Larval digenean preferences in two sympatric snail species at differing tidal levels off the Atlantic coast of Patagonia

DI GIORGIO, G.; GILARDONI, C.; BAGNATO, E.; CREMONTE, F.; ITUARTE, C.

JOURNAL OF HELMINTHOLOGY

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2017 vol. 91 p. 696 - 702

0022-149X

Larval stages of the trematodes Maritrema madrynense and Hemiuroidea fam.gen. et sp. differentially parasitized Siphonaria lessonii and S. lateralis, two sympatric pulmonate snail species on the rocky intertidal shore at Puerto Deseado,south-western Atlantic coast of Patagonia, Argentina. Snail specimens were collectedat two sampling sites with contrasting physical?chemical characteristics.One site, in the upper intertidal, was exposed to sewage from fish-processingplants, greater hydrodynamic forcing and desiccation, a wider temperaturerange, longer exposure to ultraviolet radiation and higher abundance of birds.The second site, in the lower intertidal, was generally characterized by less stressful environmental conditions. At both sites, S. lateralis showed a markedly higher density than S. lessonii (55.13 vs. 5.87 snails/m2, respectively). Despite this, the prevalence of both digeneans was higher in S. lessonii (17.37% and 3.52% for M. madrynense and Hemiuroidea, respectively) than in S. lateralis (0.09% and0% for M. madrynense and Hemiuroidea, respectively). This study demonstrateshigh parasite specificity for the host. Low densities of S. lessonii are attributed to castration of parasitized hosts and reduction of their physiological condition. The prevalence and intensity of infection of both digenean parasites were higher atthe more stressful, upper intertidal site, thus suggesting that a higher abundanceof birds and exposure to sewage pollution may promote the transmission oftrematodes.