Mercury concentration in the freshwater bonefish Cyphocharax gilbert (Curimatidae) and its parasite the crustacean Riggia paranensis (Cymothoidae)

Abstract

Fish parasites can accumulate heavy metals reaching higher concentrations than the host and may affect the host's bioaccumulation. The present study compared total mercury concentration in the liver and muscle of Cyphocharax gilbert and in the parasite Riggia paranensis sampled in the middle Itabapoana River, Brazil, also considering the reproductive stages of both fish and parasite. Mean concentrations of mercury in muscle of fish varied from 20.8 ng.g -1 in mature females to 38.1 ng.g -1 in postspawning females. The mean concentrations in fish liver varied from 60.9 ng/g in post-spawning females to 110.4 ng.g -1 in infested males. The mean concentration of mercury in parasites varied from 26.2 ng.g -1 in specimens carrying early embryo to 39.5 ng.g -1 in specimens with eggs. Positive and significant associations (P≤0.05) were found between the total mercury concentrations in parasites and muscle of host (both females and males), and between concentrations in parasites and in the liver of male hosts. These results suggest that R. paranensis can be used to indicate mercury levels in edible parts of C. gilbert.Parasitos de peixes podem acumular metais pesados em concentrações acima dos hospedeiros, podendo afetar a bioacumulação nestes. O presente estudo comparou a concentração total do mercúrio no fígado e no músculo de Cyphocharax gilbert e no parasito Riggia paranensis, coletados no trecho médio do rio Itabapoana, Brasil, considerando o estágio reprodutivo tanto dos peixes como dos parasitos. A concentração média do mercúrio nos músculos dos peixes variou entre 20,8 ng.g -1 nas fêmeas maturas e 38,1 ng.g -1 nas fêmeas desovadas. As concentrações médias nos fígados dos peixes variaram entre 60,9ng/g em fêmeas desovadas e 110,4 ng.g -1 em machos parasitados. Entre os parasitos, as concentrações médias de mercúrio variaram entre 26,2 ng.g -1 em espécimes com embriões iniciando o desenvolvimento to 39,5 ng.g -1 em espécimes com ovos . Associações positivas e significativas (P≤0.05) foram encontradas entre as concentrações totais de mercúrio em parasitos e músculos dos hospedeiros (tanto em macho como em fêmeas) e entre as concentrações nos parasitos e os fígados dos hospedeiros machos. Estes resultados sugerem que o parasito R. paranensis pode ser utilizado como bioindicador dos níveis de mercúrio nas partes comestíveis de C. gilbert.

Description and ontogeny of a 40-million-year-old parasitic isopodan crustacean:Parvucymoides dvorakorumgen. et sp. nov.

“…There is no concise distribution pattern for representatives of Cymothoidae in freshwater. Yet, the majority of cases have been reported from South American freshwater sources ( Huizinga, 1972 ; Bowman, 1986 ; Bastos & Thatcher, 1997 ; Lins et al, 2008 ; Tavares-Dias et al, 2014 ), with some species recorded from central African (see Moore, 1898 ; Van Name, 1920 ; Fryer, 1965 , 1968 ; Lincoln, 1971 ) and Asian freshwater environments ( Tsai & Dai, 1999 ; Yamano, Yamauchi & Hosoya, 2011 ). Some species have been reported from estuaries in North America ( Lindsay & Moran, 1976 ) with one record from southern Europe (Mediterranean) (see Leonardos & Trilles, 2004 ).…”

Riggia puyensis n. sp. (Isopoda: Cymothoidae) parasitizing Chaetostoma breve and Chaetostoma microps (Siluriformes: Loricariidae) from Ecuador

“…At the moment the genus Riggia Szidat, 1948 includes five species, all parasites of freshwater fish distributed in South Amer ica: Riggia paranaensis described on Cyphocharax platanus from Argentina (Szidat, 1948) and later reported on Cyphocharax gilbert from Brazil (Bastos and Thatcher, 1997;Lins et al, 2008); Riggia brasiliensis on Leporinus copelandii, Leporinus octofasciatus, Leporellus vitattus, and Schiozodon nasutus from Brazil (Szidat and Schubart, 1960); Riggia nana on L. vitattus, L. striatus, and S. nasu tus from Brazil (Szidat and Schubart, 1960); Riggia acuticaudata on Ancistrus sp. from Brazil (Oda et al, 2015;Thatcher et al, 2002); and Riggia cryptocularis on Odontostilbe paraguayensis and Ancistrus sp.…”

The Poorly KnownRiggia acuticaudata(Crustacea: Isopoda) ParasitizingAncistrussp. (Siluriformes: Loricariidae) from the Paraguay River Basin, Brazil, with Comments on its Reproductive Biology

“…The available information on Riggia species is primarily based on R. paranensis and its host, Cyphocharax gilbert (Quoy and Gaimard, 1824) (e.g., Azevedo et al, 2006;Lima et al, 2007;Lins et al, 2008), whereas information about R. acuticaudata and R. cryptocularis is basically restricted to their original descriptions. These latter 2 species are described as parasitizing the body cavity of the armored catfish, Ancistrus sp.…”