Title

Tracking the distribution of non-native marine species, charruana, viridis, and coccopoma, along the southeastern United States coastline

Samantha Spinuzzi; Kimberly Schneider; Walters, Linda; Ethan Nash; Sam Wei; Eric Hoffman

University of Central Florida, Department of Biology, Orlando, FL 32816 [email protected]

Abstract

Nonnative species can have adverse effects on the environments they colonize. Often, the species have no niche in their new environment giving them no restrictions on their population growth. They compete with native species by taking over food resources or living space, which causes the species to become invasive. At times, become so prevalent that they drive native species to local extinction.

Tracking nonnative species is crucial for understanding their population growth. Since 2006, a biannual survey of the southeastern coast has been conducted from Jupiter, Florida to Charleston, South Carolina. The survey monitors the distribution of three marine invaders, Mytella charruana (charru ), Perna viridis (Asian green mussel), and Megabalanus coccopoma (acorn ). Mytella charruana was discovered in the Indian River Lagoon, FL in 2004. Perna viridis was first introduced to Tampa Bay, FL in 1988. Megabalanus coccopoma was introduced to Florida in the early 2000s.

Currently, 82 sites are monitored every June and December. Sites are searched for approximately ten minutes, and species are found on substrates such as docks, boat ramps, jetties, and mangrove roots. The ranges of the three species have expanded and retracted throughout the years. Mytella charruana spread into Georgia and South Carolina in 2007, but the species has been absent from South Carolina since 2009. Perna viridis and Megabalanus coccopoma expanded into Georgia in 2007, but both were absent in 2010. The data observed may lead to conclusions regarding how the species colonize a and patterns in their colonization events.

Introduction

Non-native species are often capable of causing adverse affects in the environments they colonize (Vitousek 1996). If an anthropogenic introduction of a non-native species successfully colonizes a new environment and a negative impact results from this colonization then the species is deemed invasive (Rilov 2009). Invaders compete with native species for food resources and living space. At times, invasive species become so prevalent that endemic species become scarce or locally extinct. This devastation reduces the ecological richness of a region, and the presence of these species can upset the economy (Rilov 2009). For example, the loss of biodiversity in a marine environment can greatly affect the fishing industry, and some invasive species foul natural and human-made structures. Marine introductions often occur accidentally via ship fouling or ballast water. Aquaculture also causes colonization of non-native species and is referred to as deliberate introductions (Vitousek 1996). Eradication of the invaders can cost millions if not billions of dollars (Rilov 2009).

Considering the potential impact of an invasive species, there is great incentive to prevent these introductions from occurring and to better understand those that do occur. Observing the spread and distribution of non-native species can allow for better understanding of the invasive process and reveal insight regarding the extent of a species impact on an environment. In the southeastern Unites States, three non-native marine species with invasive potential were recently introduced but are not well-understood. These include two mussel species, Mytella charruana and Perna viridis, and the barnacle species Megabalanus coccopoma. These introductions are of concern due to the high success rate of and as invaders. Each species was recently introduced to the eastern Floridian coast and have since expanded their range. This project was designed to collect observational data through coastal surveys along the southeastern United States in order to track the spread of these three species. Observational data of the distribution and spread of these three species could give insight into rate of expansion, habitat preference, vectors of introduction or dispersal, and invasive impact.

Examples of successful invasions

A significant example of a mussel introduction that progressed into invasive species involves the mussel, Mytilus galloprovincialis. Mytilus galloprovincialis is a that is a notorious invader. It has colonized countries such as Hong Kong, Japan, Korea, southeast Australia, Mexico, Canada, and the United States (Branch and Steffani 2004). M. galloprovincialis was accidentally introduced to Saldanha Bay, South in 1979 (Branch and Steffani 2004). Since its introduction to Saldanha Bay, South Africa in 1979, M. galloprovincialis has naturally expanded its range across 2050km of South African coast (Robinson 2005). The species has a heightened growth and reproduction rate (compared to indigenous species) in addition to a resistance to desiccation (Hockey and van Erkom Schurink 1992) which has led it to be the dominant intertidal species along the western South African coast (Robinson 2005). In fact, 74% of all mussel biomass is recorded to be M. galloprovincialis; the effect can be observed through the immense displacement of the native mussel Aulacomya ater (Branch and Steffani 2004).

