Temporal variations of larval digenean assemblages parasitizing Heleobia parchappii (Mollusca: Cochliopidae) in two shallow lakes from the Buenos Aires province, Argentina

Abstract

The larval digenean assemblages in snail hosts are influenced by biotic and abiotic factors and by environmental disturbances due to human activities. Given their susceptibility to different types of impact, they can be useful tools for the study of temporal variations in parasite communities. The study of temporal dynamics in prevalence and species richness of larval digenean assemblages of Heleobia parchappii (D'Orbigny, 1835), in two Pampean lakes, provides a good opportunity to test the supposition that seasonal variations in digenean assemblages are determined by a series of biotic and abiotic factors that operate interdependently. To analyze the temporal variations, and to evaluate how local factors influence these digenean assemblages in Los Padres and La Brava lakes (Buenos Aires province, Argentina), 2,400 specimens of H. parchappii were collected seasonally, during one year. The digenean assemblages in Los Padres and La Brava lakes were composed of 13 and 12 species respectively. These larval digenean assemblages showed similarities in the number and in the seasonal frequency of occurrence of species (eight of which were present in both lakes). However, despite these similarities, the assemblages showed different temporal dynamics in La Brava and Los Padres lakes and, also, different correlations with the abiotic and biotic factors analyzed during this study (temperature, high of the water column and snail relative abundance). Temporal dynamics in prevalence and species richness of larval digenean assemblages of H. parchappii in both lakes seems to be influenced by a series of factors (diversity and abundance of definitive hosts, intermediate and definitive host location, snail relative abundance and anthropogenic disturbances). Our results highlight the importance of analyzing the role and interaction of local factors, especially in studies dealing with spatiotemporal fluctuations or with distance decay of similarities in species richness of parasite assemblages.

Spatio-temporal variations in larval digenean assemblages ofHeleobia parchappii(Mollusca: Cochliopidae) inhabiting four human-impacted streams

“…Kuris & Lafferty, 2005; Rifkin et al ., 2012; Buck & Lutterschmidt, 2017). In the case of H. parchappii , it was three times more abundant in coastal streams than in nearby shallow lakes (Merlo, 2013; Merlo et al ., 2019). Differences in relative abundances of H .…”

“…Several studies have already emphasized the influence of these factors on the structure of parasite assemblages at different spatial scales (see Blanar et al ., 2016). However, it should be mentioned that human disturbances derived from urbanization, land use or recreational activities seem to play an important role in the spatio-temporal variations of larval digenean assemblages in streams, as they do in shallow lakes of the area (Merlo et al ., 2019). Our results reinforce the idea that parasites can be key indicators to gauge the impact of environmental disturbances on animal communities.…”

“…The snail Heleobia parchappii (d'Orbigny, 1835) (Gasteropoda: Cochliopidae) is one of the most representative species of the genus in freshwater bodies (streams, rivers and shallow lakes) in Argentina, Uruguay and Brazil (Gaillard & De Castellanos, 1976; Castellanos & Landoni, 1995). From a parasitological point of view, this host is very interesting since it serves as host for at least 25 digenean species in Argentina, which make up species-rich digenean assemblages (Merlo, 2013; Merlo et al ., 2019). Moreover, the study of Merlo et al .…”

“…Moreover, the study of Merlo et al . (2019), carried out in human-impacted shallow lakes, made it possible to identify several factors determining the temporal variations of the digenean assemblages of H . parchappii .…”

Diversity and dynamics in larval digenean assemblages parasitizingHeleobia parchappiiin a freshwater shallow lake from the Southeastern Pampa plain, Argentina

“…In the last 20 years, much progress has been made to increase the knowledge of the diversity of digeneans in the lotic and lentic environments of Argentina, as well as their temporal and spatial dynamics in several mollusc hosts (Flores et al, 2010(Flores et al, , 2015Merlo and Etchegoin, 2011;Fernández et al, 2013;Parietti et al, 2013Parietti et al, , 2020Parietti et al, , 2021Merlo et al, 2019;among others). However, due to the large number of water bodies that cover the Argentine territory, we are still far away from having adequate knowledge of the diversity of digeneans and the factors that determine their distribution that allows us to perform robust macroecological and biogeographical studies.…”