Using lizards to evaluate the influence of average abundance on the variance of endoparasites in semiarid areas: dispersion and assemblage structure.

The distribution of parasites within host populations and communities, and the mechanisms responsible for these patterns, are poorly understood aspects of wildlife parasitology. Here, we evaluate the influence of the average abundance of endoparasite variance, using endoparasites of lizards from the Caatinga domain (semiarid region), north-eastern Brazil. We hypothesized that, due to the high number of generalist endoparasite species, they may occur randomly throughout host populations in an aggregate pattern. In addition, we evaluated the degree to which sample variance is influenced by the average abundance of endoparasite species, patterns of co-occurrence and dominance among endoparasite species and similarities between abundance and the richness of endoparasite infracommunities in several host species. Between September 2015 and February 2016, 2141 lizards (1233 infected) from 16 species were collected from six Caatinga areas. In total, 25,687 endoparasites were collected, which belonged to 13 species including nematodes, pentastomids, cestodes, trematodes and acanthocephalans. Parasite-host associations documented here included 39 newly identified interactions. Endoparasites occurred in a typical aggregate pattern of distribution within their hosts; there was no measurable preference related to the acquisition of hosts by endoparasites. Despite the new records, endoparasites found were commonly associated with lizards in Caatinga environments, which may reflect fauna composed of generalist endoparasite species.

Gill metazoan parasites of the spotted goatfish Pseudupeneus maculatus (Ostheichthyes: Mullidae) from the Coast of Pernambuco, northeastern Brazil / Metazoários parasitos de brânquias do saramunete Pseudupeneus maculatus (Ostheichthyes: Mullidae) da costa de Pernambuco, Nordeste do Brasil

Abstract This study evaluated the parasite fauna on the gills of spotted goatfish Pseudupeneus maculatus captured in the dry and rainy seasons in the coast of the State of Pernambuco, Brazil. Eight parasite species were identified belonging to the following taxa: Monogenea (Haliotrema caraïbensis, Haliotrema caballeroi and Haliotrema golvani); Crustacea (Rocinela signata, Hamaticolax scutigerulus and Caligidae gen. sp.) and Cestoda (Nybelinia indica and Pseudolacistorhynchus noodti). The most prevalent parasites were: Monogenea (100%), H. scutigerulus (35%), N. indica (11.7%), R. signata (8.3%), Caligidae gen. sp. (3.33%) and P. noodti (0.83%). Values of infestation are compared to other studies, and the uncommon occurrence of Trypanorhyncha on the gills suggests that the spotted goatfish could be an intermediate host for the parasite.

Resumo O presente estudo investigou a fauna parasitária das brânquias do peixe conhecido como saramunete Pseudupeneus maculatus, capturados nas estações seca e chuvosa na costa do estado de Pernambuco, Brasil. Oito espécies de parasitos foram identificadas, pertencentes aos seguintes táxons: Monogenea (Haliotrema caraïbensis, Haliotrema caballeroi e Haliotrema golvani); Crustacea (Rocinela signata, Hamaticolax scutigerulus e Caligidae gen. sp.) e Cestoda (Nybelinia indica e Pseudolacistorhynchus noodti). Os parasitos mais prevalentes foram: Monogenea (100%), H. scutigerulus (35%), N. indica (11,7%), R. signata (8,3%), Caligidae gen. sp. (3,33%) e P. noodti (0,83%). Os valores de infestação são comparados a outros estudos, e a ocorrência incomum de cestóides Trypanorhyncha sugere que o saramunete pode ser um hospedeiro intermediário para o parasito.

Fish parasites as indicators of organic pollution in southern Brazil.

Increasing urbanization along riverbanks is a constant source of stressors to the aquatic community, and the use of bioindicators is suitable to detect and monitor the effect of each stressor. We investigated the parasites of the 'cará' fish (Geophagus brasiliensis) as potential bioindicators in a river whose banks are subject to increasing anthropogenic pressure. Samples were taken at four points of the Sangradouro River, in Florianópolis, southern Brazil, bimonthly for 12 months. Water temperature, pH, dissolved oxygen, conductivity and salinity were measured at each point and water samples were taken for nutrient analysis (total nitrogen, nitrite, total ammonia nitrogen, total phosphorus, phosphate), and total and faecal coliforms. A generalized linear model (GLM) was constructed using the abundance of each parasite species as the response variable and biometric characteristic of the fish and water variables as possible predictors. Among the 137 fish examined, 114 (83.2%) were parasitized by at least one parasite species. Two species of ectoparasites (Sciadicleithrum guanduensis and Neascus-type metacercariae) and two species of endoparasites (Pandosentis aff. iracundus and Homalometron pseudopallidum) were observed. This is the first record of the genus Pandosentis in Brazilian waters and the first record of the species G. brasiliensis as a host for this parasite. Among the analysed groups of parasites, monogeneans and acanthocephalans proved to be the most sensitive to the concentrations of dissolved oxygen, faecal coliforms and total ammonia nitrogen in the water. Our study suggests that the abundance of both monoxenic and heteroxenous parasites can be negatively affected by organic pollution in the aquatic environment, reinforcing the potential of fish parasites as indicators of water quality.

