HELMINTHIC ENDOFAUNA OF FOUR SPECIES OF FISH FROM LOWER JARI RIVER, A TRIBUTARY OF THE AMAZON BASIN IN BRAZIL

Studies on parasites of wild fish populations are important for knowledge of biodiversity, since parasites represent a great fraction of the planet’s biodiversity. The present study investigated the helminths fauna of Leporinus friderici , Mylossoma duriventre , Hoplerythrinus unitaeniatus and Osteoglossum bicirrhosum collected from the lower Jari River, in the state of Amapá in the eastern Amazon region, Brazil. These fish, which have varying eating habits, were caught using gill nets with different mesh sizes for analysis of helminths, using standard methodologies. The helminths collected from these hosts were: Procamallanus ( Spirocamallnus inopinatus , Guyanema seriei seriei , Contracaecum sp., Eustrongylides sp. (Nematoda), Clinostomum marginatum , Dadaytrema oxycephala , Caballerotrema aruanense , Posthodiplostomum sp. (Digenea), Quadrigyrus nickoli and Neoechinorhynchus sp. (Acanthocephala). Hoplerythrinus unitaeniatus presented the highest prevalence, intensity and mean abundance of C. marginatum, while M. duriventre was the host with lowest level of this parasite. The greatest diversity was of Contracaecum sp., sole helminth found in all species of fish studied. The presence of larvae of endoparasites indicates that these fish are intermediate hosts in the Jari River basin. que esses peixes são hospedeiros intermediários para esses parasitos na bacia do Rio Jari. Palavras-chave: Amazônia; parasitos; peixes de água doce; hospedeiros.


INTRODUCTION
The Jari River basin, an important tributary of the Amazon River, has its source in the Parque Montanhas Tumucumaque (the Tumucumaque Mountain Park), on the border between Brazil and Surinam, and empties into the Amazon River in the south of the state of Amapá. The basin is divided between the states of Amapá and Pará in the north of Brazil, and covers the municipal districts of Vitória do Jari, Laranjal do Jari, Mazagão (State Amapá) and Almeirim (State Pará), covering a total area of approximately 119,540 km 2 (Epe, 2010;Epe, 2011;Amapá, 2012;Oliveira et al., 2017). The basin is directly influenced by the daily tides of the Amazon River at its mouth and has white water downstream and black water upstream, causing the amount of suspended organic matter to vary (Epe, 2011;Abreu and Cunha, 2015).
For L. friderici from the Amazon basin (State Amapá) the helminths fauna is constituted by species of digenean, nematodes and acanthocephalan (Oliveira et al., 2017) and in Paraná River basin (State Paraná) by species of digeneans, nematodes and cestodes (Guidelli et al., 2006;Takemoto et al., 2009). For M. duriventre from the Solimões River basin (State Amazonas) is constituted by species of nematodes (Silva and Tavares-Dias, 2012). In O. bicirrhosum from the Solimões basin (State Amazonas) the helminths fauna is not composed by species of endoparasites (Tavares- Dias et al., 2014) and in H. unitaeniatus from the Tapajós River basin (Benigno et al., 2012) and the Igarapé Fortaleza (the Fortaleza Stream), state of Amapá (Alcântara and Tavares-Dias, 2015) by species of nematodes, digeneans, acanthocephalan and cestode. So how is the helminths fauna of L. friderici, M. duriventre, H. unitaeniatus and O. bicirrhosum from the Jari River basin, which have different feeding habits, constituted?
Studies of the helminths community of fish can reveal information about aspects of the diet of the hosts, their trophic level in the food chain and their participation in the life cycle of parasites (Benigno et al., 2012;Tavares-Dias et al., 2014;Oliveira et al., 2015;Oliveira and Tavares-Dias, 2016;Oliveira et al., 2017). Some helminth species from fish have zoonotic potential for humans (Barros et al., 2006;Benigno et al., 2012). Therefore, the present study investigated the helminths fauna parasitizing L. friderici, M. duriventre, H. unitaeniatus and O. bicirrhosum from the Jari River basin region, in the eastern Amazon region, Brazil.

