Crassula helmsii: Decontamination to prevent further spread

Overall effectiveness category Beneficial
Number of studies: 1
Share Tweet Email

View assessment score

How is the evidence assessed?

Effectiveness

80%
Certainty

70%
Harms

not assessed

Calculating overall effectiveness category

Background information and definitions

C. helmsii is able to rapidly regenerate from small fragments of plant, and is also highly tolerant of drying out (Dawson & Warman 1987). This means it can easily be spread between water bodies, for example on equipment used for fishing or other watersports. Effective methods to decontaminate equipment, such as hot water or bleach, are therefore important in minimising the spread of C. helmsii.

Dawson F. H. & Warman E.A. (1987) Crassula helmsii (T. Kirk) Cockayne: Is it an aggressive alien aquatic plant in Britain? Biological Conservation, 42, 247-272.

Study locations

Key messages

One controlled, replicated container study in the UK found that submerging Crassula helmsii in hot water led to higher mortality than drying out plant fragments or a control.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A replicated, controlled container experiment in 2013-1014 in the UK (Anderson et al. 2015) found that exposure to hot water led to higher mortality of C. helmsii fragments compared to drying treatment or a control. Submerging C. helmsii in hot water caused 90% mortality 1 h after treatment, and all plants were dead after 1 day. Hot water followed by drying did not result in additional mortality (80% mortality after 1 h). Drying treatment only led to partial mortality (20% after 8 days and 50% after 16 days), and all fragments in the control group survived for 16 days. Two hundred and forty 60 mm plant fragments were placed in mesh bags and submerged in 14 °C water for 1 h to simulate an angling trip. Hot water samples were then submerged in 45°C water for 15 min. Samples in the drying treatment were put on plastic trays in a room with circulating air. Control samples were placed in unsealed plastic bags to hinder drying. Mortality was assessed after 1 h and 1, 2, 4, 8 and 16 days using a FluorPen.
Study and other actions tested
Referenced paper
Anderson L., Dunn A., Rosewarne P. & Stebbing P. (2015) Invaders in hot water: a simple decontamination method to prevent the accidental spread of aquatic invasive non-native species. Biological Invasions, 17, 2287-2297.

Please cite as:

Aldridge, D., Ockendon, N., Rocha, R., Smith, R.K. & Sutherland, W.J. (2020) Some Aspects of Control of Freshwater Invasive Species. Pages 555-87 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Control of Freshwater Invasive Species

Related Actions

Actions	Effectiveness	Studies	Category
Skunk cabbage: Biological control using co-evolved, host specific herbivores Action Link	No evidence found (no assessment)	0	Synopsis Link
Water primrose: Biological control using fungal-based herbicides Action Link	No evidence found (no assessment)	0	Synopsis Link
Skunk cabbage: Chemical control using herbicides Action Link	Likely to be beneficial	2	Synopsis Link