Gill metazoan parasites of the spotted goatfish Pseudupeneus maculatus (Ostheichthyes: Mullidae) from the Coast of Pernambuco, northeastern Brazil.

This study evaluated the parasite fauna on the gills of spotted goatfish Pseudupeneus maculatus captured in the dry and rainy seasons in the coast of the State of Pernambuco, Brazil. Eight parasite species were identified belonging to the following taxa: Monogenea (Haliotrema caraïbensis, Haliotrema caballeroi and Haliotrema golvani); Crustacea (Rocinela signata, Hamaticolax scutigerulus and Caligidae gen. sp.) and Cestoda (Nybelinia indica and Pseudolacistorhynchus noodti). The most prevalent parasites were: Monogenea (100%), H. scutigerulus (35%), N. indica (11.7%), R. signata (8.3%), Caligidae gen. sp. (3.33%) and P. noodti (0.83%). Values of infestation are compared to other studies, and the uncommon occurrence of Trypanorhyncha on the gills suggests that the spotted goatfish could be an intermediate host for the parasite.

New species of Cucullanus (Nematoda: Cucullanidae), an intestinal parasite of the peacock bass Cichla piquiti (Perciformes: Cichlidae) from the Tocantins River, Brazil.

Cucullanus tucunarensis n. sp. (Cucullanidae) is described parasitizing the peacock bass Cichla piquiti (Cichlidae) from the Tocantins River, Tocantins State, Brazil. The new species is unique and differs from all its congeners by having a tail tip provided with several sclerotized spine-like processes on its ventral side, present in both the male and female. Furthermore, C. tucunarensis n. sp. is compared with other species of the genus recorded in the same zoogeographical region and in the same group of hosts (Perciformes).

Tests of chronic and acute toxicity of crude oil on larvae of Chironomus kiiensis Tokunaga (Diptera: Chironomidae).

The Amazon region, known for its mega-biodiversity, also holds large reserves of petroleum and natural gas. The increasing exploitation of natural gas and crude oil in the Amazon has not been accompanied by studies evaluating the impact of these pollutants on local biological communities, particularly aquatic organisms. The aim of the present study was to determine the values of acute and chronic toxicity of crude oil from Urucu to larvae of Chironomus kiiensis Tokunaga, 1936. The LD5048h of crude oil for second-instar larvae of C. kiiensis was 26.5 mg/L, and mortality for the majority of concentrations tested was greatest during the first 24 hours of the experiment. The survival of eggs of C. kiiensis exposed to concentrations of crude oil was also evaluated but did not differ significantly among the treatments. Despite the high tolerance observed for the species in the experiments, there is a possibility that in the natural environment the oil interacts with other factors, leading to synergistic effects, so further studies are needed to assess the effects of this pollutant on aquatic insect species.

Comparative parasitism of the fish Plagioscion squamosissimus in native and invaded river basins.

Biological invasions are considered a major threat to biodiversity around the world, but the role of parasites in this process is still little investigated. Here, we compared parasite infections of a host species in the areas where it originated and where it was introduced, and in native and introduced species in the same environment, using the endoparasites of the fish Plagioscion squamosissimus (Sciaenidae) in 3 Brazilian basins. Samples were taken in 2 rivers where the species is native, i.e., Solimões River (SO) and Tocantins River (TO), and where the species was introduced, the upper Paraná River (PR). In addition, abundances of diplostomids and larval nematodes were compared between P. squamosissimus and 2 native competitors in the PR, Hoplias malabaricus and Raphiodon vulpinus. In total, 13 species of endoparasites were recorded, but only Austrodiplostomum sp. and cestode cysts were present in all localities. Although infracommunity richness was similar, their species composition was slightly different among localities. General linear models using the relative condition factor of fish as response variables, and abundance of the most prevalent parasites as possible predictors showed that the condition of fish is negatively correlated with parasite abundance only in the native range (TO). Abundance of diplostomid eye flukes was higher in the PR, and in the native species H. malabaricus when compared to the invader, which might present an advantage for P. squamosissimus if they compete for prey. However, although P. squamosissimus may have lost some of its native parasites during its introduction to the PR, it is now possibly acting as a host for native generalist parasites.

Diversity of parasites of fish from the Upper Paraná River floodplain, Brazil.

