Floating Pennywort Control in Thamesmead

Thames21 is working in partnership with housing association Peabody, NGO CABI, and the Environment Agency to develop an innovative strategy for combatting floating pennywort (an invasive non-native species) in Thamesmead’s canals. This comprehensive approach integrates physical removal and biological control, enhanced by community outreach efforts.

CABI will contribute its extensive experience in the field of weed biocontrol to combat the floating pennywort in Thamesmead by releasing specialist South American weevils. In 2023 alone, Peabody had to remove 70 tonnes of pennywort, which had overtaken the canals in the area.

The Environment Agency, with Peabody, is funding this project. They will be contributing to the monitoring of the Thamesmead canals, conducting eel surveys and water quality testing, as well as contributing to the long-term monitoring plan for this project.

Floating pennywort, known for its rapid growth rate of up to 20 centimetres per day, forms thick mats over water bodies, posing a threat to native plant, fish, and invertebrate species by outcompeting them and depleting oxygen levels in the water. This plant also disrupts recreational activities and increases the risk of flooding.

After a decade of rigorous safety testing, South American weevils (Listronotus elongatus) which feed only on floating pennywort have been approved for field release in England to manage the spread of this plant and minimize its adverse effects on watercourses, benefiting both human users and the wildlife dependent on these waterways.

The adult weevils primarily target the leaves of floating pennywort for sustenance, while the females lay eggs within the plant’s stalks. The larvae subsequently bore into the stems, damaging the structure of the plant and hindering its spread.

Thames21 is currently collaborating with Thamesmead communities to raise awareness about climate change, invasive species, and nature-based solutions such as these. Through workshops and outreach, Thames21 is empowering residents to understand these challenges, including the threat of invasive species like floating pennywort, while also promoting innovative bioremediation. By fostering dialogue and community engagement, Thames21 is encouraging stewardship and collective action to preserve Thamesmead’s natural heritage in the face of climate change, ensuring a resilient environment for future generations.

There will be events in the coming months which you can see on our ‘What’s On’ page.

In partnership with: