Nitokra incerta
(Richard, 1893)
Common Name:
A harpacticoid copepod
Synonyms and Other Names:
Nitokra is frequently misspelled as "Nitocra" in literature
Identification:
This copepod is part of the large N. lacustris group, which contains a number of subspecies and cryptic species from around the world. In the Great Lakes, all Nitokra species exhibit a 3-segmented exopod on the 1st leg, and the last segment of the exopod has 5 spines. The 5th leg of N. incerta in both sexes is distinct from that in other species that belong to the N. lacustris group in the Great Lakes (Lesko et al. 2003).
Size:
0.5-0.75 mm
Native Range:
Nitokra incerta is native to the Black and Caspian Seas region as well as parts of the Jordan River basin, southwest Asia, and Italy (Grigorovich et al. 2001).
Great Lakes Nonindigenous Occurrences:
Reported for the first time in 1999 from the Detroit River where it joins Lake Erie (Grigorovich et al. 2001).
Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, 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 Nitokra incerta are found here.
Full list of USGS occurrences
Table last updated 5/1/2024
† Populations may not be currently present.
Ecology:
This is an oligohaline species that occurs in fresh and brackish waters in salinities of up to 14.0 ppt (Por 1984; Grigorovich et al. 2001).
Means of Introduction:
The species probably arrived in the ballast water of overseas shipping. Duggan et al. (2005) found other Nitokra spp. in ballast water of ships entering the Great Lakes, although N. incerta was not present.
Status:
Established in L. Michigan (USEPA 2008).
Great Lakes Impacts:
Summary of species impacts derived from literature review. Click on an icon to find out more...
Current research on the environmental impact of Nitokra incerta in the Great Lakes is inadequate to support proper assessment. Realized:
The introduction of N. incerta is very likely responsible for the introduction of the suctorian ciliate Acineta nitocrae to the Detroit River; A. nitocrae is known to be epizooic on this copepod in the Ukraine (Grigorovich et al. 2001).
There is little or no evidence to support that Nitokra incerta has significant socio-economic impacts in the Great Lakes.
There is little or no evidence to support that Nitokra incerta has significant beneficial effects in the Great Lakes.
Management:
Regulations (pertaining to the Great Lakes)
There are no known regulations for this species. Note: Check federal, state/provincial, and local regulations for the most up-to-date information.
Control
Biological
There are no known biological control methods for this species
Physical
There are no known physical control methods for this species.
Chemical
The Great Lakes and Mississippi River Interbasin Study (GLMRIS 2012) suggests that alteration of water quality using carbon dioxide, ozone, nitrogen, and/or sodium thiosulfate could be effective in preventing upstream and downstream movement of copepods. It should be noted that the effectiveness of these methods is likely significantly diminished against copepod ephippia.
Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.
Remarks:
May not be established as there have been no reports of N. incerta since Grigorovich et al. (2001) (Reid and Hudson 2008). Moreover, after conducting numerous measurements and observations of Nitokra spp. across the Great Lakes, P. Hudson (pers. comm.) has not been able to find reliable, consistent morphological characters to possible separate N. incerta from N. hibernica, suggesting that these proposed congeners may be synonymous.
References
(click for full reference list)
Author:
Kipp, R.M., J. Larson, T.H. Makled, and A. Fusaro
Contributing Agencies:
Revision Date:
9/12/2019
Citation for this information:
Kipp, R.M., J. Larson, T.H. Makled, and A. Fusaro, 2024, Nitokra incerta (Richard, 1893): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatLakes/FactSheet.aspx?Species_ID=2373&Potential=N&Type=0&HUCNumber=DGreatLakes, Revision Date: 9/12/2019, Access Date: 5/1/2024
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.