Description
The hydrozoan Blackfordia virginica has a small, inconspicuous asexual hydroid and a sexual medusa stage (Mills and Sommer 1995; Mills and Rees 2000).
Taxonomy
| Kingdom | Phylum | Class | Order | Family | Genus |
|---|---|---|---|---|---|
| Animalia | Cnidaria | Hydrozoa | Leptomedusa | Blackfordiidae | Blackfordia |
Synonyms
Invasion History
Chesapeake Bay Status
| First Record | Population | Range | Introduction | Residency | Source Region | Native Region | Vectors |
|---|---|---|---|---|---|---|---|
| 1904 | Established | Unknown | Introduced | Regular Resident | Eastern Atlantic | Eastern Atlantic | Shipping(Ballast Water,Fouling Community) |
History of Spread
The medusa of the hydrozoan Blackfordia virginica was first collected in Norfolk Harbor in 1904, and described by Mayer (1910). Mayer also collected this species off Sandy Hook, NJ (as B. manhattensis, Mayer 1910). Based on the abundance of polyps and medusae in the Black Sea coast swamps on the Bulgarian coast, Thiel (1935) considered that it was part of an endemic 'Sarmatic' cnidarian fauna, and only recently introduced to the United States. This was based on B. virginica's absence in early American collections (of Agassiz, Fewkes, Hargitt, etc.), and the lack of records of polyps from North America. B. virginica's native distribution includes the Sea of Azov, (Naumov 1969; Thiel 1935), but canals enabled it to invade the Caspian Sea in 1956 (Logvinenko 1959). It should be noted that Russian and Ukrainian workers consider B. virginica to be of Northwest Atlantic origin, and introduced to the Black Sea (Mordukhai-Boltovskoi 1964; Shadrin 2000). Provisionally, we are following Mills and Sommer (1995) and Ruiz et al. (2000) in treating this species as an invader of Black Sea origin. A genetic analysis by Harrison et al. (2013) found that North American populations had a very low genetic diversity, compared to that of 30 other hydrozoans. There were no differing haplotypes among populations in 4 US estuaries, East, Gulf, and West coasts, supporting the possibility of a single introduction to North America, and subsequent spread (Harrison et al. 2013).
Blackfordia virginica was later reported from European Atlantic estuaries, the Loire, France (1973), and the Mira estuary, Portugal (1984) and also from South America (1963) and India (1958; 1968; 1970) (Moore 1987). In 2013, medusae and polyps were discovered in the Nordzeecanal, connecting Amsterdam to the North Sea (Faasse and Melchers 2014). B. virginica medusae were collected from San Francisco Bay tributaries in 1993 and found in preserved samples from 1970 and 1974. In 2010, medusae were found in Lake Pontchartrain LA (Harrison et al. 2013). Polyps were found in the Black Sea (Naumov 1969), in San Francisco Bay (Mills and Sommer 1995; Mills and Rees 2000), and in 1999, in Baltimore Harbor in Chesapeake Bay (Ruiz et al., unpublished data).
East Coast records:
South Carolina- Blackfordia virginica was reported as occurring in 'numerous areas', and as abundant and widespread in SC estuaries (Calder and Hester 1978).
Chesapeake Bay- Blackfordia virginica was described and collected in Hampton Roads in 1904 (Mayer 1910) and in Norfolk Sound (1920-21) (Cowles 1930), but not found in an extensive survey by Calder (Calder 1971; Calder 1972). In 1999, polyps (identified by Dale Calder) were collected from our settling plates from Baltimore Harbor (Ruiz et al., unpublished data). In 2010, medusae were collected from the Mattaponi River VA (Harrison et al. 2013).
Delaware Bay - Blackfordia virginica was reported as occurring northwards from Delaware Bay to Sandy Hook (as B. manhattensis; Mayer 1910), and as sporadic throughout the Delaware estuary (Cronin et al. 1962). Ferrante (1971) found it to be abundant around 'Artificial Island', near the mouth of the Chesapeake and Delaware Canal. In 2010, medusae were collected at Salughter Beach DE, in the lower Bay (Harrison et al. 2013).
New Jersey Coastal Bays- Blackfordia virginica was reported as occurring northwards from Delaware Bay to Sandy Hook (as B. manhattensis; Mayer 1910), and from the Mullica River (Great Bay) (Richards 1938).
Hudson River-New York Bight- Blackfordia virginica was reported as occurring northwards from Sandy Hook at the mouth of New York (as B. manhattensis; Mayer 1910), and from mesohaline waters of the Hudson estuary (Patrick 1994).
History References - Calder 1971; Calder 1972; Cowles 1930; Cronin et al. 1962; Ferrante 1971; Mayer 1910; Harrison et al. 2013; Mills and Sommer 1995; Moore 1987; Naumov 1969; Patrick 1994; Richards 1938; Thiel 1935
Invasion Comments
Native Region- We consider the native region of Blackfordia virginica to be the Sea of Azov, and Black Sea, including the coasts of Russia, Ukraine, and lagoons along the coast of Romania (Naumov 1969; Thiel 1935).
