Practical information to identify and manage non-native, invasive plants and animals
The Quiet Invasion:A Guide to Invasive Species of the Galveston Bay Area
Perna perna, Perna viridis
| ITIS TSN: | 567088 |
| Presence: | Species of Concern |
| Habitat: | Aquatic |
| Native Range: | P. perna is native to Africa, Europe and South America. P. viridis is native to the Indo-Pacific region of Asia, from the Persian Gulf to the South China Sea (Benson 2009). |
Human Health
Perna perna and Perna viridis have been found to accumulate the biotoxins that cause Paralytic Shellfish Poisoning.Prohibited Lists
As of 2010, thes species are not prohibited by the TPWD.Introduction Pathways
The brown mussel (P. perna) and green mussel (P. viridis) were introduced by ballast water and ship hull fouling via the international shipping trade (Benson 2009).Geographic Distribution
P. perna has been found along the Texas coast between Freeport and Brownsville. It was first reported in the Gulf of Mexico in 1990 at the Port Aransas Jetty and has since spread south along the Texas coast. P. viridis has been established along the Atlantic coast and the Gulf Coast of Florida as early as 1999. Neither of these species is established in the Lower Galveston Bay watershed (Benson 2009).Specific Primary Habitats
P. perna and P. viridis are primarily found in marine and estuarine habitats where they can attach to hard substrates such as jetties, rip-rap, buoys, petroleum platforms, and industrial intake pipes. Perna species can develop dense populations (up to 35,000 per square meter) on these surfaces. They are restricted to subtidal and intertidal zones of subtropical climates. Perna species can tolerate salinities ranging from 12-80 ppt (Masterson 2007a). Optimal temperatures for these mussels are 26-32°C, but they can tolerate water temperatures as low as 10°C (ISSG 2005e; ISSG 2005f).Ecological, Economic, or Social Impact
Perna perna continues to expand its range. It is successful due to rapid growth rates, wide temperature and salinity tolerances, and because of its pelagic dispersal methods. Perna viridis is similar in these traits and both species are responsible for blocking water intake pipes and sinking maritime equipment such as buoys. At high densities these species disrupt the trophic structure in invaded ecosystems. Impacts to native oyster populations are unknown (ISSG 2005e; ISSG 2005f).Physical Description
P. perna and P. viridis range in size form 80-120 mm long., with P. viridis reaching up to 165 mm in length (ISSG 2005f). The shell is smooth in both mussel species. P. perna has a brown shell while P. viridis juveniles have a distinctive, bright green color which fades to brownish green in adults (Benson 2009).Reproduction Characteristics
Perna species become sexually mature in 1-2 months in non-native waters, and reproduce sexually, via external fertilization (Masterson 2007a). P. perna spawning occurs during the winter and is triggered by a 3-4 degree temperature drop. P. viridis spawning occurs between early spring and late fall (ISSG 2005f). Perna species usually spawn 1-2 times per year, but in some areas, they have been known to reproduce year round. After fertilization, pelagic larvae remain in the water column for approximately two weeks before attaching to a suitable substrate with byssal threads (Masterson 2007a).Feeding
Perna species are filter feeders, feeding primarily on phytoplankton and organic detritus (ISSG 2005e; ISSG 2005f).Control
Early detection is key to preventing the spread and establishment of this species. Perna sp. should not be imported or released in local waterways. If found, note the location and notify the TPWD. Watercraft and equipment moved from invaded water bodies should be thoroughly cleaned an inspected before being moved. Research on antifouling paints and ballast water management are under way to try to eliminate new introductions of Perna. Eradication of these species in a water body is extremely difficult and unlikely. They can be eliminated locally (i.e. in a power plant) by mechanical or chemical control methods. Boats travelling from infested waters to uninfested waters should first be decontaminated (Benson 2009).Lists
This species belongs to the following lists:
Images
To view a larger version of an image, click on the thumbnail. Brown mussel (Perna perna). Photo courtesy of USGS, USGS NAS Database, http://nas.er.usgs.gov. |
 Green mussel (Perna viridis). Photo courtesy of USGS, USGS NAS Database, http://nas.er.usgs.gov. |
 Young green mussels (Perna viridis). Photo courtesy of USGS, USGS NAS Database, http://nas.er.usgs.gov. |
 Green mussel (Perna viridis). Photo courtesy of Buck Albert, USGS. |