Nicklin's Pearlymussel
Nicklin's Pearlymussel
Megalonaias nicklineana
| Status | Endangered |
| Listed | June 14, 1976 |
| Family | Unionidae |
| Description | A freshwater mussel. |
| Habitat | Subtropical rivers. |
| Food | A filter-feeder of phytoplankton and organic detritus. |
| Reproduction | Releases spawn into the water, where external fertilization occurs. |
| Threats | Habitat degradation by pollution and siltation. |
| Range | Guatemala, Honduras, Mexico |
Description
The Nicklin's pearlymussel is an extremely rare, little-known, freshwater, bivalve mollusk. Its shell length is about 6 in (15 cm), and the width 2 in (5 cm). The overall shape is roughly triangular, and the shell is thickest near the back (close to the hinge). The shell surface is decorated with zig-zag creases and concentric furrows. The color of the outer shell is dark brown, while the inner is a lustrous, pearly white.
Behavior
The Nicklin's pearlymussel lives on the bottom of slow-moving rivers, where it feeds on phytoplankton (single-celled algae) and particles of organic detritus, which it filters from the water. The spawn is released into the water column, where fertilization occurs. The larvae are pelagic for some time, and are likely parasites of fish. The mature larvae settle to the bottom of their river, where they adopt the sedentary adult lifestyle.
Habitat
The Nicklin's pearlymussel occurs in slow-moving, subtropical rivers.
Distribution
The Nicklin's pearlymussel is only known from a few specimens collected from rivers in Guatemala, Honduras, and southern Mexico.
Threats
Much of the known riverine habitat of the Nick-lin's pearlymussel has been severely degraded by pollution with nutrients and pesticides, and by siltation (i.e., the settling of soil particles eroded from nearby agricultural land). These mussels have also been collected for their freshwater pearls, which are of some value in making jewelry. Several of its known populations are now extirpated.
Conservation and Recovery
Little is known about the surviving populations or distribution of the Nicklin's pearlymussel. There is an urgent need for surveys of its known or potential habitat, to determine the degree of risk to its remaining populations. Its best habitats should be conserved, and the local agricultural practices modified to reduce the risk to this rare mollusk.
Contact
Instituto Nacional de Ecología
Av. Revolución, 1425
Col. Campestre, C.P. 01040, Mexico, D.F.
http://www.ine.gob.mx/
Reference
Fuller, S. L. H. 1974. "Clams and Mussels (Mollusca:Bivalvia)." In: C. W. Hart and S. L. H. Fuller (eds.). Pollution Ecology of Freshwater Invertebrates. Academic Press. New York. pp. 215-273.