The barnacle species Elminius modestus was introduced to European waters in the 1940’s and has since become widespread and well-established along the much of the European coastline (Allen et al. 2006). Elminius modestus is a small barnacle species native to southern Australia and New Zealand that arrived in European waters in around 1943 (Bishop 1947). The first record of E. modestus in Ireland was in 1956 just outside Lough Hyne Marine Nature Reserve (Beard 1957). Lough Hyne is an important reserve and one of the most studied marine environments in the world (Lawson et al. 2004). In 2001, a survey was conducted in the Lough Hyne Marine Nature Reserve, and E. modestus was discovered to be the most abundant and widely distributed barnacle species in the reserve. In some areas, all other barnacle species had been completely displaced (Lawson et al. 2004). The spread of Elminius modestus in Lough Hyne not only displaced native barnacles but the natural macroalgae that supports urchins and other algal grazing species. Thus, the presence of E. modestus in Lough Hyne has dramatically altered the natural ecological balance in the marine reserve (Lawson et al. 2004).

Description of study species

Mytella charruana, known commonly as the charru mussel, is non-native mussel originally found in the Pacific Ocean from Mexico to and in the Atlantic from Colombia to . It was discovered in a power plant’s intake pipes in Jacksonville, Florida in 1986 and was likely introduced via ballast water (Boudreaux and Walters 2006). The population did not survive, but the species was discovered in Mosquito Lagoon, located along the eastern coast of Florida, in August 2004 (Boudreaux and Walters 2006). Since this discovery, Mytella charruana has established itself in the lagoon and along the southeastern U.S. coast ranging from southeast Florida to the southeastern coast of South Carolina (USGS). The charru mussel has a dark brown to black shell with semicircular rings. Its preferred substrates in Mosquito Lagoon include manmade structures and reefs (Boudreaux and Walters 2006). The effects of the invader are currently being observed in Mosquito Lagoon, Florida.

Perna viridis, otherwise known as the Asian green mussel, was first discovered in Tampa Bay in 1989 (Baker et al. 2007). In 2002, the species was documented on the east coast in St. Augustine, Florida (USGS). The species has become a well-established invader and has already cost millions of dollars to control (Fajans and Baker 2003). Its original range spans the Persian Gulf as well as the , Sumatra, Borneo, Bali, and Sulawesi (Baker et al.). Salinity tolerance ranges from 19ppt to 44ppt, and temperature tolerance runs from 10°C to 42°C (Nair and Murugan 1991). The mussel has a brilliant green sheen and lacks ribs. In the Indo-Pacific, P. viridis is a commercially important species, and attempts to aquaculture this species has led to many invasions (Baker et al. 2007). Since its introduction to Florida, Perna viridis has established itself across the entire Floridian coast as well as the span of the Gulf of Mexico (Baker et al. 2007).

Megabalanus coccopoma, more commonly known as the acorn or titan barnacle, was discovered in St. Augustine, Florida in 2006 after being found in Brunswick, Georgia that same year (Gilg 2010). The species is a large barnacle with a distinct pink color. Its native range is the Pacific from Mexico to Ecuador (similar to Mytella charruana). During an El Niño event in 1982-1983, the M. coccopoma underwent a natural migration to southern California (Gilg 2010). However, since then the non-native barnacle was introduced to the Gulf of Mexico as well as the southeastern U.S. coast from southern Florida to South Carolina (USGS). The species has invaded other countries such as Japan in 2007 (Yamaguchi 2009). The titan barnacle’s large size may contribute to its invasive properties, but little is known about the barnacle in its invaded habitat.

The examples of Mytilus galloprovincialis and Elminius modestus developing into invasive species illuminate the possibility that under the proper circumstances a non-native species can become an ecological or economical threat. Monitoring the spread and distribution of Mytella charruana, Perna viridis, and Megabalanus coccopoma may give insight that could prevent an invasion on a catastrophic scale like those of M. galloprovincialis and E. modestus. Tracking the dispersal of the non-native species can lead to a greater understanding of human influence on the biodiversity and natural ecology of an environment and lead to a greater understanding of those human influences.

Methods

The goal of this project is to document the range and abundance of the three introduced species Mytella charruana, Perna viridis, and Megabalanus coccopoma along the southeastern coast of the United States. In order to accomplish this, a biannual survey was conducted in December and June at 82 total sites ranging from Jupiter, FL (26 56.916 N, 080 05.060 W) to Charleston, South Carolina (33 21.793 N, 79 33.3904 W) (Table 1, Figure 1).

