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Managing a rare species can be improved with knowledge of its natural history. The sheepnose (Plethobasus cyphyus) is a freshwater mussel recently listed by the US as federally endangered. We used standard methods to studyP. cyphyusbrooding behaviour, host fishes in the laboratory and under natural conditions, and glochidial morphology. We monitored a population ofP. cyphyusin the Chippewa River, WI during spring and summer 2007–2009 and 2011 and found brooding animals between mid-May and early August. Gravid individuals ranged between 5 and 27 yr (mean age ± 1 s.d. = 13 ± 4 yr).Plethobasus cyphyusbrooded glochidia in outer gills, which varied in colour from red, orange, pink, cream, or white. We observed mature glochidia more commonly in individuals with cream or white gills and these glochidia were released in a clear, adhesive, mucus matrix. In laboratory trials we found several minnow and topminnow species (29 spp.) served as productive suitable native hosts. The mean number of juvenile mussels released per cyprinid per day was significantly higher for trials conducted at 22–25°C compared with those at 18–20°C, and 83% of trials conducted at 18–20°C using suitable host species produced no juveniles. Glochidia had a unique outline and shell morphometrics that distinguishedP. cyphyusfrom seven other Chippewa River mussel species that produce similar sized glochidia. Using morphometrics we determined that mimic shiners (Notropis volucellus) were natural hosts forP. cyphyus, round pigtoe (Pleurobema sintoxia), and Wabash pigtoe (Fusconaia flava). Releasing mucus-bound glochidia has evolved in a variety of mussel species and may be more common than is currently realized. Our data show thatP. cyphyusis a cyprinid host specialist, and propagation efforts for this species can be strengthened through improved access to mature glochidia by using females with cream-coloured gills and increased juvenile production through warmer fish holding temperatures. [ABSTRACT FROM PUBLISHER]

We documented the currently known distribution of the Asian snail Bellamya (=Cipangopaludina) chinensis in Minnesota, along with another viviparid snail, Viviparus georgianus, a North American native whose range has expanded. We also recorded the first known occurrence of Bellamya japonica in Wisconsin. Bellamya chinensis and V. georgianus occurred predominately in lakes within the Minneapolis/St. Paul metropolitan area and the lakes region of northcentral Minnesota. Both species are now established in the three major watersheds that drain Minnesota. We collected Bellamya japonica at six sites in the Namekagon River, part of St. Croix River system in Wisconsin. [ABSTRACT FROM AUTHOR]

Presents a study which observed predation on zebra mussels by muskrats in two North American rivers and a sequence of events suggesting that muskrats switched prey selection from unionids to zebra mussels. Materials and methods; Results; Discussion.

Freshwater mussels are recolonizing the upper Illinois River following their extirpation by pollution in the early part the 20thcentury. From 1990 to 1999, we collected 332 individuals of 18 species between river miles 232.0 and 271.2. Age structure of the community suggests mussels began recolonizing in the early 1980s, which coincides with improvements in water quality and the upper river fish community. We found four sites with five or more species, which we considered to be recently formed mussel beds. We collected live individuals of six species (Actinonaias ligamentina, Alasmidonta marginata, Lampsilis cardium, Lasmigona costata, Pleurobema sintoxia, and Strophitus undulatus) thought to have been extirpated from the entire Illinois River mainstem, and one species (Anodonta suborbiculata) that has recently expanded its range into the upper river. Upper Illinois River tributaries and lower reaches of the Illinois River harbored source populations for the recolonizing mussels. Although the present community does not approximate the pre-disturbance fauna, these data show that given adequate time and improved conditions, mussel communities may recover from a devastating disturbance. [ABSTRACT FROM AUTHOR]

The ebony shell (Fusconaia ebena) is extirpated from much of the upper Mississippi River drainage. Nonetheless, in the past 25 years 94 live individuals were collected at 23 sites in the upper Mississippi River between Lock and Dam 6 and 26, three sites in the lower St. Croix River, and one site in the lower Wisconsin River. Most of the recent records were from the lower St. Croix River and the lower reaches of the upper Mississippi River. These data support the hypothesis thatLock and Dam 19 inhibits F. ebena from recolonizing the Mississippi River above the dam by preventing its migratory host fish, skipjack herring (Alosa cltrysochloris),from moving upstream. Populations aboveLock and Dam 19 are probably pre-lock and dam remnants that have persisted for over a half century and are at risk of extirpation. Conservation efforts should focus on artificial propagation and dam modifications that allow the passage of migratory fishes. [ABSTRACT FROM AUTHOR]