Description
Najas minor (Eurasian Water-Nymph) is a submersed plant (submersed aquatic vegetation, SAV).
Taxonomy
| Kingdom | Phylum | Class | Order | Family | Genus |
|---|---|---|---|---|---|
| Plantae | Magnoliophyta | Liliopsida | Najadales | Najadaceae | Najas |
Synonyms
Invasion History
Chesapeake Bay Status
| First Record | Population | Range | Introduction | Residency | Source Region | Native Region | Vectors |
|---|---|---|---|---|---|---|---|
| 1935 | Established | Stable | Introduced | Regular Resident | Europe | Eurasia | Shipping(Dry Ballast), Ornamental(Aquatic Plant) |
History of Spread
Najas minor (Eurasian Water-Nymph) is native to Europe and western Asia (Merilainen 1968). In North America, it was first collected from Ashtabula County OH in 1932 (Wentz and Stuckey 1971), and then reported from the tidal Hudson River (Waterford NY) in 1934 (Mills et al. 1997). Sediment records of seeds indicate a more or less simultaneous occurrence (1930's) at the head of Chesapeake Bay (Furnace Bay; Davis 1985). By 1968, N. minor was known from Lake Ontario NY (1939), reservoirs and rivers in PA (1962), WV (1947), TN and AL (1943), and FL (1958), as well as numerous locations in IL (Merilainen 1968). Najas minor seems to still be colonizing new areas, including LA (Sullivan 1980) and NH (Padgett and Crow 1993). A frequent colonist of newly created ponds and impoundments (Padgett and Crow 1993); prefers 'warmer, muddier, and more turbid' waters (Wentz and Stuckey 1971).
The vector of introduction of N. minor to North America and Chesapeake Bay is not clear. It does not appear to be widely used as an aquarium and fishpond plant (based on a Web search, Fofonoff, personal observation), but could have been accidentally introduced with more commonly cultivated species. Alternatively, it could have been introduced to the Great Lakes, the Hudson River, or upper Chesapeake Bay by shipping (Mills et al. 1993; Mills et al. 1997)
James, York, Rappahannock Rivers- N. minor was abundant in the tidal Chickahominy River, and also was found in Rappahannock (Orth et al. 1979), and Surry, Prince George, Charles City, (around the James) and Richmond Counties [along the upper Rappahannock (Harvill et al. 1992)].
Potomac River - N. minor was common but not dominant in fresh-oligohaline parts of river (Roosevelt Island to Brent Marsh) (Carter et al. 1984; Carter and Rybicki 1986; Strong and Kelloff 1993).
Patuxent River - N. minor was found from Jug Bay to the head of tide, 1991-1992 (Orth et al. 1992; Orth et al. 1993).
Upper Bay and Tributaries - Seeds of N. minor were found in sediments by Davis (1985). Live plants were not identifed to species in most submerged aquatic vegetation surveys, but much Najas sp. was reported (Bayley et al. 1979; Orth et al. 1987; Orth et al 1993). In more recent surveys, (e.g., Orth et al. 1999), N. minor was reported from the uppermost Bay (Susquehanna Flats) and the Northeast and Elk Rivers.
History References - Bayley et al. 1979; Carter et al. 1984; Carter and Rybicki 1986; Davis 1985; Harvill et al. 1992; Merilainen 1968; Mills et al. 1993; Mills et al. 1997; Orth et al. 1979; Orth et al. 1987; Orth et al. 1993; Orth et al. 1999; Padgett and Crow 1993; Strong and Kelloff 1993; Sullivan 1980; Wentz and Stuckey 1971.
Invasion Comments
Range Status- Najas minor's range appears to be stable in the Bay but expanding in North America (e.g., Padget and Crow 1991; Sullivan 1981).
Ecology
Environmental Tolerances
| For Survival | For Reproduction | |||
|---|---|---|---|---|
| Minimum | Maximum | Minimum | Maximum | |
| Temperature (ºC) | ||||
| Salinity (‰) | 0.0 | 0.0 | ||
| Oxygen | hypoxic | |||
| pH | ||||
| Salinity Range | fresh-oligo |
Age and Growth
| Male | Female | |
|---|---|---|
| Minimum Adult Size (mm) | ||
| Typical Adult Size (mm) | ||
| Maximum Adult Size (mm) | 1200.0 | 1200.0 |
| Maximum Longevity (yrs) | ||
| Typical Longevity (yrs | 0.5 | 0.5 |
Reproduction
| Start | Peak | End | |
|---|---|---|---|
| Reproductive Season | |||
| Typical Number of Young Per Reproductive Event |
|||
| Sexuality Mode(s) | |||
| Mode(s) of Asexual Reproduction |
|||
| Fertilization Type(s) | |||
| More than One Reproduction Event per Year |
|||
| Reproductive Startegy | |||
| Egg/Seed Form |
Impacts
Economic Impacts in Chesapeake Bay
Impacts of Najas minor (Eurasian Water-Nymph) are limited by the low-moderate abundance of this plant in Chesapeake Bay and its restriction to fresh-oligohaline waters.
Fisheries (=wildilife), Habitat Change - Najas minor could have possible local effects on duck-hunting by replacing superior waterfowl foods such as native Najas spp. (Hurley 1990). Impacts are uncertain because of the localized distribution of this species.
References- Hurley 1990
Economic Impacts Outside of Chesapeake Bay
Najas minor (Eurasian Water-Nymph) is considered an inferior waterfowl food (Hurley 1990), and is of concern mainly because it tends to replace superior native Najas spp. in lakes with increased nutrient input (Wentz and Stuckey 1971).