Ecology
Environmental Tolerances
| For Survival | For Reproduction | |||
|---|---|---|---|---|
| Minimum | Maximum | Minimum | Maximum | |
| Temperature (ºC) | 15.0 | 23.0 | ||
| Salinity (‰) | 3.0 | 35.0 | 3.0 | 35.0 |
| Oxygen | ||||
| pH | ||||
| Salinity Range | meso-eu |
Age and Growth
| Male | Female | |
|---|---|---|
| Minimum Adult Size (mm) | 6.0 | |
| Typical Adult Size (mm) | 10.0 | 10.0 |
| Maximum Adult Size (mm) | 22.0 | 22.0 |
| Maximum Longevity (yrs) | ||
| Typical Longevity (yrs |
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
Blackfordia virginica is apparently very rare or overlooked in Chesapeake. The hydroid is small and inconspicous, unlikely to play a major role in fouling.(Ruiz et al., unpublished data).
Economic Impacts Outside of Chesapeake Bay
The polyp of Blackfordia virginica is apparently not a conspicuous fouling organism in its introduced range, even where medusae are abundant (Mills and Sommer 1995; Moore 1987). This hydrozoan has no reported economic impacts.
References- Mills and Sommer 1995; Moore 1987
Ecological Impacts on Chesapeake Native Species
There are only two recent records of Blackfordia virginica polyps in Baltimore Harbor in 1999 (Ruiz et al., unpublished data), and medusae in the Mattaponi River (VA, Harrison et al. 2013) Its impacts on native biota are unknown.
Ecological Impacts on Other Chesapeake Non-Native Species
There are only two recent records of Blackfordia virginica polyps in Baltimore Harbor in 1999 (Ruiz et al., unpublished data), and medusae in the Mattaponi River (VA, Harrison et al. 2013) Its impacts on native biota are unknown.
References
Calder, Dale R. (1971) Hydroids and hydromedusae of southern Chesapeake Bay., Virginia Institute of Marine Science, Special Papers in Marine Science 1: 1-125Calder, Dale R.; Hester, Betty S. (1978) Phylum Cnidaria., In: Zingmark, Richard G.(Eds.) An Annotated Checklist of the Biota of the Coastal Zone of South Carolina. , Columbia. Pp. 87-93
Cowles, R.P. (1930) A biological study of the offshore waters of Chesapeake Bay, United States Bureau of Fisheries Bulletin 46: 277-381
Cronin, L. E.; Daiber, Joanne C.; Hilbert, E. M. (1962) Quantitative seasonal aspects of zooplankton in the Delaware River Estuary, Chesapeake Science 3: 63-93
Denayer, Jean-Claude (1973) Trois meduses nouvelles ou peu connues des cotes francaises: Maeotias inexspectata Ostrooumov, 1896, Blackfordia virginica Mayer, 1910, Nemopsis bachei Agassiz, 1849, Cahiers de Biologie Marine 14: 285-294
Ezhova, Elena; Spirido, Olga (2005) Patterns of spatial and temporal distribution of the Marenzelleria cf. viridis population in the lagoon and marine environment in the southeastern Baltic Sea, Oceanological and Hydrobiological Studies 34: 209-226
Ferrante, John G. (1970) A quantitative study of the zooplanbkton in the Delaware River in the vicinity of Artificial Island in 1970., In: (Eds.) Ecological study of the Delaware River in the vicinity of Artificial Island.. , Middletown, Delaware.. Pp.
Harrison, Genelle F.; Kim, Kiho; Collins, Allen G. (2013) Low genetic diversity of the putatively introduced, brackish water hydrozoan, Blackfordia virginica (Leptothecata: Blackfordiidae), throughout the United States, with a new record for Lake Pontchartrain, Louisiana, Proceedings of the Biological Society of Washington 126: 91-102
Mayer, A. G. (1910) Medusae of the World., In: (Eds.) . , Washington, D.C.. Pp. 231, 276-278
Mills, C. E.; Sommer, F. (1995) Invertebrate introductions in marine habitats: two species of hydromedusae (Cnidaria) native to the Black Sea, Maeotias inexspectata and Blackfordia virginica, invade San Francisco Bay, Marine Biology 122: 279-288
Mills, Claudia E.; Rees, John, T. (2000) New observations and corrections concerning the trio of invasive hydromedusae Maeotias marginata, Blackfordia virginica, and Moerisia sp. in the San Francisco estuary, Scientia Marina 64: 151-155
Moore, S. J. (1987) Redescription of the leptomedusan Blackfordia virginica, Journal of the Marine Biological Association of the United Kingdom 67: 287-291
Naumov, D. V. (1969) Hydroids and Hydromedusae of the U.S.S.R., , Jerusalem. Pp.
Patrick, Ruth (1994) Rivers of the United States, In: (Eds.) . , New York. Pp.
Richards, Horace Gardiner (1938) Animals of the Seashore, , Boston. Pp.
Thiel, Von Max Egon (1935) Zur kenntnis der hydromedusenfauna des Schwarzen Meeres, Zoologischer Anzeiger 111: 161-174