INVERTEBRATE INVADERS Established and Potential Exotics Gulf of Mexico Region INVERTEBRATE

Funded by the Coastal Impact Assistance Program through the INVADERS Mississippi Department of Environmental Quality For additional copies: [email protected] or 228.818.8890 Established and Potential Exotics Writers: Harriet Perry and David Yeager Gulf of Mexico Region Editors: Tom Van Devender, Lisa Hendon and Linda Skupien Cover photo: David Knott, Southeastern Regional Taxonomic Center, South Carolina Marine Resources Research Institute

PARTNER INSTITUTIONS AND AGENCIES The University of Southern Mississippi Center for Fisheries Research and Development Mobile Bay National Estuary Program NOAA National Marine Fisheries Service Mississippi Department of Environmental Quality Coastal Impact Assistance Program Mississippi Department of Marine Resources Mississippi-Alabama Sea Grant Consortium

703 East Beach Drive • Ocean Springs, MS 39564 228.872.4200 • www.usm.edu/gcrl

AA/EOE/ADAI 12/06 Zebra mussels

Photo: U. S. Geological Survey Archives

Invertebrates ZEBRA MUSSELS are thought to Seven of the top ten ports, by tonnage, are located in have invaded 1/3 of all freshwater aquatic the Gulf of Mexico, increasing the risk of introduction environments in the United States. These of invasive invertebrates by ship fouling or ballast water. Species of jellyfish, sea anemones, starfish, crabs, polychaetes invasive mussels can produce over one million and mollusks have been introduced through vessel traffic. eggs in a spawning season, so they multiply Invasive-species expert J.T. Carlton estimates that 7,000 dif- ferent species of marine life are transported daily around the rapidly. Millions of dollars are spent annually to world’s oceans and seas. Successful invaders have a short repair damages and to control their populations. life span, rapid growth, rapid sexual maturity, high Initially limited to freshwater, there is recent reproductive capacity, can colonize a variety of habitat types and are physiologically tolerant. evidence that they are becoming salt tolerant The zebra mussel is one example of an and can invade upper estuarine waters. extremely successful invader. Invertebrates filter-feeding fish must compete with these jellies for the same food source. Status: First reported in Gulf of Mex- ico in 1993 when a single specimen was collected from waters 70 km south of Louisiana by the National Marine Fisheries Service vessel R/V Oregon II. Populations are established east and west of the Mississippi River.

Drymonema dalmatinum - No official common name Vulnerable Locations: Marine waters, northern Gulf of Mexico. Native Range: Native to the Pacific and At- lantic oceans. Reported from the Adriatic Sea, Mediter- ranean Sea, Caribbean Sea and the Atlantic Ocean off Gibraltar. Also recorded from Argentina, Brazil and Co- Spotted jelly Photo: Alvaro Migotto lombia. Suspected Vector: Natural transport via circula- tion processes associated with the Loop Current and its Spotted jelly, Phyllorhiza punctata spin-off eddies or through vessel fouling. Description: Vulnerable Locations: Marine waters, Gulf of The umbrella is flatly Drymonema dalmatinum Mexico. Native Range: Native to the tropical western rounded and shield Pacific Ocean, wide distribution in Australian coastal shaped. Color ranges and lagoonal waters. Suspected Vector: Most likely from reddish-white to arrived via ship ballast or hull fouling to the Caribbean yellow-white; specimens Sea through the Panama Canal. A small population of in the northern Gulf of P. punctata has existed in Terrebonne Bay, La., for several Mexico are pink. More years; vector unknown. Origin of medusae, adult spotted than 150 long stinging Photo: Jason Steckler jellies, that invaded northern Gulf of Mexico in summer tentacles; dense ribbon-like gonadal and mouth exten- of 2000 is attributed to circulation processes associated sions that are shorter than the tentacles also extend with the Gulf of Mexico Loop Current and spin-off beneath the bell. Can exceed 700 mm in bell diameter eddies, although transport from the Terrebonne Bay with tentacles in excess of 30 m long. Resembles the population must be considered. Description: Basketball- lion’s mane jellyfish, Cyanea capillata. Negative Impacts: sized jellyfish with a white-spotted, opaque bell; mild More than 25 million jellyfish were estimated in a to no sting. Negative Impacts: Direct economic impact bloom of D. dalmatinum in 1999 off Puerto Rico. If such on the trawl fisheries. Jellyfish clog nets, damage boat a bloom occurred in the northern gulf, there would be a intakes and fishing gear, and can cause closure of pro- direct economic impact on the shrimp fishery including ductive areas to fishing activities. Indirect effects include clogged nets, damage to boat intakes and fishing gear, predation on the eggs of important forage species and and closure of areas to fishing activities. Status: Un- consumption of bivalve larvae. Fish larvae and mature known, reported from Alabama and Mississippi. CRUSTACEANS AND MOLLUSKS ACCOUNT FOR MOST OF THE INVERTEBRATE INTRODUCTIONS IN THE GULF OF MEXICO.

