Metacercariae stage of the trematode develops in crustacean or fish

Adult worms are ingested and infect mammals or birds

Eggs expelled in feces

Free-swimming life stage - Miracidium

Adult worms

Free-swimming life stage - Cercariae

Miracidiae stage of the trematode enters

Melanoides tuberculatus and larvae develop

Proper food preparationstops cycle here for humans

Generalized life cycle of trematodes that can infect Melanoides tuberculatus, or other species of aquatic snails. Hosts may differ at each stage depending on the species of trematode. Trematodes may include Clonorchis sinensis, Opisthorchis spp. (liver flukes) and Paragonimus westermani (lung fluke). Melanoides is also an intermediate host for multiple parasites on waterfowl; Philophthalmus megalurus affects the eyes of birds. As an intermediate host for Centrocestus formosanus, Haplorchis spp. fish, crustaceans, and some mammals can be affected. Proper food preparation methods are important because the metacecaria stage of these trematodes can survive some food preparation methods such as smoking and salt curing.

1 mm

Location of sites where Melanoides tuberculatus (alive and shell debris) were found during field surveys conducted between October 2004 and July 2007. Inset at upper left part of transect at Black Point. Base image is a Landsat Mosaic Orthoimage obtained from the USGS EROS Data Center.

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Graph showing salinity during a six week experiment to test the resilience of Melanoides tuberculatus to increas-ing salinity. Starting point salinity was <5 parts per thou-sand (ppt) dissolved salts. Salinities in tanks B and C were gradually increased to determine the effects on M. tuberculatus, while tank A was maintained at approxi-mately 5ppt as a control. All 30 adults place in each tank survived and juveniles appeared in tanks B and C, con-firming that the freshwater snail M. tuberculatus is adapt-ing to estuarine conditions. Experimental tanks illustrated below.

What is Melanoides tuberculatus? Melanoides tuberculatus is a snail species.

commonly known as Red-rimmed Melania.in the snail family Thiaridaefound in Biscayne National Park by the authors in 2003native to subtropical regions of Africa and Southeast Asia

Research QuestionsIs this species a danger to human health?How wide-spread is it within the park?What factors control the distribution of the species?Is its presence a threat to native animal populations?

GOAL OF RESEARCH: Began study in 2004 to map distribution of Melanoides within Biscayne National Park and to address the issues of effects on humans and native biota.

RESEARCH ACTIVITIES:map the distribution of the speciesanalyze DNA to determine number of introductionsconduct experiments on environmental tolerancesdetermine if parasites are present, and if yes what types

Biscayne National Park

Known distribution of Melanoides tuberculatus as of April,2006; the non-native snail is likely to have expanded its range from the areas shown. Map courtesy of A.J. Benson, USGS, adapted from http://nas.er.usgs.govquerries/specieslist.asp?group=mollusks

How did Melanoides get here?

Melanoides tuberculatus is native to tropical and subtropical regions of Africa and Asia (Clench, 1969). Specifics of how and when Melanoides got to the US are not known, but Murray (1971) and Roessler and others (1977) believe it was through the aquarium trade. The species was first reported in Arizona in the 1950s (Murray, 1971; Dundee, 1974) and in south Florida in 1971 (Russo, 1973). By 1977, it had reached areas adjacent to Biscayne Bay (Roessler and others, 1977). The known distribution of the species in the United States is shown in map above.

Why be concerned about Melanoides tuberculatus? 1) Human health issues2) Animal health issues3) Potential displacement of native species

What is the Distribution of Melanoides within Biscayne National Park?WHERE ARE WE FINDING Melanoides?

Both living Melanoides tuberculatus and shell debris have been found near canal mouths and in the nearshore areas in Biscayne National Park (Map at right and Figure below). Highest concentrations of live and dead shells were in the vicinity of Black Point. Field surveys in 2004 and 2006 show that M. tuberculatus are becoming increasingly abundant at Black Point (Figure below).The estimated number of M. tuberculatus per square meter approaches 60,000 on the Black Point transect at site TR4, which is about 500 meters offshore.

HOW MANY TIMES HAS Melanoides BEEN INTRODUCED?Analysis of mitochondrial DNA from samples from Black Creek Canal (C-1) and site TR2 on the Black Point transect show that the two populations are indistinguishable. These results suggest the population at Black Point is the result of a single introduction of one clonal type of M. tuberculatus.Numbers shown in Figure below illustrate how rapidly this species is spreading from a single introduction, and indicate the level of care necessary to prevent the release of non-native species.