References - Hurley 1990; Wentz and Stuckey 1971
Ecological Impacts on Chesapeake Native Species
Impacts of Najas minor (Eurasian Water-Nymph) are limited by the low-moderate abundance of this plant in Chesapeake Bay and its restriction to fresh-oligohaline waters. Impacts noted in inland lakes include:
Competition - Najas minor could replace native vegetation to some exten. It is strongly favored over native forms by eutrophication (Wentz and Stuckey 1971). It is considered an 'agressive weed' (Padgett and Crow 1993). However, the native N. guadalupensis and N. flexilis are more abundant and more salt-tolerant (Hurley 1990), although possibly less tolerant of turbidity (Wentz and Stuckey 1971).
Food/Prey - Seeds and vegetative parts are eaten by dabling and diving ducks. However, it is considered to have little nutritive value (Hurley 1990). Its native congeners N. guadalupensis and N. flexilis are considered much better quality foods (Hurley 1990).
References - Hurley 1990; Padgett and Crow 1993; Wentz and Stuckey 1971.
Ecological Impacts on Other Chesapeake Non-Native Species
Impacts of Najas minor (Eurasian Water-Nymph) are limited by the low-moderate abundance of this plant in Chesapeake Bay and its restriction to fresh-oligohaline waters. This plant could compete with introduced submersed aquatic plant species, but this has not been reported.
References
Bayley, Suzanne; Stotts, Vernon D.; Springer, Paul F.; Steenis, John (1978) Changes in submerged aquatic macrophyte populations at the head of Chesapeake Bay, 1958-1975, Estuaries 1: 73-84Carter, Virginia; Gammon, Patricia T.; Bartow, Nancy C. (1984) Submersed aquatic plants of the tidal Potomac River, Geological Survey Bulletin 1543: 1-58
Carter, Virginia; Rybicki, Nancy (1986) Resurgence of submersed aquatic macrophytes in the tidal Potomac River, Maryland, Virginia, and the District of Columbia, Estuaries 9: 368-375
Davis, F. W. (1985) Historical changes in submerged macrophyte communities of Upper Chesapeake Bay, Ecology 66: 981-993
Fernald, Merritt L. (1950) Gray's Manual of Botany, In: (Eds.) . , New York. Pp.
1996 Nonindigenous Aquatic Species Database. http://nas.er.usgs.gov/
Gleason, Henry A. (1963) The new Britton and Brown illustrated flora of the northeastern United States and adjacent Canada, In: (Eds.) . , New York. Pp.
Harvill, A. M.; Bradley, Ted R.; Stevens, Charles E.; Wieboldt, Thomas F.; Ware, Donna M. E.; Ogle, Douglas W.; Ramsey, Gwynn W.; Fleming, Gary P. (1992) Atlas of the Virginia Flora, , Burkeville, VA. Pp.
Hotchkiss, Neil (1967) Underwater and floating-leaved plants of the United States and Canada, Bureau of Sport Fisheries and Wildlife, Resource Publication 44: 1-124
Hurley, Linda M. (1990) Field guide to the submersed aquatic vegetation of Chesapeake Bay., , Annapolis, MD. Pp.
McKnight, S. Keith; Hepp, Gary R. (1995) Potential effect of grass carp herbivory on waterfowl foods, journal of Wildlife Management 59: 720-727
Merilainen, Jouko (1968) Najas minor All. in North America., Rhodora 70: 161-175
Mills, Edward L.; Leach, Joseph H.; Carlton, James T.; Secor, Carol L. (1993) Exotic species in the Great Lakes: a history of biotic crises and anthropogenic introductions., Journal of Great Lakes Research 19: 1-54
Mills, Edward L.; Scheuerell, Mark D.; Carlton, James T.; Strayer, David (1997) Biological invasions in the Hudson River: an inventory and historical analysis., New York State Museum Circular 57: 1-51
Muenscher, Walter C. (1944) Aquatic plants of the United States., In: (Eds.) . , Ithaca NY. Pp.
1997-2024 USDA PLANTS Database.. Onine databse
Orth, Robert J.; Moore, Kenneth A.; Gordon, Hayden H. (1979) Distribution of submerged aquatic vegetation in the lower Chesapeake Bay, Virginia, , Washington DC. Pp.
Orth, Robert J.; Nowak, Judith F.; Anderson, Gary F.; Whiting, Jennifer R. (1993) Distribution of submerged aquatic vegetation in the Chesapeake Bay and Tributaries and Chincoteague Bay - 1992, , Annapolis, MD. Pp.
Orth, Robert J.; Simons, Jim; Capelli, Judith; Hindman, Larry; Hodges, Stephen; Moore, Kenneth; Rybicki, Nancy (1987) Distribution of submerged aquatic vegetation in the Chesapeake Bay and tributaries- 1985, , Washington DC. Pp.
Padgett, Donald R.; Crow, Garrett E. (1993) Some unwelcome additions to the flora of New Hampshire, Rhodora 95:
Resource Management Inc. (1993) National list of plant species that occur in wetlands., , Minneapolis.. Pp.
Stevenson, J. Court; Confer, Nedra M. (1978) Summary of available information on Chesapeake Bay submersed vegetation, , Annapolis MD. Pp.
Strong, Mark T.; Kelloff, Carol L. (1994) Intertidal vascular plants of Brent Marsh, Potomac River, Stafford County, Virginia, Castanea 59: 354-366
Sullivan, Victoria I. (1981) Najas minor in Louisiana, Sida 9: 88-90
United States Army Corps of Engineers (1977) Chesapeake Bay Future Conditions Report, , Baltimore. Pp.
Wentz, W. Alan; Stuckey, Ronald (1971) The changing distribution of the genus Najas (Najadaceae) in Ohio, Ohio Journal of Science 71: 292-302