Brown mussel, Perna perna Brown mussel Green mussel, Perna viridis Green mussel Vulnerable Locations: High salinity (27-33 ppt) estuaries and marine waters, Gulf of Mexico. Native Range: Green mussels (Perna viridis) are natu- Photo: Southeastern Regional Taxonomic Center rally distributed throughout the Indo-Pacific. Brown mus- Photo: Amy Benson, USGS sels (Perna perna) are native to population growth. Green mussels were first tropical and subtropical regions of the African coastline. discovered in 1999 in Tampa Bay, Fla. Current range Suspected Vector: Vector for both mussel species is extends from Venice, La., to St. Petersburg, Fla. The thought to be international shipping via ballast water green mussel’s greater thermal tolerance will allow it to release or hull fouling. Description: The genus can be disperse throughout the Gulf of Mexico. Status: Green distinguished from other North American members of mussels are currently established only in Florida. The the family by the absence of one of two muscles used brown mussel is currently confined to Texas waters with to close the shell. The two Perna species are difficult to populations limited by summer temperatures. separate using external characteristics; shells are similar and can be highly variable. Reliable separation of the Spiny hands swimming crab, Charybdis hellerii two species requires examination of internal anatomy. Vulnerable Locations: Lower estuarine, marine The brown mussel has enlarged sensory papillae along waters of the Gulf of Mexico. Native Range: Japan, mantle margins. Color of P. perna varies from reddish Philippines, New Caledonia, Australia, Hawaii and to dark brown to black with marginal areas of yellow throughout the Indian Ocean, including the Red and green. Perna viridis adults are usually various shades Sea. Suspected Vector: Both ballast water and drift of of brown in central portion of shell; juveniles typically juveniles from green to blue-green. Occasionally both adults and juve- Cuba have niles are brown, making them difficult to separate from been suggested P. perna. Negative Impacts: Both mussels are biofoulers as a means of that can alter community structure and create fouling introduction to problems in industries that use seawater as coolant. American wa- Brown mussels first appeared in Texas in 1990 on the ters. Descrip- Port Aransas jetty and within four years had colonized tion: Fifth 1,300 km from Matagorda Bay to Vera Cruz, Mexico. legs flattened; They are also found on offshore petroleum platforms side frontal Spiny hands swimming crab in the Gulf of Mexico. Presence of Texas populations Photo: David Knott, Southeastern Regional margin has Taxonomic Center, South Carolina Marine varies; water temperatures at or above 30º C limit six sharp, Resources Research Institute Successful Invader black-tipped teeth; frontal region has six prominent above and whitish below with a tinge of blue. teeth. Overall color is dark green with dark purple on Negative Impacts: May compete with the blue crab, walking and swimming legs. Fingers of chelipeds (claws) Callinectes sapidus, for food and refuge. Although C. are dark purple. Negative Impacts: Unknown. Status: bocourti is commercially exploited in Central and South Reported in Gulf of Mexico from Anna Maria Island, America, it is a smaller crab and less desirable for pro- Fla., (mouth of Tampa Bay). Species has the potential to cessing in the United States. Competition among successfully colonize marine ecosystems of South Florida C. bocourti, C. sapidus and C. similis in northern gulf and the Gulf of Mexico. estuaries may limit populations of one or more of these species. Status: Reported from Mississippi and Ala- bama; extraterritorial occurrences in the northern Bocourt swimming crab Gulf of Mexico are sporadic and suggest that the species is not currently reproducing.

