Dwarf Wedgemussel - Biology and Ecology

Biology and Ecology

Its reproductive cycle is typical of other freshwater mussels, requiring a host fish on which its larvae (glochidia) parasitize and metamorphose into juvenile mussels. The dwarf wedgemussel is not a long-lived species as compared to other freshwater mussels; life expectancy is estimated at 10 to 12 years (Michaelson and Neves 1995).

A number of fish species have been positively identified as hosts for the dwarf wedgemussel. Michaelson and Neves (1995) confirmed the tessellated darter (Etheostoma olmstedi), Johnny darter (Etheostoma nigrum), and mottled sculpin (Cottus bairdi) as host fish for dwarf wedgemussels in the southern part of its range. Wicklow (in New Hampshire Wildlife Action Plan 2005) confirmed the slimy sculpin (. congatus) and juvenile and parr of the Atlantic salmon (Salmo salar) as host fish for dwarf wedgemussels in New Hampshire.

The dwarf wedgemussel is considered to be a long-term brooder. In general, dwarf wedgemussel glochidia may be released between March and June, with peak release times varying from south to north. Michaelson and Neves (1995) documented the reproductive cycle of the dwarf wedgemussel from North Carolina and observed that this species spawns in late summer, becomes gravid in September, and releases glochidia in April. Wicklow (in New Hampshire Wildlife Action Plan 2005) observed glochidia release beginning in March and continuing through June in the Ashuelot River in New Hampshire. In a study of dwarf wedgemussel reproduction in the Mill River, Massachusetts, McLain and Ross (2005) observed that most glochidia were released in April and May.

Reproductive output appears to be correlated with local population abundance. McLain and Ross (2005) documented that sites with the highest abundance of adult dwarf wedgemussels also demonstrated the highest proportion of gravid females, glochidial density, host infection, and density of juvenile mussels.