non-native aquatic weeds: an often underestimated problem Property Care Association - Invasive Weed Control Conference 23 rd Nov 2017 By Alex Brook Ebsford Environmental Ltd alexbrook@ebsford.co.uk

2 Invasive Weeds - Legislation Wildlife & Countryside Act (1981 as amended) - schedule 9 Part II lists: 54 plants 27 terrestrial e.g. Japanese knotweed, Himalayan balsam 13 aquatic marine e.g. giant kelp, green sea fingers 14 aquatic fresh water EU Regulation (1143/2014) on invasive alien (non-native) species 23 plants of concern 10 aquatic fresh water (8 within WCA)

3 Invasive Weeds management approach Problem identified what is it? Baseline data where is it? how much? what type of watercourse / body is it? Management considerations environmental, legislation etc. Management techniques Physical techniques Chemical techniques Environmental techniques Biological techniques Data collection & Monitoring

4 Problem Invasive Aquatic Weeds Many different plant Families with adaptations for: Living under water Living on water Growing through water Living in water & on land Some still / slow water e.g. ponds, lakes, canals, Others fast flowing e.g. streams, rivers

5 Submerged Emergent or Free floating Marginal / Amphibious Curly water weed, Canadian & Nuttall s waterweed Parrot's-Feather + + Floating Pennywort + Water Fern + + New Zealand Pygmy Weed + + +

6 Scale of problems can vary Small ponds and streams Reservoir infestation e.g. New Zealand Pygmy Weed 32 Ha emergent / marginal ~ 65,000 m 3

7 A sense of scale

8 Management Considerations Environmental Biosecurity Site designation Notable / rare / protected species Fisheries Water Extraction Regulatory Env. Impact Assessment Waste management WFD compliance Consent / permissions / AquaHerb etc. Other Catchment scale approach Flood defence impact Partnership working Source: Environment Agency: Aquatic and riparian plant management: controls for vegetation in watercourses. Project: SC120008/R1

9 EA management tool (watercourses) A useful tool for watercourses devised by the EA Provides control options Source: Environment Agency: Aquatic and riparian plant management: controls for vegetation in watercourses. Project: SC120008/R1

10 Submerged Emergent or Free floating Marginal / Amphibious Physical Techniques e.g. Mechanical / Hand Removal Chemical Techniques e.g. herbicides Environmental Techniques e.g. water level & nutrient management Biological Techniques e.g. Biological Control / / + + +?

11 Submerged Canadian* & Nuttall s waterweed Introduced 1842 Perennial North America Not obvious Rooted in sediment Only female plant present in GB Slow water ponds or lakes Spreads via fragments Problems with fishing & reduces biodiversity J F M A M J J A S O N D Growing Flowering Buds*

12 Submerged some options Canadian* & Nuttall s waterweed Stand characteristics Small infestation Hand pulling Large dense infestation Can the plants be reached with hand tools YES Hand pulling / removal NO Mechanical removal No herbicides available No specific biological control Mechanical / Cutting / Shade Ongoing management Can be controlled with Grass Carp (requires agreements from EA)

13 Submerged & Emergent Parrot s Feather Introduced 1878 South America Perennial Usually obvious Rooted to sediment Frost tolerant Slow water ponds or lakes Spreads via fragments Problems with fishing & reduces biodiversity J F M A M J J A S O N D Growing / Emergent Flowering

14 Emergent / Floating Matts Floating Pennywort Introduced 1980s South America Perennial Obvious Rooted to sediment Frost tolerant Slow water ponds, lakes, rivers & canals Spreads via fragments Problems with fishing & reduces biodiversity J F M A M J J A S O N D Growing / Emergent Flowering

15 Submerged, Emergent, Marginal / Amphibious New Zealand Pygmy Weed Introduced 1927 NZ & Australia Perennial Not always obvious Rooted to sediment Frost tolerant Slow water ponds, lakes, rivers & canals Spreads via fragments Problems with fishing & reduces biodiversity J F M A M J J A S O N D Growing / Emergent Flowering

16 Submerged / emergent some options Parrott s Feather & Floating Pennywort Mechanical removal Emergent Small stand? Stand characteristics Herbicide / removal Hand tools Submerged Small stand? Accessible? No herbicides available (emergent only) No specific biological control (parrott s feather), possible agent for pennywort Mechanical / Cutting Ongoing management Hand tools Mechanical removal

17 Free Floating Water Fern Introduced 1883 N. & Central America Perennial Obvious Free floating Slow water ponds & lakes Spreads via individuals & spores Problems with fishing & reduces biodiversity J F M A M J J A S O N D Growing Spore Production

18 Free floating some options Water Fern Recent infestation and few plants? Stand characteristics Is the infestation accessible using hand tools? An established large infestation? Herbicides available (emergent only) A specific biological control available Mechanical removal Containment YES NO Containment / Physical removal Containment. Biological control / Herbicide Azolla weevil (Stenopelmus rufinasus)

19 Invasive Weeds Summary Know your problem the weeds biology Data, data, where is it how much is there? also helps to measure success Management considerations legislation, tick all the boxes Management techniques - many appropriate to all, some not so Physical techniques Chemical techniques Environmental techniques Biological techniques Monitoring Measures success & detects new infestations Many aquatic weeds require ongoing monitoring and management, there is no silver bullet! Manage expectations!

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