title: Larval digenean preferences in two sympatric snail species at differing tidal levels off the Atlantic coast of Patagonia.
abstract: 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 collected at two sampling sites with contrasting physical-chemical characteristics. One site, in the upper intertidal, was exposed to sewage from fish-processing plants, greater hydrodynamic forcing and desiccation, a wider temperature range, 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% and 0% for M. madrynense and Hemiuroidea, respectively). This study demonstrates high 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 at the more stressful, upper intertidal site, thus suggesting that a higher abundance of birds and exposure to sewage pollution may promote the transmission of trematodes.
authors.affiliation: Laboratorio de Parasitología, Instituto de Biología de Organismos Marinos (CCT CONICET-CENPAT),Bvd. Brown 2915,U9120ACF Puerto Madryn,Chubut,Argentina.
authors.forename: G
authors.initials: G
authors.lastname: Di Giorgio
authors.affiliation: Laboratorio de Parasitología, Instituto de Biología de Organismos Marinos (CCT CONICET-CENPAT),Bvd. Brown 2915,U9120ACF Puerto Madryn,Chubut,Argentina.
authors.forename: C
authors.initials: C
authors.lastname: Gilardoni
authors.affiliation: Laboratorio de Parasitología, Instituto de Biología de Organismos Marinos (CCT CONICET-CENPAT),Bvd. Brown 2915,U9120ACF Puerto Madryn,Chubut,Argentina.
authors.forename: E
authors.initials: E
authors.lastname: Bagnato
authors.affiliation: Laboratorio de Parasitología, Instituto de Biología de Organismos Marinos (CCT CONICET-CENPAT),Bvd. Brown 2915,U9120ACF Puerto Madryn,Chubut,Argentina.
authors.forename: F
authors.initials: F
authors.lastname: Cremonte
authors.affiliation: Museo Argentino de Ciencias Naturales,Av. Ángel Gallardo 470,C1405DJR,Buenos Aires,Argentina.
authors.forename: C
authors.initials: C
authors.lastname: Ituarte
mesh_terms: D000818:Animals; D001118:Argentina; D058507:Host Specificity; D007814:Larva / Q000502:physiology; D012908:Snails / Q000469:parasitology* / Q000502:physiology; D061350:Sympatry; D014200:Trematoda / Q000502:physiology*