This project was funded by the U.S. Geological Survey Geology Venture Capital Fund for 2007. The work was done in cooperation with Biscayne National Park.

Acknowledgements For additional information on south FL research refer to: http://sofia.usgs.gov or the Factsheet at http://pubs.usgs.gov/fs/2008/3006/Data for this project are available at:http://sofia.usgs.gov/exchange/flaecohist/

Why is the presence of Melanoides of particular concern in south Florida?Conditions in south Florida are favorable for the parasitic life cycle shown in figure above:1) Potential snail, fish, and crustacean hosts present in large numbers. 2) Many activities bring people and animals in contact with the hosts.

Fish and shellfish popular food sources in region; sometimes eaten raw or undercooked. 1990 to 2000, Florida had highest incidence in nation of illness caused by ethnic food (Simonne and others, 2004). Water birds and small mammals, such as raccoons, frequent shoreline to feed on crabs, fish, and invertebrates. Fishing, swimming, and other water sports bring people in to contact with the water.

3) Exposure to potentially infected untreated human waste a concern in area underlain with porous limestone and where septic tanks account for approximately 21% of the waste disposal.

Expanding range and adaptation of the species:1) Climate of south Florida similar to that of southeast Asia where M. tuberculatus is native, increasing likelihood of spread of Melanoides and displacement of native south Florida species.2) As climate change occurs, Melanoides will likely continue its spread geographically.3)3) Estuarine and marine adaptations have increased its range.

Resource managers and the general public need to be aware of this non-native/invasive snail and take steps to prevent its spread and additional introductions.

What factors are controlling the distribution of Melanoides within Biscayne National Park?

In its native habitat, Melanoides tuberculatus is considered primarily a freshwater species; however, in south Florida, it is adapting to estuarine salinity conditions (Russo, 1973; Roessler and others, 1977).

Collected live in Biscayne Bay at just under normal marine salinity (up to 33 parts per thousand (ppt) dissolved salts). Salinity tolerance experiments have demonstrated the ability of the species to survive and reproduce in high salinities (Figure at right).None of the original adult specimens died as salinity was gradually increased during the 6-week-long experiment.Juveniles appeared during the second week and survived, even though one tank reached extreme conditions (45 ppt, higher than normal marine salinity).

Although experimental results such as these may not translate directly to the natural environment, they indicate that the population of M. tuberculatus in Biscayne Bay is no longer restricted to freshwater.

Other environmental factors such as temperature, oxygen levels, and substrate need further investigation.

Temperature appears to be a limiting factor; not surprising as the natural range is tropical to subtropical.

Murray (1971) found that Melanoides tuberculatus are restricted to waters between 64 and 77 F (18 -25 C). Mitchell and Brandt (2003) conducted a series of experiments and found that M. tuberculatus could not survive in water dropping to 59 F (15 C) for more than one month, or waters that drop below 50 F (10 C) for more than two days. All snails in experimental tanks died within minutes when water reached 113 F (45 C) and within 8 days when water reached 104 F (40 C). Our experimental results to date support these findings. In Biscayne Bay, temperature is not likely to be a limiting factor because water temperatures range between 95 and 63 F (35 -17 C).

Mitchell (2005) reports that M. tuberculatus are resistant to desiccation and Neck (1985) that they are resistant to low oxygen levels.

1cm

From BNPFrom BNP

From BNPFrom BNP 80°15' W80°20' W80°25' W

25°35' N

25°30' N

25°25' N

Transect at Black Point follows channel out from shore

From BNPFrom BNP

Department

of the Interior

NATIONALPARK

SERVICEThe Non-Native Red Rimmed Melania (Melanoides tuberculatus) in Biscayne Bay National Park, Florida, the Geographic Distributionand Potential Health Threats. James B. Murray, G. Lynn Wingard, William B. Schill

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4128

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63042551 696 464

192627,913

135719,667

3965739

Distance from shore at Black Point

TR1 TR2 TR3 TR4 TR5

Raw counts of Melanoides tuberculatus, live and dead, collected in 2004 and 2006 along a transect from Black Point. Black num-bers are the actual counts retrieved from three bottom grab samples (using a petite ponar device) at each site. Red num-bers represent estimates of the numbers of individuals per square meter based on the raw counts.

2006ed #/m2

00410/12/2

Estimat

From BNPFrom BNP