The survey began in June 2006 and included 48 sites ranging from Jupiter, FL (26 56.916 N, 080 05.060 W) to New Smyrna Beach, FL (29 04.409 N, 080 54.754 W) (Table 1, Figure 2). After Mytella charruana was discovered in Mosquito Lagoon, there was concern that the charru mussel would continue to disperse throughout the Indian River Lagoon, which is why the sites were chosen in the IRL. In the December 2007 survey, 28 new sites were added to the existing survey. These sites were located farther north and ranged from Jacksonville, FL (30 08.080 N, 81 35.788 W) to Savannah, GA (32 09.870 N, 81 09.415 W) (Table 1, Figure 1). These sites were chosen as a result of reports regarding the discovery of M. charruana in Georgia and Jacksonville (USGS). In December 2008, 3 new sites were added in South Carolina, and in June 2009, two sites in St. Augustine, FL were added (Table 1, Figure 1). These sites were added due to reports in USGS. During 2006 and 2007, Mytella charruana was the only target species on the survey. Perna viridis and Megabalanus coccopoma were added to the survey in 2008 in light of the rapid spread of P. viridis (Baker et al. 2007) and limited knowledge on the impact of M. coccopoma (Gilg et al. 2010).

Hard substrates were searched in order to monitor the range of potential habitat for the three introduces species. These substrates included docks, pilings, boat ramps, jetties, rocks, mangrove roots, and human-made debris such as concrete blocks. While each site was surveyed, the air and water temperatures were taken using a standard water thermometer. Salinity was also measured using a refractometer. The search for the species at a site was timed, and each search fell within a standard time of 10 minutes. The time searched at a site occasionally varied depending on the conditions of the site. In some cases, substrates were searched in less than 10 minutes, or the area was large enough that a 10 minute search was not sufficient. To standardize the time searched relative to the amount of specimens collected, the count per unit was calculated using the ratio of live specimens collected to the time taken during the search. Any non-native target species found during the search were collected and measured. Length was recorded for mussels and height and width were recorded for barnacles.

Table 1: Survey Sites

Site Name Coordinates Date Added 1 Burt Reynolds Park, Jupiter, FL 26 56.531 N, 080 05.060 W June 2006

