Zebra mussels are an invasive, fingernail-sized mollusk that is native to fresh waters in Eurasia. Their name comes from the dark zig-zagged stripes on each shell.
The zebra mussel [Pallas, 1771] is a shellfish named for the striped pattern of its shell. This mussel is typically found attached to objects, surfaces, or other mussels by threads extending from underneath the shells. It is native to the seas of Black, Caspian, and Azov, and the Ural River.
Zebra mussels arrived in the Great Lakes in the 1980s via ballast water that was discharged by large ships from Europe. They have spread rapidly throughout the Great Lakes region and into the large rivers of the eastern Mississippi. They are now also found in Texas, Colorado, Utah, Nevada, and California.
Impacts of invasive mussels. The zebra mussels negatively impact the ecosystems and marine environment. They primarily consume phytoplankton which are microscopic marine algae that native species need for food, and they attach to native mussels to incapacitate them.
Zebra mussels are notorious for their biofouling capabilities by colonizing water supply pipes of hydroelectric and nuclear power plants, public water supply plants, and industrial facilities. Power plants have to spend millions of dollars removing zebra mussels from clogged water intakes.
They colonize pipes, constricting flow, therefore reducing the intake in heat exchangers, condensers, fire-fighting equipment, air conditioning, and cooling systems. Navigational and recreational boating can be affected by increased drag due to attached mussels. Small mussels can get into engine cooling systems causing overheating and damage. Navigational buoys have been sunk under the weight of attached zebra mussels. Deterioration of dock pilings increase when they are encrusted with zebra mussels. Continued attachment of zebra mussels can cause corrosion, affecting structural integrity of ships and pipes.
The U.S. Geological Survey (USGS) documents the geographic distribution of the zebra mussel and studies mussel behavior and biology. The resulting information is critical in helping to develop strategies aimed at containing and controlling the mussel’s spread since they are an invasive species.
Catching and transporting zebra mussels for use as bait, food, and aquarium pets is highly discouraged by the USGS. It is also not recommended for human consumption since they are filter feeders, thus mussels can accumulate pollutants in their tissues that may not be healthy for people to consume.
Mytella charruana from the Manila Bay PICES collectors.
Photo Credit: J. Conejar-Espedido.
Invasion of Manila Bay. Mytella charruana (d’Orbigny, 1842) is a bivalve, known as the charru mussel, and is not native to the Philippines. This species was discovered in 1842 in Central and South America by Alcide d’Orbigny, a French naturalist. The Charru’s color ranges from brown to black. The Charru in the Philippines has been reported in 2017 to be 5.65 cm, unlike the small 2.5 cm zebra mussel. The Charru also feeds mainly on phytoplankton, and is an invasive species.
Instead of merely disposing the mussels, the National Integrated Fisheries Technology and Development Center (NIFTDC), in contrast to the USGS, suggests to the fish farmers not to discard the Mytella charruana that have flourished, particularly in Dagupan, Pangasinan; the rationale being, this mussel meat is not only a protein-rich edible mollusk that is healthy for families, but also for crabs, tiger prawns, and shrimps raised in captivity.
The tropical Atlantic Mytella charruana that was introduced in 2014 into the Philippines is now invasive in the South Harbor of Manila Bay, Cavite, and Pangasinan. The source of invasion is likely through ballast water discharge or fouled ship hulls. The strong biological characteristics of this species are likely to displace both the indigenous and non-indigenous mollusks. The Supreme Court has taken notice of the environmental condition of Manila Bay and through a 2008 Mandamus, ordered the Executive Department of the Philippine Government to restore the environmental quality of Manila bay. The effects of the Mandamus in rehabilitating the bay have yet to be seen, upon which good management of biological marine invasion lies.
Main References:
- Benson, A.J., Raikow, D., Larson, J., Fusaro, A., Bogdanoff, A.K., and Elgin, A., 2023, Dreissena polymorpha(Pallas, 1771): U.S. Geological Survey (USGS), Nonindigenous Aquatic Species Database; Gainesville, Florida, Revision Date: 7/19/2022, Access Date: 3/6/2023, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=5
- Shell Morphology and Anatomy of the Philippine Charru Mussel Mytella charruana (d’Orbigny 1842), https://www.asianfisheriessociety.org/publication/downloadfile.php?id=1146&file=Y0dSbUx6QTBORGczTWpFd01ERTJNRFUyTVRRM01UQXVjR1Jt
