Amygdalum papyrium is a member of the family Mytilidae. The fragile shell of the Atlantic paper mussel is white with a glistening, smooth periostracum (thin organic layer covering the outer layer of the shell) that is bluish green to yellow in color. The shell is elongate, compressed, and wider at the posterior end. Umbones are present near, but not at, the anterior end. The interior of the shell is iridescent white with smooth margins (Mikkelsen and Bieler 2008). A. papyrium attaches to the substratum as well as to each other with byssal threads often forming dense beds that support rich faunal and infaunal invertebrate assemblages.

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Amygdalum papyrium occurs in the North and South Americas from Maryland to Florida, and the Gulf of Mexico, and Venezuela (Mikkelsen and Bieler 2008). The Atlantic paper mussel is common in the Indian River Lagoon.

The Atlantic paper mussel is short lived, living less than one year, and reaches sexual maturity within a few months (Walker et al. 2003). Amygdalum papyrium grows rapidly to a shell length of less than 32 mm. The largest shell reported for this species from Skidaway Island, Georgia is 39. 5 mm. This specimen was collected in late March just before a large die-off. In the same population, there were more females than males.

Modiola arborescens not Dillwyn, 1817

Depth range based on 184 specimens in 9 taxa.
Water temperature and chemistry ranges based on 30 samples.

Environmental ranges
  Depth range (m): 0 - 2250
  Temperature range (°C): 10.124 - 27.753
  Nitrate (umol/L): 0.457 - 25.092
  Salinity (PPS): 32.616 - 36.956
  Oxygen (ml/l): 2.826 - 5.180
  Phosphate (umol/l): 0.095 - 1.613
  Silicate (umol/l): 0.567 - 17.786

Graphical representation

Depth range (m): 0 - 2250

Temperature range (°C): 10.124 - 27.753

Nitrate (umol/L): 0.457 - 25.092

Salinity (PPS): 32.616 - 36.956

Oxygen (ml/l): 2.826 - 5.180

Phosphate (umol/l): 0.095 - 1.613

Silicate (umol/l): 0.567 - 17.786
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Habitat Type: Marine

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Amygdalum papyrium is a filter-feeder.

Groups commonly associated with the Atlantic paper mussel beds are porifera (sponges), cnidarians (hydroids, corals and anemones), annelids (worms), crustaceans, other bivalves, bryozoans, and echinoderms (sea stars, sea urchins, and sea cucumbers).

The abundance of Atlantic paper mussel was reported to range from 25 m2 to as high as 3325 m2 (Nassau River 1993), but can vary regionally. In the Indian River Lagoon, Amygdalum papyrium densities were reported from 25 m2 to as high as 525 m2.

The Atlantic paper mussel is a semelparous species reproducing only once during its life time. This species is dioecious, having both males and females. The spawning period in a population from Skidaway Island, Georgia was reported to be between October and January with a few remaining ripe individuals found in February (R.L. Walker et al. 2003).

The embryology of Amygdalum papyrium has not been well studied. However, other members in this family, such as Lithophaga bisulcata, Mytilus edulis, and Perna perna, have been well studied. The larvae of mytilid mussels appear to quickly develop into veligers followed by pediveligers (competent larvae) within a few weeks (Siddall 1980, Scott 1988a and b). Metamorphosis of the pedivleiger occurs once an appropriate area to settle is encountered (Siddall 1980, Scott 1988a). The larvae of A. papyrium stay in the water column for several weeks and recruit in the summer months (R.L. Walker et al. 2003).

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Reasons: Common marine species (Abbott, 1968).