2 Lighthouse park, Jupiter, FL 26 56.916 N, 080 04.973 W June 2006

3 Hobe Sound National Wildlife Refuge, Hobe Sound, FL 27 02.247 N, 080 06.669 W June 2006

4 Jimmy Graham Park, Hobe Sound, FL 27 06.092 N, 080 08.531 W June 2006

5 Sandsprit Park, Stuart, FL 27 09.831 N, 080 11.604 W June 2006

6 Jensen Causeway Park, Jensen Beach, FL 27 15.168 N, 080 13.300 W June 2006

7 Indian River Drive, Jensen Beach, FL 27 15.795 N, 080 14.034 W June 2006

8 Savanna Recreation Area, Fort Pierce, FL 27 23.291 N, 080 18.533 W June 2006

9 County Ramp (near overpass), Fort Pierce, FL 27 27.353 N, 080 19.444 W June 2006

10 Ft. Pierce Inlet, Fort Pierce, FL 27 28.460 N, 080 17.471 W June 2006

11 Ft. Pierce Residential, Fort Pierce, FL 27 29.383 N, 080 20.160 W June 2006

12 Oslo Boat Ramp, Vero Beach, FL 27 35.209 N, 080 21.921 W June 2006

13 McWilliams Park, Vero Beach, FL 27 39.244 N, 080 22.176 W June 2006

14 Wabasso Causeway Island Park, Vero Beach, FL 27 45.235 N, 080 25.633 W June 2006

15 Main St. Dock, Sebastian, FL 27 49.047 N, 080 28.096 W June 2006

16 Sebastian Inlet State Park, Sebastian, FL 27 51.347 N, 080 27.084 W June 2006

17 John Jorgensen Landing, Grant-Valkaria, FL 27 56.240 N, 080 31.786 W June 2006

18 Goat Creek Bridge, Grant-Valkaria, FL 27 57.904 N, 080 32.536 W June 2006

19 Castaway Point Park, Palm Bay, FL 28 02.407 N, 080 34.3825 W June 2006

20 Front Street Park, Melbourne, FL 28 04.790 N, 080 36.018 W June 2006

21 POW-MIA Park, Melbourne, FL 28 12.267 N, 080 39.667 W June 2006

22 Pineda Causeway (SR 404) eastbound, Melbourne, FL 28 12.660 N, 080 37.417 W June 2006

23 Rotary Park, Melbourne, FL 28 13.811 N, 080 40.248 W June 2006

24 Riverwalk park, Rockledge, FL 28 16.086 N, 080 41.246 W June 2006

25 Lee Wenner Park, Merritt Island, FL 28 21.359 N, 080 43.295 W June 2006

26 US Constitution Park, Cocoa Beach, FL 28 21.434 N, 080 37.706 W June 2006

27 Kiwanis Island Park, Merritt Island, FL 28 21.523 N, 080 40.717 W June 2006

28 McFarland Park, Cocoa, FL 28 23.436 N, 080 44.494 W June 2006

29 Kelly Park, Merritt Island, FL 28 24.131 N, 080 39.772 W June 2006

30 Jetty Park, Cocoa Beach-Cape Canaveral, FL 28 24.513 N, 080 35.52 W June 2006

31 Nicol Park, Cocoa, FL 28 28.616 N, 080 46.045 W June 2006

32 Freddie Patrick Park, Cocoa, FL 28 28.626 N, 080 46.045 W June 2006

33 Kennedy Point Park, Titusville, FL 28 33.217 N, 080 47.661 W June 2006

34 Sand point Park, Titusville, FL 28 37.221 N, 080 48.371 W June 2006

35 Parrish Park, Titusville, FL 28 37.561 N, 080 47.661 W June 2006

36 Merrit Island Wildlife Refuge, Titusville, FL 28 42.355 N, 080 43.224 W June 2006

37 Haulover Canal (Bairs Cove), Titusville, FL 28 44.071 N, 080 45.367 W June 2006

38 Scottsmore Landing, Mims, FL 28 46.237 N, 080 50.731 W June 2006

39 Sunrise Park, Oak Hill, FL 28 52.498 N, 080 50.433 W June 2006

40 River Breeze, Oak Hill, FL 28 53.916 N, 080 51.141 W June 2006

41 Hiles Boat Ramp, New Smyrna Beach, FL 28 59.318 N, 080 52.233 W June 2006

42 Menard May Park, New Smyrna Beach, FL 28 59.352 N, 080 54.064 W June 2006

43 North causeway Dock, New Smyrna Beach, FL 29 01.885 N, 080 54.985 W June 2006

44 North Causeway Boat Ramp, New Smyrna Beach, FL 29 01.886 N, 08 54.958 W June 2006

45 Buena Vista Park, New Smyrna Beach, FL 29 02.251 N, 080 54.505 W June 2006

46 Crawford Street, New Smyrna Beach, FL 29 02.612 N, 080 54.236 W June 2006

47 Ponce Inlet South Site, New Smyrna Beach, FL 29 03.951 N, 080 55.041 W June 2006

48 Ponce Inlet, New Smyrna Beach, FL 29 04.409 N, 080 54.754 W June 2006

49 Vilano Boat Ramp, St. Augustine, FL 29°54'43.29"N, 81°18'31.65"W June 2009

50 Euclid Avenue, St. Augustine, FL 29°56'58.24"N, 81°18'36.05"W June2009

51 Hood Landing, Jacksonville, FL 30 08.080 N, 81 35.788 W Dec 2007

52 Lighthouse Marine, Jacksonville, FL 30 16.916 N, 81 44.398 W Dec 2007

53 Arlington Boat Ramp, Jacksonville, FL 30 20.030 N, 81 36.702 W Dec 2007

54 Lonnie Wurn, Jacksonville, FL 30 22.523 N, 81 35.143 W Dec 2007

55 Lions Club, Jacksonville, FL 30 22.691 N, 81 37.238 W Dec 2007

56 Sister's Creek, Jacksonville, FL 30 23.460 N, 81 27.330 W Dec 2007

57 Joe Carlucci, Jacksonville, FL 30 23.517 N, 81 27.789 W Dec 2007

58 Mayport #3 (Michael Scanland), Jacksonville, FL 30 23.793 N, 81 25.681 W Dec 2007

59 Palms Fish Camp, Jacksonville, FL 30 24.280 N, 81 30.414 W Dec 2007

60 St. Marys Ramp, St Marys, GA 30 43.239 N, 81 33.030 W Dec 2007

61 North River Ramp, St Marys, GA 30 43.990 N, 81 32.341 W Dec 2007

62 Crooked River State Park, St Marys, GA 30 50.713 N, 81 33.583 W Dec 2007

63 Harriet's Bluff , Woodbine, GA 30 52.059 N, 81 35.089 W Dec 2007

64 Satilla River, Woodbine, GA 30 58.380 N, 81 43.453 W Dec 2007

65 Jekyll Island, Thalmann, GA 31 02.518 N, 81 25.351 W Dec 2007