Green crab, Carcinus maenas Vulnerable Locations: Estuarine and shallow coastal waters of the Gulf of Mexico. Native Range: Atlantic coasts of Europe and northern Africa from Norway and the British Isles south to Mauritania. Suspected Vec- tors: Dispersed as adults by a variety of anthropogenic and natural mechanisms including: 1) ballast, 2) ships’ hulls, 3) packing materials (seaweeds) used to ship live marine organisms, 4) bivalves moved for aquaculture, - 5) rafting, 6) migration on surface currents and 7) move- Photo: David Knott, Southeastern Regional Taxonomic Cen ment of submerged aquatic vegetation for coastal zone ter, South Carolina Marine Resources Research Institute management initiatives. Once established in an area, green crabs can spread by planktonic transport of larvae. Bocourt swimming crab, Callinectes bocourti Description: Surface of carapace finely granular, about Vulnerable Locations: Estuarine waters, Gulf of ¾ as long as wide with five yellow-tipped side frontal Mexico. Native Range: Jamaica, Belize to Brazil; cen- teeth; frontal area between eyes has three rounded teeth. ter of abundance in coastal waters of northern South Carapace color is variable, usually mottled, dark brown America. Suspected Vector: Ballast water and drift of to dark green, with granules for the most part yellow. juveniles and adults from Caribbean. Description: Flat- Females have orange background color and whitish tened fifth legs; frontal margin has six triangular frontal granules. Walking legs are green, speckled with black; teeth with tips reaching a nearly common level; color fourth pair of legs is shorter than the first; last pair is highly variable, but generally olive green to brown with somewhat flattened and with hairs (setae). Negative reddish markings; chelipeds red to dark reddish brown Impacts: Implicated in the destruction of the soft-shell THE FRESHWATER ZEBRA MUSSEL IS BECOMING SALT TOLERANT. clam (Mya arenaria) fisheries in New England and the reduction of populations of other commercially important bivalves including the scallop, Argopecten irradians, and the northern quahog, Mercenaria mercenaria. Ability to outcompete native species for food resources, a high reproductive capacity and wide environmental tolerances give green crabs the capacity to fundamentally alter community structure. They are voracious predators on other crab species. Status: Dispersed globally, U.S. reports include Atlantic and Pacific coast estuaries. It is one of the most successful invaders in coastal ecosystems. Temperature may limit southward expansion of northeast populations. Green crab

Photo: Kathlyn Smith

Zebra mussel, Dreissena polymorpha Vulnerable Locations: Fresh and estuarine waters of the Gulf of Mexico. Native Range: Black, Caspian and Azov seas. Suspected Vector: Original U.S. introduction into the Great Lakes through ballast water; further dispersal through larval transport and hull fouling. Description: Small bivalve, usually striped (hence the name zebra). Some speci- mens dark or light colored with no stripes. Can grow to two inches long, most under one inch; generally found in clusters. Only fresh- water mollusc able to attach to underwater objects and surfaces. Negative Impacts: Zebra mussels pose a multibillion-dollar threat to U.S. industrial, agricultural and municipal water supplies and are a costly nuisance for freshwater shipping, boating and fishing. Large infestations disrupt aquatic food chains, causing shifts in native species populations. Status: Established in the Great Lakes and most of the large navigable rivers in the eastern U.S. Found in the Gulf of Mexico in coastal Louisi- ana with a single occurrence in Mississippi Sound.