MATERIAL AND METHODS
Species of L. friderici, M. duriventre, H. unitaeniatus and O. bicirrhosum were collected in December 2014 from the lower Jari River, near the Jarilândia community in the state of Amapá, in the north of Brazil (Figure 1).
The fish were captured using gill nets with different mesh sizes. The standard length (cm) and body weight (g) of the fish collected were measured. Each fish was then subjected to necropsy, and the gastrointestinal tract and viscera were examined with the aid of a stereomicroscope and microscope to collect endohelminths. This work was carried out in accordance with the principles of the Colégio Brasileiro de Experimento Animal (the Brazilian College of Animal Experimentation/COBEA). All the fish were collected pursuant to a collection authorization granted by IBAMA/ICMBio -Nº 27447-1/2011.
The collection, fixation, preservation and preparation of the parasites for identification followed the recommendations of Eiras et al. (2006). The species of the parasites were identified in accordance with Schmidt and Hugghins (1973), Petter (1974), Thatcher (1980Thatcher ( , 2006, Moravec (1998) and Caffara et al. (2011). The ecological terms used were adopted from those recommended by Rohde et al. (1995) and Bush et al. (1997).

RESULTS
A total of 55 fish of four species from hosts such as L. friderici (16.2 ± 2.1 cm and 141.1 ± 53.8 g), M. duriventre (21.9 ± 1.7 cm and 350.7 ± 59.7 g), H. unitaeniatus (20.3 ± 1.3 cm and 219.3 ± 65.2 g) Figure 1. Location of the collection sites of the fish species in the lower Jari River, a tributary of the Amazon River in northern Brazil.

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and O. bicirrhosum (39.2 ± 9.9 cm and 549.2 ± 382.6 g) were necropsied. Of this total, 60% were parasitized by one or more species of helminthes, and a total of 433 parasites from nine taxa was collected. Among the species o helminthes collected, larvae of Contracaecum sp. were found in all the hosts, but Procamallanus (Spirocamallnus) inopinatus Travassos, Artigas & Pereira, 1928 do not occurred only in O. bicirrhosum. Hoplerythrinus unitaeniatus was the host with the greatest parasitic prevalence, intensity and abundance of Clinostomum marginatum Rudolphi, 1819, while M. duriventre was the least parasitized by this endoparasite (Table 1).
All host species had endoparasites in the larval stages (Table 2). In the four hosts, the number of parasites ranged from one to six, but infection by zero or one parasite predominated. Hoplerythrinus unitaeniatus had the greatest richness of helminths species (Figure 2).