66 Blythe Island Regional Park, Brunswick, GA 31 09.144 N, 81 32.813 W Dec 2007

67 Champney River Ramp, Brunswick, GA 31 20.191 N, 81 26.924 W Dec 2007

68 Darien City Ramp, Darien, GA 31 22.097 N, 81 26.212 W Dec 2007

69 Blue-N-Hall Ramp, Darien, GA 31 24.345 N, 81 23.548 W Dec 2007

70 Harris Wildlife Refuge, Townsend, GA 31 37.278 N, 81 15.813 W Dec 2007

71 Sunbury Ramp, Midway, Georgia 31 45.868 N, 81 16.622 W Dec 2007

72 Demeries Creek, Richmond Hill, GA 31 47.146 N, 81 15.274 W Dec 2007

73 Ft. McAllister, Richmond Hill, GA 31 53.350 N, 81 12.241 W Dec 2007

74 Skidaway Narrows, Savannah, GA 31 56.833 N, 81 04.059 W Dec 2007

75 Chatham County Ramp, Tybee Island, GA 32 00.966 N, 80 53.459 W Dec 2007

76 Turner Creek, Savannah, GA 32 01.206 N, 80 59.569 W Dec 2007

77 Thunderbolt Ramp, Thunderbolt, GA 32 02.178 N, 81 02.656 W Dec 2007

78 Houlihan Ramp, Port Wentworth, GA 32 09.870 N, 81 09.415 W Dec 2007

79 Hunting Island State Park, St Helena, SC 32.359663 N, 80.453568 W June 2010

80 Bennett's Point Boat Ramp, Walterboro, SC 32 56.0898 N, 80 45.4621 W Dec 2008

81 Charleston City Marina, Charleston, SC 32°46' 45.18"N, 79°57'5.39"W Dec 2008

82 Buck Hall Landing, McClellanville, SC 33°2'17.93"N, 79°33'39.04"W Dec 2008

Figure 1: Map of 82 sites on survey (See Table 1)

Results

Mytella charruana

The search for Mytella charruana began in June 2006. The survey at that time consisted of 48 sites located in the Indian River Lagoon (Table 1). During this survey, M. charruana was found at only one site (43) which is near Mosquito Lagoon (Table 2, Figure 2).

Mytella charruana was not seen again until the December 2007 survey. The charru mussel was discovered at 7 sites with the southernmost site located in Jacksonville, Florida (53) and the northernmost site located in Richmond Hill, Georgia (73)(Table 2, Figure 2).

During the June 2008 survey, Mytella charruana had expanded its range considerably within the survey sites. Mytella charruana occupied 14 sites on the survey beginning with the same southernmost site in Jacksonville, Florida (53) and ending at the northernmost site in Thunderbolt, Georgia (77)(Table 2, Figure 2). The charru mussel was discovered at eight sites not previously occupied on previous surveys. Of all the sites with populations during the December 2007, only one site (73) was lacking mussels. The difference between populated sites from December 2007 and June 2008 reflected that Mytella charruana had expanded its range and population densities.

Mytella charruana was documented at 17 survey sites in December 2008. The southernmost site was located in Jacksonville, Florida (45) and the northernmost site was located in Thunderbolt, Georgia (77) (Table 2, Figure 2). There were 6 sites in which the charru mussel had not been previously documented prior to the December 2008 survey, and the remaining 11 of the 17 sites had populations during the previous survey (Table 2, Figure 2). The southern range of Mytella charruana had increased since the previous survey, and the populated sites between the northernmost and southernmost sites had increased. The newly populated sites reflected that the charru mussel had continued to colonize new locations since the last survey.

In June 2009, Mytella charruana was present at 12 sites on survey, which is a large reduction in range compared to the previous December 2008 survey (Table 2, Figure 2). Of the 12 sites with M. charruana present, all were sites that had previously documented the presence of the species. Eleven of the 12 sites were populates during the previous survey except site 62, which had populations present in June 2008 but not December 2008. The southernmost site was located in Jacksonville, Florida (54) and the northernmost site was located in Richmond Hill, Georgia (77) (Table 2, Figure 2). The southernmost site was the farthest north to date, but the northern site had remained the same since June 2008. The June 2009 survey marked the first decrease in the species range since the survey began.

Mytella charruana was discovered at 20 sites during the December 2009 survey. Both the southernmost site (43) and the northernmost site (77) (Table 2, Figure 2) were previously documented to be the most southern and northern sites to support charru mussel populations. There were two sites on the December 2009 survey in which M. charruana had not been discovered previously (50,66)(Table 2, Figure 2), which indicated that the mussel was spreading to new locations. Ten of the 18 previously populated sites had charru mussels present during the June 2009 survey, and the remaining 8 sites had populations during other preceding surveys. The December 2009 survey suggested that Mytella charruana recovered its range and populations density from the previous year (Table 2, Figure 2).

