Parasite fauna of introduced pumpkinseed fish Lepomis gibbosus: first British record of Onchocleidus dispar (Monogenea)

Abstract

A survey of pumpkinseed Lepomis gibbosus from a stillwater fishery in southern England revealed infections by the ancyrocephalid monogenean Onchocleidus dispar at 100% prevalence. Host specificity of O. dispar to North American centrarchid fish suggests that it is a non-native parasite, introduced to Britain with L. gibbosus. Mean intensity of O. dispar was significantly higher in male (25.5 parasites) compared to female (15) and immature (7) hosts, but was not influenced by host standard length or sampling time. This sex-biased parasitism is likely to be related to both ecological and physiological factors, such as differential exposure to infective stages during nest building, or higher susceptibility to infection due to enhanced host stress levels. O. dispar significantly dominated the external surfaces and the outer gill arches. Analysis of the spatial distribution of the parasite between the 9 regions of gill surface determined that as density increased, higher numbers of parasites were found on the anterior and central gill regions compared to posterior (distal) regions. Apparent microhabitat selection is discussed in terms O. dispar lifecycle, maximising oxygen availability, avoiding unstable areas and increasing intraspecific contact. The absence of O. dispar in the gills of roach, rudd and gudgeon sampled from the same fishery supports the assumption that this parasite is currently of little threat to native fish populations. KEY WORDS: Lepomis gibbosus · Monogenean · Microhabitat · Exotic species · Sex-biased parasitism Resale or republication not permitted without written consent of the publisherDis Aquat Org 97: [65][66][67][68][69][70][71][72][73] 2011 of North America (Hoffman 1999, Collins & Janovy 2003. Due to a general paucity of data on parasites from non-native fish in Britain and limited understanding of this monogenean in L. gibbosus, the current study was undertaken to confirm identification and establish the preference of O. dispar in terms of host sex, size and gill microhabitat. This study represents the first description of the parasite fauna of L. gibbosus in Britain. MATERIALS AND METHODS Fish samplingAn initial sample of 39 Lepomis gibbosus was obtained for parasitological examination from a fully enclosed stillwater fishery (coarse fishing lake) in southwest England in February 2008. The lake is 1.8 ha, with an average depth of 1.5 m, and has no inflow or outflow. All fish were captured by means of seine netting and transported live to holding facilities at the Environment Agency, Brampton. Following the detection of Onchocleidus dispar within these fish, an additional sample of native fish species was obtained in the same month. This sample consisted of 18 roach Rutilus rutilus, 10 gudgeon Gobio gobio and 11 rudd Scardinius erythrophthalmus, which were screened only for the presence of O. dispar. A further 85 L. gibbosus were netted in October 2008 and February 2009. Fish caught in October were killed on site by anaesthetic overdose using benzocaine solution, and immed...

Introduction and spread of non-native parasites withSilurus glanisL. (Teleostei: Siluridae) in UK fisheries

“…This finding closely follows the detection of the ancyrocephalid monogenean Onchocleidus dispar (Mü ller, 1936) in pumpkinseed Lepomis gibbosus (L.) introduced into the UK (Hockley et al, 2011). Andrews & Chubb (1984) recorded Proteocephalus osculatus (Goeze, 1782), a common parasite of catfish in Russia, from S. glanis imported to a fish farm in Yorkshire, England.…”

Parasites of non-native freshwater fishes introduced into England and Wales suggest enemy release and parasite acquisition

“…There was a significant difference in the mean number of specialist parasite species per population between the ranges (Mann-Whitney U Test: Z = -2.86, P \ 0.01), but not in the mean numbers of internal, external and generalist parasite species per population (Mann-Whitney: P [ 0.05 in all cases). Of these parasites recorded in the introduced range, the following were new additions to the British freshwater fish parasite fauna (Kirk 2004): Thaparocleidus vistulensis and Ergasilus sieboldi in S. glanis , Onchoceleidus dispar from L. gibbosus (Hockley et al 2011) and Ancyrocephalus pricei from A. melas. The cestode parasite Proteocephalus ocellatus was also detected in the intestinal tract of S. glanis; although it has previously been recorded in imported fish on an aquaculture site, it was thought to have been eradicated (Andrews and Chubb 1984).…”

“…The relatively high host specificity of these parasites has so far limited disease risks to native fish populations (e.g. Hockley et al 2011;Reading et al 2011). However, examples of serious disease outbreaks following the translocation of monogenean parasites, such as Gyrodactylus salaris (Bauer et al 2002;Bakke et al 2007), highlights the importance of continued monitoring and prompt risk assessment to inform management (Williams et al 2013).…”

Monogenean parasites of Lepomis gibbosus Linnaeus introduced into the River Durance, France

“…Despite L. gibbosus being present in Europe for more than 100 years (Welcomme, 1981) (Gusev, 1985;Galli et al, 2005;Hockley et al, 2011;Ondračková et al, 2011). The single undetermined Gyrodactylus sp.…”

“…Presence of monogeneans in parasite communities of European L. gibbosus has been confi rmed in the Danube River Basin (Roman, 1953;Kiškaroly, 1977;Grupcheva & Nedeva, 1999;Ondračková et al, 2011), and in Italy (Galli et al, 2005) and France (Lambert, 1979). They have also been recorded in newly established populations in colder regions such as Norway (Sterud & Jørgensen, 2006) or England (Hockley et al, 2011). On the other hand, monogenean parasites were absent at some other sites, such as the warm-water discharge canal of the Szczecin Power Plant in the Oder River Basin, Poland (Piasecki & Falandysz, 1994), or in the River Elbe near the city of Pardubice, Czech Republic (Ondračková, unpublished data).…”