The aim of the present study was to provide a current survey of the species of parasites found in the Upper Paraná River floodplain, as well as to investigate which strategies and mechanisms used by parasites, are favored and which environmental factors influence the parasite community in the studied environments. During a seven-year period from February 2000 to September 2007, 3,768 fish belonging to 72 species were collected and analyzed for the purpose of studying the parasite fauna. A total of 337 species of parasites were reported, including 12 new descriptions: one myxosporid, Henneguya paranaensis Eiras, Pavanelli and Takemoto, 2004; eight monogeneans, Kritskyia annakohnae Boeger, Tanaka and Pavanelli, 2001; Kritskyia boegeri Takemoto, Lizama and Pavanelli, 2002; Kritskyia eirasi Guidelli, Takemoto and Pavanelli, 2003; Demidospermus labrosi França, Isaac, Pavanelli and Takemoto, 2003; Demidospermus mandi França, Isaac, Pavanelli and Takemoto, 2003; Pseudovancleaveus paranaensis França, Isaac, Pavanelli and Takemoto, 2003; Tereancistrum curimba Lizama, Takemoto and Pavanelli, 2004 and Tereancistrum toksonum Lizama, Takemoto and Pavanelli, 2004; two digeneans, Sanguinicola platyrhynchi Guidelli, Isaac and Pavanelli, 2002 and Dadayius pacupeva Lacerda, Takemoto and Pavanelli, 2003 and one cestode, Nomimoscolex pertierrae Chambrier, Takemoto and Pavanelli, 2005. In addition, several other species were reported for the first time in new hosts or in the floodplain. Monogeneans presented the highest number of species, followed by digeneans. The infection site with the highest species richness was the intestine, with 127 species.

Ecology of endoparasites of the fluvial stingray Potamotrygon falkneri (Chondrichthyes: Potamotrygonidae) from the upper Paraná River floodplain, Brazil.

The present study investigated the ecological relationships between endoparasites and the host Potamotrygon falkneri from the upper Paraná River by using as indicators the host's relative condition factor (Kn), sex and hepatosomatic relation (HSR). Forty-seven specimens of P. falkneri were analyzed between March 2005 and September 2006. Statistical analysis showed that the Kn was positively correlated with the abundance of Acanthobothrium regoi and Rhinebothrium paratrygoni; only the abundance of A. regoi was positively correlated to the HSR, whereas R. paratrygoni did not present correlation and there was no influence of the host's sex on the abundance and prevalence of parasites. This is the first study concerning the ecology of parasites of potamotrygonids.

Diversity of parasites of fish from the Upper Paraná River floodplain, Brazil / Diversidade dos parasitos de peixes da planície de inundação do Alto Rio Paraná, Brasil

The aim of the present study was to provide a current survey of the species of parasites found in the Upper Paraná River floodplain, as well as to investigate which strategies and mechanisms used by parasites, are favored and which environmental factors influence the parasite community in the studied environments. During a seven-year period from February 2000 to September 2007, 3,768 fish belonging to 72 species were collected and analyzed for the purpose of studying the parasite fauna. A total of 337 species of parasites were reported, including 12 new descriptions: one myxosporid, Henneguya paranaensis Eiras, Pavanelli and Takemoto, 2004; eight monogeneans, Kritskyia annakohnae Boeger, Tanaka and Pavanelli, 2001; Kritskyia boegeri Takemoto, Lizama and Pavanelli, 2002; Kritskyia eirasi Guidelli, Takemoto and Pavanelli, 2003; Demidospermus labrosi França, Isaac, Pavanelli and Takemoto, 2003; Demidospermus mandi França, Isaac, Pavanelli and Takemoto, 2003; Pseudovancleaveus paranaensis França, Isaac, Pavanelli and Takemoto, 2003; Tereancistrum curimba Lizama, Takemoto and Pavanelli, 2004 and Tereancistrum toksonum Lizama, Takemoto and Pavanelli, 2004; two digeneans, Sanguinicola platyrhynchi Guidelli, Isaac and Pavanelli, 2002 and Dadayius pacupeva Lacerda, Takemoto and Pavanelli, 2003 and one cestode, Nomimoscolex pertierrae Chambrier, Takemoto and Pavanelli, 2005. In addition, several other species were reported for the first time in new hosts or in the floodplain. Monogeneans presented the highest number of species, followed by digeneans. The infection site with the highest species richness was the intestine, with 127 species.

