Metazoan parasites of Brazilian menhaden Brevoortia aurea (Spix & Agassiz, 1829) (Osteichthyes: Clupeidae) from the coastal zone of the state of Rio de Janeiro, Brazil

Community ecology of the metazoan parasites of the Atlantic thread herring, Opisthonema oglinum (Lesueur, 1818) (Actinopterygii: Clupeidae) from the Sepetiba Bay, Rio de Janeiro, Brazil

This study aimed to evaluate the parasitic fauna of Opisthonema oglinum (Lesueur, 1818) from Southeastern Brazil. Between September 2017 and March 2018, a total of 100 specimens of O. oglinum from the Sepetiba Bay, Rio de Janeiro, Brazil (22°54'S, 43°34'W) were examined. Ninety one specimens of O. oglinum were parasitized by at least one species of metazoan with a mean of 5.84 ± 7.98 parasites/fish. Seven species were collected: 2 digeneans, 2 monogeneans, 2 copepods and 1 nematode. The digenean Parahemiurus merus (Linton) was the most abundant and dominant species, representing 43% of metazoan parasites collected. The parasite species richness was positively correlated with the total length of the hosts. Only Neobomolochus elongatus Cressey showed a positive correlation between host's total length and parasite prevalence. The mean parasite species diversity was not correlated with host's total length, but significant differences among the mean parasite diversity between males and females was observed. Opisthonema oglinum represents a new host record for Caligus mutabilis Wilson, Hysterothylacium sp. and Cribomazocraes travassosi Santos and Kohn. The copepod N. elongatus is recorded for the first time on the Brazilian coast.

Anisakidae Skrjabin & Karokhin, 1945 and Raphidascarididae Hartwich, 1954 nematodes in lutjanidae (pisces: perciformes) from the Brazilian Northeast Coast

Abstract The present study aimed at describing and evaluating the fauna of Anisakidae and Raphidacarididae nematodes of lutjanid fish (snappers) from the Brazilian northeastern coast unloaded at the city of Aracaju, capital of the State of Sergipe. A total of 186 lutjanids of 5 different species were analyzed including 69 Lutjanus analis, 51 L. vivanus , 29 Ocyurus chrysurus, 23 L. synagris, and 14 L. jocu. Nematode specimens found in the viscera of these fish were clarified with lactophenol. Illustrations of each of these specimens were prepared to help identify these samples and compose their taxonomic description and classification. At necropsy, 3,183 nematodes belonging to two families were collected from fish viscera which included the following: Anisakidae: Anisakis, Terranova , Contracaecum, and Goezia; Raphidascarididae: Raphidascaris (Ichthyascaris) and Hysterothylacium . A total of six genera of nematodes were found at postmortem examination of which adult worms of only three genera (Goezia, Raphidascaris and Hysterothylacium) were detected in the fish examined. Larvae of Terranova sp. were found only in the musculature of O. chrysurus . Most of the nematode larvae were present in the mesentery and organs of the fish necropsied. Therefore, the zoonotic potential of these nematodes cannot be ruled out. There was a significant negative correlation between the intensity of parasitism by anisakids and the total body length of O. chrysurus; the intensity of parasitism was greater in smaller and shortef fish. There was a significant positive correlation between the abundance of these parasites and the length of L. synagris; the presence of these parasites increased according to the fish’s body length. To the authors’ knowledge, these are the first records of Raphidascaris (Ichthyascaris ) sp. and Hysterothylacium sp. in L. vivanus , of Terranova sp. in O. chrysurus and L. jocu, and of Goezia sp. in L. analis. These novel findings add the Brazilian northeast coast and the State of Sergipe in the geographic distribution of these parasites in the country.

