Mesomysis intermedia Czerniavsky, 1882

Nonindigenous Occurrences: Paramysis intermedia was Intentionally introduced into Lake Balkhash, Kazakhstan, in 1958 to strengthen the forage base for commercial fish. Since its introduction, Paramysis intermedia has become naturalized in the lake and is the most widespread mysid due to its broad salinity tolerance (Isbekov et al. 2019). Paramysis intermedia was first observed in 2008 in the Gulf of Finland and the Gulf of Riga in the Baltic Sea (Herkül et al. 2009). This species was successfully introduced to the artificial reservoirs of the Volga River, Russia (Borodich and Havlena 1973) including the Saratov Reservoir (Kurina 2017). It is considered an alien species in the Aral Sea, Kazakhstan (Aladin et al. 2004) and was recorded in the Small Aral Sea (Plotnikov et al. 2016). It has also spread to the Ob River basin (Bukhtarma Reservoir and the Irtysh River) due to accidental introductions via industrial fishing (Yangina 2017).

This species starts pubescence once it grows to a length of 7 mm. Females mature and reproduce earlier when in waters of higher temperatures.  Paramysis intermedia reproduces in the summer, and the number of embryos females produce is positively correlated with its body length. The females carry, on average, 7-30 eggs in a brood pouch and can produce 3 generations per year. Embryonic development is a 6-stage process that occurs and is completed in the brood pouch. Reproduction ends when the water becomes cooler. In the Caspian Sea, reproduction ceases in October at temperatures of 15-16°C, while in the Kuibyshev Reservoir (Volga River) it ceases at 8–10°C. (Borodich and Havlena 1973). Paramysis intermedia has a non-specific food preference and preys on zooplankton (Spencer et al. 1991; Bij de Vaate et al. 2002).

Potential pathway(s) of introduction: Transoceanic shipping (ballast water)

Paramysis intermedia does not currently occur near the Great Lakes Basin. Paramysis intermedia is native to the rivers connected to the Black and Caspian seas (Audzijonyte et al. 2006). This species can travel downstream by moving with the current (Borodich and Havlena 1973). In 2008, this species was first recorded in the Gulf of Riga and the Gulf of Finland of the Baltic Sea. Paramysis intermedia occurs in ports that have direct trade connections with the Great Lakes (NBIC 2009). There are nonindigenous occurrences of Paramysis intermedia in waters that contain species that were introduced via ballast water (Ricciardi and Rasmussen 1998).

Paramysis intermedia may be introduced to the Great Lakes via ships declaring “No Ballast on Board” (NOBOB), which are exempt from ballast water exchange. The majority of ships entering the Great Lakes are NOBOB vessels and 43% of these ships contain residual water with less than 10‰ salinity (Joehengen et al.  2005). In the study, the temperature of the residual water from the vessels sampled ranged from -0.7 to 23.9°C; thus Paramysis intermedia is likely to survive the salinity and temperature of the NOBOB ballast water. Its eggs are contained in the female’s brood pouch (Borodich and Havlena 1973); thus, it is unlikely that the eggs can hitchhike or survive in ballast water. The adult forms are likely able to survive in ballast water due to their tolerance of a broad range of salinities (Ricciardi and Rasmussen 1998).

Paramysis intermedia has a moderate probability of establishment if introduced to the Great Lakes (Confidence level: High).

The native and introduced ranges of Paramysis intermedia have similar climate and abiotic conditions to that of the Great Lakes (Reid and Orlova 2002; Grigorovich et al. 2003; U.S. EPA 2008). This species is likely capable of overwintering in the Great Lakes; it occurs in reservoirs elsewhere that have ice cover in the winter (Borodich and Havlena 1973; Isbekov et al. 2019). Paramysis intermedia prefers shallow, sandy/muddy habitats; thus this species is likely to find a suitable habitat in the Great Lakes. This species may benefit from increased salinization attributed to climate change because it can better tolerate higher salinities compared to species native to the Great Lakes. Paramysis intermedia has the potential to invade North American lakes that currently lack other mysid shrimp (Ricciardi and Rasmussen 1998). Paramysis intermedia has a non-specific, omnivorous diet; it will probably find an appropriate food source in the Great Lakes.

This species has expanded far from its native range all the way into the Baltic Sea and Ob River basin. It was deliberately introduced to the Volga River and successfully established a population in its lower reaches and predominates the mysid community there (Borodich and Havlena 1973). In the 1960s, Paramysis intermedia was introduced from the Don River to the Aral Sea and became numerous in 1961 (Aladin et al. 2004).

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental

If introduced to the Great Lakes, Paramysis intermedia may reduce zooplankton biomass through feeding, and consequently impact planktivorous fish populations (Spencer et al. 1991; Ricciardi and Rasmussen 1998); however, studies have not been conducted to determine if these effects are significant where Paramysis intermedia has been introduced.  Studies suggest that due to biomagnification of contaminants from mysids to fish, levels of PCB and mercury in pelagic fish are higher in North American lakes that contain mysids compared to those that lack mysids (Rasmussen et al. 1990; Cabana et al. 1994); however, the aforementioned studies do not specifically investigate the impacts of Paramysis intermedia on biomagnification of contaminants.

There is little or no evidence to support that Paramysis intermedia has the potential for significant socio-economic impact if introduced to the Great Lakes.

It has not been reported that Paramysis intermedia poses a threat to human health or water quality. There is no evidence that this species negatively impacts infrastructure, economic sectors, recreational activities and associated tourism, or the aesthetic appeal of the areas it inhabits.

There is little or no evidence to support that Paramysis intermedia has the potential for significant beneficial impacts if introduced to the Great Lakes.

It is unknown if the introduction of Paramysis intermedia to the Great Lakes would increase fish productivity or become established as a prominent component in the food web. Paramysis intermedia was intentionally introduced to fisheries in Europe to improve productivity but no significant changes to productivity were ever recorded. However, it can potentially compete with fish for zooplankton and harm fish populations (Spencer et al. 1991; Ricciardi and Rasmussen 1998).

*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.