O objetivo do presente trabalho foi realizar um novo levantamento das espécies de parasitos encontradas na planície de inundação do Alto Rio Paraná, bem como investigar quais estratégias e mecanismos utilizados pelos parasitos são mais favorecidos e quais fatores ambientais estão influenciando a comunidade parasitária nos ambientes estudados. Durante o período de fevereiro de 2000 a setembro de 2007, 3.768 espécimes de peixes pertencentes a 72 espécies foram coletados e analisados, visando o estudo da fauna parasitária. Até o momento foram registradas, 337 espécies de parasitos, sendo 12 novas espécies: uma de mixosporídeo, Henneguya paranaensis Eiras, Pavanelli e Takemoto, 2004; oito de monogenéticos, Kritskyia annakohnae Boeger, Tanaka e Pavanelli, 2001; Kritskyia boegeri Takemoto, Lizama e Pavanelli, 2002; Kritskyia eirasi Guidelli, Takemoto e Pavanelli, 2003; Demidospermus labrosi França, Isaac, Pavanelli e Takemoto, 2003; Demidospermus mandi França, Isaac, Pavanelli e Takemoto, 2003; Pseudovancleaveus paranaensis França, Isaac, Pavanelli e Takemoto, 2003; Tereancistrum curimba Lizama, Takemoto e Pavanelli, 2004 e Tereancistrum toksonum Lizama, Takemoto e Pavanelli, 2004; duas de digenéticos, Sanguinicola platyrhynchi Guidelli, Isaac e Pavanelli, 2002 e Dadayius pacupeva Lacerda, Takemoto e Pavanelli, 2003 e uma de cestóide, Nomimoscolex pertierrae Chambrier, Takemoto e Pavanelli, 2005. Além dessas novas espécies, várias outras foram registradas pela primeira vez em novos hospedeiros ou na planície. O grupo dos monogenéticos foi o que apresentou maior número de espécies encontradas, seguido pelos digenéticos. O intestino foi o sítio de infecção que apresentou a maior riqueza, com 127 espécies.

Ecology of endoparasites of the fluvial stingray Potamotrygon falkneri (Chondrichthyes: Potamotrygonidae) from the upper Paraná River floodplain, Brazil / Ecologia de endoparasitos da raia fluvial Potamotrygon falkneri (Chondrichthyes: Potamotrygonidae) da planície de inundação do alto rio Paraná, Brasil

The present study investigated the ecological relationships between endoparasites and the host Potamotrygon falkneri from the upper Paraná River by using as indicators the host's relative condition factor (Kn), sex and hepatosomatic relation (HSR). Forty-seven specimens of P. falkneri were analyzed between March 2005 and September 2006. Statistical analysis showed that the Kn was positively correlated with the abundance of Acanthobothrium regoi and Rhinebothrium paratrygoni; only the abundance of A. regoi was positively correlated to the HSR, whereas R. paratrygoni did not present correlation and there was no influence of the host's sex on the abundance and prevalence of parasites. This is the first study concerning the ecology of parasites of potamotrygonids.

O presente estudo investigou as relações ecológicas entre os endoparasitos e os hospedeiros Potamotrygon falkneri do alto rio Paraná, utilizando como indicadores o fator de condição relativo (Kn), sexo e relação hepatossomática (HSR) dos hospedeiros. Entre março de 2005 e setembro de 2006, 47 espécimes de P. falkneri foram analisados. As análises mostraram que o Kn estava positivamente correlacionado com a abundância de Acanthobothrium regoi e Rhinebothrium paratrygoni; apenas a abundância de A. regoi estava correlacionada positivamente com a HSR, enquanto R. paratrygoni não apresentou correlação e não houve influência do sexo do hospedeiro na abundância e prevalência dos parasitos. Este é o primeiro estudo sobre ecologia de parasitos de potamotrigonídeos.

Helminths parasitizing larval fish from Pantanal, Brazil.

Fish larvae of 'corvinas' (Pachyurus bonariensis and Plagioscion ternetzi) from Sinhá Mariana Lagoon, Mato Grosso State, were collected from March 2000 to March 2004, in order to determine the parasitic fauna of fishes. Larvae from the two species were parasitized by the same endoparasites: Contracaecum sp. Type 2 (larvae) (Nematoda: Anisakidae) in the mesentery and Neoechinorhynchus (Neoechinorhynchus) paraguayensis (Acanthocephala: Neoechinorhynchidae) in the stomach and the terminal portion of the intestine. Statistical analysis showed that there was a significant positive correlation between the standard length of hosts and the abundance of acanthocephalans and nematodes, and that the prevalence of nematodes presented a significant positive correlation with the standard length of the two species of hosts, indicating the presence of a cumulative process of infection. The present study constitutes the first record of nematodes and acanthocephalans parasitizing larval fish, as well as the first record of endoparasites in fish larvae in Brazil. In addition, it lists a new locality and two species of hosts for Contracaecum sp. Type 2 (larva) and N. (N.) paraguayensis.