Community ecology of the metazoan parasites of Brazilian sardinella, Sardinella brasiliensis (Steindachner, 1879) (Actinopterygii: Clupeidae) from the coastal zone of the State of Rio de Janeiro, Brazil

AbstractBetween March 2010 and August 2011 were necropsied 100 specimens of Sardinella brasiliensis (Steindachner, 1879), from the coast of the State of Rio de Janeiro, Brazil (22°51’S, 43°56’W), to study their community of metazoan parasites. All specimens of S. brasiliensis were parasitized by at least one species of metazoan parasite, with mean of 68.7 ± 71.2 parasites/fish. Eleven species were collected: 3 digeneans, 1 monogenean, 2 cestodes, 3 nematodes and 2 copepods. The digenean Myosaccium ecaude Montgomery was the most abundant, prevalent, and dominant species, representing 72.7% of metazoan parasites collected, showing positive correlation between host’s total length and parasite abundance. Total parasite abundance was positively correlated with host’s total length. Three pairs of adult endoparasites showed significant positive association and covariation. The parasite community of S. brasiliensis showed dominance by digeneans. Sardinella brasiliensis represents new host record for most found parasite species.

Parasite assemblages of estuarine-dependent marine fishes from Mar Chiquita coastal lagoon (Buenos Aires Province, Argentina)

The estuarine-dependent marine fish includes marine species that inhabit, at some stage of their life cycle, the Mar Chiquita coastal lagoon, Buenos Aires Province, Argentina. In the present study, we examined for parasites a total of 209 fishes belonging to following the estuarine-dependent marine species: Brevoortia aurea, Odontesthes argentinensis, Mugil platanus, Paralichthys orbignyanus, Micropogonias furnieri, and Pogonias cromis. The parasite fauna in the six host species comprised 43 parasite species, the majority of which represented new locality and new host records. A high percentage of fish was parasitized with at least one parasite species. The greatest values of prevalence were registered for M. furnieri, B. aurea, and P. cromis, at the component community level, followed by P. orbignyanus, O. argentinensis, and M. platanus. On the other hand, B. aurea, O. argentinensis, M. furnieri, and P. cromis showed similar percentages of both larval and adult stages of parasites. In the case of M. platanus, adult stages dominated the total number of parasites, whereas P. orbignyanus harbored mainly larval stages. Out of the six fish species herein studied, M. platanus seems to generally act only as definitive host in the local parasite's life cycle. From a parasitological point of view, the expression "estuarine-dependent marine fishes" remains valid, although the contribution of the fish species in the lagoon to the maintenance of parasite populations is relatively minor.

Parasite biodiversity and its determinants in coastal marine teleost fishes of Brazil

Recent studies of the forces behind the diversification of parasite assemblages have shed light on many aspects of parasite biodiversity. By using only parasite species richness as their measure of diversity, however, previous investigations have ignored the relatedness among parasite species and the taxonomic structure of the assemblages, which contain much information about their evolutionary origins. Here, we performed a comparative analysis across 50 species of fish from the coast of Brazil; we evaluated the effects of several host traits (body size, social behaviour, feeding habits, preference for benthicvs. pelagic habitats, depth range, and ability to enter brackish waters) on the diversity of their assemblages of metazoan parasites. As measures of diversity, we used parasite species richness, as well as the average taxonomic distinctness of the assemblage and its variance; the latter measures are based on the average taxonomic distance between any two parasite species in an assemblage. Unlike parasite species richness, taxonomic distinctness was unaffected by the number of host individuals examined per species. Fish body length proved to be the main predictor of parasite species richness, even when controlling for the confounding influences of host phylogeny and sampling effort, although it did not correlate with measures of parasite taxonomic distinctness. Predatory fish also had higher parasite species richness than planktivores, but this trend could not be confirmed using phylogenetically independent contrasts between host taxa. The main host feature associated with the taxonomic diversity of parasites was schooling behaviour, with schooling fish having more taxonomically diverse parasite assemblages than those of their non-schooling relatives. When focusing on endoparasite species only, both predatory feeding habits and a broad depth range were associated with the taxonomic distinctness of parasites. Our results suggest that certain host traits (i.e. body size) determine how many parasite species a host can accumulate over evolutionary time, whereas different host features influence the processes causing the taxonomic diversification of parasite assemblages.