There are few options available to manage C. fragile ssp. tomentosoides. Chemical herbicides are not a viable option of control and end up doing harm. Mechanical removal techniques such as trawling, cutting, and suctioning may reduce density temporarily, but they are expensive and the populations will quickly rebound. Manual removal will not work either. C. fragile ssp. tomentosoides readily reproduces from fragments. There are a variety of naturally occurring organisms that feed on C. fragile ssp. tomentosoides but no one or combination of species can offer sufficient control these species do not readily discriminate between the native and introduced C. fragile subspecies. Preventing the spread of C. fragile ssp. tomentosoides through quarantine measures and public education are some of the only ways to insure it does not become spread (Trowbridge, 1999).
A two year study was undertaken for the Department of Environment and Heritage (Australia) by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) to identify and rank introduced marine species found within Australian waters and those not found within Australian waters.
All of the non-native potential target species identified in this report are ranked as high, medium and low priority, based on their invasion potential and impact potential. C. fragile tomentosoides is identified as one of ten most damaging potential domestic target species, based on overall impact potential (economic and environmental). A hazard ranking of potential domestic target species based on invasion potential from infected to uninfected bioregions identifies C. fragile tomentosoides as a 'medium priority species' - these species have a reasonably high impact/or invasion potential.
For more details, please see Hayes et al. 2005.
The rankings determined in Hayes et al. 2005 will be used by the National Introduced Marine Pest Coordinating Group in Australia to assist in the development of national control plans which could include options for control, eradication and/or long term management.
Nyberg and Wallentinus (2005) state that C. fragile ssp. tomentosoides is one of five top risk species in Europe. The authors study quantitatively ranked species traits which facilitate introduction and predominance using interval arithmetic to search for common patterns among 113 marine macroalgae introduced in Europe. From the abstract Nyberg and Wallentinus (2005) “Three main categories were used: dispersal, establishment and ecological impact. These were further subdivided into more specific categories, a total of 13. Introduced species were compared with the same number of native species randomised from the same families as the introduced. Invasive species (i.e. species having a negative ecological or economical impact) were also compared with non-invasive introductions, separately for the three algal groups. In many categories, as well as when adding all species, the introduced species ranked more hazardous than the native species and the invasive species ranked higher than the non-invasive ones. The ranking within the three main categories differed, reflecting different strategies between the species within the three algal groups. When all categories (excluding salinity and temperature) were summed, the top five risk species, all invasive, were, in descending order, C. fragile ssp. tomentosoides, Caulerpa taxifolia, Undaria pinnatifida, Asparagopsis armata and Grateloupia doryphora, while Sargassum muticum ranked eight and Caulerpa racemosa ten. Fifteen of the twenty-six species listed as invasive were among the twenty highest ranked
2. Trowbridge, C. D. 1999. An assessment of the potential spread and options for control of the introduced green macroalga Codium fragile ssp. tomentosoides on Australian shores. Center for Research on Introduced Marine Pests and CSIRO Marine Research.
3. Trowbridge, C. D. 2001. Coexistence of introduced and native congeneric algae: Codium fragile and C. tomentosum on Irish rocky intertidal shores. Journal of Marine Biology Ass. U. K. 81:931-937.
4. Trowbridge, C. D., and W. F. Farnham. 2004. Spatial variation in littoral Codium assemblages on Jersey, Channel Islands (southern English Channel). Botanica Marina 47 (2004): 501-503.
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