Freshwater bristleworm, Amphicteis invalida Grube, 1860, Hypania invalida occidentalis Ostroumouff, 1897, Phenacia oculata Schmankevitch, 1875

Habitat: Hypania invalida is one of few polychaete species (<2%) able to inhabit freshwater. It lives within a muddy tube on various substrates, with a preference for fine substrates ranging from silt to gravel (Kothé 1968; Manoleli 1975; Popescu-Marinescu 1980; Rusev and Marinov 1964; Sporka 1998; Filinova et al. 2008; Norf et al. 2010, Zoric et al. 2011). It is scarce in areas with high velocity currents (Devin et al. 2006, Filinova et al. 2008, Norf et al. 2010). It may also inhabit sandy areas covered with zebra and quagga mussel beds, as H. invalida uses their shells for shelter and consumes their waste products as food (Šporka and Nagy 1998; Kurina and Seleznev 2019).  Despite this,  aggregations are not as dense in mussel beds as on soft substrates (Norf et al. 2010; Yakovleva and Yakovleva 2010). Populations can quickly build up to high densities of >10,000 individuals/m2 (46,875 ind/m2 max reported) in favorable conditions (i.e., after the building of a dam) (Popescu-Marinescu 1992; Norf et al. 2010; Pavel et al. 2021). This species also prefers to live in areas with low phosphorus concentrations (Vuckovic et al. 2021).

Food Web: In multiple surveys, H. invalida was observed to co-occur with the Caspian mud shrimp, Chelicorophium curvispinum (Klink and Bij de Vaate 1996; Bossche et al. 2001). It is classified as an active filter feeder and deposit feeder (Manoleli 1975), almost exclusively consuming diatoms (Manoleli et al. 1974). H. invalida has a positive relationship with mollusk populations due to having a food source from mollusk waste products (Kurina, 2023).

Life History: Hypania invalida reproduces sexually; males discharge sperm into the water column to fertilize eggs retained within the females’ dwelling tubes. Females typically carry between 50–250 eggs per clutch (Norf et al. 2010), though up to 970 eggs in a single female dwelling tube has been reported (Skal’skaya 2008). Mean egg size is 225 x 190 µm (Norf et al. 2010). Eggs are relatively protected in the mother’s dwelling tube (Schroeder and Hermans 1975). This species is iteroparous (produces multiple generations per breeding season) and females can produce new clutches every two weeks under ideal conditions with the potential for a single female to produce at least 1200 larvae in a lifetime (Norf et al. 2010). Offspring are brooded for about 2 weeks before they leave the parental dwelling tube and enter the water column. Larvae are <300µm when they colonize the sediment, reaching sexual maturity within 12 weeks after settlement. The ratio of females to males is typically 1:1, though following a population decline, females seem to become slightly more numerous than males. Additionally, females may grow larger and heavier than males (max ash-free dry mass- male: 0.10 g, female: 0.19 g). The maximum individual lifespan of H. invalida is roughly 10 months (Norf et al. 2010). H. invalida therefore has an extremely fast reproductive lifespan, which may give it an edge as an invasive species (Krodkiewska et. al, 2023).

Hypania invalida has a moderate probability of establishment if introduced to the Great Lakes (Confidence level:High).
Hypania invalida has an extensive invasion history throughout Europe (Gherardi et al. 2009), with a spreading pattern that seems to suggest dispersal through a corridor connecting the Danube and Rhine rivers. This species originates in the Ponto-Caspian, a region where climatic conditions are similar to those of the Great Lakes; many other Ponto-Caspian species have successfully invaded the Great Lakes. Other environmental parameters and preferences make most of the Great Lakes basin suitable potential habitat. Sandy bottoms covered with zebra mussel beds also serve as potential habitat  (Norf et al. 2010; Yakovleva and Yakovleva 2010). Food resources, including both diatoms and dreissenind waste products, are widely available in the Great Lakes (Manoleli et al. 1974; Manoleli 1975, Šporka and Nagy 1998; Kurina and Seleznev 2019, Kurina 2023). Reproductive characteristics (high fecundity, short generation time, maternal care, dispersive larvae) greatly increase the odds of establishment and rapid spread (Schroeder and Hermans 1975, Ricciardi and Rasmussen 1998; Bossche et al. 2001;  Bij de Vaate et al. 2002; Devin and Beisel 2007; Norf et al. 2010).

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

Environmental

Panov et al. (2009) list H. invalida as a white-list species, meaning there is a low risk of it causing significant ecological impacts to introduced areas. There are currently no reports of significant environmental impacts attributed to the presence of this species. Zoric et al. (2010) conclude that this species has limited influence on the overall benthic community. Although in some instances very dense populations have been recorded (46,875 ind/m2), these are without mention of impact on other species (Popescu-Marinescu 1992; Norf et al. 2010; Pavel et al. 2021.

There is little or no evidence to support that Hypania invalida has the potential for significant socio-economic impacts if introduced to the Great Lakes.

Hypania invalida has moderate potential for benefit to the Great Lakes.
Hypania invalida was intentionally introduced to areas of the Volga River in the 1950s-1960s to enhance the nutrition base for tank-raised fish (Dzuban and Slobodchikov 1980). However, this practice has not been repeated and there were no reports of significant benefits from the introductions. H. invalida has the potential to improve water quality by decreasing the amount of organic matter in sediment and water, and can promote the activity of aerobic bacteria by incorporating pockets of air in the sediment (Krodkiewska et al., 2023).

Control
There are no known 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.