Photo: U. S. Geological Survey Archives Did You Know? Whiteleg shrimp, Litopenaeus vannamei Vulnerable Locations: Estuarine and shallow coastal waters of the Gulf of Mexico. Native Range: Eastern Pacific from Sonora, Mexico, to Tumbes in northern Peru. Suspected Vector: Aqua- culture release. Description: The rostrum, the spinelike projec- tion of the front Whiteleg shrimp Photo: Robert Adami, Texas Parks & of the carapace, is Wildlife Department moderately long and armed with upper and lower teeth; lower teeth num- ber two to four, occasionally five to eight. Closely resem- bles the common gulf white shrimp, but is a lighter color, especially the legs, and is sometimes called the “white- legged” shrimp. Negative Impacts: Exotic shrimp viruses associated with L. vannamei may pose a risk to Gulf of Mexico and southeastern U.S. Atlantic wild penaeid shrimp fisheries. Other crustacean fisheries may also be at risk from introduced viruses. Status: Aquaculture of the Pacific white shrimp in the United States began in Texas and in Florida. Although collected periodically in commercial shrimp trawls off Texas, there is currently no evidence that populations have established themselves in Giant river prawn Photo: Southeastern Regional Taxonomic Center, South Carolina the wild in the northern Gulf of Mexico. Marine Resources Research Institute

Giant river prawn, Macrobrachium rosenbergii long with 11-14 upper teeth and eight to 10 lower Vulnerable Locations: Wide range of freshwater and teeth. First and second legs have pincers; pincers in estuarine ecosystems including swamps, lakes, ponds, adult males are blue or orange. Orange spots may be ditches, bays and bayous. Requires brackish water to com- visible on tail. Negative Impacts: Unknown at pres- plete early life stages. Native Range: South and Southeast ent; winter low temperatures in the northern Gulf Asia, Oceania and the western Pacific. Suspected Vector: of Mexico may prevent establishment of populations Aquaculture release. In some areas this species is sold in in the wild. Status: Reported from a single bayou in the aquarium trade. Description: Large shrimp; rostrum Mississippi. FLORIDA HAS THE HIGHEST NUMBER OF INTRODUCED INVERTEBRATES. Did You Know? MISSISSIPPI HAS THE LOWEST. Channeled apple snail, Pomacea canaliculata Vulnerable Locations: Wide range of freshwa-

ter ecosystems including swamps, lakes, ponds and Rapa whelk ditches. Native Range: South America. Suspected Vec- Photo: tor: Aquarium and aquaculture releases. Description: Juliana Harding Shell is round and, in older snails heavy. Deep sutures (grooves) separate five to six whorls. Shell opening is large and round to oval. All apple snails have a tubelike Rapa whelk, siphon. There are several species of introduced apple snails, and an expert may be needed to identify speci- Rapana venosa mens from the wild. Channeled apple snails lay up to Vulnerable 1,000 small pink eggs on hard surfaces such as docks, Locations: Estuarine plant stems, rocks and seawalls. Negative Impacts: The waters of the Gulf channeled apple snail is an agricultural pest that is a of Mexico. Native destructive plant eater. This species will eat all types Range: Marine of aquatic vegetation and has few natural enemies. and estuarine waters Mississippi has banned importation of all members of the western Pacific, the of the apple snail family. Louisiana has identified the Sea of Japan, Yellow and channeled apple snail as a threat to rice production. East China seas, the Bohai Sea. Channeled apple snails are salinity tolerant and can Suspected Vector: Release of larvae from ballast withstand temperatures found in the northern Gulf water or transport of egg masses from one area of Mexico. Status: Established in Florida and Texas; to another. Description: Shell heavy, round and reported from Alabama. with a short spire. Body whorl is large and inflat- ed. Shell opening is large, deep orange and ringed with small teeth. Background color of shell varies Channeled apple snail from gray to reddish-brown; most specimens have black veins that run throughout the shell. Shell length of specimens from Virginia is four to six inches. Negative Impacts: Rapa whelks are preda- tory snails that feed on a variety of bivalves. In the Chesapeake Bay their preferred prey is the hard clam, but they will attack other mollusks. Their occurrence in estuaries in the Gulf of Mexico may impact oyster populations. Status: Currently established in Chesapeake Bay in U.S. waters.

Photo: Florida Department of Environmental Protection