Podonevadne trigona ovum
(Zernov, 1901)
Common Name:
Water flea
Synonyms and Other Names:
Podon ovum, Podon triangulis Zernov
Identification:
Podonevadne trigona ovum is a subspecies of Podonevadne trigona that is found in the Ponto-Azov basin. The setae on the exopodites have the formula: 2,1,1,1 (Mordukhai-Boltovskoi 1965). Exopodites of thoracic limbs II and III with one seta (Rivier 1998). Caudal claws are straight rather than diverging. Freshwater individuals have a wider and higher brood pouch than brackish individuals (Rivier 1998).
Size:
0.4 – 0.5 mm length for parthenogenetic females at instar III
Native Range:
Ponto-Azov basin (Rivier, 1998). Nonindigenous Occurrences: Podonevadne trigona ovum has expanded its range to include Kahovka in 1959 after the construction of the reservoirs in the Dnieper and Don rivers (Rivier 1998). It has been found in the reservoirs of Dnieper River, Don River basin, and Tsimlyansk reservoir by 1966 (Zinevici et al. 2011).
This species is not currently in the Great Lakes region but may be elsewhere in the US. See the
point map
for details.
Ecology:
Podonevadne trigona ovum is an onychopod cladoceran native to the brackish waters of the Ponto-Caspian basin and can tolerate a wide range of environmental conditions (Panov et al. 2007). Although the optimal temperature for Ponto-Caspian invasive onychopods is above 15°C, they can survive cold waters during the winter as resting eggs in bottom sediments. This species can live in freshwater and can tolerate salinities up to 22‰, although tolerance appears to depend on chloride concentration rather than total salinity (Aladin and Potts 1995). Optimal salinity for this species is 3–8‰ (Rivier 1998). In general, cladocerans cannot tolerate anoxic conditions (Havel et al. 2009). Although Podonevadne trigona ovum has no specific habitat requirements, it prefers very low to no water flow velocity and may be somewhat susceptible to strong streamflow (Zinevici et al. 2011). In the Danube canal, the highest abundance of it were recorded in the summer and in the middle sector of the canal due to a preference for a lentic freshwater environment (Zinevici et al. 2013). This species is also found in submerged and emergent macrophytes, and heterogeneous environments. Its diet is composed of ciliates, rotifers, nauplii, small cladocerans, and nanoplanktonic algae (Egloff et al. 1996; Zievici et al. 2011).
This species is capable of parthenogenesis, and does so when environmental conditions are favorable, but switches to sexual reproduction in the winter and produces resting eggs in the bottom sediments that are hardy and are capable of surviving a variety of harsh conditions (Rivier 1998; Panov et al. 2007). It has limited mobility as it lacks effective organs used for movement (Zinevici et al. 2011) and is estimated to move at a speed of 1 m/hour (Egloff et al. 1996).
Means of Introduction:
Podonevadne trigona ovum has a low probability of introduction to the Great Lakes (Confidence Level: High). Potential pathway(s) of introduction: Transoceanic shipping
Podonevadne trigona ovum has not been reported in or near the Great Lakes basin. This species has limited mobility (Zinevici et al. 2011). The eggs of Podonevadne trigona ovum may be transported by birds, but it is unlikely that it would be carried overseas. The resting egg stage of this species is hardy and may be able to survive ballast tank environments for long periods of time; however, it may be flushed out during ballast exchange.
It has the potential to be introduced to the Great Lakes if the distribution of Podonevadne trigona ovum spreads to the eastern Baltic, and survives transport via an existing invasion corridor between the eastern Baltic and the Great Lakes (Panov et al 1999; Grigorovich et al 2003). This species has already been observed outside its native range in the Danube-Black Sea canal, the reservoirs and lagoons of the Bug, Dneipr, Dniestr, Don, and Volga rivers (Zinevici et al. 2011), and Kakhovka (Rivier 1998).
Status:
Not established in North America, including the Great Lakes Podonevadne trigona ovum has a moderate probability of establishment if introduced to the Great Lakes (Confidence Level: Moderate).