DISCUSSION
Four species of nematodes, three digeneans and two acanthocephalans were found in L. friderici, M. duriventre, H. unitaeniatus and O. bicirrhosum, and with larval stages. However, for L. friderici from the Amazon basin the endohelminths fauna is constituted by one species of digenean, two nematodes and one acanthocephalan (Oliveira et al., 2017) and in Paraná River basin by 11 species of digeneans, 12 nematodes, two acanthocephalans and one cestode (Guidelli et al., 2006;Takemoto et al., 2009 (Alcântara and Tavares-Dias, 2015). Larvae of Contracaecum sp. were found also on musculature of H. unitaeniatus and O. bicirrhosum, due to migration into host. This nematode has a low host parasitic specificity, being a common anisakid in freshwater fish from Brazil, mainly in carnivorous hosts (Luque et al., 2011;Benigno et al., 2012;Alcântara and Tavares-Dias, 2015;Oliveira and Tavares-Dias, 2016;Oliveira et al., 2017). The greatest prevalence of Contracaecum sp. occurred in H. unitaeniatus and O. bicirrhosum, both of which are carnivorous hosts that feed on insects, crustaceans, mollusks and small fish (Soares et al., 2011;Benigno et al., 2012;Froese and Pauly, 2017;Oliveira et al., 2017). These fish are secondary intermediary hosts for this anisakid which uses species of crustaceans as primary intermediate hosts Moravec, 2009;Oliveira et al., 2017) and birds and fish-eating mammals to complete its life cycle (Navone et al., 2000;Barros et al., 2006;Moreira et al., 2009). This is the first record Contracaecum sp. for M. duriventre. Larvae and adults of P. (S.) inopinatus infected L. friderici, M. duriventre and H. unitaeniatus, with moderate prevalence and low abundance. These finding indicates that that these omnivorous fish (L. friderici, M. duriventre and H. unitaeniatus) are definitive hosts of this nematode that uses chironomids as intermediate hosts Oliveira et al., 2017). Larvae of Eustrongylides sp. were found in low abundance only in H. unitaeniatus and O. bicirrhosum, both carnivorous hosts. However, the greatest prevalence was in H. unitaeniatus. Therefore, H. unitaeniatus and O. bicirrhosum acts as secondary intermediate hosts for Eustrongylides sp., a nematode that uses species of earthworms as primary intermediate hosts (Martins et al., 2009) and reaches its adult phase in piscivorous birds (Barros et al., 2006;Martins et al., 2009;Benigno et al., 2012;Meneguetti et al., 2013). Larvae of Eustrongylides sp. has been reported in varied infection levels in different species of fish from several hydrographic basins in Brazil (Vicente and Pinto, 1999;Luque et al., 2011), but the species have not been identified. Low levels of infection by Guyanema seriei seriei Petter, 1974 were found in the mesentery of H. unitaeniatus as reported for this same host of the Vila Nova River basin (Oliveira et al., 2018). Petter (1974) described this nematode Dracunculoidea superfamily in the same host from Guyana. The life story of this nematode is unknown, but species of Dracunculoidea have a life  (Moravec, 2004). This is the first report of Eustrongylides sp. for O. bicirrhosum and widens the distribution of this nematode and of G. seriei seriei for the Jari River basin, in the eastern Amazon region.
Dadaytrema oxycephala Diesing, 1836 Travassos, 1931 infects species of Characidae, Serrasalmidae and Doradidae from the Brazil (Kohn et al., 2007). Low levels of infection by D. oxycephala were found in M. duriventre when compared to Piaractus brachypomus Cuvier, 1818 from the lower Amazonas River (Oliveira and Tavares-Dias, 2016). This was the first report of D. oxycephala for M. duriventre. In H. unitaeniatus, the prevalence and abundance of metacercariae of Posthodiplostomum sp. were low, but there was a greater prevalence of C. marginatum. On the other hand, the levels of infection by C. marginatum were least that in H. unitaeniatus reported by Alcântara and Tavares-Dias (2015). Mollusk species are the primary intermediate hosts of the Posthodiplostomum and C. marginatum species, fish are the secondary intermediate hosts and fish-eating birds are the definitive hosts (Klaas, 1963;Ritossa et al., 2013). This is the first report of Posthodiplostomum sp. for H. unitaeniatus. Adults of Caballerotrema aruanense Thatcher, 1980 were found infecting only O. bicirrhosum, due to its host specificity. While the life cycle of this digenean is still unknown, it appears to use O. bicirrhosum as a definitive host. However, such levels of infection by digenean species are related to the life habits of these hosts, which in the ambient of the present study ingest mollusks containing infective forms.
Acanthocephalans Neoechinorhynchidae Ward, 1917 and Quadrigyridae Van Cleve, 1920 have amphipods, ostracods, isopods and copepods as their intermediate hosts, while fish are their paratenic hosts (Schmidt, 1985;Taraschewski, 2008). In H. unitaeniatus, levels of infection by Quadrigyrus nickoli Schmidt and Hugghins, 1973 were greater than those of Neoechinorhynchus sp. for L. friderici. Contrastingly, the levels of Q. nickoli in H. unitaeniatus were lower than those described for Hyphessobrycon eques (Fujimoto et al., 2013). Therefore, when arthropod species containing acanthella are swallowed by fish, this stage continues until the cystacanth stage.

CONCLUSIONS
The parasites community of L. friderici, M. duriventre, H. unitaeniatus and O. bicirrhosum was composed mainly by endoparasites in larval stages due to the feeding habits of these intermediate hosts, which can serve of food for definitive hosts. Furthermore, it was characterized by species with moderate prevalence and low abundance. There was little interspecies variation of parasites among the different hosts. The diversity of endoparasites using different organs of H. unitaeniatus indicates that species can coexist in the same fish because they occupy different sites in the host.