Mesocyclops pehpeiensis
Hu, 1943
Common Name:
A copepod
Synonyms and Other Names:
Mesocyclops Leuckarti pehpeiensis Hu, 1943, Mesocyclops ruttneri Kiefer, 1981, and Mesocyclops sp. (leuckarti group)
Identification:
The morphological features shared by most Asian species of Mesocyclops (absence of spines next to exopodal insertion on the antennal basipod, inner basis of first leg naked, seminal receptacle with lateral arms forming concave [or even V-shaped] margin) (Van de Velde 1984; Holynska 2000) are clearly present in M. pehpeiensis. Antennula are 17-segmented with groups or rows of spinules on segment 1, 4, 5 and 7–13 and segment 17 with one deep notch. Antennary basis with caudal spinule pattern of M. leuckarti, row of 6–7 spinules at level of medial setae and 2–4 spinules near distal margin. Maxillulary palp without spinules. Maxillar syncoxa shows frontally distinct rows of spinules. Medial distal margin of P1 basis without spine. Distal margin of connecting
plate of P4 with two large acute outgrowths, medial expansion of P4 basis naked. Pediger 5 without hairs laterally and dorsally. Seminal receptacle with two short lateral arms, slightly curved at their ends and transverse ducts from copulatory pore slightly Vshaped. Caudal rami without hairs on medial margin and armed with spinules at bases of lateral and external terminal setae. Legs 1-3 have the inner margin of the basiopod haired (first leg is not naked), leg 4 basiopod is naked (Ueda and Reid 2003).
Size:
to 1.7mm (US population max 1.52mm)
Native Range:
Temperate and tropical areas of Asia. The native range of Mesocyclops pehpeiensis extends from Central Asia (South Kazakhstan, Uzbekistan) through India, South East Asia, China to the Japanese Islands (as far as Honshu). (Reid 1994; Kawabata & Defaye, 1994; Mirabdullayev et al., 1995; Mirabdullayev, 1996; Ueda & Ishida, 1997; Ueda et al., 1997). Reports of the species from Malaysia (Lim and Fernando, 1985) and Sri Lanka (Dussart and Fernando, 1988) are apparently not conspecific with M. pehpeiensis according to Guo (2000)
Great Lakes Nonindigenous Occurrences:
Present in Mexico (Suárez-Morales et al 2005) and Cuba (Diaz et al 2006). Isolated populations have been reported in Europe, typically in greenhouse ponds, in Austria (Kiefer 1981), Spain (Montoliu et al 2015), and Ukraine (Anufriieva and Shadrin 2016). The first US records of this species were recorded from ricefields in Louisiana and Mississippi, and it is now established in the south-central United States (Reid 1993; Reid & Marten 1995). Reid (1996) found it in greenhouses and ponds of Kenilworth Aquatic gardens in Washington, D.C. Two CV copepodids (juveniles) were collected from ER60 (EPA monitoring station in western Lake Erie) on April 3, 2016. An adult female was found at the same site in August 2017 and a second adult female was found in a November 2017 sample collected nearshore in East Harbor, Lake Erie, Ohio.
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 Mesocyclops pehpeiensis are found here.
Full list of USGS occurrences
Table last updated 5/2/2024
† Populations may not be currently present.
Ecology:
The overall known latitudinal range of this species extends roughly from 50°N to 7°S. In North America the known range of this species was established between 30 and 37°N (Reid 1993, 1996). The southernmost limit of the known distributional range of this species in the Americas was expanded with the Mexican record, setting the known meridional limit of M. pehpeiensis in the Americas at 14°N latitude. Lake Erie records from 2016 expand the known northern limit in the Americas to 42°N. According to Reid (1993), this species is more of an epibenthic form dwelling in the littoral zones. M. pehpeiensis is considered thermophilic (Anufriieva and Shadrin 2016).
Phong et al. (2008) report a mean longevity of 50.9 days across 19 female M. pehpeiensis with a mean clutch size of 90.6 eggs (sample size=100) and mean interclutch period of 1.5 days (sample size=27).