In June 2010, one site in St. Helena, South Carolina (79) was added to the survey (Table 1). Mytella charruana was present at only four sites on the survey (Table 2, Figure 2). The southernmost site was located in Jacksonville, Florida (54), and the northernmost site was located in Brunswick, Georgia (66) (Table 2, Figure 2). Each of those four sites had been occupied by the species during the previous survey (Table 2, Figure 2). This survey confirmed that M. charruana had experienced a large decline in range and population density especially when compared to the previous survey. Excepting June 2006, the charru mussel had its smallest recorded range on the survey during June 2010.

The following survey in December 2010 showed Mytella charruana was present at 9 sites (Table 2, Figure 2). The southernmost site was in New Smyrna Beach, Florida (45) and the northernmost site was located in Woodbine, Georgia (63) (Table 2, Figure 2). The charru mussel had regained some of its range, but all sites with populations had been previously colonized during previous surveys. Despite Mytella charruana recovering its populations slightly since the June 2009 survey, but the range was still limited compared to December 2009.

Table 2: Mytella charruana: Dec 2006 and June 2007 omitted due to zero findings during surveys. Count per unit measured as number of live individuals found divided by minutes searched. See Table 1

Site June Dec June Dec June Dec June Dec 2006 2007 2008 2008 2009 2009 2010 2010 43 0.05 - - - N/A 0.05 - - 45 - - - 0.70 N/A - - 0.02 50 N/A N/A N/A N/A - 0.05 - - 52 N/A - - 30.35 - - - - 53 N/A 0.45 1.30 - - 0.15 - 4.34 54 N/A 3.30 5.20 3.48 2.75 10.45 0.10 7.09 55 N/A 9.50 7.10 29.10 9.75 0.45 - 24.08 56 N/A - 0.15 0.40 - 2.05 0.05 5.70 57 N/A - 0.30 0.30 - 0.05 0.05 7.45 58 N/A - - 0.81 - 0.4 - 0.15 59 N/A - 0.85 1.80 1.2 0.7 - 4.00 60 N/A - - 1.60 0.2 4.6 - - 61 N/A - 0.30 1.62 2.33 0.8 - - 62 N/A - 0.05 - 0.25 0.55 - - 63 N/A 1.40 1.0 0.25 0.05 4.55 - 0.05 65 N/A - - 0.61 0.4 - - - 66 N/A - - - - 0.3 0.05 - 71 N/A 0.70 4.1 0.70 0.15 0.625 - - 72 N/A 3.70 6.40 4.89 0.05 13.35 - - 73 N/A 14.30 - - - 0.2 - - 74 N/A - 1.15 - - 0.0625 - - 75 N/A - 0.15 1.80 1.06 0.05 - - 76 N/A - - 0.10 - - - - 77 N/A - 2.55 0.50 1.0 0.05 - - Total 1 7 14 17 12 20 4 9

Figure 2: Map of sites with Mytella charruana 2006-2010 (See Table 2)

Perna viridis

During the June 2008 survey, P. viridis was discovered at 8 sites (Table 3, Figure 3). The southernmost site in New Smyrna Beach, FL (44) and northernmost site in St. Marys, Georgia (61) (Table 3, Figure 3) indicated that the Asian green mussel had a smaller but overlapping range with Mytella charruana (Table 2).

In December 2008, P. viridis was recorded at 7 sites on the survey. Out of those 7 sites, one site had not been colonized the preceding survey (46) (Table 3, Figure 3). The southernmost site shifted to a more northern site in New Smyrna Beach, Florida (45), but the northernmost site remained constant from the previous survey (61) (Table 3, Figure 3). Overall, the range of the Asian green mussel did not vary much between June 2009 and December 2008.

During the June 2009 survey, Perna viridis was found at 7 sites, but the range had shifted. The southernmost site was located in St. Augustine, FL (49), which had been added as a site during that survey (Table 1, Table 3, Figure 3). The northernmost site was found in St. Marys, Georgia (62), which was farther north than the previous northern site (Table 3, Figure 3). One of the 7 sites was newly colonized, which was the northernmost site (62). The remaining 4 sites each had populations during the previous survey. The June 2009 survey showed that Perna viridis had shifted its range north.

In December 2009, the Asian green mussel was present at 5 sites on the survey (Table 3). Each of the five sites had supported populations during previous surveys. The most southern site with P. viridis present was in New Smyrna Beach, Florida (45), and the most northern site was Jacksonville, Florida (58) (Table 3, Figure 3). The range of Perna viridis shifted south and the range of the species had been reduced compared to previous surveys.

