Ectoparasite crustaceans of ten fish species from the upper Araguari River in northern Brazil.

Fish parasites are an important part of aquatic biodiversity and knowing these species and their interactions with their hosts helps in monitoring the aquatic biota. The present study investigated the ectoparasite crustacean fauna of ten fish species from the upper Araguari River, in the state of Amapá, northern Brazil. A total of 508 fish were collected and analyzed from July to November 2014, of which 82.6% (109) were parasitized by one or more crustacean ectoparasite species. In the ten host fish species, a total of 308 ectoparasite specimens were collected, from 12 taxa, such as Argulus multicolor Stekhoven, 1937, Argulus spinulosus Silva, 1980, Argulus sp.1, Argulus sp.2, Argulus sp.3, Dipteropeltis sp., Dipteropeltis hirundo Calman, 1912, Dolops bidentata Bouvier, 1899, Dolops striata Bouvier, 1899 (Argulidae), Braga fluviatilis Richardson, 1911, Braga amapaensis Thatcher, 1996 (Cymothoidae) and Excorallana berbicensis Boone, 1918 (Corallanidae). Higher levels of prevalence and abundance were recorded for Hoplias aimara (Valenciennes, 1847) and Tometes trilobatus Valenciennes, 1850, respectively. These ectoparasites were found in the fins, integument, mouth, and anus of the host fish. Argulus sp.2 and D. bidentata were the most abundant parasites (65.1%), and had the highest species richness. This study registered 36 novel host-parasite interactions, and thus represents a new record for all host species here examined.

Spatial distribution, host specificity, and affinity of Branchiura for surface and macrohabitat types in fish species from the Brazilian Amazon.

This study investigated the spatial distribution, parasite interactions, and affinities of Branchiura parasites according to macrohabitat and surface type on fish from the Araguari River, Amapá State, in the Brazilian Amazon. This study presents novel information on the interactions of branchiuran species with host fish, and how the morphology of their attachment structures is associated with different host surface morphologies, with and without scales. A total of 558 fish specimens of 26 species were collected, of which 109 fish (10 species) were parasitized by at least one branchiuran parasite; these were selected for further study. The parasites were collected from the buccal cavity, gills, fins, and integument of the host fish. Parasites with suction discs (Argulus) were mainly associated to hosts with small scales and no scales, while parasites with hooks (Dolops) were mainly associated to hosts with large scales. Overall, parasites with suction discs were more specialized per site than those with hooks.

Global distribution patterns of Caligus Müller, 1785 (Copepoda: Caligidae) associated to teleost fishes, with physiological and histopathological data and description of treatment strategies.

This review surveyed information on Caligus Müller, 1785 to identify global infestation patterns and geographic distribution in teleost fishes, as well as physiological and histopathological data and description of treatment strategies. A total 990 samples of Caligus spp. (N = 212 species) obtained of 233 scientific papers on farmed and wild teleost species from 99 families and 30 orders were used, and the highest number of occurrences was on Carangidae. Caligus spp. was predominantly found in marine environments, and only Caligus lacustris and Caligus epidemicus were found in teleost fish of freshwater environments. There was a high prevalence of Caligus spp. on hosts and infestation occurred predominantly in both the tegument and the gills. Caligus species are distributed across different countries and some particularities were identified and discussed. Caligus elongatus and Caligus bonito bonito had the broadest geographic distribution. Histomorphological and hematological disorders caused by infestation by Caligus spp. were reported and discussed, as well as chemotherapeutic products used for controlling and treating the infestations. Variation in the distribution and geographic patterns of Caligus spp. were little evident in many ecosystems and due to the limited data on the infestation of these sea lice on teleost populations in different regions.

Morphological and functional structure of two Ergasilidae parasites determine their microhabitat affinity on the gills of an Anostomidae fish from the Amazon.

The aim of this study was to investigate the microhabitat affinities of Ergasilus sp. and Therodamas longicollum on the gills of Leporinus fasciatus ("aracu-piau"), an anostomid fish from the Amazon. A total of 143 specimens of L. fasciatus were examined, of which 35% had their gills parasitized by at least one ergasilid species. A total of 159 specimens of Ergasilus sp. and 97 specimens of T. longicollum were recovered. Both ergasilids species exhibited a greater affinity for attachment in arch 1 of the gills of the host. There was a negative correlation between the abundance of Ergasilus sp. and the abundance of T. longicollum within each gill arch. Analysis of distribution along the gill arch showed a higher occurrence of Ergasilus sp. in Section 5, while T. longicollum occurred mainly in Section 3 of the gills. There was a positive correlation between the abundance of these ectoparasites and the size of the gill arch. Ergasilus sp. occurred only on the filament of the gill arch and exhibited affinity for the proximal region, while T. longicollum occurred only in the gill arch itself. The results reveal that these two parasite species compete in the gills of the host without the overlapping of their niches.

Integrative taxonomy of a new species of Therodamas (Ergasilidae) infecting the Amazonian freshwater fish Leporinus fasciatus (Anostomidae).

Crustaceans of the subclass Copepoda are an important component of the invertebrate aquatic fauna. They occur in all aquatic environments and include some representatives that are free-living organisms and others that have a parasitic lifestyle. The genus Therodamas comprises marine and freshwater copepods whose females are parasites of fish in their adult phase, with only seven species described so far. During a field survey of fish parasites in the Jari River, a large tributary of the Amazon River system, in Brazil, we found a new species of the genus Therodamas infecting Leporinus fasciatus. Therodamas longicollum n. sp. is the second strictly freshwater species known. Phylogenetic analysis showed that the new species is grouped in the family Ergasilidae, and divergence estimates showed that T. longicollum n. sp. diverged from its ancestor at around 66.34 Ma, in the late Upper Cretaceous. Therodamas longicollum n. sp. differs from its congeneric in that it does not have lobes and/or expansion of the anterior neck region. Besides describing a new Therodamas species, thereby increasing the diversity of the genus to eight species, this study points out the existence of a lineage of these copepods that has adapted to the freshwater environment of the Amazon. This study also corroborates the genus Therodamas as part of the family Ergasilidae.

Diet composition of the electric eel Electrophorus voltai (Pisces: Gymnotidae) in the Brazilian Amazon region.

The diet composition of the electric eel Electrophorus voltai was studied in specimens collected from the River Jari, state of Amapá, eastern Amazon region, Brazil. Analysis on their stomach contents revealed that fish, especially Megalechis thoracata, were the most frequent prey item, whereas arthropods and plant material were the least frequent intakes. This is the first stomach content analysis on E. voltai, and it corroborates that electric eel species are piscivorous.

Community structure of metazoan parasites in Hemibrycon surinamensis (Characidae) from the Matapi River in the State of Amapá, Brazil.

The aim of this study was to investigate the community of metazoan parasites in Hemibrycon surinamensis from the Matapi River, State of Amapá, Brazil. Among the 31 examined fish, 77.4 % were parasitized by Jainus hexops, Tereancistrum ornatus (Monogenea), Contracaecum sp. (Nematoda), Clinostomus marginatum and Posthodiplostomum sp. (Digenea). However, the dominance was of monogeneans J. hexops and T. ornatus, and among the endoparasites, the predominance was of species at the larval stage. The parasites showed random dispersion. Brillouin diversity index varied from 0 to 0.9, evenness from 0 to 0.7 and species richness from 0 to 3 parasites per host. Low levels of parasitic infection were observed and discussed. The results indicate that this intermediate host occupies a low position in the food web. This is the third eco-epidemiological study for H. surinamensis.