The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Blackfordia virginica
(Black Sea jellyfish)
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Blackfordia virginica Mayer, 1910

Common name: Black Sea jellyfish

Taxonomy: available through www.itis.govITIS logo

Size: polys - 1-2mm; medusae 10 mm (Mills and Sommer 1995).

Native Range: Black Sea (Mills and Sommer 1995).
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Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Blackfordia virginica are found here.

StateYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
California197020053Lower Sacramento; San Francisco Bay; San Pablo Bay
Louisiana200920091Eastern Louisiana Coastal
South Carolina200820081Cooper
Virginia199320102Lower Chesapeake Bay; Mattaponi

Table last updated 5/25/2018

† Populations may not be currently present.

Means of Introduction: One researcher has concluded, based on genetics, this species is native to the Black Sea and was likely transported to the East Coast of North America prio to 1910 in ship ballast water (Thiel 1935; Mills and Sommer 1995).  Specimens deposited at the California Academy of Sciences reveal this species was collected in the early 1970s in the Bay area, but was misidentified as Phialidium sp.  One collection was of 150 to 200 individuals from the Napa River in September 1970.  A second contained eight individuals from the Petaluma River in September 1974.  Therefore, it is likely that this species has been in the San Francisco Bay area and has gone undetected for over 20 years (Mills and Sommer 1995).

Status: Established in California.  Reported from Virginia.

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: Unlike the other Black Sea jellyfish introduced into this area, both males and females of this species have been collected (Mills and Sommer 1995).  Also introduced to the Ganges River in Calcutta, India in 1926 (Carlton 1985).

References: (click for full references)

Carlton, J.T.  1985.  Transoceanic and interoceanic dispersal of coastal marine organisms: The biology of ballast water.  Oceanogr. Mar. Biol. Ann. Ref. 23:313-371.

Mills, C.E., and F. Sommer. 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.

Theil, M.E.  1935.  Zur Kenntnis der Hydromedusenfauna des Schwarzen Meeres.  Aool. Anz 111:161-174.

Author: Fuller, P.

Revision Date: 4/3/2006

Citation Information:
Fuller, P., 2018, Blackfordia virginica Mayer, 1910: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=1050, Revision Date: 4/3/2006, Access Date: 10/22/2018

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.

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URL: https://nas.er.usgs.gov
Page Contact Information: Pam Fuller - NAS Program (pfuller@usgs.gov)
Page Last Modified: Tuesday, October 02, 2018


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2018]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [10/22/2018].

Contact us if you are using data from this site for a publication to make sure the data are being used appropriately and for potential co-authorship if warranted. For queries involving fish, please contact Pam Fuller. For queries involving invertebrates, contact Amy Benson.