Perna viridis was found at only 2 sites in June 2010. The southernmost site was also a newly colonized site located in Cocoa, Florida (32) (Table 3, Figure 3). The northern site had sustained populations during previous surveys and was located in St. Augustine, Florida (50) (Table 3, Figure 3). Perna viridis displayed the most diminished range during the June 2010 survey. This noticeable reduction in the species range coincided with the reduced range of Mytella charruana during the same survey.

In December 2010, P. viridis was found at 5 sites on the survey. Of those 5 sites, each had been colonized in previous surveys (Table 3, Figure 3). The southernmost site was located in Cocoa, Florida (32) and the northernmost site was found in Jacksonville, Florida (58) (Table 3, Figure 3). The Asian green mussel recovered its range to previous sites, but was not able to colonize new sites between June and December 2010.

Table 3: Perna viridis: Count per unit measured as number of live individuals found divided by minutes searched. See Table 1

Site June Dec June Dec June Dec 2008 2008 2009 2009 2010 2010 32 - - - - 0.1 0.10 44 0.15 - - - - - 45 1.35 0.16 N/A 0.033 - 0.06 46 N/A 0.05 - - - - 49 N/A N/A 0.4 - - - 50 N/A N/A 3.4 1.05 1.0 1.35 54 0.10 - - - - - 56 0.90 1.20 0.7 0.35 - - 57 2.00 1.30 3.33 0.55 - 0.65 58 3.40 1.25 2 0.3 - 0.10 59 0.55 0.80 0.6 - - - 61 0.05 0.05 - - - - 62 - - 0.4 - - - Total 8 7 7 5 2 5

Megabalanus coccopoma

During the June 2008 survey, M. coccopoma was found at 5 sites on the survey (Table 4, Figure 4). The most southern site was located in Cape Canaveral, Florida (30), and the most northern site was located in Jacksonville, Florida (59) (Table 4, Figure 4). At the time of the survey, the acorn barnacle had the southernmost range of the three species.

In December 2008, M. coccopoma was discovered at 5 sites on the survey (Table 4, Figure 4). Three sites were newly colonized on the survey (42, 43, and 47) and all those sites were located in New Smyrna Beach, FL (Table 4). Site 42 in New Smyrna Beach, Florida was the most southern site with populations, and the northernmost site was also in New Smyrna Beach (48) (Table 4, Figure 4).

During the June 2009 survey, Megabalanus coccopoma was discovered at 3 sites on the survey. All three sites did not have populations previously documented during previous surveys (Table 4, Figure 4). The southern site of the range was located in Ft. Pierce, Florida (10) and the northern site was located in Cocoa, Florida (32) (Table 4, Figure 4). The June 2009 survey indicated the smallest and most southern range of the acorn barnacle since the species was added to the survey.

Megabalanus coccopoma occupied 9 sites on the December 2009 survey. Out of those 9 sites, 3 sites had not been previously populated during other surveys (Table 4, Figure 4). The southern range began at site 16 in Sebastian, Florida and ended at the northern site 65 Thalmann, Georgia. Site 65 was also one of the newly populated sites. Based on the December 2009 survey, Megabalanus coccopoma expanded its range north and occupied new sites within the previous range.

Figure 3: Map of sites with Perna viridis from 2006-2010

In June 2010, M. coccopoma populated 9 sites on the survey. One site located in St. Marys, Georgia (61) was the only newly populated site on the survey (Table 4, Figure 4). The remaining sites had all sustained populations during previous surveys. The southernmost site was located in Ft. Pierce, Florida (10) and the northernmost site was also the newly colonized site (61) (Table 4, Figure 4). During the June 2010 survey, it was discovered that the ranges of Mytella charruana and Perna viridis were greatly reduced, but Megabalanus coccopoma had a fairly constant range from the previous survey.

In December 2010, the acorn barnacle was discovered at 8 sites on the survey. The southernmost site was located in Ft. Pierce, Florida and was also a newly colonized site (9) (Table 4, Figure 4). The remaining 7 sites each had sustained populations during previous surveys. The northernmost site was located in Jacksonville, Florida (58), which indicated that the range of M. coccopoma had been shifted south. Overall, the range of Megabalanus coccopoma was similar to that of the previous survey.

