Could Fish Feeding Behaviour and Size Explain Prevalence Differences of the Nematode Eustrongylides excisus among Species? The Case Study of Lake Garda

Abstract

The nematode Eustrongylides excisus is a parasite of freshwater fish- and fish-eating birds, with known differences on prevalence values among fish species. Thus, the present study aims to explore the hypothesis that the feeding behavior and the size of fish belonging to different trophic levels could explain such differences. For that, 14 sampling sites were selected to perform a fish parasitological survey on Lake Garda (Italy) during spring-summer 2020. Amplification of nuclear ribosomal internal transcribed spacer (ITS) rDNA sequences of nematodes morphologically ascribable to the genus Eustrongylides allowed to identify them as E. excisus. From the five studied fish species (Perca fluviatilis, Lepomis gibbous, Coregonus lavaretus, Alosa fallax lacustris and Micropterus salmoides), only three presented the parasite E. excisus: P. fluviatilis, L. gibbous and M. salmoides, with significant differences in prevalence values among species (p = 0.002). Additionally, there were differences in prevalence values within the same fish species captured from different sampling sites. Findings showed that mainly piscivorous fish were positive for E. excisus and how the prevalence was highest in M. salmoides. As regard the fish size, a negative correlation between body size and E. excisus was found in P. fluviatilis due to the feeding habit of juvenile perch which feed mainly zooplankton and benthic invertebrates (i.e., oligochaetes, which are the first intermediate hosts of E. excisus). The study findings advance novel knowledge in the field of pathogens of zoonotic importance in the aquatic environment.

<i>Eustrongylides</i> spp. parasite risk management in <i>Atherina boyeri</i> from Lake Trasimeno

“…favor oligochaete population growth, as confirmed by Goncharov et al ( 2018 ). Nevertheless, despite an increasing prevalence rate starting from 2016 registered in sand smelt up to 2021 (Franceschini et al , 2022 ), in the last two years, the prevalence of infested hosts has decreased remarkably even though the cormorant population has remained stable or even increased ( Table 1 ) (Dezfuli et al , 2015 ; Branciari et al , 2016 ; Agnetti et al , 2019 ; Covelli, 2019 ; Mazzone et al , 2019 ; Parco Valle Lambro, 2019 ; Menconi et al , 2020; Guardone et al , 2021 ; Menconi et al , 2021 ; Franceschini et al , 2022 ; Rusconi et al , 2022 ; Castiglione et al , 2023 ). Generally, eutrophication and warm water temperatures create optimal conditions for the parasite.…”

“…The primary causes of the increase in the incidence, geographic distribution, and frequency of zoonotic fish-related health issues are climate change and the rising demand for exotic, raw, and undercooked foods (Lohmus and Björklund, 2015 ; Shamsi and Sheorey 2018 ). In light of some wellknown parasitic zoonoses, researchers have recently focused on the propagation of Eustrongylides , a nematode found in many Italian and worldwide freshwater basins (Menconi et al , 2020; Guardone et al , 2021 ; Menconi et al , 2021 ; Franceschini et al , 2022 ; Morey et al , 2022 ; Rusconi et al , 2022 ; Honcharov et al , 2022 ). Albeit few medical reports have been observed, Eustrongylides spp.…”

“…Its existence in the same lake was later observed in other commercially important fish species (Branciari et al , 2016 ; Franceschini et al , 2022 ). The parasite has recently been found in fish from various lakes in northern Italy and two lakes in central Italy ( Table 1 ) (Dezfuli et al , 2015 ; Branciari et al , 2016 ; Agnetti et al , 2019 ; Covelli J, 2019 ; Mazzone et al , 2019 ; Parco Valle Lambro, 2019 ; Menconi et al , 2020; Guardone et al , 2021 ; Menconi et al , 2021 ; Franceschini et al , 2022 ; Rusconi et al , 2022 ; Castiglione et al , 2023 ).…”

Helminth Communities of Common Fish Species in the Coastal Zone off Crimea: Species Composition, Diversity, and Structure

“…Other significant factors driving fish parasite faunas are characteristics of the locality, predator–prey relationships, relationships between different phylogenetic groups of parasites, and stochastic processes across multiple scales and intensities [ 41 ]. The importance of the host size has been confirmed in many studies [ 42 , 43 , 44 , 45 , 46 , 47 , 48 ], although others have revealed no clear relationships with the host size [ 17 , 49 ].…”

First Report of Proteocephalus longicollis (Zeder, 1800) in Alosa fallax lacustris (Fatio, 1890) from Lake Garda (Italy): Morphological and Molecular Study

“…Among them, the presence of Diphyllobothrium latum (Linnaeus, 1758) has been studied by Gustinelli and colleagues [ 15 ], reporting no positivity for plerocercoid larvae in A. fallax lacustris from four big lakes in the north of Italy. According to Menconi et al [ 16 ], the presence of the nematode Eustrongylides excisus (Ägerskiöld, 1909) has been investigated in A. fallax lacustris from Lake Garda, with only negative results. In Europe, the genus Alosa has been investigated for parasites, considering mainly anadromous and marine species such as Alosa alosa (Linnaeus, 1758) and A. fallax nilotica; a study carried out by Bao et al [ 17 ] reported the presence of Anisakis simplex (Rudolphi, 1809) and Anisakis pegreffii (Campana-Rouget & Biocca, 1955) in both A. alosa and A. fallax lacustris from the Western Iberian Peninsula Rivers.…”