Mesocyclops species in general are voracious predators, feeding on rotifers, cladocerans, and dipteran larvae (Williamson 1986; Gliwicz and Umana 1994; Brandl 1998a, 1998b; Rao and Kumar 2002; Chang and Hanazato 2003; Kumar and Rao 2003; Dieng et al 2003; Nagata and Hanazato 2006; Sarma et al 2013). M. pehpeiensis is a omnivorous tactile predator (Dieng et al 2003) and will feed on phytoplankton in addition to zooplankton (Sarma et al 2013). In mesocosm experiments (Chang 2005) M. pehpeiensis restructured the zooplankton community. The population of a small cladoceran, Bosmina fatalis, was affected negatively, but B. longirostris was not similarly affected. On the other hand, small rotifers responded positively to M. pehpeiensis. In laboratory experiments, Hwang et al (2009) found M. pehpeiensis to severely supress the population growth of all four cladoceran species tested -- including rare Great Lakes native species Scapholeberis kingii. Mesocyclops edax populations in DC ponds disappeared shortly after the discovery of M. pehpeiensis in those systems (Reid 1996).
Means of Introduction:
Movement of this species is typically associated with the transfer of ornamental plants or aquaculture, or experimental biocontrol of mosquitos. Introductions to Mexico were associated with prawn culture (Suarez-Morales et al 2005). Anufiieva and Shadrin (2016) considered the Ukraine population to most likely have been introduced via long-distance transportation on birds. Adults originally collected in New Orleans were introduced into Jennings ricefields in 1990 and into both Jennings and Cleveland ricefields in 1991 as part of mosquito-control experiments (G.G. Marten, personal communications, 1990, 1991 in USFWS 2018).”
Status:
Established in the Great Lakes, but population currently local to western Lake Erie. Densities appear low, but the species may avoid detection due to its preference for epibenthic and littoral habitats.
Great Lakes Impacts:
Current research on the environmental impact of Mesocyclops pehpeiensis in the Great Lakes is inadequate to support proper assessment. Two members of this genus -- Mesocyclops edax and Mesocyclops americanus -- are native to the Great Lakes. Reid (1996) reported that in the ponds of Washington, D.C., M. pehpeiensis coexists with Mesocyclops edax and M. americanus; however, on later return the native species had disappeared. This would suggest that, despite the fact that these are omnivorous-carnivorous forms (Suárez-Morales et al. 2003), this introduced species is capable of successfully competing for part of the resources available in these systems.
There is little or no evidence to support that Mesocyclops pehpeiensis has significant socio-economic impacts in the Great Lakes.
Current research on the beneficial effect of Mesocyclops pehpeiensis in the Great Lakes is inadequate to support proper assessment.
M. pehpeiensis has been evaluated as a potential biocontrol of dengue fever (Aedes albopictus mosquito larvae) and was deemed to merit consideration (Dieng et al 2002).
Management:
There are no known regulations for this species. Note: Check federal, state, and local regulations for the most up-to-date information.
Control
Biological
There is a variety of pelagic planktivorous fish in the Great Lakes that likely feed on M. pehpeiensis.
Physical
Mesocyclops pehpeiensis is a thermophile. The thermal regime of the Great Lakes may confine this species’ range to warmer, nearshore waters.
Chemical
The Great Lakes and Mississippi River Interbasin Study (USACE 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.
Remarks:
In Louisiana and Mississippi the species was initially reported as Mesocyclops sp. (leuckarti group) by Marten (1989), and later as M. ruttneri by Marten et al. (1993), Reid (1993), and Reid and Marten (1995). The District of Columbia population was also reported as M. ruttneri by Reid (1996). The taxonomy and native distributions of this group is not well delineated ... this species may be native to North America (Hudson, Personal Communication 2019).
References
(click for full reference list)
Author:
R. Sturtevant
Contributing Agencies:
Revision Date:
9/12/2019
Peer Review Date:
9/5/2018
Citation for this information:
R. Sturtevant, 2024, Mesocyclops pehpeiensis Hu, 1943: 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=2794&Potential=N&Type=0&HUCNumber=DGreatLakes, Revision Date: 9/12/2019, Peer Review Date: 9/5/2018, Access Date: 5/2/2024
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.