Table 4: Megabalanus coccopoma: Count per unit measured as number of live individuals found divided by minutes searched. See Table 1

Site June Dec June Dec June Dec 2008 2008 2009 2009 2010 2010 9 - N/A - - - 0.25 10 - - 1.01 - 0.3 - 16 - - 0.08 0.75 0.95 0.50 30 0.15 - - - 0.3 0.90 32 - - 0.15 0.25 0.05 - 42 - 0.05 - 0.05 - - 43 - 0.09 N/A 0.05 - - 45 1.70 0.12 N/A 0.5 0.1 0.18 47 - 0.1 N/A - - N/A 48 1.50 0.30 N/A N/A - 6.25 50 N/A N/A - 1.55 0.15 0.60 57 0.50 - - 0.05 0.05 0.15 58 - - - 0.35 0.7 0.20 59 0.35 - - - - - 61 - - - - 0.05 - 65 - - - 0.1 - - Total 5 5 3 9 9 8

Figure 4: Map of sites with Megabalanus coccopoma from 2008-2010

Discussion

The three non-native species Mytella charruana, Perna viridis, and Megabalanus coccopoma have each been present along the southeastern coastline throughout the duration their induction to the biannual survey. The persistence of each species at the same locations over multiple years supports that the species maintain viable populations and are well-established in the United States (Boudreaux, Gillis 2006). Each species has a range that overlaps with the other species, which indicates that the three species are capable of living on similar substrate and are able to tolerate the same salinity and temperature levels. The establishment of the three non- native species could be a result of both well-adapted individuals and continual reintroduction (Gillis 2009). Reintroduction could explain why certain sites on the survey tend to support higher densities of species compared to other sites that are further from points of introductions.

Mytella charruana

The presence of Mytella charruana in the Indian River Lagoon in 2004 was a great concern (Boudreaux and Walters 2006). The survey sites dedicated to the Indian River Lagoon have shown little presence of the charru mussel, which could indicate that M. charruana has not been introduced to most of the lagoon. This assumption is substantiated by the evidence that Mytella charruana has yet to be found on the survey south of New Smyrna Beach, FL.

Sites north of New Smyrna Beach, FL have been more successful in supporting populations of M. charruana possibly due to multiple reintroductions to Jacksonville, FL ports. The Gulf Stream moves north along the eastern United States coast, so the dispersal of larvae southward may not be likely. This could be an explanation as to why Mytella charruana is not found south of New Smyrna Beach.

The range of M. charruana crashed in June 2009 and June 2010. The crashes may be explained by extreme weather temperatures. Mytella charruana is a tropical species, and thus it may be sensitive to cold temperatures. The winter of 2009/2010 was particularly cold, which could explain why the June 2010 crash was so much larger than the June 2009 crash. Of the three non-native species observed in this study, Mytella charruana has the northernmost range, which could indicate that the charru mussel was most affected by the cold.

Perna viridis

The Asian green mussel has a more southern range compared to the charru mussel. The areas with the highest population densities have been in Jacksonville, FL and St. Augustine, FL. St. Augustine, FL has been the most successful in maintaining populations, which could be due to reintroductions in the city’s ports. Perna viridis has been found as south as Cocoa, FL which could indicate that the mussel has been introduced at more southern ports than Mytella charruana. In the winter months of December 2009 and January 2010, the south eastern United States experienced a cold snap with record-low temperatures. The cold snap came into effect shortly after the December 2009 survey was completed, and at the time. Perna viridis suffered a noticeable decline its range just as Mytella charruana had. Perna viridis may be more cold intolerant than M. charruana since the species experienced a range crash despite having a more southern range (Baker 2007).

Megabalanus coccopoma

Megabalanus coccopoma has seen high densities of populations in many locations in Florida including St. Augustine, New Smyrna Beach, Sebastian, and Ft. Pierce. This could be due to a more southern introduction of the species (although the first documented east coast introduction in Florida was in St. Augustine). Megabalanus coccopoma was not significantly affected by the cold snap in the winter of 2009/2010. The species did not see a decline in its range and actually maintained the total number of sites from the previous survey. This could be because M. coccopoma has the southernmost range of the three non-native species because the species is rarely found north of Florida. Another explanation could be that the acorn barnacle is more cold tolerant than the other two species.

It is difficult to determine whether the non-native species in this study are incurring a negative impact on the colonized environments. It is possible that these species are currently in a lag period and will eventually cause damage, or the impact is too slight or non-existent. In either case, the presence of the species is an alteration of the natural biodiversity of the colonized areas, and therefore, documenting the presence and abundance of these species will allow us to acknowledge these changes. Regardless if the species increase or reduce diversity, it is clear that human interference is responsible for the alteration of natural .

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ACKNOWLEDGMENTS

Partial support for this work was provided by the National Science Foundation Scholarships in Science, Technology, Engineering, and Mathematics (S-STEM) program under Award No. 0806931. Any opinions, findings, and conclusions and recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Partial support for this work was also provided by the UCF Office of Research and Commercialization.