Management Information
Location Specific Management InformationBlack Lake (United States (USA))
The management option adopted to deal with the problem of invasive macrophytes was to introduce the herbivorous sterile triploid grass carp (Ctenopharyngodon idella). During
September-October 1997, 150 grass carp measuring 229 to 254 mm (9 to 10”) total length each were released into the lake at a density of 11 fish per hectare.
As changes in the standing crop of aquatic plants can alter fish assemblages, WDFW’s Warmwater Enhancement Program conducted a baseline fisheries survey at Black Lake in late summer 1997, before the introduction of the carp. This survey would be useful when monitoring the long-term effects of grass carp herbivory at the lake. Europe
E. densa has been identified to pose an important threat to plant health, environment and biodiversity in the EPPO (European and Mediterranean Plant Protection Organization ) region. EPPO has as its members 47 countries (nearly every country in the European and Mediterranean region). EPPO recommends strongly to countries endangered by these species to take measures to prevent their further introduction and spread or manage unwanted populations (for example publicity, restriction on sale and planting, control) (EPPO Reporting Service, September 2005). Hawke's Bay Region (New Zealand)
E. densa is a "regional surveillance plant". The Hawke’s Bay Regional Council monitors regional surveillance plants, so that data on them can be gathered to better access whether they should be included in some later revised Regional Pest Management Strategy.
Please see the Hawkes Bay Regional Council: Pest management Strategy Part II for defintions of pest designation. Lake Rotorua (New Zealand)
Chemical weed control has been carried out in Lake Rotorua since 1957. Three applications of diquat herbicide between 1977 and 1986 resulted in periodic decreases in submerged vascular plant growths in the lake. During 1977 the most abundant submerged vascular plants recorded were Lagarosiphon major and Elodea canadensis. E. densa, was first recorded in the lake in 1977. By 1986 it had spread to become the most dominant vascular plant in the lake forming almost 35% of the vegetation recorded. The authors of the study note that E. densa when compared with the other vascular plants is highly susceptibale to diquat, suggesting that its abundance could not be due to decreased action by diquat, the authors add that the vacant space filled by loss of vegetation due to diquat treatment could have been filled in by E. densa.
Lake Tarawera (New Zealand)
Submerged vegetation was surveyed during 1993-94 using the qualitative SCUBA survey method adopted for a similar 1988 survey. E. densa was first recorded in the lake in 1988. Comparisions between the results of the two surveys indicate that E. densa has not spread as rapidly as another alien invasive macrophyte Ceratophyllum demersum. The authors speculate that the rapid expansion of C. demersum could have restricted the E. densa spread. E. densa has established in south Kotukutuku Bay, where it has formed monospecific stands in 1-10 m of water and has displaced native species as well as Lagarosiphon major and Elodea canadensis. Mediterranean
E. densa has been identified to pose an important threat to plant health, environment and biodiversity in the EPPO (European and Mediterranean Plant Protection Organization ) region. EPPO has as its members 47 countries (nearly every country in the European and Mediterranean region). EPPO recommends strongly to countries endangered by these species to take measures to prevent their further introduction and spread or manage unwanted populations (for example publicity, restriction on sale and planting, control) (EPPO Reporting Service, September 2005). Murray-Darling Basin (Australia)
In a risk assessment test excersise using 22 potential pest plants from aquatic and riparian habitats in the Murray-Darling Basin (MDB) showed that out Of the 22 weeds assessed, five were deemed to be of very high priority to the MDB system. E. densa was one of the five 'very high priority' species,
indicating that it impacts strongly on the aquatic values of the river system. Nelson (New Zealand)
E. densa has been designated as a 'Total control pest' by the the Tasman-Nelson Regional Pest Management Strategy. The strategy has its effect over the combined area that lies within the administrative boundaries of the Tasman District Council and Nelson City Council. The objective of the strategy is to eradicate known infestations of E. densa in the Tasman-Nelson region by 2006. Please see Hierarchy of Plant Designations for an explanation of designation terminology. Silver Lake (United States (USA))
During 1990 the introduction of sterile grass carp (Ctenopharyngodon idella) was proposed to reduce the biomass of submersed aquatic plants. 83,000 triploid grass carp (size range: 200 - 250 mm long) were stocked in the lake at a density of about 124 fish ha during May - June -1 1992. A five year monitoring programme was put into place to study the impact of the herbivorous fish on Silver Lake’s ecosystem. By 1994, little, if any, submersed aquatic vegetation was detected in the lake. A fisheries survey of Silver Lake was carried out during the fall of 1997 to monitor the success of the restoration programme. The authors observe that "although the the impact of stocking grass carp on resident fish communities remains controversial, it has been demonstrated that herbivory by the fish is a cost-effective aquatic plant management tool in the Pacific Northwest". They also note that @stocking grass carp may result in population declines and/or changes in the structure of the sport fish community". Tahiti Is. (French Polynesia (Polynésie Française)) 
Decree No. 65 CM of January 23, 2006 presents a list of 35 invasive plants declared to be "Species that threaten biodiversity", one of which is Egeria densa. These plants are subject to a ban on new imports, propagation and planting, and prohibition of transfer from one island to another of any whole plant, fragment of plant, cutting, fruit or seed. Tasman District (New Zealand)
E. densa has been designated as a 'Total control pest' by the the Tasman-Nelson Regional Pest Management Strategy. The strategy has its effect over the combined area that lies within the administrative boundaries of the Tasman District Council and Nelson City Council. The objective of the strategy is to eradicate known infestations of E. densa in the Tasman-Nelson region by 2006. Please see Hierarchy of Plant Designations for an explanation of designation terminology. Waikato Region (New Zealand)
E. densa is classified as a “Potential Plant Pest” by Environment Waikato, which means it is recognised as a potentially invasive weed in the Waikato Region. Please see definitions for hierarchy of pest designations.