The climate of the Great Lakes is similar to the Ponto Caspian basin (U.S. EPA 2008). Its life cycle aligns with the seasons (Zinevici et al. 2011). The resting egg stage that occurs over the winter is hardy and may be able to survive the harsh winters of the Great Lakes basin, but this has not been specifically tested. It reproduces rapidly and has a short generation time. If introduced to the Great Lakes, this species may establish a population via asexual reproduction; in the Danube-Black Sea Canal, the population of Podonevadne trigona ovum was formed primarily by parthenogenetic females, a common method of reproduction in favorable environmental conditions. It is likely to find a food source in the Great Lakes because it feeds on ciliates, rotifers, nauplii, small cladocerans, and nanoplanktonic algae (Egloff et al. 1996; Zinevici et al. 2011). If established, it may be preyed on by macroinvertebrates and small fish, but may not impact establishment significantly. It has been reported to occur in the Aral Sea as a nonnative species twice (Aladin 1995) and has extended its range to include the Danube-Black Sea canal (Zinevici et al. 2011). It has spread through all parts of the Danube-Black Sea canal ecosystem (64 km) in 20 years after initially failing to establish in 1985 and is now expected to populate littoral lakes in the Romanian Black Sea coast (Zinevici et al. 2013). However, its spread has had limited success in the Volga river. Between 2015 and 2017, it did not expand its range in the Volga river, and is still contained within the Volgograd Reservoir where it was first introduced in the early 2000’s and is found in low abundance (15 in/m3) (Lazareva 2019). It has been reported as a species of concern in Finnish waters (Pienimäki and Leppäkoski 2004).
Great Lakes Impacts:
Summary of species impacts derived from literature review. Click on an icon to find out more...
Podonevadne trigona ovum has the potential for moderate environmental impact if introduced to the Great Lakes.
This species established in the Danube-Black Sea canal, subsequently outcompeted indigenous species, and was one of the few dominant species in the zooplankton structure (Zinevici et al. 2011). Its presence there has significantly altered the zooplankton food web. Matitisky et al. (2014) determined that Podonevadne trigona ovum is not a host to any parasites known to negatively impact the Great Lakes. It is not yet known whether this species affects the health or genetics of native populations, impacts water quality, or alters the physical components of the ecosystem. There is little or no evidence to support that Podonevadne trigona ovum has the potential for significant socio-economic impacts if introduced to the Great Lakes.
It has not been reported that Podonevadne trigona ovum poses hazards to human health, damages infrastructure, negatively affects water quality, adversely impacts economic sectors, inhibits recreational activities or associated tourism, or diminishes the perceived aesthetic or natural value of the areas it inhabits in a significant manner.
There is little or no evidence to support that Podonevadne trigona ovum has the potential for significant beneficial impacts if introduced to the Great Lakes.
There have not been studies that show that Podonevadne trigona ovum can act as a biological control agent for aquatic weeds or other harmful nonindigenous organisms. This species is a predatory zooplankton, but is not selective in its feeding behavior, so it is unlikely that it can significantly control populations of other nonindigenous zooplankton. Podonevadne trigona ovum does not have significant commercial, recreational, or medical value.
Management:
Regulations (pertaining to the Great Lakes region) There are no known regulations for this species.*
*Ballast water regulations applicable to this species are currently in place to prevent the introduction of nonindigenous species to the Great Lakes via shipping. See Title 33: Code of Federal Regulations, Part 151, Subparts C and D (33 CFR 151 C) for the most recent federal ballast water regulations applying to the Great Lakes and Hudson River.
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
There are no chemical control methods for this species.
Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.
References
(click for full reference list)
Author:
Baker, E., E. Byrnes, and J. Li.
Contributing Agencies:
Revision Date:
1/3/2022
Citation for this information:
Baker, E., E. Byrnes, and J. Li., 2024, Podonevadne trigona ovum (Zernov, 1901): 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=3620&Potential=Y&Type=2&HUCNumber=DGreatLakes, Revision Date: 1/3/2022, Access Date: 3/28/2024
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.