Prevalence of infection with Pleurogonius malaclemys Hunter, 1961 (Trematoda: Digenea) in Tritia obsoleta (Say, 1822) (Gastropoda: Caenogastropoda: Nassariidae) in relation to environment quality

Penny Demetriades, e-mail:

Marine Academy of Technology and Environmental Science, 195 Cedar Bridge Road, 08050 Stafford Township, NJ, United States

Tritia obsoleta (Say) is a snail inhabiting estuarine mudflats and salt marshes along the Eastern Coast of the United States. It is the intermediate host of Pleurogonius malaclemys whose definitive host is the diamondback terrapin (Malaclemys terrapin terrapin). P. malaclemys forms dome-like cysts on the snail’s operculum. The study was aimed at observing differences in the snail’s physical parameters (shell height, thickness, and snail weight) under the effect of the environmental quality and the prevalence of P. malaclemys. Snails were collected, along with samples of water and bottom deposits, from two locations in Barnegat Bay, New Jersey. In the area with poorer quality of sediment and water, the prevalence of parasite’s cysts was significantly higher, and the shells were thinner and lower. Histological analyses revealed the presence of metacercariae and tissue anomalies. Increasing prevalence of the parasite was correlated with deteriorating ecosystem health, leading to a combined detrimental effect on the host. This study is a model of the repercussions of deteriorating habitat quality on host-parasite relationships, and the health of the organisms in question.

Key words
mud snail; Pleurogonius malaclemys; Malaclemys terrapin terrapin; shell composition; shell height; shell thickness; histology; habitat quality; parasite

Altman I. 2010. Trematode parasites of the mudsnail Ilyanassa obsoleta: an analysis of parasite communities at different scales. PhD Thesis, Dissertations 579, University of New Hampshire, Durham. Available online at (accessed 10 July 2020).
ATSDR (Agency for Toxic Substances and Disease Registry) 2004. Toxicological profile for strontium. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service. Available online at (accessed 20 February 2020).
Bejda A. J., Phelan B. A., Studholme A. L. 1992. The effect of dissolved oxygen on the growth of young-of-the-year winter flounder, Pseudopleuronectes americanus. Environmental Biology of Fishes 34: 321.
Berg L. R. 1941. The effect of varying levels of calcium intake on the calcium balance, shell thickness, and blood calcium level of White Leghorn pullets. Thesis, Kansas State College of Agriculture and Applied Science. Available online at (accessed 10 July 2020).
Bighiu M. A., Watermann B., Guo X., Almroth B. C., Eriksson-Wiklund A. K. 2017. Mortality and histopathological effects in harbour-transplanted snails with different exposure histories. Aquatic Toxicology 190: 11–20.
Burke R. L. 2016. Eastern mud snails with parasitic cysts. (accessed 10 July 2020)
Chodkowski N., Williams J. D., Burke R. L. 2016. Field surveys and experimental transmission of Pleurogonius malaclemys (Digenea: Pronocephalidae), an intestinal parasite of the Diamondback Terrapin Malaclemys terrapin. Journal of Parasitology 102: 410–418.
Cohen A. N. 2011. The exotics guide: non-native marine species of the North American Pacific Coast. Center for Research on Aquatic Bioinvasions, Richmond, CA, and San Francisco Estuary Institute, Oakland CA. Available online at (accessed 29 March 2019).
Curtis L. A. 1997. Ilyanassa obsoleta (Gastropoda) as a host for trematodes in Delaware Estuaries. Journal of Parasitology 83: 793–803.
Curtis L. A. 2009a. The gastropod Ilyanassa obsoleta as a resource: utilization by larval trematodes in a low-prevalence system. Journal of Parasitology 95: 799–807.
Curtis L. A. 2009b. Growth, trematode parasitism, and longevity of a long-lived marine gastropod (Ilyanassa obsoleta). Journal of the Marine Biological Association of the United Kingdom 75: 913–925.
Gustafson K. D., Bolek M. G. 2015. Effects of trematode parasitism on the shell morphology of snails from flow and nonflow environments. Journal of Morphology 277: 316–325.
Hunter W. S. 1967. Notes on the life history of Pleurogonius malaclemys Hunter, 1961 (Trematoda: Pronocephalidae) from Beaufort, North Carolina, with a description of the cercaria. Proceedings of the Helminthological Society of Washington 34: 33–40. Available online at (accessed 29 March 2019).
Johnson D. S., Short M. I. 2013. Chronic nutrient enrichment increases the density and biomass of the mudsnail, Nassarius obsoletus. Estuaries and Coasts 36: 28–35.
Lafferty K. D. 2009. The ecology of climate change and infectious diseases. Ecology 90: 888–900.
Mierzwa D. 2008. Chemical composition and structure of the shell of Cepaea vindobonensis (Férussac, 1821) (Gastropoda: Pulmonata: Helicidae) from localities of different substrata. Folia Malacologica 19: 97–101.
Moffitt C. M., James C. A. 2011. Dynamics of Potamopyrgus antipodarum infestations and seasonal water temperatures in a heavily used recreational watershed in intermountain North America. Aquatic Invasions 7: 193–202.
Osman W., El-Samad L. M., Mokhamer El-H., el-Touhamy A., Shonouda M. 2015. Ecological, morphological, and histological studies on Blaps polycresta (Coleoptera: Tenebrionidae) as biomonitors of cadmium soil pollution. Environmental Science and Pollution Research 22: 14104–14115.
Ragland P. C., Plikey O. H., Blackwelder B. W. 1969. Comparison of the Sr/Ca ratio of fossil and recent mollusc shells. Nature 224: 1223–1224.
Ren L. 2013. Baseline characterization of phytoplankton and harmful algal blooms in Barnegat Bay-Little Egg Harbor, New Jersey (Year One). Report prepared for NJDEP-Science and Research and New Jersey Sea Grant. Available online at (accessed 20 February 2020).
Roberts C. 2012. The ocean of life: the fate of man and the sea. Penguin Books, New York.
Rundle S. D., Spicer J. I., Coleman R. A., Vosper J., Soane J. 2003. Environmental calcium modifies induced defences in snails. Proceedings of the Royal Society B 271: 67–70.
Song Y., Zhou Q., Song X., Zhang W., Sun T. 2004. [Accumulation of pollutants in sediments and their eco-toxicity in the wastewater irrigation channel of western Shenyang] (in Chinese). Journal of Applied Ecology 15: 1926–1930.
Sures B., Nachev M., Stelbach C., Marcogliese D. J. 2017. Parasite responses to pollution: what we know and where we go in ‘Environmental Parasitology’. Parasites & Vectors 10: 65.
Tucker A. D., Yeomans S. R., Gibbons J. W. 1997. Shell strength of mud snails (Ilyanassa obsoleta) may deter foraging by Diamondback Terrapins (Malaclemys terrapin). The American Midland Naturalist 138: 224–229.

Folia Malacologica (2020) 28: 242-252
First published on-line: 2020-09-02 00:00:00
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