Management Resources/Links
2. Barreto, R., R. Charudattan, A. Pomella, & R. Hanada. 2000. Biological control of neotropical aquatic weeds with fungi. Crop Protection 19:697-703.
Summary: Information on description, economic importance, distribution, habitat, history, growth, and impacts and management of species. 5. Champion, P.D.; Clayton, J.S. 2001. Border control for potential aquatic weeds. Stage 2. Weed risk assessment. Science for Conservation 185. 30 p.
Summary: This report is the second stage in the development of a Border Control Programme for aquatic plants that have the potential to become ecological weeds in New Zealand. Importers and traders in aquatic plants were surveyed to identify the plant species known or likely to be present in New Zealand. The Aquatic Plant Weed Risk Assessment Model was used to help assess the level of risk posed by these species. The report presents evidence of the various entry pathways and considers the impact that new invasive aquatic weed species may have on vulnerable native aquatic species and communities.
Available from: http://www.doc.govt.nz/upload/documents/science-and-technical/SFC185.pdf [Accessed 13 June 2007] 6. Clunie, P., Stuart, I., Jones, M., Crowther, D., Schreiber, S., McKay, S., O'Connor, J., McLaren, D., Weiss, J., Gunasekera, L., Roberts, J., 2002. A Risk Assessment
of the Impacts of Pest Species in the Riverine Environment in the Murray-Darling Basin 7. Dutartre, A., J. Haury, and A. Jigorel. 1999. Succession of Egeria densa in a drinking water reservoir in Morbihan (France). Hydrobiologia 415: 243-247.
Summary: A scientific study conducted in France on a drinking water reservoir with detailed management information regarding species. 9. Hawkesbury-Napean River Management Forum., 2002. Independent Expert Panel On Environmental Flows For The Hawkesbury Nepean, Shoalhaven And Woronora Catchments. Status of the Health of the Hawkesbury
Nepean River 10. Kay, S. H and Hoyle, S. T, 2001. Mail Order, the Internet, and Invasive Aquatic Weeds. J. Aquat. Plant Manage.
39: 88-91 11. Lara, M. V., P. Casati, & C. Andrea. 2002. CO2-concentrating mechanisms in Egeria densa, a submersed aquatic plant. Physiologia Plantarum 115:487-495.
Summary: Information on description, economic importance, distribution, habitat, history, growth, and impacts and management of species. 12. May, Michael, Cristina Grosso, and Josh Collins., 2003. Brazilian waterweed. Practical Guidebook for the Identification and Control of Invasive Aquatic and Wetland Plants in the San Francisco Bay-Delta Region San Francisco Estuary Institute Oakland, California
Summary: Information on description, economic importance, distribution, habitat, history, growth, and impacts and management of species.
Available from: http://www.sfei.org/nis/waterweed.htm [Accessed 22 June 2005].
The Guidebook is available from: http://www.sfei.org/nis/ 13. Mendes, D.; Pitelli, R.A.; Coelho, L., 2004. Effect of herbicide concentrations on biological aspects of Fusarium sp. (isolation FCAV#940). Planta daninha vol.22 no.1 Viçosa Jan./Mar. 2004 14. Mueller K. W. and Downen, M. R. 2000. 1997 Black Lake Survey: A coastal warmwater fish community before the introduction of grass carp. Warmwater Enhancement Program Washington Department of Fish and Wildlife 15. Mueller, Karl W., 1997. Silver lake survey: The forage fish community after removal of aquatic vegetation by grass carp. 16. National Pest Plant Accord, 2001. Biosecurity New Zealand.
Summary: The National Pest Plant Accord is a cooperative agreement between regional councils and government departments with biosecurity responsibilities. Under the accord, regional councils will undertake surveillance to prevent the commercial sale and/or distribution of an agreed list of pest plants.
Available from: http://www.biosecurity.govt.nz/pests-diseases/plants/accord.htm [Accessed 11 August 2005] 17. Pierini, S. A., & S. M. Thomaz. 2004. Effects of inorganic carbon source on photosynthetic rates of Egeria najas Planchon and Egeria densa Planchon (Hydrocharitaceae). Aquatic Botany 78:135-146.
Summary: Information on description, habitat, history, and growth of species. 20. Tanner, C. C., Clayton, J. S. Coffey, B. T., 1990. Submerged-vegetation changes in Lake Rotoroa (Hamilton, New Zealand) related to herbicide treatment and invasion by Egeria densa. New Zealand Journal of Marine and Freshwater Research, 1990, Vol. 24: 45-57 Results Page: 1
|
