Impact of the cestodeTriaenophorus nodulosuson the exoticLepomis gibbosusand the autochthonousPerca fluviatilis

Abstract

The effects of plerocercoids of the cestode Triaenophorus nodulosus infecting the livers of native Eurasian perch Perca fluviatilis and non-native pumpkinseed Lepomis gibbosus was investigated in 17 sites along the Moselle watershed. With a single exception, infected individuals were not observed in the main channel whether or not northern pike Esox lucius, a final host, was present. In ponds where the pike was present, the prevalence of T. nodulosus averaged 86% in Eurasian perch and 15% in pumpkinseed. The parasite was not present at all in ponds when pike were absent. Parasite load, hepatosomatic index (HSI), gonadosomatic index (GSI) and body condition index (CI) were compared between hosts in one site where parasite prevalence and fish abundance was highest. HSI in infected perch was significantly higher than in uninfected perch, whereas no differences in HSI were detected between infected and uninfected pumpkinseed. While perch were more frequently infected and had a greater average parasite load than pumpkinseed, there were no significant differences in either indicator between the two species. Furthermore, no significant differences in GSI or CI were observed between infected and uninfected fish in either species, by either gender or maturity stage. We hypothesize that pumpkinseed is more resistant to the parasite or less likely to feed upon infected copepods than perch.

Limited parasite acquisition by non-native Lepomis gibbosus (Actinopterygii: Centrarchidae) at two ponds in the Upper Rhine basin, Germany

“…In accordance with Masson et al . (2015), who examined the effect of the cestode T. nodulosus on the health of L. gibbosus in France, there was no relationship between CI and overall or individual parasite abundance in this study. Indeed, a lack of parasitism impact on host condition has previously been documented in many fish host–metazoan parasite systems (e.g.…”

“…Although some of these parasites have a circumpolar distribution encompassing the centrarchid native range, it is assumed that they were acquired in the host's non-native range. Use of L. gibbosus as an intermediate host by the cestode T. nodulosus , and as a paratenic host by B. claviceps , has previously been documented in both its native (Hoffman, 1999) and introduced range (Košuthová et al ., 2009; Masson et al ., 2015 for T. nodulosus ; Aisa & Gattaponi, 1981 for B. claviceps ). The life cycle of T. nodulosus includes both cyclopoid copepods and a range of fish species as intermediate hosts, with esocid fish as definitive hosts (Kuperman, 1973).…”

“…Although L. gibbosus appears to be a competent host for this species, low infection intensities indicate potential resistance to this parasite, as also noted by Masson et al . (2015). The cosmopolitan species B. claviceps is a specific parasite of eels, although other fish species may serve as paratenic hosts, thereby representing a possible additional source of eel infection (Scholz, 1997).…”

“…Fobert et al ., 2013) throughout Europe in recent decades, knowledge regarding parasite communities in this widely established non-native species remains scarce (but see Hockley et al ., 2011 or Stoyanov et al ., 2018). The majority of parasite studies to date have focused on a single parasite species, either acquired (Stavrescu-Bedivan et al ., 2014; Masson et al ., 2015) or co-introduced (Rubtsova, 2015; Kvach et al ., 2017), or a select group of parasites such as endoparasites (Košuthová et al ., 2009), nematodes (Pilecka-Rapacz & Sobecka, 2008) or monogeneans (Sterud & Jørgensen, 2006; Havlátová et al ., 2015). In their native range, centrarchid fishes exhibit high parasite diversity, summarized in Hoffman (1999).…”

Parasitic versus nutritional regulation of natural fish populations

“…Infection level was categorized as defined above. The parasitic index (PI, Masson, Vanacker, Fox, & Beisel, ) was computed as PI = ( W p / W f ) × 100, W p being the total weight of cysts and W f the total weight of the individual fish, in g. A potential physiological effect of the parasite on YOY perch was also assessed through the hepatosomatic index (HSI, Masson et al., ) with = (( W l − W p )/ W f ) × 100, W l being the total weight of liver in g, including cysts in case of infection.…”